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1
Persson, Kjell. "Integrated geophysical-geochemical methods for archaeological prospecting." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279.
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Hawke, Philip James. "The geophysical signatures and exploration potential of Australia's meteorite impact structures." University of Western Australia. School of Earth and Geographical Sciences, 2004. http://theses.library.uwa.edu.au/adt-WU2005.0053.
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[Truncated abstract. Please see the pdf version of the abstract for the complete text.] Thirty impact structures of confirmed or possible status are currently identified in Australia. Twenty-two of these structures are confirmed by the presence of meteorite fragments or shock metamorphic features that are diagnostic of meteorite impact. The remainder have an impact origin supported by strong secondary evidence. New impact structures are being discovered in Australia at a rate of about one every year, with geophysics a key tool in the identification of candidate structures for further investigation. It is estimated that between two and five times the current number of impact structures are yet to be discovered on the Australian continent. Past compilations of the geophysical signatures of impact structures, particularly of their potential field responses, have been focused on structures formed in mainly crystalline targets. From these studies the expected gravity response is an overall low due to fracturing of the target rocks, with a local gravity high common over the centre of large complex structures, due to the structural uplift of denser material. An overall demagnetisation of the target rocks by the high shock pressures generated by the impact is also expected, although central magnetic highs may also be produced by remanently magnetised melt or the uplift of magnetic rocks from depth. The geophysical signatures of fifteen Australian impact structures are discussed, including individual case studies on nine structures and a detailed study of the Yallalie structure. Only one of the structures discussed here was formed in crystalline rocks, with a further two in mixed sedimentary / crystalline targets. The other structures that were studied were formed in either Phanerozoic basins or mildly-deformed Proterozoic sedimentary rocks. The potential field responses of these structures show a greater variability than was expected, particularly between structures that were formed in different types of target rock. A positive gravity response is found over four structures formed in clastic sedimentary rocks deposited in a Phanerozoic basin. These anomalies are due to the emplacement of denser rock into the central uplift. A decrease in density due to brecciation is not apparent in this target rock type. Furthermore, it is suggested that by collapsing pore space and removing water, the density of wet sedimentary rocks may be locally increased by impact. Circular magnetic anomalies are found outside the central uplift of six impact structures formed in either Phanerozoic or weakly-metamorphosed Proterozoic sedimentary basins.Four possible sources for these anomalies are proposed; remanently magnetised melt or suevite surrounding the central uplift, creation of new magnetic minerals along internal faults within the crater by post-impact hydrothermal fluids, deformation of a flat-lying magnetic layer within the target stratigraphy, and magnetic (maghemite, heavy minerals) minerals concentrated within the post-impact crater fill. It is not possible to definitively identify an impact crater from geophysical evidence alone. Consequently, candidate structures selected from geophysical data, even those as strongly supported as Silverpit, should not be given equal status to structures that have been proven beyond doubt by diagnostic geological criteria. However, it is proposed that structures that possess several pieces of secondary evidence, such as circular shape, interpretation of characteristic geophysical features and crater morphometry, be reclassified as “provisional” impact structures and be given a status that is between “possible” and “probable”. A global compilation of the natural resources known to be associated with impact structures has been undertaken. Where possible, an economic value is calculated for the total definable resource for each structure. The prospectivity of impact structures for petroleum, mineral or water resources is reconfirmed by this work. Almost 20% of all known terrestrial impact structures are associated with some form of resource that is, or has been, exploited. The most numerous, and generally most valuable, of these resources are hydrocarbon accumulations stored in structural traps or brecciated rocks within, or around, the structure. The structural displacements resulting from crater formation can expose from beneath cover, or preserve from erosion, a pre-existing, or progenetic, mineral deposit. While the massive base-metal deposits of the Sudbury Mining Camp are perhaps the most famous of all impact-related economic resources, they require the preservation of the melt sheet formed by a very large (>150 km diameter) impact structure. The Sudbury mineralisation is probably unique on the Earth, but may be a valid target for metal exploration on other planets. Other types of natural resource include surface or ground water, deposits of chemical or organic-rich sedimentary material, hydrothermal ores and industrial diamonds.
3
Sunderland, Andrew. "Characterising and improving a magnetic gradiometer for geophysical exploration." University of Western Australia. School of Physics, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0111.
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[Truncated abstract] Magnetic gradiometers are powerful tools for mineral exploration. The magnetic field contains valuable information about the mineral content of the surveyed terrain. The magnetic gradient specifies the amount of spatial variation in the direction and magnitude of the magnetic field. Surveys that measure the magnetic gradient provide vastly more information about geological targets than the magnetic field alone. This technology could have enormous benefits in terms of new discoveries and lower exploration costs. The magnetic gradient is normally calculated by subtracting the outputs of two total field magnetometers which are separated by a baseline. In 1997, a direct string magnetic gradiometer (DSMG) was developed that directly measures magnetic gradients using only a single string as its sensing element. This thesis describes research conducted to improve the sensitivity and performance of the DSMG. The main advantage of the DSMG is that only gradients can induce second harmonic vibrations in the string. Thus, the DSMG is insensitive to uniform magnetic fields that we are not interested in, such as the global magnetic field of the Earth. By using inductive electronics to measure second harmonic string vibrations, we can select to measure the magnetic gradient of nearby targets. Recent work has shown that a magnetic gradiometer with a noise floor of 0.01 nT/m/ v Hz should be sufficiently sensitive for geophysical exploration. In order to reach this goal, this thesis presents an investigation of all noise sources affecting the DSMG. ... Gas damping is negligible in high vacuum and no vibration isolation is required. This means that longer strings with low resonant frequencies can be used. Using theoretical modelling, I show that a space borne DSMG should be able to match the white noise level of SQuID based magnetic gradiometers and have a lower 1/f noise corner. Deployment in space could be the most viable application of the DSMG because of the ease of operation and enhancement of sensitivity. If the thermal noise level is reduced then other sources of noise will start to become more important. When rotated in the Earth's magnetic field, the DSMG detects a pseudo magnetic gradient despite the field being almost uniform. A possible cause is magnetically susceptible parts which are magnetically aligning with the Earth's field. I have conducted a thorough investigation of magnetic susceptible parts in the DSMG and reported the results in this thesis. In the DSMG, a pair of inductive pickup coils are used to measure the string's displacement with a root mean square accuracy of 1011 m/ v Hz. This is adequate at present but the inductive electronics may not be sensitive enough after other improvements in the DSMG are implemented. Here, I present a new capacitive displacement readout with a high sensitivity of 1013 m/ v Hz. The thesis also presents some magnetic gradient measurements in the lab and the results of a ground survey in the field. These trial measurements are used to characterise the DSMG and demonstrate its effectiveness for airborne surveying.
4
GRUSZKA, THOMAS PETER. "INDUCED POLARIZATION AND ITS INTERACTION WITH ELECTROMAGNETIC COUPLING IN LOW FREQUENCY GEOPHYSICAL EXPLORATION." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184239.
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Starting from the dynamic equations of electromagnetics we derive mutual impedance formulas that include the effects of induced polarization (IP) and electromagnetic (EM) coupling. The mutual impedance formulas are given for four geometries: a fullspace, a cylinder in a fullspace, a halfspace, and a layer over a halfspace. IP effects are characterized by a Cole-Cole model, the properties of which are fully investigated. From the general mutual impedance formulas specific limiting forms are defined to characterize the IP and EM effects. Using these limiting forms a framework is developed to justify the addition or multiplication of the two effects. The additive and multiplicative models are compared in the cylinder and layer geometries with the conclusion that the additive model proves to be more accurate over a wider range of frequencies than the multiplicative model. The nature of the IP and EM effects is illustrated in all four geometries showing the effects of relevant parameters. In all cases it is shown that the real part of the mutual impedance contains important IP information that is less influenced by EM effects. Finally the effects of boundaries are illustrated by the cylinder and layer geometries and a theory is developed to incorporate EM effects and IP effects from multiple regions which utilizes frequency dependent real dilution factors. We also include a brief review of some EM "removal" schemes and dilution theory approximations.
5
Aguirre, Gerardo 1960. "AN APPRAISAL OF THE ELECTRICALLY THIN CONDUCTIVE SHEET MODEL IN GEOPHYSICAL PROBING." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/275495.
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Alaia, Raffaele <1975>. "3D probability tomography: theoretical developments and applications to high-resolution geophysical prospecting." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/2103/.
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The theory of the 3D multipole probability tomography method (3D GPT) to image source poles, dipoles, quadrupoles and octopoles, of a geophysical vector or scalar field dataset is developed. A geophysical dataset is assumed to be the response of an aggregation of poles, dipoles, quadrupoles and octopoles. These physical sources are used to reconstruct without a priori assumptions the most probable position and shape of the true geophysical buried sources, by determining the location of their centres and critical points of their boundaries, as corners, wedges and vertices. This theory, then, is adapted to the geoelectrical, gravity and self potential methods. A few synthetic examples using simple geometries and three field examples are discussed in order to demonstrate the notably enhanced resolution power of the new approach. At first, the application to a field example related to a dipole–dipole geoelectrical survey carried out in the archaeological park of Pompei is presented. The survey was
finalised to recognize remains of the ancient Roman urban network including roads, squares and buildings, which were buried under the thick pyroclastic cover fallen during
the 79 AD Vesuvius eruption. The revealed anomaly structures are ascribed to wellpreserved remnants of some aligned walls of Roman edifices, buried and partially
destroyed by the 79 AD Vesuvius pyroclastic fall. Then, a field example related to a gravity survey carried out in the volcanic area of Mount Etna (Sicily, Italy) is presented, aimed at imaging as accurately as possible the
differential mass density structure within the first few km of depth inside the volcanic apparatus. An assemblage of vertical prismatic blocks appears to be the most probable
gravity model of the Etna apparatus within the first 5 km of depth below sea level. Finally, an experimental SP dataset collected in the Mt. Somma-Vesuvius volcanic
district (Naples, Italy) is elaborated in order to define location and shape of the sources of two SP anomalies of opposite sign detected in the northwestern sector of the
surveyed area. The modelled sources are interpreted as the polarization state induced by an intense hydrothermal convective flow mechanism within the volcanic apparatus,
from the free surface down to about 3 km of depth b.s.l..
7
Tsang, Wing-shing, and 曾永成. "Borehole geophysics limitations of natural gamma and gamma-gamma density logging methods." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B42577238.
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Theodoridis, John Apostolis 1972. "Borehole electromagnetic prospecting for weak conductors." Monash University, School of Geosciences, 2004. http://arrow.monash.edu.au/hdl/1959.1/5225.
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Schmidt, Armin R. "Visualisation of multi-source archaeological geophysics data." Rome: Fondazione Ing. Carlo M. Lerici, 2002. http://hdl.handle.net/10454/3281.
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Tost, Brian Christopher. "Low porosity mistaken for natural gas hydrate at Alaminos Canyon, Gulf of Mexico: Implications for gas hydrate exploration in marine sediment reservoirs." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366475207.
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De, Wit Michiel Cornelis Jan. "A geophysical investigation and geological interpretation of part of the diamondiferous gravels on the farm Grasfontein (356 JP), west of Bakerville." Pretoria : [s.n.], 2000. http://upetd.up.ac.za/thesis/available/etd-09112006-103628.
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Tsang, Wing-shing. "Borehole geophysics limitations of natural gamma and gamma-gamma density logging methods." Click to view the E-thesis via HKUTO, 2003. http://sunzi.lib.hku.hk/hkuto/record/B42577238.
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Biedler, Murray W. "Delineation of buried stream channels using geophysical techniques." Thesis, Rhodes University, 1994. http://hdl.handle.net/10962/d1005498.
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This study sets out to evaluate the use of geophysical methods for delineating buried stream channels, which can act as zones of preferential flow within a less hydraulically conductive aquifer. This information is important for gaining an understanding of flow dynamics of alluvial systems. The most reliable method of delineating the dimensions of aquifers is by drilling, which is an expensive proposition and is best preceded by a preliminary geophysical study to help define target zones for a drilling program. The study area is located adjacent to the Coerney River in the Sundays River Valley. Geologically it consists of approximately 5 metres of alluvial fines, covering 3 metres of coarse cobbles and boulders, all underlain by alternating siltstone and sandstone beds of indeterminate thickness. Throughout the area the water is very shallow at approximately 2 metres depth and the groundwater tends to be very saline. An air photo study revealed an old oxbow channel that had been covered over by subsequent agricultural land use. The geophysical methods available for the study were portable seismic refraction, electrical resistivity and electromagnetics. Preliminary field tests clearly showed that seismics did not produce valid results. The methods of electrical resistivity and electromagnetics produced good data and were subjected to further assessment. A grid was surveyed over the study area and both geophysical methods were applied at regularly spaced stations. Soil samples were taken over the same survey grid and analyzed for electrical conductivity in a soils laboratory. The results were compared to the geophysical data in an attempt to quantify the relationship between geophysical response and soil salinity. The data from the electromagnetic survey showed areas of low electrical conductivity which was a possible indication of zones of preferential groundwater flow. A transect of boreholes was drilled over selected electrical conductivity lows and successfully intersected the buried stream channel. A comparison of the borehole logs with the layered earth models from the Vertical Electrical Soundings indicated that the electrical resistivity method was not responding to the features of the buried stream channel and the cobblestone layer. This proved the electromagnetic method to be more valuable for this particular study
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Titus, Nortin P. "Response of NaI(T1) detectors in geophysical applications." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50441.
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Thesis (MSc)--Stellenbosch University, 2005.Some digitised pages may appear illegible due to the condition of the original hard copy.
ENGLISH ABSTRACT: Airborne gamma-ray spectrometry is used for exploration and environmental monitoring over large areas. Such datasets of 7-ray are acquired using large 16l NaI(T1) detector crystals mounted in an aircraft. The response of these detectors to naturally occurring radioactive isotopes is a function of detector volume, efficiency and resolution. This response is modelled using the Monte Carlo method. A photon-electron transport computer code, NIPET, is written to calculate the intrinsic efficiency and photofraction of these large prismatic crystals. The intrinsic efficiency indicates the number of incident photons that interact in some way with the detector resulting in a deposition of energy in the crystal. The photofraction, on the other hand, indicates how many of these photons that impinge on the detector are actually recorded with their full initial energy. This study presents explicity calculated photofraction values for 16l NaI(Tl) crystals. Comparison of these new values, calculated with this computer program, with that of published values for small 3" x 3" crystals shows good agreement. However, for large crystals, the calculated values differ from those in the literature by almost 15%. The study also finds that for the gamma-ray energy range between 0.2 - 3.0 MeV, these detectors have an intrinsic efficiency above 90%, whereas the photofraction values range from 80% for low energy photons to above 40% for high energy photons in the case of large crystals.
AFRIKAANSE OPSOMMING: Lug gamma-straal spektroskopie is nuttig vir eksplorasie en omgewings ondersoeke oor groot areas. Metings word tipies gedoen met 16l NaI(T1) detektors wat monteer is in ’n vliegtuig. Die respons van hierdie detektors ten opsigte van natuurlike radioaktiewe isotope is ’n funksie van detektorvolume, doeltreffendheid en oplosvermoë. Hierdie respons word gemodeleer deur gebruik te maak van ’n Monte Carlo tegniek. ’n Rekenaarprogram, NIPET, is geskryf om die intrinsieke doeltreffendheid en fotofraksie vir hierdie groot prismatiese kristalle te bereken. Die intrinsieke doeltreffendheid dui die breukdeel van die invallende fotone aan wat ’n interaksie ondergaan binne die detektor kristal en sodoende energie deponeer. Die fotofraksie, daarenteen, dui die breukdeel invallende fotone aan wat absorbeer word deur die kristal met hul voile invallende energie. In hierdie tesis word eksplisiete fotofraksiewaardes vir 16l NaI(T1) kristale bereken. Goeie ooreenstemming word gevind tussen fotofraksie waardes bereken met hierdie program en die waardes gepubliseer in die literatuur vir klein 3" x 3" kristalle. Vir groter kristalle is daar egter swakker ooreenstemming. Berekende fotofraksie waardes verskil met 15% van die waardes in die literatuur. Daar word ook bevind dat vir gamma-energie tussen 0.2 - 3.0 MeV, die intrinsieke doeltreffendheid vir hierdie tipe detektors bo 90% is en dat fotofraksiewaardes wissel tussen 80% vir lae energie tot bo 40% vir hoë foton energie.
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Stevenson, Frederick. "Response of the Black Mountain, South Africa, sulfide deposit to various geophysical techniques and implications for exploration of similar deposits." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/558021.
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Ahmad, Khalid. "Investigating the source of thermal anomalies in the northern United Arab Emirates (UAE) desert using geophysical methods." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2010. http://scholarsmine.mst.edu/thesis/pdf/Ahmad_09007dcc807ad423.pdf.
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Thesis (Ph. D.)--Missouri University of Science and Technology, 2010.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed June 30, 2010) Includes bibliographical references (p. 129-135).
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Rosa, Henrique. "Estudo de caracterização de eletrofacies por meio de perfis geofisicos de poços e de amostras de testemunhos utilizando estatistica multivariada." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265408.
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Orientadores: Saul Barisnik Suslick, Alexandre Campane VidalTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica e Instituto de Geociencias
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Resumo: Este estudo se foca na elaboração de um método de caracterização de eletrofácies, o qual utiliza dados de perfis geofísicos de poços referentes às classes litológicas identificadas nos testemunhos desses poços, por meio do emprego de análises qualitativas associadas a tratamentos estatísticos multivariados. A princípio, o estudo visa estabelecer uma rotina de análises qualitativas para os dados litológicos extraídos dos testemunhos e associados aos perfis, por meio de ferramentas estatísticas básicas, com o objetivo de identificar agrupamentos de classes litológicas e caracterizar as eletrofácies presentes no intervalo testemunhado. Numa segunda etapa, aplica-se a técnica estatística multivariada da Análise de Agrupamentos em dois passos, a qual gera agrupamentos (eletrofácies) por meio da associação dos dados dos perfis com as classes litológicas descritas nos testemunhos. Numa terceira etapa, esses agrupamentos são avaliados quantitativamente por intermédio de ferramentas estatísticas, as quais incluem a Análise de Variância Simples (one way Anova), o Teste de Médias e a Análise Discriminante. Como exemplo de aplicação, utiliza-se um conjunto de dados que inclui perfis e descrições de testemunhos de três poços verticais do Campo Escola de Namorado, localizado na Bacia de Campos, no Estado do Rio de Janeiro. Os resultados obtidos mostram um bom desempenho da Análise de Agrupamentos em dois passos para a caracterização de eletrofácies, e permitem que se obtenham informações acerca da qualidade da amostragem, no que se refere aos ajustes das mesmas com as profundidades de perfis, além de proporcionar agilidade ao processo de investigação exploratória de dados de perfis em relação às classes litológicas a estes associadas.
Abstract: This study is focused on the elaboration of a method for electrofacies characterization which uses well log data related to the lithological classes identified in the core samples of the wells, based upon qualitative approach and multivariate statistics analysis. The first step of this method involves the establishment of a qualitative approach routine which includes the analysis of a package of well log data, which are extracted from the cored intervals, using basic statistics tools (histograms and cross plots) and aiming to delineate and characterize electrofacies. The second step involves the utilization of a classical multivariate technique called Two Steps Cluster Analysis, which generates clusters (electrofacies) based upon the association between well log data and the lithological classes identified from the core samples. The details of the Cluster Analysis technique are showed during the development of this study. During the third step of proposed method, all the clusters generated in the previous steps are quantitatively evaluated by ordinary statistical tools, which include one-way Anova, Test of Means and Discriminant Analysis. As an example of application of this method it is used a complete package of data which includes well logs and macroscope reports of three sets of core samples, extracted from three vertical wells, located in the producing Oil Field of Namorado, in the Campos Basin, Rio de Janeiro State, Brazil. The results of the statistical tests show a good performance for the Two Steps Cluster Analysis tool in characterizing electrofacies. Furthermore, all the statistical tests applied in this study allow the researcher to obtain information about the quality of the sampling process and the accuracy related to the correlation between the sampling and the logging depth, speeding-up the process of the exploratory investigation by using well log data and associated to the lithological classes present in the cored intervals of the oil wells.
Doutorado
Reservatórios e Gestão
Doutor em Ciências e Engenharia de Petróleo
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Ledwaba, Lebogang John. "An overview of energy minerals in the Springbok Flatsbasin, South Africa : implications for geochemical and geophysical exploration." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1019880.
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This study is informed by the rising demand for power needs in South Africa and aims at understanding the geophysical and geochemical characteristics of the energy minerals in the Springbok Flats Basin and relating them to the prevailing geological and structural setting for improved exploration targeting. The Springbok Flats Basin is part of the Karoo sediments and host to uranium, coal and coal bed methane (CBM) resources. The lithology sections in the basin indicate presence of basaltic lavas at the top, underlain by mudrocks, siltstones, sandstones, conglomerates and diamictite, with interbedded coal beds occasionally. The coals are uraniferous and shale bounded and of lower Beaufort age at 250 Ma. The regional radiometric data identifies the regional extent of the Springbok Flats Basin as a basin with low total count values. This information is useful in exploration as it gives an idea of the limits of the area where to focus application for prospecting licenses. The reduced to pole of the total magnetic field, residuals and first vertical derivative maps clearly show the high magnetic susceptibility nature of the surrounding Bushveld rocks as compared to the low Karoo sediment susceptibility within the basin. There are distinct ring shaped picks within the basin possibly due to known Karoo dolerite sills in particular to the central south western part of the grid. The regional geochemical mapping program is a cost-effective way of providing an overview of the relative abundance levels, regional trends and anomalous patterns in the underlying lithological units. Background values of elements in soils over different lithological units and the identification of anomalous values relative to these elements can easily be identified. The geochemical results show an excellent correlation between soil chemistry and underlying geological formations. A few distinct gravity highs are clearly shown within the basin. Assuming the effect of the Letaba basalt to the gravity readings is uniform across the basin; these distinct anomalies could be due to Karoo dolerite sills as they coincide with areas of distinct high magnetic signature. A conceptual model was generated assuming that the Karoo sediments’ layering is uniform across the gravity profile but changes in the residual are due to an increased thickness of the sill supported by the gentle changes on the surface topography. Satellite imagery has got its challenges especially in areas of vegetation but it does provide a very useful tool in exploration. A number of spectral analysis techniques and band rations can be used to differentiate the areas underlain by the Letaba basalts, the Karoo sandstones/shale and Bushveld granites for mapping purposes. The priority focus will be on the shallower Karoo sediments because of the potential for cheaper mining. Exploration targeting needs to be guided by observed geochemical and geophysical characteristics in order to prioritize areas taking into account the presence of Karoo intrusives such as the dolerite sills that tend to devolatize the coal hence affecting the quality/rank. Structures and gravity signatures are very important in delineating areas with thick sediments that have a potential for CBM. The same understanding in targeting goes a long way in planning drill holes, resource modelling and pre-feasibility stages for mine planning. A high resolution airborne geophysical survey is recommended over the basin to better resolve structures. Geophysical borehole logging is recommended to be part of the exploration drilling programs in the Springbok Flats Basin in order to define the in-situ geophysical characteristics. Geophysical logging is useful in particular for the uranium reserves that cannot be delineated from the surface due to deep intersection.
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Vinhas, Maria Cecilia Sodero 1968. "Aplicação de métodos geofísicos aplicados em pontos selecionados do Estuário do Rio Itanhaém." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/286645.
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Orientador: Sueli Yoshinaga Pereira, Rodrigo de Souza PortugalTese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências
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Resumo: Essa pesquisa objetivou a aplicação e o entendimento da relação de três métodos geofísicos: eletrorresistividade, sísmica de refração e sismoelétrica; em pontos selecionados no Estuário do Rio Itanhaém e se eles podem ser validados pelas informações geológicas e hidrogeológicas da região. Os levantamentos foram realizados em duas etapas. A primeira etapa foi o de reconhecimento de campo, realizado no período de 21 a 26 de setembro/2009 que é considerado um período menos chuvoso. Os pontos escolhidos foram denominados de Ponto Praia, Ponto Chácara, Ponto Lixão e Ponto Country Club. A segunda etapa consistiu na coleta de dados propriamente dita nos pontos Chácara, Lixão e Country Club; o ponto Praia foi excluído por estar próximo às grandes torres de transmissão de energia, fazendo com que houvesse interferência nos dados. No ponto Lixão foi verificada a existência de gás metano, na superfície, através das bolhas de ar nas poças de água, no Ponto Country se localizava próximo a dois brejos e um pequeno córrego, e por fim o Ponto Chácara se localizava próximo ao Rio Branco, onde foi possível perceber a influência do aquífero livre na coleta dos dados. O período da segunda etapa dos levantamentos de dados ocorreu entre setembro de 2010 e agosto de 2011. Os levantamentos resultaram em um perfil vertical central, dos pontos selecionados, onde foram encontrados os seguintes materiais: areia, sedimentos arenosos, areia argilosa, argila seca, dois tipos de aquífero (de água doce e de água salobra), além de solos saturados e não saturados, e lixo. Em alguns levantamentos atingiram a rocha sã. Os levantamentos eletrorresistivos foram os que tiveram melhor resultado, os levantamentos de sísmica obtiveram uma camada apenas em quase todos os levantamentos, sendo que em um deles, o segundo campo do Ponto Country Club, se obteve mais de uma camada de material. Os levantamentos sismoelétricos não tiveram seus tratamentos finalizados, pois se percebeu que era necessária a utilização pré-amplificador; sua ausência no levantamento no campo, aliado a presença de linhas elétricas nos locais do levantamento, prejudicou nos resultados dos dados coletados, fato indicado pela presença das linhas harmônicas nos dados, e consequentemente não ter finalizado o algoritmo de tratamento desses dados
Abstract: This research intended the application and understanding about connexion among three geophysical methods: eletrical resistivity, refraction seismic and eletrical seismic; in selected places along Itanhaem River Estuary and if they can be accepted by geological and hydrogeological information of the region. The survey was accomplished in two phases. The first one was to recognize field of study, which was realized from 21st to 26th of September 2009, that is considered a less rainy season. The chosen sites were: Praia Point, Chácara Point, Lixão Point and Country Club Point. The second phase was the data collection, at these chosen sites, Chácara, Lixão and Country Club; The Praia Point was excluded because it was very near of large power transmission towers and it was causing interference in the collected information, at the Lixão Point was verified existence of methane, on the surface, through the air bubbles in puddles, in the case of Country Club Point was located near two swamps and a small stream, the Ranch Point was located near the river called Branco, and it was possible to realized the free influence of this aquifer in data collection. The second phase period of data collection, occurred between September 2010 and August 2011. The surveys resulted in a central vertical shape of the selected sites, where the following materials were found sand, sandy sediments, clayey sand, dry clay, two types of groundwater (freshwater and brackish water), and saturated and unsaturated soils and waste. In some surveys reached the bedrock. The electrical resistivity surveys were those who obtained better results, the seismic surveys obtained only a layer in almost all surveys, and in one of them, the second Country Club Point, got more than one layer of material. The electrical seismic surveys were not their treatments finalized, because it was realized the need to use a preamplifier; its absence in the field survey, combined with the presence of power lines in the survey sites, affected the collected data results, condition indicated by the presence of harmonic lines in the data, and consequently have not finalized these data processing algorithm
Doutorado
Geologia e Recursos Naturais
Doutora em Ciências
20
Mori, Roberta Tomi 1988. "Integração de dados sísmicos 3D e de perfis geofísicos de poços para a predição da porosidade de um reservatório carbonático da Bacia de Campos." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287783.
Full textAbstract:
Orientador: Emilson Pereira LeiteDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências
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Resumo: Uma boa caracterização geológica dos reservatórios é de grande importância para a diminuição dos riscos da perfuração de um poço seco, assim como os custos de exploração e desenvolvimento de tal reservatório. No presente trabalho, buscou-se predizer os valores de porosidade de um reservatório através da integração de dados sísmicos 3D com perfis geofísicos de poços através de dois métodos: Regressão Linear Multiatributo e Redes Neurais Artificiais. O reservatório em questão é de constituição carbonática de origem Albiana, do final do Cretáceo Inferior. Na primeira etapa, foram traçados horizontes baseando-se em eventos sísmicos contínuos nas seções sísmicas, chamados superfícies cronoestratigráficas, no intervalo de profundidade que abrange o reservatório. Na segunda etapa, foram obtidos predições dos valores de porosidade do reservatório, assim como os respectivos modelos 3D, através dos dois métodos acima citados. Com a RLM, foram obtidos valores altos, baixos e intermediários de porosidade, variando desde 5% até 40%. Já com a RNA, tais valores variaram de 5% a 30%. Em ambos os métodos, os valores de porosidade apresentaram um crescimento da porção sudoeste em direção à porção nordeste, apresentando baixos valores nas profundidades referentes aos horizontes traçados. Picos com os valores máximos de porosidade foram observados em pontos dispersos por todo o volume 3D. Comparando-se os resultados obtidos pelos dois métodos, ficou evidente a maior eficácia da RNA, a qual apresentou correlação de 0,90 entre os valores reais e os valores preditos e erro de 2,86%, enquanto que os resultados obtidos através da RLM apresentou correlação de 0,55 e erro de 5,45%. Além disso, foi feita uma comparação com os aspectos geológicos do reservatório, na qual concluiu-se que as baixas porosidades da porção sudoeste se deve à presença de microporosidade e as altas porosidades da porção nordeste, à macroporosidade original das rochas. Concluiu-se também que as baixas porosidades encontradas nas regiões dos horizontes sísmicos estão relacionadas às diferentes texturas de rochas, já que as rochas presentes nessas regiões possuem maiores quantidades de matriz carbonática (packstones e wackestones) quando comparadas com as rochas das regiões entre os horizontes (grainstones)
Abstract: A good geological reservoirs characterization is very important for reducing the risk of drilling a dry hole as well as the costs for reservoir exploration and development. In this study, it was attempted to predict the porosity values of a reservoir through the integrations of 3D seismic data with geophysical well logs using two different methods: Multiattribute Linear Regression and Artificial Neural Networks. The studied reservoir has a carbonate composite, with the age of Albian, in late Early Cretaceous. On the first stage of the study, horizons have been traced based on continuous seismic events on seismic sections, in depths that cover the reservoir. On the second stage, it was obtained some predictions of reservoir porosity values, as well as their 3D models by the two methods that was already mentioned. High, low and intermediate porosity values have been obtained by the MLR, ranging from 5% to 40%. With the ANN, these values ranged from 5% to 30%. In both methods, the porosity values grew from south-west portion toward the northeast portion, with low values on the depths related to the horizons traced. We can observe maximum value peaks of porosity at points scattered throughout the 3D volume. A comparison of the results obtained by the two methods evidence the greater efficiency of the ANN, with a correlation of 0,90, between actual porosity and predicted values, and 2.86% of error, while the results obtained by the MLR showed a correlation of 0,55 and an error of 5.45%. Furthermore, we have made a comparison between the results obtained and the reservoir geological features, which allows us to conclude that the low porosity in the south-west portion is because of microporosity, while the high porosity in the northeast is because of the original macroporosity of the rocks. We also conclude that low porosity found on horizon surfaces are related to different rock textures, once the rocks on these horizon regions have more carbonatic matrix in their constitution (packstones and wackestones) than the rocks in the other regions between the horizons (grainstones)
Mestrado
Geologia e Recursos Naturais
Mestra em Geociências
21
Bezzeghoud, Maissa. "Aplicação de técnicas geofísicas não invasivas à prospeção de sítios pré-históricos do Alentejo: 3 casos de estudo." Master's thesis, Universidade de Évora, 2020. http://hdl.handle.net/10174/28105.
Full textAbstract:
Cada vez mais os arqueólogos se apercebem que existe uma necessidade de
estudar os sítios arqueológicos recorrendo a métodos não destrutivos e não
intrusivos, dando importância às técnicas de prospeção geofísicas, em particular ao
Georradar. Este é, na atualidade, uma das metodologias geofísicas mais utilizadas
a nível mundial para o estudo arqueológico. Em Portugal a utilização destas
metodologias para fins arqueológicos (e por arqueólogos) está ainda a dar os
primeiros passos.
Este trabalho pretende mostrar as potencialidades destas técnicas e incentivar os
arqueólogos nacionais a abrirem as suas portas a este tipo de recursos, não apenas
na qualidade de clientes, mas sobretudo como autores.
O presente trabalho descreve a aplicação do Georradar em três estações
arqueológicas neolíticas e calcolíticas do Alentejo Central: Menir do Patalou (Nisa);
Menir do Monte da Caeira (Vimieiro); Povoado de Santa Cruz 13 (Brotas).
Mais especificamente este estudo tem como objetivos: a descoberta da localização
dos alvéolos de encaixe de dois menires; a descoberta das áreas de maior
abundância de estruturas pertencentes a um povoado calcolítico, com o propósito
de planificar futuras escavações; a definição de uma metodologia de aquisição de
dados geofísicos mais adequados a sítios arqueológicos neolíticos e calcolíticos; e
a definição de uma metodologia de interpretação dos dados adquiridos em campo; Abstract:
Application of non-invasive geophysical techniques to the
exploration of prehistoric sites in Alentejo: 3 cases studies
More and more archaeologists are realizing that there is a need to study
archaeological sites using non-destructive and non-intrusive methods, giving
importance to geophysical prospecting techniques, in particular GPR. This is
currently one of the most widely used geophysical methodologies in the world for
archaeological studies. In Portugal the use of these methodologies for
archaeological purposes and by archaeologists is still taking its first steps.
This thesis intends to show the potential of these techniques and to encourage
national archaeologists to open their doors to this type of resources, not only as
clients but mainly as authors.
This paper describes the application of Georadar in the following three Neolithic and
Chalcolithic archaeological stations in Central Alentejo: Menir do Patalou (Nisa);
Menir do Monte da Caeira (Vimieiro); Povoado de Santa Cruz 13 (Brotas).
More specifically this study has as the following objectives: the discovery of the
location of the two menhirs alveoli; the discovery of the most abundant areas of
structures belonging to a chalcolithic settlement, with the purpose of planning future
excavations; the definition of a methodology of geophysical data acquisition more
adequate to Neolithic and Chalcolithic archaeological sites; and the definition of a
methodology for the interpretation of the data acquired in the field.
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Agnoletto, Ethiane 1988. "Caracterização litológica e identificação de alvos exploratórios na região de Flor da Serra, Província Aurífera Alta Floresta (MT), utilizando dados magnéticos e geoelétricos." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287296.
Full textAbstract:
Orientadores: Emilson Pereira Leite, Antônio João Paes de BarrosDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências
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Resumo: A região garimpeira de Flor da Serra situa-se na porção Leste da Província Aurífera Alta Floresta, Norte do Mato Grosso, inserida no contexto geológico da porção Centro-Sul do Cráton Amazônico, constituída por suítes plutono-vulcânicas de idade paleoproterozóica e coberturas sedimentares associadas. Várias ocorrências de ouro estão dispostas em grandes zonas de descontinuidade crustal que delimitam terrenos geocronológicos e geológicos. O expressivo adensamento de corpos filoneanos e o histórico de produção destaca essa região de expressivo potencial exploratório. Neste contexto, o trabalho teve por objetivo a identificação de novos alvos exploratórios por meio da análise de dados geofísicos, descrição de testemunhos de sondagem e mapeamento de cavas garimpeiras. A integração desses dados contribuiu em especial à evolução do conhecimento geológico da região Flor da Serra, e também de maneira geral para o setor leste da PAAF. A área de estudo está inserida na Suíte Intrusiva Flor da Serra, que é constituída eminentemente por gabros, dioritos a monzogabros, entretanto com o mapeamento de cavas garimpeiras e descrição de furos de sondagem, verificou-se a existência de quatro unidades geológicas principais: (i) Granitóides do Embasamento de composição tonalítica a granodiorítica com associação de magnetita + granada, intrudidos por rochas da (ii) Unidade Granodiorítica a Tonalítica de mesma composição. Essa unidade é truncada por (iii) Diques Máficos a Intermediários e localmente há presença de (iv) Rochas Cataclásticas a Miloníticas. Os litotipos foram variavelmente afetados por sete tipos de alteração hidrotermal (ordem temporal): (i) alteração potássica intensa, (ii) silicificação pervasiva, (iii) carbonatação, (iv) alteração com muscovita, (v) propilitização mais pontual, (vi) alteração Quartzo-Sericita-Pirita (QSP) com substituição total da rocha e, (vii) vênulas de calcita tardias. Foram realizados levantamentos geofísicos utilizando métodos geoelétricos (Polarização Induzida/Resistividade - IP/RES) e magnetometria em escala de depósito. Valores anômalos de cargabilidade e resistividade obtidos após aplicação de um algoritmo de inversão com vínculo de suavidade definiram zonas de intensa silicificação e de QSP. Essas zonas estão diretamente relacionadas a um minério do tipo disseminado, além de terem possibilitado a delimitação da interface saprólito-rocha sã (manto intempérico profundo de até 50 m). Para facilitar a interpretação geológica, foram gerados mapas do campo magnético anômalo reduzido ao equador magnético e da amplitude do sinal analítico. Esse último possibilitou a definição de um stock granítico intrusivo no embasamento heterogêneo. Para eliminar ruídos remanescentes nos mapas de anomalias magnéticas, foram aplicados os filtros cosseno direcional e continuação para cima, com geração de mapa que confirmou o padrão estrutural vigente no Sistema Flor da Serra. Essa estruturação está associada à diferentes níveis crustais, balizam os principais corpos filoneano da região e também estão associadas a alteração QSP. A integração dos principais lineamentos estruturais; bolsões de alta cargabilidade e resistividade; mapeamento detalhado de cavas desativadas e zona de borda da intrusão possibilitou a definição de pontos de interesse prospectivo metalogenético
Abstract: The gold mining area of Flor da Serra is located in the East portion of the Alta Floresta Gold Province (PAAF), North of the state of Mato Grosso, inserted into the geological context of the South-Central portion of the Amazon Craton, which comprises plutono-Paleoproterozoic volcanic suites and associated sedimentary cover. Several gold occurrences are arranged in large zones of crustal discontinuities demarcating land geochronological and geological. The significant densification of filoneano bodies and production history highlights the significant exploration potential of the area. In this context, this study aimed to identify new exploration targets through analysis of geophysical data, description of drill core samples and prospecting pits. The integrated analysis of these data contributed in particular to the development of the geological knowledge of Flor da Serra, and also generally for the eastern sector of the PAAF. The study area covers the Intrusive Suite Flor da Serra which consists essentially of gabbros, diorites to monzogabros, however mapping of prospecting pits and description of borehole samples confirmed the existence of at least four main geological units: (i) granitoids in Basement of tonalitic to granodioritic composition association with magnetite + garnet rocks intruded by (ii) granodioritic to tonalitic of the same composition. This unit is truncated by (iii) the Intermediate Mafic Dykes and locally by (iv) cataclastic to mylonitic rocks. Rocks of the Flor da Serra have been affected by the following hydrothermal alteration types (temporal sequence): (i) intense potassic alteration, (ii) pervasive silicification, (iii) carbonation, (iv) alteration with muscovite, (v) punctual propylitization, (vi) Quartz-Sericite-Pyrite (QSP) alteration with total replacement of the rock and (vii) late calcite veinlets. The geophysical survey consisted of the application of geoelectrical methods (Induced Polarization/Resistivity - IP/RES) and magnetometry at deposit scale. Anomalous values of chargeability and resistivity allowed defining zones of intense silicification and QSP closely related to a disseminated ore type, beyond the boundaries of the saprolite-bedrock interface (deep weathering mantle of up to 50 m). To facilitate geological interpretation, maps of the magnetic anomalous field reduced to the magnetic equador and the analytic signal amplitude were generated. The latter allowed the identification of granitic intrusive stock in heterogeneous basement. To improve the final product and eliminate remaining noise cosine directional filter and upward continuation to 100 m were applied, providing a map which confirmed the structural pattern prevailing in the Flor da Serra system. This structural system is associated with different crustal levels, controls the main filoneano bodies of the region and is attached to QSP alteration. The integration of the main structural lineaments; zones of high chargeability/resistivity; detailed mapping of deactivated pits; and boundary zone of the intrusion led to the definition of prospective metallogenic targets
Mestrado
Geologia e Recursos Naturais
Mestra em Geociências
23
Armstrong, Kayt. "Archaeological geophysical prospection in peatland environments." Thesis, Bournemouth University, 2010. http://eprints.bournemouth.ac.uk/16238/.
Full textAbstract:
Waterlogged sites in peat often preserve organic material, both in the form of artefacts and pa1aeoenvironmenta1 evidence as a result of the prevailing anaerobic environment. After three decades of excavation and large scale study projects in the UK, the subdiscipline of wetland archaeology is rethinking theoretical approaches to these environments. Wet1and sites are generally discovered while they are being damaged or destroyed by human activity. The survival in situ of these important sites is also threatened by drainage, agriculture, erosion and climate change as the deposits cease to be anaerobic. Sites are lost without ever being discovered as the nature of the substrate changes. A prospection tool is badly needed to address these wet1and areas as conventional prospection methods such as aerial photography, field walking and remote sensing are not able to detect sites under the protective over burden. This thesis presents research undertaken between 2007 and 2010 at Bournemouth University. It aimed to examine the potential for conventional geophysical survey methods (resistivity, gradiometry, ground penetrating radar and frequency domain electromagnetic) as site prospection and landscape investigation tools in peatland environments. It examines previous attempts to prospect peatland sites, both in archaeology and environmental science. These attempts show that under the right circumstances, archaeological and landscape features could be detected by these methods, but that the reasons why techniques often fail are not well understood. Eight case-study sites were surveyed using a combination of conventional techniques. At three of the sites ground truthing work in the form of excavations, bulk sampling and coring was undertaken to validate the survey interpretations. This was followed up by laboratory analysis ofthe physical and chemical properties ofthe peat and mineral soils encountered. The key conclusion of the case study work undertaken is that conventional geophysical prospection tools are capable of detecting archaeological features in peat1and environments, but that the nature of the deposits encountered creates challenges in interpretation. Too few previous surveys have been adequately ground truthed to allow inferences and cross comparisons. The upland case studies demonstrated that geophysical survey on shallow types ofupland peat using conventional techniques yields useful information about prehistoric landscapes. The situation in the lowlands is more complex. In shallow peat without minerogenic layers, timber detection is possible. There are indications that in saturated peat the chemistry ofthe peat and pore water causes responses in the geophysical surveys, which could be developed as a proxy means to detect or monitor archaeological remains. On sites where the sediments are more complex or affected by desiccation, timbers were not detected with the methods attempted. However, important landscape features were and there are indications that geophysical surveys could be used as part of management and conservation strategies. This thesis concludes that geophysical prospection contributes to theoretically informed wet1and archaeology as a tool for site detection, landscape interpretation, and conservation. Future research should aim to further our understanding of the relationship between geophysical response and peat1and geochemistry, alongside a more extensive programme of surveys and ground-truthing work to improve survey methodologies and archaeological interpretations.
24
Madi, Kakaba. "Neotectonics and its applications for the exploration of groundwater in the fractured Karoo aquifers in the Eastern Cape,South Africa." Thesis, University of Fort Hare, 2010. http://hdl.handle.net/10353/362.
Full textAbstract:
This study is part of an NRF sponsored research project entitled “Neotectonics and its applications for the exploration of groundwater in the fractured Karoo aquifers in the Eastern Cape” under the NRF Niche area of Water Resources Management and Sustainable Development in the Eastern Cape Province. The identification of relatively highly productive wells in the Karoo fractured aquifers is extremely difficult. This study aims to identify neotectonic zones and lower stress fields, and apply the results to groundwater exploration in the Eastern Cape Province. The methodologies adopted in this study include: a comprehensive literature review, extensive field mapping and investigation such as road cuts, sampling for laboratory studies, examination of seismic data, study of hot and ordinary springs, and interpretation of aerial photography and satellite images. Three main neotectonic belts were identified in the Eastern Cape (southern neotectonic belt, northern neotectonic belt and eastern neotectonic belt) based on literature review and field interpretations. The southern neotectonic belt (from the Cape Fold Belt to the lower Beaufort Group boundary) is characterized by the reactivation of the Coega-Bavianskloof and Sauer faults, the presence of a hot spring near Fort Beaufort, the slickenlines and discrete slickenlines and specifically the seismic events that were recorded in the Eastern Cape from 1850 to 2007. In this southern neotectonic belt the remote sensing has also revealed the presence of the Fort Beaufort fracture, the quartz veins seen in some dolerites and the different vegetation types along it may indicate that this fracture is possibly a fault; moreover the Quaternary sediments and weathered dolerites indicate that the Fort iii Beaufort fracture is characterized by groundwater circulation and accordingly is a good target for groundwater exploration, this fracture is a post-Karoo structure and possibly a neotectonic feature. In addition, the kaolin deposit, chiefly developed in the Dwyka tillite near Grahamstown is clearly controlled by neotectonic fracture zones. The northern neotectonic belt near the country of Lesotho is marked by the presence of the Senqu seismotectonic regime and hot springs. The Quaternary Amatole-Swaziland (formerly Ciskei-Swaziland) axis of uplift makes the eastern part of the province the third neotectonic zone, the asymmetric meanders of the Mbashe river in the vicinity of Qunu near Mthatha derived possibly from this Quaternary uplift; this asymmetric feature of meanders implies that the river has tried to maintain stability of its valley where tilting occurred. Within these neotectonic belts the central part of the Eastern Cape may be considered a static and inactive belt. A northwesterly trend for the maximum principal compresssional stress predominates in the Eastern Cape and is correlated with the present major structural control of the province. The current stress regime determination was derived from faults, joints and quartz veins only on kaolin deposits. Systematic joints reflect regional tectonic stress trajectories at the time of fracturing. Discharge rates of groundwater from boreholes as provided by the Department of Water and Forestry were used to confirm and predict water exploration targets. The region of Tabankulu (near Kwazulu Natal) in the northern neotectonic belt has remarkable discharge rates of groundwater (11.1 l/s, 4.65 l/s, 6.49 l/s, 42 l/s). The region of Mthatha, nearly surrounding the Amatole-Swaziland axis (former Ciskei-Swaziland iv axis) of uplift which might have generated some new faults, has a number of springs. These two regions should serve as case studies for future research. Apart from these two regions, two others regions can be considered as case studies for future groundwater exploration targets: the Bath Farm hot spring near the Fort Beaufort neotectonic fault and the vicinity of what is known as the Fort Beaufort fracture near Teba and Cimezile villages 20km north west of Fort Beaufort. It is concluded that the study of neotectonics and stress fields may be a useful tool for groundwater exploration in the Karoo fractured aquifers in the Eastern Cape, and in similar regions elsewhere in South Africa and in Africa.
25
Gaffney, Christopher F. "The Schlumberger Array in geophysical prospection for archaeology." Thesis, University of Bradford, 1990. http://hdl.handle.net/10454/3373.
Full textAbstract:
The Schlumberger array, or Schlumberger, was one of the first resistance arrays to be used to detect buried archaeological features. The early work used fixed probes and widely spaced traverses. Recent simulation work, ýhowever, suggested that the array should give improved resolution and depth penetration over the Twin-Probe array. This thesis is an attempt to operationalise the Schlumberger for use in archaeological prospection. This has been achieved via a co-ordinated use of laboratory simulation and-field studies. Initial fieldwork in England suggested. that the. - use of point electrodes created response patterns that were dependent upon the relative direction of linear targets. This was verified using a simulation tank modified to represent field procedure. The recognition of this response, therefore, required each survey area to be surveyed twice. The re-survey requires the two current probes to be positioned at right angles to the original survey points. The Schlumberger was then used in a battery of methods to investigate the problem of the archaeological interpretation of- small, discrete scatters of ceramic sherds that cover the landscape in Greece. The research has indicated a variation of intra-site patterning that may be significant to the function of these sites. Overall, the results suggest that the relationship between the 'site' and its environment is a complex one, one that can be oversimplified when the ceramic evidence is viewed in isolation. The Schlumberger indicated possible structural elements within some of these sites.
26
Viberg, Andreas. "Remnant echoes of the past : Archaeological geophysical prospection in Sweden." Doctoral thesis, Stockholms universitet, Institutionen för arkeologi och antikens kultur, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-79239.
Full textAbstract:
The aim of this thesis has been to investigate the benefits, pitfalls and possibilities of using geophysical methods in archaeological projects. This is exemplified by surveys carried out at archaeological sites in different geographical and chronological contexts. The thesis also aims at investigating the cause for the under-use of the methods in Swedish archaeology by looking at previously conducted surveys. The methods used during these surveys have been Ground-penetrating radar (GPR), magnetometer, slingram and a kappameter. The surveys in the mountain tundra region of Lapland show that magnetic susceptibility surveys is a valuable aid in discovering heaps of fire-cracked stones and when combined with magnetometry, also hearths. GPR and magnetometer surveys within the Migration Period ringfort Sandbyborg provided the spatial layout of the fort and indicated, along with results from recent excavations and metal detections, many similarities with the ringfort Eketorp II. The non-magnetic character of the sedimentary bedrock on Öland and Gotland is suitable for magnetometer surveys and the method is also highly appropriate for the detection of the remains of high-temperature crafts. GPR surveys at St. Mary’s Dominican convent in Sigtuna produced the spatial layout of the central cloister area. The investigations also show that the geology, pedology, land use and the character of commonly occurring prehistoric remains in Sweden, in certain circumstances and in certain areas, have restricted the possibility of successfully carrying out geophysical surveys. Care must therefore be taken to choose the right instrument for the survey and to tailor the sampling density of each geophysical survey, according to the character and size of the expected archaeological remains, in order to maximize their information return. To increase the use of geophysical methods in Sweden the educational opportunities, both for surveyors and professional archaeologists, need to improve.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Manuscript.
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Whitmore, Norman Daniel. "An imaging hierarchy for common-angle plane wave seismograms /." Access abstract and link to full text, 1995. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/9605996.
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MacInnes, Scott Charles. "Lateral effects in controlled source audiomagnetotellurics." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184322.
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A popular electrical exploration method is controlled source audiomagnetotellurics (CSAMT). Although the CSAMT method has had practical sucess, the theory used in CSAMT interpretation remains limited. The controlled source in CSAMT is a grounded electric dipole placed as far as is practical from the survey area. When the source-receiver separation is large enough, source fields can be adequately modeled by a single plane wave and conventional magnetotelluric interpretation methods can be used. Quite often however, data collected at lower frequencies can not be interpreted with magnetotelluric algorithms. If the electrical distance between source and receiver is too small, mathematical models must explicitly include the dipolar nature of the source fields to accurately model the data. Models which include a dipole source are limited. Most interpretation of CSAMT data is based upon horizontally layered models. In this dissertation, the model of plane layers excited by an arbitrary source is extended to include the effects of lateral changes in layer thickness. The method developed for modeling undulating interfaces mimics nature more accurately than plane-layered models, while preserving the utility of quick evaluation and insight lost to more general numerical methods. While the main emphasis here is on CSAMT applications, the theoretical results are valid for any source type. Topographic effects are modeled for plane wave and magnetic dipole sources. The effects of relief in basement topography on the response of a horizontal loop-loop system are computed and compared with scale-model measurements. CSAMT field data which can not be adequately explained by plane-layered models are analyzed using models with variable layer thickness. The correctness of the theoretical development is verified by comparison with physical measurements. The utility of the theory is illustrated by application to problems which can not be explained by plane-layered models.
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Rigoti, Augustinho. "Reduction of ambiguity in geological models using multiple data sets." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66266.
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Jepsen, Jacob P. "Detecting Remnants of the Past: Archaeo-Geophysical Prospection of Fremont Sites in Southern Utah Valley." BYU ScholarsArchive, 2021. https://scholarsarchive.byu.edu/etd/9153.
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The variable contexts of Fremont habitation sites in Utah Valley often make identification of those sites very challenging for archaeologists. Pit houses and other structures throughout the valley are frequently in plowed fields or other disturbed contexts that obscure their more exact location and nature. The application of geophysical technologies at archaeological sites throughout the world, including in North America, has proven to be an effective means of subsurface archaeological survey. However, geophysical techniques have been underutilized in Fremont archaeology. This paper reports on the employment of two geophysical methods, ground-penetrating radar (GPR) and fluxgate gradiometer surveys, at three known Fremont habitation sites in southern Utah Valley – the Wolf Village, Wolf Mound, and Snow Farm sites. The preliminary geophysical surveys and later ground-truthing of various geophysical anomalies reveals the effectiveness of these methods in identifying where architectural or other cultural features exist below the surface.
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Vieth, Kai-Uwe. "Kinematic wavefield attributes in seismic imaging /." [Karlsruhe] : Die Universität, 2001. http://www.ubka.uni-karlsruhe.de/vvv/2001/physik/2/2.pdf.
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Kirchner, Andreas. "Efficient repeat-modelling of time-lapse seismograms for reservoir monitoring /." [Karlsruhe] : Die Universität, 2001. http://www.ubka.uni-karlsruhe.de/vvv/2001/physik/2/2.pdf.
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Thesis (Doctoral)--Universität Karlsruhe, 2000.Abstract in German. Hochschulschrift = Thèse/Mémoire. Also available via the World Wide Web. http://www.ubka.uni-karlsruhe.de/cgi-bin/psview?document=2001/physik/2
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Zaske, Jörg Helmut. "Identification and attenuation of multiple reflections using wavefront characteristics /." [Karlsruhe] : Die Universität, 2000. http://www.ubka.uni-karlsruhe.de/cgi-bin/psgunzip/2000/physik/1/1.pdf.
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Thesis (Doctoral)--Universität Karlsruhe, 2000.Abstract in German. Includes bibliographical references (p. 107-111). Also available via the World Wide Web. Also available via the World Wide Web. http://www.ubka.uni-karlsruhe.de/cgi-bin/psview?document=2000/physik/1 http://www.ubka.uni-karlsruhe.de/cgi-bin/psview?document=/2000/physik/2
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Calle, Ochoa Andres Eduardo. "InterSis : uma interface grafica para modelamento sismico." [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287053.
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Orientadores: Martin Tygel, Rodrigo de Souza PortugalDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: o modelamento desempenha importante papel nos estudos de processamento e inversão de dados sísmicos. Muitos problemas complicados podem ser melhor atacados e entendidos quando os fenômenos de propagação de ondas envolvidos podem ser modelados, pelo menos em modelos geológicos mais simples. Tendo em vista ser o modelamento sísmico uma área de vasta aplicação e interesse, um grande número de pacotes computacionais existem capazes de oferecer sofisti-cadas capacitações para propósitos de modelagem. Esses pacotes são sujeitos entretanto, a severas limitações em sua utilização, não só devido aos seus altos custos, quanto também à inacessibi-lidade de seus códigos fonte. Por outro lado, as alternativas que existem, na forma de pacotes de uso livre, não representam substituição satisfatória. Isto porque os pacotes de modelamento disponíveis, geralmente desenvolvidos em ambientes científico-acadêmicos, não são suficiente-mente amigáveis e flexíveis, por exemplo na especificação de parâmetros de entrada, disposição gráfica de resultados, etc. o objetivo desta dissertação é investigar os principais problemas associados à construção de uma interface gráfica capaz de suportar uma variedade de programas de modelamento existentes e disponíveis como programas livres. Como resultado dessas investigações, é apresentada neste tra-balho a interface gráfica chamada InterSis. A interface InterSis foi construída de modo a aceitar, de forma simples e unificada, programas de modelamento destinados à propagação de ondas em meios 2D e 2.5D.InterSis foi desenvolvida utilizando os pacotes de domínio público GTK + (Graphical Tool/dt) e SU (Seismic Una). No seu presente estágio, InterSis é capaz de atuar como efetiva plataforma para os programas: (a) Seis88, um programa bem estabelecido de traçado de raios em mode-los elásticos e isotrópicos, desenvolvido por V. Cerveny e I. Psencík e (b) fd2d um programa de diferenças finitas para a equação de onda acústica, desenvolvido por 1. Costa. Como uma pro-priedade de particular interesse, InterSis utiliza a informação fomecida pelo programa Seis88 para computar os parâmetros do chamado método CRS (do Inglês Common-Reflection-Suiface). Desta forma, a interface proposta pode ser de valia nos estudos de imageamento e inversão que utilizam o método CRS. Vale notar que, devido à sua estrutura de caráter geral, InterSis pode ser bem adaptada a outros programas de modelamento
Abstract: Modelling plays an important role in seismie data processing and inversion. Several compli-cated problems can be better addressed and understood, when the wave propagation involved ean be modelled, at least in simple versions ofthe geological model. As a wide topie of application and interest, a number of commercial softwares exist that offer sophisticated capabilities for modelling purposes. These packages are subjected to a number of limitations on their use, not only of costs, but also because their source codes are not accessible. On the other hand, the few ahematives existo in the form of open packages do not represent an easy replacement. The available modelling codes, mainly developed within academie-scientific environments, are not friendly and flexible enough, e.g., in the specification of input parameters and display of resu1ts. The aim of this work is to investigate the main problems connected with the construction of a graphica1 interface that would be an useful support to a number of modelling programs available as open codes. As a result of the investigations, a graphical interface, ca1led InterSis, has been developed. InterSis ean accept and handle, in a simple and unified way,softwares that involves seismic modelling in 2D and 2.5D media. InterSis was developed using the public-domain softwares GTK + (Graphica/ Too/kit) and SU (Seismic Unix). In its present stage, it is able to be an effective platform for the following programs : (a) Seis88, a well-established ray-tracing program developed by v. Cerveny and I. PsenãK and (b) fd2d a finite-difference program for the acoustie wave equation developed by J. Costa. As a particular feature, InterSis uses the information provided by Seis88 to compute the parameters ofthe COmnJOlI-Rejlectioll-Surface (CRS) method. In this way, the proposed intedàce ean be useful to imaging and inversion studies based on the CRS method. It is to be noted that, due to its general s1ructure, InterSis can be well adapted to other modelling programs
Mestrado
Reservatórios e Gestão
Mestre em Ciências e Engenharia de Petróleo
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Jrad, Abir. "Application des méthodes géophysiques à la prospection archéologique." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4301.
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Ce travail de thèse porte sur la recherche géophysique de la proche sub-surface appliquée aux objets et structures archéologiques. L'objectif est de définir une méthodologie d'étude géophysique de sites archéologiques dans un contexte Méditerranéen : en France et en Tunisie, ainsi que " l'empreinte géophysique " des principaux objets archéologiques. La méthode géophysique principale utilisée est la méthode magnétique. Les cartographies magnétiques obtenues sont couplées aux cartographies et mesures électromagnétiques et aux tomographies électriques (ERT) et sismiques. Ce volet de prospection sur le terrain est corrélé aux mesures magnétiques de laboratoire, permettant une meilleure contrainte des modélisations directes et synthétiques proposées pour les différents objets étudiés. Dans une première partie, la thèse se concentre sur les structures et objets archéologiques de combustion. Cette partie précise la signature magnétique de ces objets et souligne son rehaussement dû à l'effet du feu. Dans un second temps, la thèse fait porter l'analyse sur l'empreinte géophysiques des structures d'aménagement et sa variation reliée aux différents matériaux et techniques utilisés ainsi qu'aux propriétés du terrain encaissant. D'autres objets sont par la suite étudiés pour une meilleure compréhension des anomalies magnétiques potentiellement produites. La diminution de la qualité du signal magnétique et donc du rapport signal sur bruit est traité vers la finThis dissertation deals with the applied geophysics to archaeological objects and structures in the close subsurface. The aims are to define a geophysical methodology for the study of archeological sites in a Mediterranean context : in France and in Tunisia, and also the geophysical signature of the main archaeological features. The main geophysical method used is the magnetic method. The obtained magnetic mappings are coupled with the electromagnetic cartographies and measurements, and with the electrical tomographies (ERT) and the seismic surveys. This ground prospecting is correlated with the magnetic measurements of laboratory, allowing a better constraint of the forward and synthetic modelling, proposed for the various studied features. First, the thesis concentrates on the study of the archaeological structures of combustion. This part specifies the magnetic signature of these objects and underlines the raising owed to the effect of the fire. Secondly, this work analyzes the geophysical imprint of the building structures and its variation connected with the various materials and techniques used as well as the surrounding ground properties. Other objects are afterward studied for a better understanding of the potentially produced magnetic anomalies. Last but not least, the decrease of the quality of the magnetic signal and thus the signal-to-noise ratio, is handled
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Morelatto, Rodrigo. "Filtragem de dados sísmicos utilizando o tensor estrutural." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265169.
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Orientador: Ricardo Caetano Azevedo BilotiDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências
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Resumo: O tensor estrutural é uma ferramenta muito versátil, e pode ser utilizado para detectar bordas, estimar coerência e inclinações locais. Neste trabalho, o tensor estrutural é empregado para estimar inclinações locais em dados sísmicos. As inclinações estimadas com essa ferramenta são comparadas com as inclinações obtidas com duas implementações diferentes de destruidores de onda plana. Esses três métodos são testados contra diferentes conjuntos de dados, quatro sintéticos e um real. As inclinações estimadas com o tensor estrutural foram robustas e precisas o suficiente para aplicações práticas, comparáveis às inclinações obtidas com os destruidores de onda plana. Por fim, é apresentada uma aplicação prática para as inclinações estimadas com o tensor. Essas inclinações são empregadas para filtrar dados sísmicos ao longo dos eventos, utilizando dois métodos diferentes: filtragem adaptativa e o filtro preditor de estruturas. Esse tipo de filtragem é especialmente útil para interpretação, pois os dados são filtrados ao longo dos eventos, reduzindo a perda de informação e atenuando o ruído
Abstract: The structure tensor is a very versatile tool, which can be used to detect edges, estimate coherency and local slopes. In this work we employ the structure tensor to estimate local slopes. We compare the slopes obtained with this tool with the slopes obtained by two different implementations of plane-wave destruction filters. Those three methods were tested against different datasets, four synthetic and one real. The slopes detected through the structure tensor were reliable and comparable to the ones obtained with plane-wave destruction filters. Finally, we present an application for the slopes detected by the structure tensor. We show how to employ them to filter seismic data along structures using two different methods: adaptive filtering and structure prediction filtering. This kind of filtering is useful for interpretation, because it filters the data along the seismic events, reducing the loss of information and noise at the same time
Mestrado
Reservatórios e Gestão
Mestre em Ciências e Engenharia de Petróleo
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Cuenca-Garcia, Carmen. "The interface of geophysical & geochemical survey at Scottish archaeological sites : exploring the potential of an integrated approach for archaeological prospection." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4535/.
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This thesis illustrates how geophysical and geochemical methods can be combined to study archaeological sites and obtain enhanced interpretations of the results using the complementary information they provide. Whilst these two disciplines tend to be used independently, this thesis brings them together, with a view to exploring their relationships and developing strategies that lead to non-destructive and cost-effective surveys. The investigation focuses on the correlation of geophysical and geochemical results over common archaeological features and their analysis using soil geochemistry in order to understand the factors of contrast involved in their detection. Five case study sites in Scotland were selected, each one presenting a specific challenge to be assessed by the integrated methodology developed in this thesis. The research employed a range of geophysical (earth resistance, magnetometry, magnetic susceptibility, FDEM and GPR) and geochemical (total phosphate and multi-element analysis) techniques routinely used in archaeological prospection. The different geophysical responses obtained over targeted archaeological features were considered with respect to soil texture, organic matter content, pH, conductivity and chemical composition from archaeological deposits, topsoil and subsoil samples. The results not only provide a nuanced understanding of the character of the archaeological features surveyed, but begin to develop a better insight of how the setting of a site may affect geophysical and geochemical datasets at Scottish archaeological sites. This thesis concludes that the detection of archaeological anomalies depends upon inter-related and site-specific contrast factors including: general site settings (e.g. the effect of highly variable glacial drift deposits), the type of features to be detected (e.g. cut or impervious), and the effect of soil post-depositional processes inside archaeological features and surrounding matrix. For example, at the prehistoric site at Forteviot site (Perthshire) redox processes inside archaeological ditches contribute to their negative magnetic response. Also, chemical composition related to anthropogenic organic materials may enhance the conductivity of theoretical impervious features as illustrated at the Bay of Skaill site (Orkney).
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Grinc, Michal. "Lithospheric structure in Central Europe : integrated geophysical modelling." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00921044.
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The main aim of this thesis is to gain new knowledge about the lithospherical structure and tectonics of the Carpathian-Pannonian Basin region. We applied three different methods: 1Dautomatic modelling, 2D integrated geophysical modelling and 3D inversion to achieve this goal.These methods are similar concerning the used databases but differ by used processing andinterpretation. At first we apply 1D automatic modelling to get a very first overview of thestudied region. Secondly, we apply 2D integrated modelling of the lithosphere which combines the interpretation of surface heat flow, geoid, gravity, and topography data in the Carpathian-Pannonian Basin region and surrounding areas. This approach is able to constrain the complicated lithospheric structures of the studied region better than interpreting each data set onits own. We present four 2D integrated models of the lithosphere in the Carpathian-PannonianBasin region and surrounding areas. Finally, based on the 3D Inversion algorithm, we present the geophysical models of the lithosphere in the Carpathian-Pannonian region. The algorithm returns the density structure of the lithosphere from joint inversion of free air gravity, geoid andtopography data based on a Bayesian approach. The models are based on different input data sets and constrained by different a priori data. Based on our modelling we cannot confirm theextreme thinning (less than 70 km) of the Pannonian Basin lithosphere proposed by other authors.On the other hand, the results show the increasing trend of the lithospherical thickness of theCarpathian Arc from the Western Carpathians toward the Eastern Carpathians which confirms theprevious theories about the propagation of subduction process. We got some controversial resultsin the area of the Southern Carpathians. The results based on 3D inversion show extremely thinlithosphere in the area; on the other hand, the results based on 2D integrated modelling do notsupport such thinning. However both methods indicate that it is probable that the MoesianPlatform is bend and underthrusted underneath the Southern Carpathians. The south-eastern edge of the Pannonian Basin based on 3D inversion shows unexpected and surprisingly thinlithosphere. Since the area is quite large, we could exclude an effect of flexure, therefore this area might be potentially interesting for further investigation.
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Guerrero, Olivier. "Comparaison et couplage de méthodes géophysiques pour l'amélioration des reconnaissances des sols dans les projets géotechniques en milieu périurbain." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0137/document.
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Dans le cadre d’un projet d’aménagement, la reconnaissance du sous-sol est une étape prépondérante pour la construction d’un bâtiment. Le géotechnicien se doit de définir le comportement mécanique des sols à partir d’un nombre limité de sondages. La problématique soulevée par les prospections géotechniques est qu’il est difficile d’une part d’étendre une information ponctuelle dans l’environnement proche des sondages, et d’autre part d’estimer la variabilité latérale des matériaux. Dans cette optique, cette thèse développe une approche novatrice de combinaison de méthodes géophysiques aidant à la quantification de la variabilité spatiale des structures géoélectriques du sous-sol. Dans un second temps, au regard des limites rencontrées dans la modélisation 3D des structures géoélectriques du sous-sol, nous avons mis au point un processus innovant de modélisation 3D des propriétés physiques du sous-sol par combinaison de méthodes géophysiques. Les travaux menés ont permis de caractériser les paramètres régissant le positionnement et la quantité de données sources nécessaires.Enfin, un dispositif innovant de mesure de Tomographie de Résistivité Electrique en Cinématique (TREC) a été développé. La validation du dispositif sur trois sites différents a permis de mettre en évidence sa capacité à détecter les structures géoélectriques des sols sur un linéaire de plusieurs centaines de mètres. Ce dispositif constitue un outil précieux pour l’étude des structures géoélectriques du sous-sol dans le cadre de prospections géophysiques à grand rendementThe geotechnical study of a building project is a decisive step for the construction of it. The geotechnical engineer must define the mechanical behavior of soils from a limited number of drills. The problem of the geotechnical surveys is, on the one hand that difficult to extend a punctual data in the near space to the drills,and on the other hand to estimate the lateral variability of materials. In this context, this thesis develops an innovative approach by combination of geophysical methods to quantify the spatial variability of geoelectrical structures. In asecond time, against the known limits of the 3D modeling of soil geoelectrical structures, we have developed an innovative process of 3D modeling of the physical properties of soil by geophysical methods combination. These works allow characterizing the parameters who governing the positioning and the number of necessary primary data.Finally, an innovative measuring device of Kinematic Electrical Resistivity Tomography (KERT) has been developed. The validation of the device on three different site has allowed to highlight its ability to detect the soil geoelectrical structures within a linear of hundreds meters. This device is a valuable tool for studying soil geoelectrical structures in the context of high yield geophysical prospection
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Jouen, Thomas. "Caractérisation de l'évolution de l'état de biodégradation des massifs de déchets non dangereux en post-exploitation : Application de méthodes géophysiques." Thesis, Paris, Institut agronomique, vétérinaire et forestier de France, 2018. http://www.theses.fr/2018IAVF0010/document.
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Le stockage est la méthode de traitement des déchets non dangereux la plus communément utilisée dans le monde entier car elle est un moyen simple et économique pour leur élimination. Malgré une volonté nationale et européenne pour réduire le stockage de déchets biodégradables, une quantité non négligeable est encore enfouie entrainant la mise en place de modes de gestion spécifique. Autrefois exploitées comme de simples fosses de remplissage, les installations de stockage de déchets non dangereux (ISDND) sont aujourd’hui des ouvrages complexes dont l’objectif est de réduire l’impact environnemental et de valoriser énergétiquement le biogaz produit par la biodégradation de la matière organique. Afin d’accélérer les processus de biodégradation un casier de déchets peut être exploité en mode bioréacteur en réinjectant des lixiviats pour augmenter la teneur en eau des déchets. Le défi des années 2000 était de dimensionner et valider les systèmes de réinjection de lixiviat pour garantir une distribution optimale de la teneur en eau dans les massifs de déchets. Aujourd’hui, la question est de de suivre l’évolution de la biodégradation en tous points d’un massif pour notamment comprendre l’effet de ce mode de gestion. Les méthodes géophysiques en plus d’être non-destructives et spatialisantes sont utilisées depuis des années sur les ISDND et pourraient être sensibles à l’évolution de la biodégradation d’un massif de déchets, comme cela a été démontré pour la biodégradation d’autres milieux. Ainsi la problématique de cette thèse est d’évaluer la capacité de certaines méthodes géophysiques pour suivre l’évolution des paramètres bio-physico-chimiques d’un massif de déchets au cours de sa biodégradation. Un premier travail bibliographique a permis d’identifier quatre méthodes électriques parmi les méthodes géophysiques disponibles pour répondre à cette question :• La résistivité électrique• Le potentiel spontané• La polarisation provoquée• La polarisation provoquée spectraleAprès cet état de l’art, le travail de thèse a été séparé en trois parties. La première a été consacrée à la mise en place du suivi de ces quatre méthodes à l’échelle du laboratoire dans des conditions contrôlées, la seconde à analyser le suivi géophysique long terme sur le site industriel de la SAS Les Champs Jouault et la dernière a évaluée les observations à ces deux échelles. Enfin, la conclusion présente le potentiel de la méthode de mesure du potentiel provoquée comme la plus pertinente pour suivre l’évolution de la biodégradation d’un déchet non dangereux au cours du temps et aborde son utilisation dans un cadre industrielStorage is the most commonly used waste treatment method in the world because it is a simple and economical way to dispose of solid waste. Despite a national and European desire to reduce the storage of biodegradable waste, a significant amount is still buried, leading to the implementation of specific management methods. Formerly exploited as mere filling pits, MSWL are today complex structures whose objective is to reduce the environmental impact and energetically valorize the biogas produced by the biodegradation of organic matter. In order to accelerate biodegradation processes, a waste cell can be operated in bioreactor mode by reinjecting leachates to increase the water content of the waste. The challenge of the 2000s was to size and validate leachate re-injection systems to ensure optimal distribution of water content in the waste mass. Today, the question is to monitor evolution of the biodegradation in all points of a waste mass in particular to understand the effect of this management mode. Geophysical methods in addition to being non-destructive and spatializing have been used for years on MSWLs and could be sensitive to the evolution of a waste mass biodegradation, as has been demonstrated for the biodegradation of others environments. Thus the problematic of this thesis is to evaluate the capacity of certain geophysical methods to monitor the evolution of the bio-physicochemical parameters of a waste mass during its biodegradation. A first bibliographic work identified four electrical methods among the geophysical methods available to answer this question:• Electrical resistivity• Self potential• Time domain induced polarization• Spectral induced polarizationAfter this state of the art, the thesis work was separated into three parts. The first one was devoted to the implementation of the monitoring of these four methods at the laboratory scale under controlled conditions, the second to analyze the long-term geophysical monitoring at the industrial site of SAS Les Champs Jouault and the last one to evaluate the observations at these two scales. Finally, the conclusion presents the potential of time domain induced polarization method as the most relevant to monitor the evolution of a waste mass biodegradation over time and discusses its use in an industrial setting
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Gustafsson, Ny Björn. "Casting Identities in Central Seclusion : Aspects of non-ferrous metalworking and society on Gotland in the Early Medieval Period." Doctoral thesis, Stockholms universitet, Institutionen för arkeologi och antikens kultur, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-95380.
Full textAbstract:
The aim of this thesis has been to investigate and interpret late Iron Ageand Early Medieval traces of non-ferrous metalworking on the islandGotland, Sweden. Gotland was not, based on the archaeological record, anintegrated part of the common Scandinavian culture. Instead a local,endemic cultural expression had developed; a seclusion which lasted forcenturies despite the islands central position in the Baltic Sea. In thepast, key elements for the understanding of local settlement- and burialpractices as well as the local material culture were mainly recovered andreported by local farmers. A specific category of such finds – so-called‘bronze slag’ is discussed and partly reinterpreted in the first study ofthis thesis. Two further studies treat different aspects of metalworkingand metalworkers – one discusses common archaeological notions ofScandinavian workshops, production sites and metalworkers from a criticalperspective while the other mainly focuses on the Gotlandic finds frommetal-detector surveys carried out over the last 35 years. Based on whereand to which extent, both from a quantitative and a qualitative point ofview, these finds occur a hierarchical classification into four sub groupsis presented – ordinary farm sites with traces of non-ferrous metalworking,workshop sites, potential workshop sites and last, extrovert harboursettlements. A fourth study presents an attempt to evaluate the usefulnessof magnetometry in delimiting extant traces of high-temperature crafts,such as metalworking. The last study of the thesis presents an attempt touse trace elements analysis of skeletal lead in human bone to identifypotential non-ferrous metalworkers. As the wearing of endemic Gotlandic jewellery appears to have been centralin the manifestation of the local identity it is argued that themetalworking artisans played a crucial role in defining how this identitywas signalled and displayed via the jewellery and dress-related metalobjects. It is further suggested that these artisans might have played animportant role in upholding the local economy before the advent of localminting.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 5: Manuscript.
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Pernod, Philippe. "Modélisation physique des profils sismiques de subsurface : application à la détection de cavités." Valenciennes, 1989. https://ged.uphf.fr/nuxeo/site/esupversions/dd9d6052-ffcf-4644-a2ee-d2e9f164dd25.
Full textAbstract:
Ce mémoire de thèse décrit la réalisation et la mise au point d'un modèle physique simple et modulable destine à étudier la possibilité de détection de cavités souterraines a faible profondeur par méthodes sismiques. En premier lieu sont exposés les principes d'élaboration du modèle (choix des matériaux, dimensionnement. . . ) Et une étude détaillée des fonctionnements et des propriétés de la source impulsionnelle utilisée. Dans un second temps, le modèle est utilisé pour tester l'adéquation de méthodes classiques en sismique "Source-gather" "Common-offset" "Common-depth point" à la détection des cavités. Une dernière partie suggère des solutions pour la résolution de cas réels complexes. Enfin est suggéré un nouveau choix des matériaux constituant le modèle afin de simuler de manière plus fidèle la réalité.
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Gondet, Sébastien. "Occupation de la plaine de Persépolis au Ier millénaire av. J.-C. (Fars central, Iran)." Thesis, Lyon 2, 2011. http://www.theses.fr/2011LYO20026/document.
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Fondée par Darius Ier (522-486 av. J.-C.), Persépolis constituait une des résidences royales temporaires des souverains de l’Empire achéménide (550-330 av. J.-C.). Elle était également un centre administratif et économique, capitale d’une vaste province, la Perse, située au cœur de l’Empire. L’organisation de Persépolis reste largement méconnue de même que celle du vaste territoire, la plaine environnante, qu’elle contrôlait.Notre étude vise à mieux comprendre d’une part l’occupation du site de Persépolis qui va de la terrasse monumentale à la nécropole royale à 6 km au nord, d’autre part la mise en valeur de la plaine, en replaçant la période achéménide dans le contexte plus large du Ier millénaire av. J.-C. Dans un premier temps, l’étude prend en compte les dynamiques environnementales de la région. Les recherches sont fondées sur les méthodes de prospections archéologiques (reconnaissances à vue et méthodes géophysiques). Elle aboutit à une reconstitution d’une ville répartie en plusieurs blocs de fonctions différentes (habitats ordinaires, zones artisanales, résidences de l’élite et bâtiments de prestige) séparés les uns des autres par de vastes espaces non-bâtis mais probablement aménagés.Pour la plaine (100 km par 30 km), la prospection des sites achéménides a dû prendre en compte les graves destructions liées à la modernisation (agriculture, urbanisation, voies de communication) et s’est concentrée sur quelques sites préservés et des zones de piedmonts sélectionnées. Ces recherches ont montré une occupation très distendue essentiellement localisée dans la partie nord de la plaine et incluant la zone de Persépolis. La partie sud de la plaine était beaucoup moins exploitée. Cependant cette reconstitution doit tenir compte de la réduction sévère du potentiel archéologique, tout particulièrement dans le cadre de l’étude de l’occupation à la période achéménide, lorsque l’exploitation du sol reposait sur des installations rurales de dimensions modestesFounded by Darius I (522-486 BC), Persepolis represented one of the seats of the kings of the Achaemenid Empire (550-330 BC). Moreover, the site served as an administrative and economic centre and acted as capital for the vast province, named Persia, situated in the heart of the Empire. The spatial character of both the royal site as well as the wider hinterland it controlled, the vast surrounding plain, are however largely unknown.The study aims at providing better insight in both the occupation of the site of Persepolis, stretching from the monumental terrace to the royal necropolis 6 km farther north, along with that of the supporting plain. It therefore frames and evaluates the Achaemenid period within the context of the first millennium BC. At the outset, the study integrates the environmental dynamics of the region. The research was based on the methods of archaeological survey (field survey and geophysical methods) and allowed to reconstruct a ‘city’ composed of different functional zones (common housing, industrial quarters, elite residences, and royal monuments) separated from one another by large areas, presumably unbuilt though exploited.For the plain (100 by 30 km), the survey of Achaemenid sites was biased by the important destructions by recent development (industrialised agriculture, urbanism, transport and communication). Research has therefore been focussed on a number of preserved sites on the one hand and on selected piedmont areas on the other. These surveys brought to light a scattered occupation, predominantly situated in the northern part of the plain, also encompassing the Persepolis zone, while the southern region of the plain was less occupied. Nonetheless, this reconstruction should take into account the important reduction of archaeological potential, particularly in the case of a study focussing on the Achaemenid occupation since settlement in the wider Persepolis area was first and foremost of rural natural and of rather modest size
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Benech, Christophe. "Interprétation conjointe de cartographies magnétique et électromagnétique des propriétés magnétiques des sols anthropisés." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2000. http://tel.archives-ouvertes.fr/tel-00411992.
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Les propriétés magnétiques interviennent dans deux méthodes de prospection : la méthode magnétique où l'on mesure les variations spatiales du champ magnétique terrestre et le méthode électromagnétique basse fréquence où l'on émet un champ artificiel et où l'on mesure la réaction du sol à ce champ.La thèse présentée ici propose une méthode d'interprétation simultanée des données de ces deux types de méthode. Une telle démarche peut en effet permettre de caractériser les différents types d'aimantations affectant le proche sous-sol et de mieux évaluer la profondeur et la géométrie des sources magnétiques.
Une vaste prospection magnétique réalisée sur le site hellénistique d'Apamée de l'Euphrate montre l'intérêt de la prospection dans le contexte d'une fouille d'urgence et l'intérêt qu'il y a à affiner l'interprétation des données magnétiques.
Le premier chapitre présente une synthèse concernant l'étude des propriétés magnétiques des sols sur échantillons. Ces propriétés permettent de caractériser les comportements des horizons superficiels et d'en étudier les processus pédologiques et anthropiques. Les prospections magnétique et électromagnétique permettent de cartographier ces propriétés magnétiques, cartographies qui peuvent être complétées par des études sur échantillons.
Il existe de nombreux appareils électromagnétiques permettant de mesurer la susceptibilité magnétique apparente mais leurs performances, particulièrement en termes de profondeurs d'investigation, sont très variables. Une étude théorique et expérimentale réalisée sur un site test montre que l'écartement et l'orientation des bobines choisis pour le CS150 en font l'appareil possédant la meilleure profondeur d'investigation, de l'ordre de 1 m, et pour lequel la conductivité du terrain n'a qu'une très faible influence sur la réponse en phase.
L'interprétation conjointe des données magnétique et électromagnétique est basée sur le filtrage linéaire des données électromagnétiques qui permet de restituer l'anomalie magnétique due à l'aimantation induite. L'étude théorique montre que le principal écart observé entre les données magnétique brute et électromagnétique filtrée vient de la différence de profondeur d'investigation entre les appareils.
Enfin, des essais expérimentaux sur des sites archéologiques ont permis dans un cas, de dissocier l'aimantation rémanente de l'aimantation induite et de calculer la profondeur de la source magnétique et dans l'autre cas, de dissocier l'aimantation visqueuse de l'aimantation induite et là aussi de calculer la profondeur de la source magnétique.
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Bruniaux, Guillaume. "Reconstitution paléogéographique et prospection archéologique en zone littorale par approches géophysiques multi-méthodes et multi-échelles." Thesis, La Rochelle, 2017. http://www.theses.fr/2017LAROS026/document.
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L’étude archéologique d’un site est réalisée sur la base d’une fouille, qui est une étude précise sur une ouverture restreinte. En amont de cette opération, la prospection géophysique offre la possibilité de localiser une zone susceptible d’apporter des informations majeures par une cartographie détaillée du site. Ces travaux de thèse se focalisent sur un protocole original de prospection magnétique pour détecter des structures pluri-métriques à pluri-décimétriques et une démarche méthodologique pour estimer la conservation d’un niveau d’occupation archéologique. Ces développements ont été réalisés pour apporter un maximum d’information sur l’occupation anthropique et cibler une zone de fouille suivant la problématique archéologique associée au site. Dans les zones littorales et suivant la période chronologique considérée, l’environnement associé à une occupation était différent. La modification relativement rapide des environnements côtiers résulte de la remontée du niveau marin depuis la fin du dernier maximum glaciaire. Dans le cadre d'une étude paléoenvironnementale associée à un site, l’objectif de la prospection géophysique est similaire à celle effectuée pour une fouille : localiser une zone d’implantation des carottages paléoenvironnementaux. La démarche méthodologique développée dans ces travaux est basée sur une approche paléogéographique de l’environnement à partir de prospections géophysiques multi-méthodes et multi-échelles. Des prospections électromagnétiques (Slingram), des sections électriques et des diagraphies électriques (direct-push) apportent une représentation cartographique et stratigraphique des contrastes géophysiques de la subsurface. Deux zones d’étude ont été sélectionnées pour tester et mettre en place ces démarches méthodologiques, le site néolithique du Pontet (Charente-Maritime) et les ports antiques de Narbonne. Ces deux sites sont dans des contextes archéologiques, géographiques et géologiques différentsArchaeological study of a site is based on an excavation which is a comprehensive study on a restricted gap. Before excavation, geophysical survey supplies the possibility to locate an area likely to provide details by detailed mapping of the site. This PhD work focus on an original magnetic survey protocol to detect pluri-metric and pluri-decimetric structures and a methodological approach to estimate the conservation of an archaeological level occupation. These developments have provided maximum information on anthropogenic settlement and to target excavation zone according to the archaeological problem of the site. In coastal zones and according to the considered chronological period, the environment of the settlement was different. The relatively rapid change in coastal environments results from the rise of sea level since the end of the last glacial maximum. As part of a paleoenvironmental study of a site, the objective of geophysical survey is similar to that for excavation : locating an area to paleoenvironmental coring. The methodological approach developed in this work is based on a paleogeographic approach to the site environment using multi-method and multi-scale geophysical surveys. Electromagnetic survey (Slingram), electrical tomography and direct-push electrical resistivity logging provide a cartographic and stratigraphic representation of the geophysical contrasts of the subsurface. Two study areas were selected to test and implement these methodological approaches, the Neolithic site of Le Pontet (Charente-Maritime) and the ancient harbours of Narbonne. These two sites are in different archaeological, geographical and geological contexts
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Jeannin, Mathieu. "Etude des processus d'instabilités des versants rocheux par prospection géophysique : apport du radar géologique." Phd thesis, Université Joseph Fourier (Grenoble), 2005. http://tel.archives-ouvertes.fr/tel-00012178.
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L'évaluation de la stabilité des falaises est complexe, du fait de l'incertitude des mécanismes de rupture et de la méconnaissance de l'état de fracturation interne du massif. Les méthodes géophysiques permettent d'obtenir de l'information sur la structure interne du massif. Le radar géologique a montré son efficacité pour détecter et caractériser les fractures. Plusieurs profils radar (réflexion, transmission, CMP) sont testés sur deux falaises verticales calcaires proches de Grenoble. La combinaison de profils verticaux et horizontaux permet de mieux contraindre la géométrie 3D du réseau de fractures. Les analyses de vitesses radar, déduites des acquisitions CMP, permettent de caractériser directement les larges fractures ouverture en profondeur. La tomographie radar fournit une image 2D de l'intérieur du massif, mais avec une trop faible résolution. Dans une gamme de fréquences donnée, la détection de fractures par le radar va dépendre de l'ouverture et du remplissage, qui contrôlent le coefficient de réflexion. Une stratégie de caractérisation des fractures est proposée en utilisant la sensibilité fréquentielle de la réflectivité. L'inversion des coefficients de réflexion radar, basée sur un algorithme de voisinage, permet de retrouver les paramètres caractéristiques des fractures modélisées. La méthode du rapport spectral entre un signal réfléchi (mesuré) et un signal de référence (connu), permet de calculer facilement le coefficient de réflexion. Une étude numérique 2D (FDTD) est menée pour le choix du signal de référence. L'inversion des coefficients de réflexion radar synthétiques est testée pour une configuration de fracture ouverte rencontrée sur le terrain.
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Escalas, Oliver Magdalena. "Anàlisi temps-freqüència de l’estat de polarització del senyal magnetotel·lúric = Polarisation analysis of the magnetotelluric signal in the time-frequency domain." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/336095.
Full textAbstract:
El mètode magnetotel·lúric (MT) és una tècnica geofísica que proporciona la distribució de la resistivitat elèctrica en el subsòl a partir de les fluctuacions temporals del senyal electromagnètic (EM) natural mesurades a la superfície terrestre. El senyal MT sovint esdevé contaminat per soroll EM d’origen antropogènic (soroll cultural). La seva detecció i eliminació és un dels reptes actuals per millorar la qualitat de les respostes obtingudes amb el mètode MT. L’estudi de les característiques del senyal MT i del soroll cultural és un pas clau per poder diferenciar ambdós senyals i eliminar posteriorment el soroll.
En general el senyal MT no presenta un estat de polarització concret en el domini temps-freqüència (t-f), ara bé, algunes de les seves fonts naturals com les pulsacions geomagnètiques del tipus Pc3 o les ressonàncies Schumann es caracteritzen pel seu estat de polarització. En canvi, el soroll cultural sol estar polaritzat linealment en una direcció determinada a causa de la posició fixa de les seves fonts a l’espai.
Tenint en compte que l’estat de polarització del senyal MT està estretament lligat a les característiques de les seves fonts, en aquesta tesi es proposa la seva anàlisi com a eina per identificar i caracteritzar algunes de les seves fonts naturals i les fonts de soroll cultural que el contaminen. Atès que tant el senyal MT com el soroll cultural són senyals variables amb el temps i presenten múltiples freqüències, s’ha considerat adient analitzar el seu estat de polarització en el domini temps-freqüència (t-f).
La principal contribució d’aquesta tesi és el desenvolupament, per primer cop, d’un mètode per analitzar l’estat de polarització del senyal MT en el domini (t-f) a partir de les sèries temporals dels camps elèctric i magnètic. S’han establert les bases teòriques del mètode, que permet obtenir els atributs de polarització d’ambdós camps en el domini (t-f) mitjançant la transformada wavelet, i s’ha implementat en un codi anomenat MTWAVELETS.
El mètode desenvolupat s’ha aplicat a l’anàlisi de nombroses sèries temporals MT mesurades a diferents localitzacions i que presenten o bé indicis de soroll cultural o bé indicis de la presència de senyals geomagnètics amb un estat de polarització determinat.
A partir de l’anàlisi de sèries temporals MT mesurades a Hontomín (Espanya) i a Lamezia Terme (Itàlia) s’ha detectat el soroll cultural creat per línies elèctriques, la circulació de trens per vies fèrries electrificades amb corrent continu, aerogeneradors i entorns industrials i urbans, i s’ha determinat la posició relativa d’aquestes fonts respecte els punts de mesura. S’ha caracteritzat el comportament que presenten l’amplitud i els atributs de polarització d’aquests senyals sorollosos en el domini (t-f), de manera que a partir d’ara pot identificar-se fàcilment la presència d’aquestes fonts contaminants a sèries temporals MT.
D’altra banda, l’anàlisi de dades mesurades a Tramutola (Itàlia) ha suggerit que les pulsacions geomagnètiques del tipus Pc3 són una de les causes de l’oscil·lació que presenten les respostes MT en aquest site en el domini (t-f). Així mateix, s’han detectat i analitzat els quatre primers modes de les ressonàncies Schumann a partir de sèries temporals MT mesurades a Huidobro (Espanya). L’anàlisi (t-f) dels seus atributs de polarització ha permès diferenciar aquest senyals geomagnètics de la resta del senyal MT.
La nova eina desenvolupada en aquesta tesi constitueix una aportació significativa per a l’anàlisi del senyal MT, ja que permet detectar i caracteritzar les seves fonts, ja siguin naturals o de soroll. Té nombroses aplicacions: en l’àmbit de la millora de les respostes MT per a la identificació del soroll cultural i de senyals geomagnètics que puguin alterar-les, i en l’estudi de la ionosfera i la magnetosfera per a la caracterització de senyals geomagnètics.The magnetotelluric (MT) signal is usually affected by electromagnetic anthropogenic noise (cultural noise). At present, its detection and removal is one of the challenges to improve the responses of the MT method. The MT signal does not generally have a specific polarisation state in the time-frequency (t-f) domain. However, some of its natural sources such as Pc3 geomagnetic pulsations or Schumann resonances have characteristic polarisation properties. In contrast, cultural noise is usually linearly polarised in a certain direction due to the fixed location of its sources in space. The major contribution of this thesis is the development, for the first time, of a method for polarisation analysis of the MT signal in the (t-f) domain. It is proposed as a tool to identify and characterise some of its natural sources and those of cultural noise. It provides the polarisation attributes of the MT signal in the (t-f) domain computed in terms of the wavelet transform, since both the MT signal and the cultural noise show time and frequency variations. The theoretical basis of the method has been established, and it has been implemented in a code named MTWAVELETS. Cultural noise created by power lines, electrified DC railways, wind turbines and industrial areas has been detected and characterised from the analysis of MT time series acquired at Hontomín (Spain) and Lamezia Terme (Italy). The analysis of MT time-series from Tramutola (Italy) points to Pc3 pulsations as one of the causes of the oscillation of the MT responses in the (t-f) domain at this site. Moreover, the first four modes of the Schumann resonances were detected and analysed from MT time-series acquired at Huidobro (Spain). The new tool developed in this thesis is a major contribution to the analysis of the MT signal since it allows detecting and characterising its sources, both natural and noisy. It has many applications: in the scope of improving the quality of the MT responses due to the identification of cultural noise and geomagnetic signals capable of altering them, and in the scope of the study of the ionosphere and the magnetosphere due to the characterisation of geomagnetic signals.
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Brandeberry, Jessica L. "A Passive Seismic Investigation of the Crustal Structure under Ohio." Connect to full text in OhioLINK ETD Center, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1196909328.
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Thesis (M.S.)--University of Toledo, 2007.Typescript. "Submitted as partial fulfillment of the requirements for The Master of Science in Geology." "A thesis entitled"--at head of title. Accompanied by CD-ROM which contains the following files: 2000-2003 Teleseismic Reduced Traveltimes.xls; 2000-2003 Teleseismic Traveltimes.xls; 2004 Teleseismic Reduced Traveltimes.xls; 2004 Teleseismic Traveltimes.xls; 2005 Teleseismic reduced Traveltimes.xls; 2005 Teleseismic Traveltimes, xls; 2006 Teleseismic Reduced Traveltimes. xls; 2006 Teleseismic Traveltimes. xls; Complete Thesis.doc; Regional Earthquake Data.xls; Teleseismic Earthquake Data.xls. Bibliography: leaves 78-80.
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Gavazzi, Bruno. "Méthode magnétique multi-échelle à trois dimensions appliquée à l'étude archéologique du site de Qasr 'Allam, oasis de Bahariya, Egypte." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAG029/document.
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Cette étude propose d'examiner les vestiges archéologiques de Qasr ʿAllam enfouis sous les sédiments en développant une approche géophysique adaptée aux contextes du site. La mesure du champ total à l'aide de magnétomètres vectoriels à vanne de flux permet la mise au point de dispositifs multi-capteurs qui permettent une acquisition au rapport rapidité/densité hautement modulable. Ainsi des cartes verticales et horizontales de l'anomalie de l'intensité du champ magnétique à différentes échelles sont établies. L'utilisation et le développement d'outils d'interprétation issus de la théorie du potentiel, couplés à des fouilles ciblées, permettent à la fois de d'obtenir des informations sur les sources et d'améliorer la méthode grâce aux preuves-terrain. Les résultats ainsi obtenus révèlent la présence d'un système d'irrigation complexe et étendu, d'un ensemble cultuel massif du 8e/7e siècle avant l'ère commune et d'un second ensemble plus petit postérieur de plusieurs siècles. Entre ces deux derniers un changement environnemental brutal d'un milieu humide à aride a manifestement eu lieu. Tous ces résultats permettent d'établir des cartes des vestiges pour l'étude archéologique et l'établissement d'un périmètre de protection du siteThis study proposes to investigate the archaeological remains covered by sediments in Qasr ʿAllam by developing a geophysical method adapted to the contexts of the site. The measurement of the magnetic total field with fluxgate vector magnetometers allows the design of multi-captor devices which enable an acquisition of data with a highly adjustable rapidity/density ratio. Thus, vertical and horizontal maps of the anomaly of the magnetic total field's intensity are established. The use and development of interpretative tools derived from the theory of potential fields in association with targeted excavations allow the procurement of information on the sources as well as the improvement of the method through field evidences. The results reveal the existence of a large and intricate irrigation system, of a massive cultic facility dating from the 8th/7th century before the Common Era, and of a smaller complex built a few centuries later. Evidences also show that a massive change from humid to arid environmental conditions took place during the time separating the two latter. All these results allow the establishment of maps of the remains for archaeological studies and the establishment of a perimeter of protection of the site
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Tamba, Robert. "From archaeological prospection to communication using learning theory. Multi-variable maping and 3D representations in archaeology and built heritage." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/393977.
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La geofísica arqueològica es basa en la mesura de propietats físiques. S'aplica per la documentació de jaciments arqueològics. Inclou una seqüència de tasques que en tres fases (1) el camp, (2) la transformació de les dades I (3) la finalització del projecte.
A través de la presentació de tres casos d'estudi, la recerca presentada aquí il.lustra diverses aportacions. Primer, s'avalua la seqüència de tasques d'un projecte per proposar punts de control de la qualitat i consistència de les dades. Després s'ha plantejat una aproximació didàctica dels resultats de geofísica arqueològica per mil-lorar els formats de transmissió de la informació. Finalment, s'ha estudiat la inter-acció de diferents tipus de dades arqueològiques amb la informació obtinguda de la geofísica.
L'avaluació de la seqüència de treball ha permès definir punts de control de la qualitat de la prospecció. Durant la fase de camp es recomana l'ús d'un qüestionari pel disseny de l'estratègia de prospecció, es defineixen els objectius arqueològics i les limitacions del projecte, i es prepara l'entorn del jaciment prèviament a l'adquisició de les dades. La transformació de les dades requereix la identificació i caracterització del soroll d'adquisició, la vectorització de les dades i la producció de mapes sintètics. La finalització ha d'incloure les metadades del projecte, les representacions dels resultats en diferents formats i l'ús de formats oberts de fitxers.
L'aproximació didàctica dels resultats ha permès classificar els formats de lliura-ment de resultats. La memòria tècnica representa una presentació conductista. L'estructura és fixa i lineal. Amb una presentació cognitiva es varien els formats. En suplement a la memòria tècnica s'ha generat una memòria gràfica, una seqüència animada i un model. El model representa una visió constructivista, ja que permet a
l’usuari tenir un control directe de la interpretació de les dades i observar-les des de diferents perspectives.
Finalment, s’ha estudiat la combinació de tres tipus d’informació arqueològica amb dades geofísiques: un model topogràfic digital, dades de prospecció de materials superficials i resultats d’excavacions. El model topogràfic digital va ser combinat amb dades de georadar per avaluar l’estat de conservació d’un artefacte monumental. Les dades de prospecció superficial s’han interpretat conjuntament amb les dades geofísiques per caracteritzar la seqüència d’ocupació d’una vila romana. Les dades d’excavació arqueològica s’han integrat amb els resultats geofísics en una plataforma comuna per documentar la destrucció d’un assentament romà.The research was placed at the confluence of three fields: Archaeological Geophysics, Archaeology and Learning Theory. The two latter were considered in order to im-prove the transmission process of archaeological geophysics results. Archaeological Geophysics is based on the use of methods that measure the contrast in physical properties. It is applied to map the context of archaeological sites. The mapping helps with the management of the research. The outputs of Archaeolog-ical Geophysics projects are produced through a nested sequence of decisions and actions. The sequence was separated in three phases: field, data transformation and data finalisation. The field phase includes the design of the project and the data acquisition survey. The transformation phase is dedicated to the processing of the acquired data and to their interpretation. During the finalisation, the data and metadata of the project are archived and the results are transmitted to the end-user. Geophysical results are not often integrated in the communication process of archae-ological findings. The main hypothesis of the research was that this absence can be explained by failure situations that occur during any phase of a project. Failure situation can be explained by results with insufficient resolution, not adequately transformed or poorly transmitted. The main objective of the research was to pro-pose solutions to identify and limit these failure situations in order to improve the final transmission of the results. Three approaches were proposed. The transmission process was analysed considering the different Learning Theory currents. A behaviourist approach gave a linear understanding of the information. It is based on standards and clearly defined con-tents. Its main vector would be the technical report. The cognitive contribution was the diversification of the formats of transmission. In addition to the technical report, a graphical report, an animated sequence and a model of the results were systematically produced. This associated material was created taking into account the relation between text, image and sound in order to improve the understanding process. The model represented the constructivist current. It enables the end-user having a personalised experience of the created environment through increased control and interactivity. The second approach was to describe in detail the workflow of an Archaeological Geophysics project. The description aimed to define control points that could favour a better quality of the produced material. Control points were defined at each phase. In the field phase they include (1) the use of questionnaire during the design of the project, (2) the production of a diagram stating the archaeological objectives, the used methods and their limitations and (3) an appropriate preparation of the environment of the site prior to the acquisition of the data. The control points of the transformation phase were (1) the characterisation of the acquisition noise, (2) the vectorisation of the results with associated attributes and (3) the production of synthetic maps. The finalisation phase should include (1) the metadata of the project, (2) several parallel formats of transmission of the results and (3) open source formats for the digital archive.