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1
Wombacher, Frank. "The stable isotope geochemistry and cosmochemistry of cadmium." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=967287685.
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Thomas, Katherine S. S. M. Massachusetts Institute of Technology. "Organic geochemistry and stable isotope constraints on Precambrian biogeochemical processes." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/69474.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2011.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 91-101).<br>Details of the biogeochemical cycles and the dominant mechanisms present in Precambrian remain heavily debated topics. The events of the Late Proterozoic onset to glaciations and what types of early life existed in the Archean are two of the many provoking topics within the Precambrian. We set out to improve the understanding of these geologic intervals by examining stable isotopic signatures and molecular fossils (biomarkers) in Late Proterozoic and Mesoarchean ages sedimentary rocks in Northwestern Territories, Canada and Pilbara, Western Australia, respectively. This thesis presents sulfur, carbon, oxygen and nitrogen stable isotopic data along with distribution of steranes and hopanes biomarkers. Geochemical data is analyzed in the context of elucidating the key biological and environmental factors involved in the Mesoarchean marine biosphere and the Late Proterozoic onset of glaciations. Stable isotopic analysis of the Gorge Creek Group in Pilbara, Western Australia reveals organisms capable of microbial sulfur disproportionation were likely the dominant biological players in Mesoarchean deep-ocean sulfur cycling. Biomarker and isotopic proxies of the Coppercap Formation reveal diverse biological activity directly prior to the Sturtian Glaciation with communities of green and purple sulfur bacteria as well as methanotrophs and cyanobacteria. Possible environmental implications of these communities co-existing are explained in context of changes in ocean chemistry and the diversification of eukaryotic life.<br>by Katherine S. Thomas.<br>S.M.
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Morisset, Natalie Carleton University Dissertation Geology. "Stableisotope and radioisotope geochemistry of the Panda Hill carbonatite, Tanzania." Ottawa, 1992.
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Khademi-Moghari, Hossein. "Stable isotope geochemistry, mineralogy, and microscopy of gypsiferous soils from central Iran." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23945.pdf.
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Dong, Shuofei. "Stable (Cu, Zn) and radiogenic (Pb) isotope geochemistry of airborne particulate matter." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/10746.
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The aim of the thesis was to test the isotope systematics of Cu, Zn and Pb in atmospheric particulate matter and potential source material in order to critically discuss its implications and applications to studies of global biogeochemical cycles and anthropogenic impact. Four specific objectives were addressed: First, we tailored existing analytical methods to enable for the first time accurate and precise Cu and Zn isotope ratio measurements in dust and aerosol samples with low element content. Second, we studied the Pb, Cu and Zn isotope composition in aerosols collected in London to test their potential to trace anthropogenic sources in the urban atmosphere. Third, we characterized the Cu and Zn isotope systematics of major Asian and African dust sources and constrained possible controls and implications on the marine isotope signature. Finally, we investigated the isotope fractionation of Zn during dissolution experiments with acidic solution of natural dust to test the possible effect of atmospheric processing on the isotope signature of deposited Zn. The conclusions from this work are: First, stable isotopes confirm that brake and tyre emissions are the likely dominant sources of Zn and Cu in urban aerosols and that recycled Pb deposited originally from leaded gasoline still contributes significantly to the burden of atmospheric Pb in London. Second, we show that the Cu and Zn isotope signatures vary significantly between the major Asian and African dust sources and we find a significant correlation between Cu isotope ratio and illite content. Mass balance calculation suggest that bulk samples record faithfully the isotope signature of the <4 μm fraction. Third, significant isotope fractionation of Zn is observed during dust dissolution suggesting that the isotope signature of Zn deposited in the surface ocean is not only controlled by source mixing but also by atmospheric processing during long range transportation. The work clearly supports the initial hypothesis that metal isotopes are powerful sources to study global and regional biogeochemical cycles.
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Faure, Kevin. "A stable isotope study of the Kaap Valley Tonalite, Barberton Mountain Land, South Africa." Master's thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/15849.
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Bibliography: pages 100-109.<br>The Kaap Valley Tonalite (KVT) was a homogenous hornblende+ biotite tonalite that had been subjected to overail propylitic and potassic alteration. Petrographic studies reveal that carbonate alteration and increased proportions of hydrous minerals occur along the KVT and Barberton greenstone belt contact zone, and along major shear zones within the KVT.
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Peel, Kate Elizabeth. "Studies into the Stable Isotope Geochemistry of Copper and Zinc in Aquatic Systems." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503795.
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Hopley, Philip J. "Palaeoenvironmental reconstruction of South African hominin-bearing cave deposits using stable isotope geochemistry." Thesis, University of Liverpool, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402265.
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Scott, Gillian Anne. "Contemporary ecology and stable isotope geochemistry of benthic foraminiferids in the Celtic Sea." Thesis, Bangor University, 1998. https://research.bangor.ac.uk/portal/en/theses/contemporary-ecology-and-stable-isotope-geochemistry-of-benthic-foraminiferids-in-the-celtic-sea(ed14ac68-ce51-4156-8420-773fee552fb7).html.
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The primary aim of this thesis was to assess the value of foraminifera in downcore studies of shelfsea stratification using both assemblage and geochemical characteristics. An examination of the modern distribution of foraminifera in the context of stratification in the Celtic Sea and comparison of these distributions with measured environmental variables was undertaken to this end. In addition, several species were examined for their stable oxygen and carbon isotopic composition with reference to the ambient bottom and porewaters. Cruises were run to the Celtic Sea in July, 1995 and July-August, 1996, during which hydrographic data, water and surface sediment samples were collected from 138 stations. Fifty-three samples were subsequently analysed for grainsize, geochernical and foraminiferal properties, while the water samples were analysed for oxygen isotopic composition. A total of six multicores were extracted and sectioned. Each section was analysed for porewater carbon isotopic composition and foraminiferal content. Selected foraminifera from both the surface and subsurface samples were analysed for the oxygen and carbon isotopic composition of their test calcite. Statistical analyses of the foraminiferal data indentifed four distinct assemblages which have potential for palaeostratification studies. The mixed-type assemblage included Cibicides lobatulus, Ammonia beccarfi, Quinqueloculina seminulum, Textularia bockii and Spiroplectammina, wrightfi. The stratifiedtype assemblages included Bulimina marginata, Hyalinea balthica, Nonionella turgida and Adercotryma glomeratum while Stainforthis fusiformis was diagnostic of the front. Bulimina gibba, Elphidium excavatum forma selseyensis and Eggerelloides scabrus defined an eastern asseblage. It is believed that the true controls on these assemblages are oxygen and food supply. Ammonia beccarii precipitated its test in oxygen isotopic equilibrium while Q. seminulum was consistently, negatively offset by approximately 0.5 O/oo. This demonstrates the potential of these species in palaeo-temperature and particularily, palaeo-stratifcation studies. The 'microhabitat effect' was examined for several species of foraminifera but was not observed.
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De, Baun Derik K. "Silica Replacement in the Southern White Pine Range, East Central Nevada| A Stable Isotope Study." Thesis, California State University, Long Beach, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10841608.
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<p> In the southern White Pine Range (SWPR) silica is found to have been deposited from hydrothermal solution within the Currant Gap Detachment fault (CGD). Silica has been observed to occur in three modes of deposition: (1) narrow veins within the lower plate Pole Canyon limestone, (2) bulk silicification of carbonates and (3) breccia matrix found in proximity to the CGD. </p><p> Through stable isotope analysis of oxygen from quartz samples and hydrogen from fluid inclusions we see that there is a history of meteoric waters penetrating into the Lower Pole Canyon Formation, in the lower plate of the CGD. This study reveals that silica in the SWPR formed from aqueous fluids at temperatures between 260 °C and 315 °C within lower plate quartz veins and 150 °C to 300 °C within the upper plate of the CGD. These temperature ranges are in line with what would be expected in a brittle regime (T < 350 °C).</p><p>
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Fan, Majie. "Geochemistry and Basin Analysis of Laramide Rocky Mountain Basins." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195756.
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The Laramide Rocky Mountains in western U.S.A is an important topographic feature in the continental interior, yet its formation and evolution are poorly constrained. This study uses the oxygen and strontium isotope geochemistry of freshwater bivalve fossils from six Laramide basins in order to reconstruct the spatial evolution of the paleotopography and Precambrian basement erosion in late Cretaceous-early Eocene. In addition it uses the sedimentology, detrital zircon U-Pb geochronology, and isotope paleoaltimetry of early Eocene sedimentary strata to constrain the tectonic setting, paleogeography and paleoclimate of the Wind River basin. Annual and seasonal variation in ancient riverwater δ¹⁸O reconstructed from shell fossils shows that the Canadian Rocky Mountains was 4.5±1.0 km high in late Cretaceous-early Paleocene, and the Laramide ranges in eastern Wyoming reached 4.5±1.3 km high, while the ranges in western Wyoming were 1-2 km high in late Paleocene. The ⁸⁷Sr/⁸⁶Sr ratios of riverwaters reconstructed from the same fossils show that Proterozoic metamorphic carbonates in the Belt-Purcell Supergroup were not exposed in the Canadian Rocky Mountains during Late Cretaceous-early Paleocene, but that Precambrian silicate basement rock was exposed and eroded in the Laramide ranges during late Paleocene-early Eocene. The sedimentary environment of the early Eocene Wind River basin changed from gravelly fluvial and/or stream-dominated alluvial fan to low-sinuosity fluvial systems. Tectonic uplift of the Washakie and Wind River Range in early Eocene formed the modern paleodrainage system, although the elevation of the basin floor was only ~500 m high at that time, and early Eocene paleoclimate is more humid than modern climate.
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Martinez, Iúma Aparecida. "Stable isotope geochemistry of the Okenyenya igneous complex, Namibia : constraints on contamination and fluid interaction." Master's thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/21694.
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The δ¹⁸O values of coexisting silicate minerals in rocks comprising the tholeiitic olivine gabbro - quartz monzodiorite suite, are consistent with the attainment of isotope equilibrium and largely closed system conditions. The majority of the temperatures calculated by conventional mineral-pair thermometers are spurious, as a result of oxygen isotope diffusion during slow cooling. Closure temperatures for oxygen diffusion of 560ᵒC and 540ᵒC have been calculated for the anorthite-clinopyroxene and plagioclase-biotite mineral-pairs in the tholeiitic leucogabbro sample, respectively. The oxygen isotope data for the silicate minerals are consistent with contamination of the magmas by material having the oxygen isotope composition of the southern Etendeka rhyolite (δ¹⁸O = + 11.5‰). It is suggested that the assimilant may have been derived from the same source as the southern Etendeka rhyolite, as opposed to the rhyolite itself, which would be expected to occur at a high crustal level. Simple oxygen and strontium isotope mass balance calculations are used to constrain the lower (14 % and 19.5 % respectively) and upper (57 % and 71.6 % respectively) limits of the maximum possible amount of a southern Etendeka rhyolite contaminant assimilated.
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Jemielita, Richard Alfred. "Geochemistry and stable isotope study of porphyry-related mineralisation, central Front Range, Colorado, U.S.A." Thesis, University of Aberdeen, 1987. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU004472.
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The central part of the Front Range mineral belt, Colorado, is a Precambrian crystalline basement terrain intruded by early Tertiary porphyries and closely associated mesothermal ore deposits. The ore deposits are gold- and silver-bearing base metal sulphide-quartz veins arranged in more or less well developed concentric mineral zones centred on concealed porphyry plutons. Central areas of pyritic mineralisation are surrounded by peripheral zone of galena-sphalerite-bearing veins, often separated by a transitional zone of composite mineralisation. Molybdenite-bearing and uraninite-bearing veins are locally abundant proximal to the central pyritic zones and are closely associated spatially and temporally with highly evolved quartz bostonite intrusions. The mineral veins are enveloped in narrow selvages of sericitized and argillized wallrock and are entirely fracture controlled. A low density lithogeochemical survey of the country rocks revealed strong lithological controls on the distributions of selected trace elements and radiation emission values. Positive Rb/Sr anomalies are tentatively linked to concealed intrusions, and corresponding positive anomalies of Pb, Zn, Mo and W are associated with known molybdenite mineralisation. Sericitized rocks are characterised by low Sr and enhanced Rb, Zn, Pb, Mo and Ag values, and areas of depleted country rock Sr values may be related to vein wallrock alteration. D/H and <SUP>18</SUP> O/<SUP>16</SUP> O signatures of fresh country rocks indicate variable magmatic water overprinting and similar analyses of sericitised rocks show that alteration was accomplished by magmatic hydrothermal fluids at 340<SUP>o</SUP> -515<SUP>o</SUP> C. Mineralisation and alteration in the area were caused by hydrothermal fluids evolved from highly differentiated Laramide quartz bostonite intrusions. K-Ar ages of ca. 62 Ma have been obtained from alteration sericites from the peripheral mineral zone. Similar studies in the central pyritic zone have yielded ages of ca. 59 Ma suggesting the existence of long lived hydrothermal activity in the area characterised by widespread high-temperature alteration, followed by thermal decay and collapse towards core zones. The ore deposits investigated during this study display numerous features in common with porphyry-style and other intrusive-related mineralisation characteristic of Cordilleran terrains, but also exhibit significant differences. The combination of these features contribute to the distinct and possibly unique character of these mineral deposits.
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McEwan, C. J. A. "Geology, geochemistry and stable isotope studies of an epithermal hydrothermal system, Rosita Hills, Colorado." Thesis, University of Aberdeen, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383565.
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The Rosita Hills volcanic centre is an alkali-calcic mid-Tertiary caldera complex overlying ortho- and paragneissic basement on the eastern margin of the Wet Mountains graben in southcentral Colorado. There were two mineralising events at the Rosita centre. Au, Ag and base metal mineralisation occurred in a phreatomagmatic breccia pipe at the northern margin of the complex. Later, Ag and base metal mineralisation occurred in veins in the centre of the complex. Mapping, petrological and XRD studies outline 4 alteration facies related to hydrothermal activity at the centre. Propylitic/argillic, K-feldspar-sericitic, advanced argillic and silicic alteration assemblages are recognised. The areas of most intense alteration are controlled by the dominant structural trends within the caldera. Sub-volcanic magma movement is postulated as the dominant cause of the fracture patterns. A lithogeochemical grid survey for Au, Ag, Sr, Rb, Cu, Pb, Zn and Mn across areas of hydrothermal alteration reveal complex patterns indicative of multi-stage hydrothermal activity. District-wide Sr, Zn and Mn depletions are related to the propylitic/argillic alteration. Au, Ag, Rb and Cu enhancements are related to the K-feldspar-sericite alteration. Late stage advanced argillic alteration modified the trace element dispersion patterns by leaching previously formed enhancements. Stable isotope studies (O and H) of whole rock and mineral separate (quartz and sericite) samples from veins and hydrothermal eruption breccias show that the hydrothermal fluid had both meteoric and magmatic components. δD values from whole rock samples show a crudely concentric pattern centring on areas of sericitic and advanced argillic alteration in the middle of the lithogeochemical grid. Fluid inclusion data from vein gangue minerals (quartz, baryte and sphalerite) and from silicified rock in the advanced argillic alteration zone again show that the hydrothermal fluid had more than one component fluid. A highly saline, high temperature fluid occurs in quartz associated with base metal mineralisation. Less saline inclusions occur in the upper parts of the system in the silicic alteration. The data indicate that mixing of these two end-member fluids precipitated the vein mineralisation. The source of metals in the Bassick breccia pipe orebody was a highly differentiated magma body underlying the breccia pipe. Incipient ring faulting probably controlled the emplacement of the magma. Other similar breccia pipes in Colorado are postulated as overlying Cu-Mo porphyry mineralisation. The source of the metals in the Rosita vein orebodies was the volcanic host rocks (and the Precambrian basement?). The Rosita Hills vein mineralisation shows features typical of adularia-sericite systems in the western United States. The Au:Ag ratio in these deposits can be related to the origins of the crust underlying the deposits.
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Klein, Trevor Isaac. "Investigating nitrate attenuation in an urban stream using stable isotope geochemistry and continuous monitoring." Master's thesis, Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/319212.
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Geology<br>M.S.<br>Urbanization affects in-stream biogeochemical processes that control nutrient export. Attempts to restore urban streams will not be successful unless the biological and physical controls on water quality are thoroughly understood. The objective of this study was to identify the relative influences of tributary dilution, groundwater discharge, and biological processing on nitrate concentrations in an urban stream during high and low flow periods. A wastewater treatment plant (WTP) on Pennypack Creek, an urban stream near Philadelphia, PA, increases nitrate concentrations to a mean of 8.5 mg-l-1 (as N). Concentrations decrease to 5.5 mg-l-1 about 7.5 km downstream. Reaches along this distance were sampled for nitrate concentration and delta-15N at fine spatial intervals to determine the reasons for this decrease. To quantify the effects of dilution, samples were collected from tributaries, groundwater springs, and upstream and downstream of tributaries or groundwater discharge zones identified through terrain analysis and continuous temperature modeling. These methods were also used to identify and sample reaches along which hyporheic flow occurred, where nitrate biological processing is often concentrated. In addition, loggers were installed at closely spaced sites to monitor daily fluctuations in nitrate, dissolved oxygen, and related parameters, which provided further indications of biological processing. Longitudinal sampling revealed decreases in nitrate concentration of 2 and 6.5 mg-l-1 during high and low flow, respectively. During high flow, delta-15N varied from 9.5 to 10.5 per mille downstream of the WTP, while delta-15N varied from 10.14 to 11.06 per mille throughout this reach during low flow. Mixing analysis indicated that groundwater discharge and biological processing both control nitrate concentration during both flow periods. Larger declines in nitrate concentration were observed during low flow than during high flow, and delta-15N fell between biological and groundwater signatures, indicating that both processes were enhanced. Continuous nitrate concentrations displayed distinct diurnal cycles often out-of-phase with dissolved oxygen cycles, indicating autotrophic processing. However, shifts occurred in nitrate cycle timing at a weekly scale wherein daily maximum concentrations were observed as many as 6 hours closer to noon than previously. These shifts were comparable to shifts observed across seasons in other studies, and by the end of the summer, nitrate and dissolved oxygen cycles were in-phase. Furthermore, shifts in nitrate cycles could not be linked to shifts in daily fluctuations of WTP discharge. Longitudinal sampling and continuous monitoring suggest that biological processing is an important control on nitrate concentrations in urban systems, though documenting its signature may be complicated by groundwater discharge and anthropogenic inputs.<br>Temple University--Theses
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Stevenson, Emily Isabel. "Stable strontium isotope fractionation in marine and terrestrial environments." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:a2d97fc7-3e9d-484a-8026-11c118fcc3fd.
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The work reported in this thesis applies a new isotope tracer, stable strontium isotopes (δ<sup>88/86</sup>Sr), to address questions concerning changes in global climate that occur in response to continental weathering processes, and to constrain the modern marine geochemical Sr cycle. Stable Sr isotopes are a relatively new geochemical proxy, and as such their behavior needs to be understood in differing forms of marine calcium carbonate, the archives from which records of past stable Sr variability in the oceans can be constructed. Foraminifera, coccoliths and corals (both aragonite and high Mg calcite) acquire δ<sup>88/86</sup>Sr values lighter than that of modern day seawater, (approximately 0.11, 0.05, 0.2 and 0.19 ‰ lighter than seawater at ~25°C respectively) providing a measureable offset which can be used to constrain the modern Sr outputs from the ocean and provide a better understanding of the modern Sr cycle. Using foraminifera as a sedimentary archive the first marine δ<sup>88/86</sup>Sr record of seawater over the last two glacial cycles has been constructed, and used to investigate changing carbonate input and output over this 145 kyr period. Modelling of the large excursion of δ<sup>88/86</sup>Sr to heavier values during Marine Isotope Stage (MIS) 3, reveals that this is more likely to be due to local changes in seawater or post-depositional alteration, rather then whole ocean changes. In the terrestrial environment δδ88/86<sup>Sr</sup> has been measured in the dissolved load of rivers from the Himalaya. It is found that, in general, rivers draining carbonate catchments possess lighter isotopic δ<sup>88/86</sup>Sr values than those from rivers draining silicates. Covariations of either δ88/86Sr vs. δ30Si or δ<sup>88/86</sup>Sr vs. 1/[Sr] can be used to distinguish between rivers draining different catchment areas.
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Calkins, Brad Thomas 1953. "Petrographic, geochemical, X-ray, and stable isotope studies at the Morenci porphyry copper deposit, Greenlee County, Arizona." Thesis, The University of Arizona, 1997. http://hdl.handle.net/10150/278615.
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Morenci is located in southeast Arizona. Copper grade hypogene mineralization averages 0.15%; one or more generations of supergene enrichment have increased mineralization to 0.96%. Intense supergene alteration has made it difficult to determine phyllosilicate paragenesis. The purpose of this study is to differentiate hypogene from supergene phyllosilicates. Forty-nine samples from five drill holes were obtained for petrographic, geochemical, mineralogical, and stable isotope data. Petrographic examination, X-ray diffraction and X-ray powder camera techniques established alteration of feldspars to kaolinite, montmorillonite, and sericite. Whole rock analyses using XRF determined cationic gains and losses that correspond with kaolinite and sericite. Stable isotopes of oxygen and hydrogen using kaolinite and sericite from 14 samples were tested to determine provenance of water. Stable isotope data show a trimodal distribution of phyllosilicates consistent with early hypogene alteration of magmatic origin, and two generations of supergene enrichment due to meteoric waters.
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Walowski, Kristina. "From Cinder Cones to Subduction Zones: Volatile Recycling and Magma Formation beneath the Southern Cascade Arc." Thesis, University of Oregon, 2015. http://hdl.handle.net/1794/19310.
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Volatiles (H2O, CO2, S, Cl) play a key role in magmatic processes at subduction zones. In this study, the dissolved volatile contents of olivine-hosted melt inclusions from cinder cones in the Lassen segment of the Cascade arc are used to investigate dehydration of subducted oceanic lithosphere, magma formation in the sub-arc mantle wedge, and mafic magma storage and evolution in the crust.
Relatively young, hot oceanic lithosphere subducts beneath the Cascade arc. The hydrogen-isotope and trace-element compositions of melt inclusions, when integrated with thermo-petrologic modeling, demonstrate that fluids in Cascade magmas are sourced from hydrated peridotite in the deep slab interior and that the oceanic crustal part of the slab extensively dehydrates beneath the forearc. In contrast to their slab-derived H, the melt inclusions have B concentrations and isotope ratios that are similar to mid-ocean ridge basalt (MORB), requiring little to no slab contribution of B, which is also consistent with extensive dehydration of the downgoing plate before it reaches sub-arc depths. Correlations of volatile and trace element ratios in the melt inclusions (H2O/Ce, Cl/Nb, Sr/Nd) demonstrate that geochemical variability in the magmas is the result of variable amounts of addition of a hydrous subduction component to the mantle wedge. Radiogenic isotope ratios require that the subduction component has less radiogenic Sr and Pb and more radiogenic Nd than the Lassen sub-arc mantle and is therefore likely to be a partial melt of subducted Gorda MORB. These results provide evidence that chlorite-derived fluids from the deep slab interior flux-melt the oceanic crust, producing hydrous slab melts that migrate into the overlying mantle, where they react with peridotite to induce further melting.
The basaltic magmas that erupted at Cinder Cone near Mt. Lassen trapped melt inclusions during olivine crystallization at ~7-15 km depth. The melt inclusion compositions require that two different mantle-derived magmas were involved in the eruption, and temporal changes show that arrival of the two batches correlates with two explosive phases of activity. Both magmas experienced rapid crustal contamination before erupting, illustrating the complexities of cinder cone eruptions.
This dissertation includes previously published and unpublished co-authored material.
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Brown, Christine P. "A stable isotope study of fluid-rock interaction in serpentinites of the Franciscan Complex, San Rafael Mountains, California." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1526895.
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<p> The fluid history of serpentinites from three locations in the Franciscan Complex, San Rafael Mountains, California is evaluated with petrologic and stable isotope data that allow interpretation of the serpentinization history and tectonic origin of these rocks. Petrologic evidence shows that most samples were originally serpentinized in a relatively low temperature seafloor hydrothermal environment, but some rocks underwent subsequent recrystallization. Data obtained from serpentine-magnetite geothermometry indicate that the serpentinization temperatures ranged from 168°C to 306°C. Oxygen isotopic values suggest that the serpentinites may have originated in a forearc setting. Hydrogen isotopic values obtained do not reflect the original conditions of serpentinization, but indicate that the rocks subsequently underwent isotopic exchange with meteoric water once they were emplaced onto the continent.</p>
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Fang, Yi. "A stable isotope study of fluid-rock interactions in the San Gabriel fault zone and its relationship to seismic process." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1527313.
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Sutcliffe, Nadine C. "Strontium stable isotope behaviour accompanying melting and magmatism in the Earth-Moon system." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:826ae843-3115-4a3e-975a-f6306f923d4e.
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This thesis concerns the application of a new technique for measuring the stable isotopes of Sr, specifically pertaining to mass dependent fractionation in high temperature processes on the Earth and Moon. Processes such as mantle melting and differentiation on Earth and the formation of the Lunar Magma Ocean are investigated by the application of a double-spike TIMS method to terrestrial and lunar material to obtain high-precision <sup>87</sup>Sr/<sup>86</sup>Sr, <sup>88</sup>Sr/<sup>86</sup>Sr and <sup>84</sup>Sr/<sup>86</sup>Sr data. Measurements of mantle-derived mafic material provide insights into the <sup>88</sup>Sr/<sup>86</sup>Sr composition of the silicate mantle. Ocean Island Basalts possess restricted δ<sup>88</sup>Sr compositions, whilst Mid-Ocean Ridge Basalts from the Pacific, Atlantic and Indian ridges reveal variations in δ<sup>88</sup>Sr, the majority of which is seen within the FAMOUS section of the Mid-Atlantic Ridge. These variations are attributed partly due to the effects of plagioclase crystallisation and partly due to mantle source heterogeneity. Analyses of mineral separates from three different igneous systems provide an understanding of δ<sup>88</sup>Sr fractionation at a mineral-scale. The possibility of δ<sup>88</sup>Sr fractionation as a result of magmatic differentiation has also been assessed, and found to occur between the basalt and rhyolitic end-members of the Icelandic Hekla suite. Variations in the <sup>87</sup>Sr/<sup>86</sup>Sr ratios of these rocks are also found, and considered most likely to be due to contamination. Analyses of lunar rocks indicate that the highland suite appears to be relatively uniform in δ<sup>88</sup>Sr, whilst significant fractionation to light δ<sup>88</sup>Sr compositions occurs in the mare basalts. Such variations are thought to be associated with the crystallisation of plagioclase during the differentiation of the lunar magma ocean. Lastly, precise <sup>87</sup>Rb/<sup>86</sup>Sr and <sup>87</sup>Sr/<sup>86</sup>Sr data yield a model age for the Moon of 4.523 ± 0.019 Ga.
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Barrett, Paul. "A comparative organic geochemical and stable isotope study of the Cenomanian-Turonian organic-rich sediments from Tunisia, Germany and the UK." Thesis, University of Newcastle Upon Tyne, 1998. http://hdl.handle.net/10443/957.
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A comparative multidisciplinary study has been undertaken of organic-rich Cenomanian-Turonian (C-T) sediments from Tunisia, Germany and the UK. Three hundred samples were taken from a total of 7 field localities and have been analysed using bulk and stable carbon isotope geochemistry (all samples), palynofacies (most samples) and molecular biomarker and pyrolysis geochemistry (selected samples). Most of the sections are thermally immature. All but one of the sections could be correlated using the organic carbon S13C curve, which shows a strong (<3%o) excursion at the C-T boundary, followed by a gradual return to background values (ca. -25.5%o). Relative to this excursion, there is a slight apparent difference in the stratigraphic development of the organic-rich sediments at different locations. Of the sediments studied, the Balhoul Formation of Tunisia shows the highest concentration and best preservation of organic matter (0.2-8.0% TOC, 50-850 hydrogen index); together with darker colours and more frequent lamination, this suggests a more poorly oxygenated regime than in NW Europe (0.2-4.0% TOC, 6-140 HI), probably related to an upwelling intensified oxygen minimum zone (OMZ) on the south Tethyan margin. Data from the two northernmost (offshore) Tunisian sections indicate poorer preservation, which by modem analogy is attributed to deeperwater deposition below the suboxic core of the OMZ. Methylhopanes and bisnorhopane are abundant in the richest (OMZ core) facies. Principal Component Analysis of kerogen pyrolysates from Py-GC and Py-MS analyses are dominated by the relative variations of aliphatic and aromatic compounds between the sections which largely reflect differences in the preservation of the predominantly marine organic matter (30-98% AOM).
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Moertle, Jasmine A. "Stable isotope evidence for a complex fluid evolution of the Northwestern British Columbia Coast Mountains related to terrane accretion." Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10147322.
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<p> Stable isotope analysis of thirty-five samples from the Northwestern Coast Mountains indicates a complex fluid history related to terrane accretion, metamorphism, and magmatism. The greenschist to amphibolite facies metasedimentary rocks from the Western Metamorphic Belt have variable δD and δ<sup> 18</sup>O values that appear to be in isotopic equilibrium with metamorphic fluids at low water-rock ratio conditions. Carbon isotope values indicate organic rich protoliths. Stable isotope values from the Coast Shear Zone indicate the involvement of both magmatic and meteoric-hydrothermal fluids during deformation, in contrast to meteoric-free fluid systems related to Au-mineralization along strike to the north (Goldfarb et al., 1988). The Coast Mountain Batholith and Central Gneiss Complex have homogeneous δD and δ<sup> 18</sup>O values that indicate magmatic fluids at low water-rock ratio (Magaritz and Taylor, 1976). Further to the east, large amounts of meteoric-hydrothermal fluids circulated through a network of ductile-to-brittle normal faults (Andronicos et al., 2003; Heah, 1990).</p>
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Vennemann, Torsten Walter. "A geochemical and stable isotope study of some rocks from the Bandelierkop formation, southern marginal zone of the Limpopo Belt, South Africa( vol.1 Text)." Doctoral thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/23476.
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The Bandelierkop Formation of the Southern Marginal Zone (SMZ) of the Limpopo Belt consists of metamorphosed ultramafic, mafic and sedimentary rocks. Metamorphic conditions indicated by the petrography of these different rock groups are consistent with upper amphibolite to granulite facies. The ultramafic and mafic rocks are geochemically akin to peridotitic-pyroxenitic intrusive rocks and high-Mg basalts respectively. Metamorphism of these two rock groups in the SMZ was an essentially closed system process, except for the highly volatile phases such as H₂O and CO₂. The metasediments appear to represent a sequence of high (Mg+Fe)-greywackes and/or deep-water shales with minor amounts of iron formation material. The unusually mafic character of the metasediments can be ascribed to a high ultramafic + mafic source component to the original sediment. Some modification of the major and trace element compositions of the pelitic rocks has been caused by the removal of partial melts and the metamorphism of the pelitic rocks is not therefore considered to have occurred under closed system conditions. Variable extraction of partial melts is implied by the chemical variations shown by the pelitic rocks and is also suggested by the presence of large pegmatitic felsic bodies which are commonly found close to the pelitic rocks. Detailed petrographic study of the Bandelierkop Formation rocks suggests an increase in metamorphic grade, and/or a decrease in water activity, from south to north within the Southern Marginal Zone. Peak metamorphic conditions of 730°C + 65°C at pressures of 6.1 ± 1.5 kbars may be deduced from a careful application of several cation thermometers and barometers on selected mineral analyses. A rigorous application of garnet-biotite thermometry to the pelitic rocks indicates that the transition from orthoamphibole gneisses in the south to orthopyroxene-bearing rocks in the north of the SMZ terrane, is a function of changing biotite composition and/or decreasing water activities rather than an increase in metamorphic temperatures. In contrast to the major and trace element data, the stable isotope data for the ultramafic and mafic rocks in the SMZ indicate open system behaviour for some of these rocks, but closed system behaviour for the pelites. Extraction of SO to 70% partial melts from the pelitic rocks, should not, however, have affected the δ¹⁸O value of the restite. Petrological and stable isotope data in the SMZ rocks are consistent with retrogression in all these rocks and open system behaviour for oxygen in some ultramafic and mafic rocks, being caused by the crystallization and accompanying fluid release of melts produced during prograde metamorphism of the pelitic rocks. Small scale (-5 to 30m's) heterogeneity is implied by both oxygen and carbon stable isotope compositions of closely spaced rock samples, even for those collected from within large "shear zones", suggesting small fluid/rock ratios for most of the samples in the high-grade terrane or heterogeneous stable isotopic compositions of the fluids. Furthermore, a similarity in mineral-mineral stable isotope fractionation factors is observed for all the pelitic rocks, including the orthoamphibole gneisses found immediately south of the orthopyroxene isograd. These features preclude the presence of pervasive fluid infiltration after peak metamorphism. Two implications are, that granulite facies metamorphism in the SMZ terrane was not caused by an influx of mantle derived CO₂-rich fluid and, that the orthoamphibole gneisses are not retrogressed equivalents of the granulites found to the north of the orthopyroxene isograd. It is suggested that this isograd represents a change in the water activities of the rocks during metamorphism. Apparent disequilibria in mineral - mineral stable isotope fractionations observed amongst different minerals within any one pelitic rock, may be explained by a combination of the crystallization of residual melt within these rocks and oxygen diffusion amongst minerals which have not reached their oxygen-closure. The concordant quartz-plagioclase, quartz-biotite and plagioclase-biotite oxygen isotope equilibration temperatures are taken to represent minimum crystallization temperatures for the melts (-560°C), while successively higher quartz-orthopyroxene, quartz-amphibole and quartz-garnet oxygen isotope equilibration temperatures are a function of increasing closure temperatures for the orthopyroxene, amphibole and garnet respectively. The minimum estimate to peak metamorphic temperatures is given by the quartz-garnet oxygen isotope temperature averaging 736 + 52°C. If oxygen diffusion experiments performed in hydrothermal systems are appropriate for the SMZ rocks, then cooling rates for the SMZ terrane could have been as low as 12 to 25°C/My over a temperature range of 480 to 600°C. Stable isotope modeling of hypothetical fluids that may have been in equilibrium with the high-grade rocks, suggests that a mixture of CO₂ and H₂O, with CO₂/H₂O mole ratios > 0.1 can precipitate both quartz and carbonate of stable isotope composition similar to those determined for quartz and carbonate from the mineralized Archaean lode gold deposits of the Murchison and Pietersburg greenstone belts. A model involving granulite facies metamorphism, partial melt extraction and subsequent release of fluids, Au, K and S upon crystallization of such melts, appears to be viable for gold mineralization occuring in the adjacent lower grade greenstone belts and in the high-grade terrane of the Southern Marginal Zone.
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Barna, Joshua M. "VARIABILITY IN GROUNDWATER FLOW AND CHEMISTRY IN THE HOUZHAI KARST BASIN, GUIZHOU PROVINCE, CHINA." UKnowledge, 2019. https://uknowledge.uky.edu/ees_etds/65.
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Understanding how karst aquifers store and transmit water and contaminants is an ongoing problem in hydrogeology. Flowpath and recharge heterogeneity contribute to the complexity of these systems. This thesis explores karst-conduit connectivity and water chemistry variability in the Houzhai catchment in Guizhou province, China. Artificial tracer tests were conducted during both the monsoon and dry seasons to understand temporal variability in connectivity and water velocity between karst features. Multiple flowpaths through the catchment are activated during the monsoon season and partially abandoned during the dry season. Additionally, gradient reversals during monsoonal high-flow events and as a result of pumping can be significant. Synoptic water samples from several karst features taken during both monsoon and dry seasons elucidate spatial and temporal variability within the catchment. In general, water residence time is longer during the dry season and flow within the Houzhai catchment is temporally dependent. Time-series sampling at the outlet spring during a monsoonal storm event captured chemical variability and identified multiple flowpaths. Overall, this study refines widely applicable methods for studying karst systems to this catchment and provides a foundation for future studies in similar settings.
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Basapuram, Laxmi Gayatri Devi. "Lake Victoria - Carbon, Nitrogen, Phosphorus and Stable Isotope (δ13C) comparison between lake and catchment sediments". Thesis, Linköpings universitet, Tema Miljöförändring, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-149283.
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Lake Victoria situated in East Africa faces an acute problem with eutrophication. Many reasons like agricultural production, industrialization, anthropogenic processes, the introduction of species, and economic activities have caused a stress to the overall well-being of the lake. Excess carbon, nitrogen, and phosphorus drive an increase in productivity which affects eutrophication. Previous studies on sediments and nutrient concentrations in the lake have concluded that nutrient concentrations increase due to release from the catchment. This study focuses on catchment sediments collected from four different sites and compares the results with sediments from two additional sites in the lake. The sediment core from Siaya indicates the highest concentrations of TOC (180 g/kg), TN (13 g/kg) and TP (17000μg/L). It is a rural site and poor agricultural practices such as the burn and slash, use of too many fertilizers, clearance of land, atmospheric deposition and precipitation increase elemental concentrations in the sediments compared to the more urban sites. In the lake sediments, the BILL core had higher concentrations of TP (430g/kg) and TN (16 g/kg) compared to the other site (LV-95) which is located far away from the margins of the lake. This core, however, had high TOC levels (180g/kg). The increase of nutrient levels in lake sediments is thought to be due to non-point sources from the catchment. Analyses of stable carbon isotope were used to infer the different organic matter source in the sediments. Based on the range of values for δ13C vs. C/N it is inferred that aquatic algal production and C4 vascular plants are the dominant sources for the organic matter input. The chemical characterization of catchment and lake sediments provides a qualitative link to nutrient influx and eutrophication in the lake.
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Li, Tianjiao. "The Geochemistry and Runoff Process in Wolf Creek Research Basin, Whitehorse, Yukon Territory." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/30302.
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This study investigates the runoff process and groundwater behavior in a subarctic watershed called Wolf Creek Research Basin, in Whitehorse, Yukon Territory, Canada. This basin is underlain by discontinuous permafrost that is typical of high latitude watersheds. Goundwater supports the stream flow year round and dominated the hydrology in most of the study period as baseflow. The baseflow was concentrated in dissolved ions. However, the baseflow was diluted during the melt season in May and June of 2012. Multiple chemical and isotopic tracers were used to develop a robust three-component (groundwater, soilwater and precipitation) mixing model for runoff generation. The concentrations of weathering ions decreased with the increased discharge during the melt. Soilwater was responsible for about 60% of the streamwater on the hydrograph in the melt season. The infiltration of the meltwater from the snowpack and the thawed water from the seasonal frost to the baseflow existed. The tritium concentrations indicated that there was fast moving hydrogeological system within the basin. The baseflow was also characterized as relatively enriched in both 13C and 14C, and concentrated in DIC. DIC was the major loss of carbon in Wolf Creek Research Basin.Le pergélisol est grandement sous-jacent dans les bassins-versants à haute latitude. Cette étude examine le processus de ruissellement et le comportement des eaux souterraines dans un bassin-versant subarctique de Wolf Creek, à Whitehorse, territoire du Yukon au Canada. Les eaux souterraines soutenaient l’écoulement fluvial et dominaient l’hydrographe comme débit de base durant la majorité de la période d’étude. Le débit de base était concentré d’ions dissipés. Par contre, le débit de base était dilué durant la saison des fontes au mois de mai et juin 2012. Plusieurs traceurs chimiques et isotopiques étaient utilisé afin de développer un modèle de trois composants (eau souterraine, eau interstitielle de sol et précipitation) de ruissellement. Les concentrations de la déségrégation des ions diminuaient avec l’augmentation du débit durant la fonte. Les eaux interstitielles des sols étaient responsables de 60% de l’eau de ruisseau sur l’hydrographe durant la saison de fontes. L’infiltration de l’eau de fonte du manteau neigeux et l’eau du gel du débit de base existaient. Les concentrations de tritium indiquent qu’il y avait un système hydrogéologique qui se déplaçait à grande vitesse dans les limites du bassin. Le débit de base était aussi caractérisé comme étant enrichi en 13C et 14C, avec des concentrations en carbone inorganique dissous.
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Rodland, David Laurence. "Spatial variability in modern brachiopod assemblages: paleoecological and geochemical implications." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/27858.
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An accurate understanding of global patterns through geologic time depends upon multi-scale analyses of spatial variation within narrow temporal intervals. This work investigates geochemical and paleoecological patterns in modern brachiopod faunas which may serve as analogues for ancient brachiopod assemblages. The paleoclimatic utility of delta18O in the phosphatic phase of lingulid brachiopod shells requires valve secretion in equilibrium with seawater, an assumption tested (and rejected) when analyzed at scales ranging from millimeters to kilometers. By contrast, biological encrustation of the brachiopod fauna of the Southeast Brazilian Bight shows strong sensitivity to microenvironmental conditions such as host identity, shape, and size, and may prove useful for studies of ancient planktonic productivity. Comparison of encrustation patterns on naturally occurring brachiopods and bivalves collected from the same sites, and occupying the same size range, demonstrates that the results of encrustation studies on modern bivalves cannot be directly applied to ancient brachiopods. However, careful comparisons may reveal patterns of epibiont selectivity and the impact of changes in the relative abundance of host shells through geologic time. Finally, neither epibiont abundance nor diversity increase with host age as indicated by dated brachiopod shells from the past 1000 years. These results suggest that the temporal resolution of epibiont assemblages matches their spatial resolution, and strengthen evidence for competition among encrusting taxa. By documenting geochemical and paleoecological variation within shells and across a continental shelf, this work demonstrates the importance of understanding spatial variation across all scales before interpreting trends through time.<br>Ph. D.
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Widanagamage, Inoka Hasanthi. "STABLE STRONTIUM ISOTOPE FRACTIONATION IN ABIOTIC AND MICROBIALLY MEDIATED BARITE IN MODERN CONTINENTAL SETTINGS." Kent State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=kent1445344122.
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Gu, Ailiang. "Stable Isotope Geochemistry of Sulfate in Groundwater of Southern Arizona: Implications for Groundwater Flow, Sulfate sources, and Environmental Significance." Diss., The University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2005_023_sip1_w.pdf&type=application/pdf.
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Watkins, Richard Charles. "Foraminiferal biostratigraphy, palaeocology and stable isotope geochemistry of the Santonian to Lower Campanian chalks of the Anglo-Paris Basin." Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295837.
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Lysiak, Nadine Stewart J. "Investigating the migration and foraging ecology of North Atlantic right whales with stable isotope geochemistry of baleen and zooplankton." Restricted access (UM), 2008. http://libraries.maine.edu/gateway/oroauth.asp?file=orono/etheses/37803141.pdf.
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Heimhofer, Ulrich. "Response of terrestrial palaeoenvironments to past changes in climate and carbon-cycling : insights from palynology and stable isotope geochemistry /." Zurich : [Swiss Federal Institute of Technlogy], 2004. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=15463.
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Shah, Mumtaz Muhammad. "Hydrothermal dolomites in the plateform carbonates (early albian) of the Ranero zone (NW Spain) : Distribution, petrography, geochemistry and their genesis." Thesis, Saint-Etienne, EMSE, 2011. http://www.theses.fr/2011EMSE0627/document.
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Ce mémoire décrit les corps dolomitiques des zones de Ranero et El Moro (vallée de la Karantza, zone Cantabrique, NO de l’Espagne) et précise les variations temporelles et latérales de leurs attributs pétrographiques et géochimiques. Les corps dolomitiques sont portés par les calcaires Albiens, déposés sur la marge du bassin Basque-Cantabrique en période d’intense subsidence. Les dolomies sont formées par replacement et par cémentation, et précédées et suivies par divers types de ciment calcitique. L’étude pétrographique, minéralogique et géochimique (XRD, ICP, XRF, isotopes stables et Sr) est conduite le long de sections transverses sur les corps dolomitiques et permet de comparer les caractéristiques de plusieurs stades de circulations hydrothermales. Deux épisodes contrastés de dolomitisation sont identifiés. Les dolomies précoces sont ferreuses, très localement associées à une minéralisation de type MVT, appauvries en δ18O (de -14 à -10‰ V-PDB) et remplacent largement les calcaires massifs en générant des zebras. Les dolomies tardives sont non-ferreuses, plus sévèrement appauvries en δ18O (-19 to -15‰ V-PDB), et ne semblent pas remplacer le calcaire mais, au contraire, les dolomies précoces. Toutes ces dolomies sont pratiquement stœchiométriques (49.76 à 51.59 mole% CaCO3). Leurs inclusions fluides ont piégé des saumures de haute température (Th de 120 à 200°C). Leur contenu en Sr, radiogénique, suggère que les fluides responsables de la dolomitisation ont préalablement circulé à travers des roches silicoclastiques. La texture comme les propriétés pétrophysiques des dolomies sont largement affectées par les déformations cataclastiques et un épisode tardif de dédolomitisation (météorique).Le premier épisode de dolomitisation résulte probablement de l’expulsion des fluides issus de la compaction du bassin adjacent et de leur migration le long des fractures affectant la marge de la plateforme carbonatée Albienne. Ces fluides précoces étaient riches en Mg, Fe et peut-être légèrement acides pour pouvoir remplacer les calcaires. Les fluides responsables du deuxième épisode de dolomitisation sont pauvres en Fe, paraissent plus chauds et en relation avec une anomalie thermique<br>This study documents the temporal and lateral variation in petrographic and geochemical signatures of fault-related dolomite bodies in the Ranero and El-Moro areas (Karrantza valley, Cantabrian mountains; NW Spain). These dolomite bodies are hosted in Albian carbonates, which were deposited at the margin of the Basque-Cantabrian Basin during an intense rift-related subsidence. Fluid circulations generated replacive and cementing dolomites, paragenetically predated and followed by various calcite cements. Petrography, mineralogical and geochemical systematics (XRD, ICP, XRF, stable and Sr isotopes) along sections cutting the dolostone bodies document successive hydrothermal stages. Two contrasting dolomite formation events are evidenced. Early dolomites are ferroan, locally associated with MVT mineralisation, δ18O depleted (-14 to -10‰ V-PDB) and mostly replace limestone producing abundant zebra lithotypes. Later dolomites are non-ferroan, severely δ18O depleted (-19 to -15‰ V-PDB), and do not replace limestones but rather previous dolomites. Dolomites are generally stoichiometric (49.76 to 51.59 M% CaCO3). Fluid inclusions record high temperature brines (Th 120 to 200°C). Sr isotope data suggest that the dolomitising fluids interacted upstream with siliciclastic lithologies. The dolomite fabric and its petrophysical properties are variably altered through cataclastic deformation and late (meteoric) dedolomitisation.The first episode of pervasive ferroan dolomitisation probably resulted from compactional dewatering of basinal fluids from the nearby Basque trough and hydrodynamic fluid flow along the fractures in the Albian carbonate platform. These early fluids must have been Mg, Fe-rich and slightly acidic (limestone-replacive). The second episode of very hot and localized dolomitisation may be related to a thermal anomaly and/or convective flow of Fe-poor fluids
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Grabb, Kalina C. "Stable Isotope Systematics of Abiotic Nitrate and Nitrite Reduction Coupled With Anaerobic Iron Oxidation: the Role of Reduced Clays and Fe-Bearing Minerals." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17417576.
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Under anaerobic conditions, it is widely assumed that nitrate (NO3-) and nitrite (NO2-) reduction is primarily the result of microbial respiration (Burgin and Hamilton, 2007; Granger et al., 2008). However, it is also proven that the abiotic reduction of nitrate and nitrite by reduced iron(II) (Fe(II)), whether mineral-bound or surface-associated, may also occur under certain environmentally relevant conditions (Chao and Kroontje, 1966; Straub et al., 1996; Picardal, 2012,). With a range of experimental conditions, nitrogen and oxygen stable isotope systematics of abiotic nitrite reduction by Fe(II) were investigated in an effort to characterize the biotic and abiotic processes in the environment. While homogenous reactions between NO2- and Fe(II) in artificial seawater (ASW) showed little reduction, heterogeneous reactions involving Fe-containing minerals showed considerable nitrite loss. Specifically, rapid nitrite reduction was observed in experiments that included reduced nontronite clay and an Fe(II)-Fe(III) hydroxide mineral, termed green rust. These iron oxides and clay minerals offer both a source of reduced iron in the mineral matrix as well as a surface for Fe(II) activation. Additional control experiments with corundum as a non-Fe containing mineral surface showed little NO2- loss, implicating a more dominant role of structural iron in the clays during nitrite reduction. In experiments with nontronite and green rust the isotope effects (15ε and 18ε) ranged from 3 to 16‰ for 15ε and 2 to 6‰ for 18ε. Nitrite reduction rates and 15ε values within an experimental condition were directly correlated with slower reactions having higher isotopic fractionation. The apparent 18ε was affected by oxygen atom exchange with water, which lowered the isotope effect. Although little data exist for comparison with the dual isotopes of microbial NO2- reduction, these data serve as a benchmark for evaluating the role of abiotic processes in nitrogen (N) reduction, particularly in sediment systems low in organic carbon and high in reduced iron.<br>Engineering Sciences
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Grant, George W. "Characterization and climate reconstruction of the Ekblaw site, Quttinirpaaq NationalPark, Canada." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1556837847169027.
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Gustin, Mae Sexauer. "A PETROGRAPHIC, GEOCHEMICAL AND STABLE ISOTOPE STUDY OF THE UNITED VERDE OREBODY AND ITS ASSOCIATED ALTERATION, JEROME, ARIZONA." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/187546.
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The United Verde orebody, a Proterozoic volcanogenic massive sulfide deposit, is hosted by the Cleopatra Formation. The Cleopatra Formation is subdivided into two distinct members, the Upper and Lower, on the basis of alteration facies, whole rock geochemistry and the chemistry of alteration minerals. The Lower member was deposited prior to ore deposition and consists of five major alteration facies. Facies Bl, the most distant from the orebody represents the recharge area for the ore-forming fluid. Facies B2 surrounds the major discharge area or the chlorite pipe. These three facies contain chlorite and quartz as alteration minerals in variable amounts. Two facies, 81 and S2, contain quartz and sericite as alteration minerals. Mass balance calculations show progressive removal of Na and Ca, and addition of MgO and FeO* from the area of recharge (facies Bl) to facies B2 to the chlorite pipe. Whole rock δ¹⁸O values are high relative to least altered Cleopatra Formation in the recharge area and low in the discharge zone. Mineralogy and geochemistry of samples from the Upper member indicate that it was deposited following ore deposition and interacted with fluids rich in silica and iron. The hydrothermal fluid, which is interpreted to have been seawater, evolved to a high temperature slightly acidic, reduced fluid during water-rock interaction(log a₀₂ = -33 to -41; log a(H2S) = -2.6 to -5.0). The fluid δ¹⁸O and δ¹³C₀₂ values increased. Calculated δ¹³C₀₂ and δ¹⁸O fluid values, and sphalerite and chlorite chemistry imply that mixing of the hydrothermal fluid with seawater occurred in the orebody. the upper The levels of the chlorite pipe and in limited range in δ³⁴S values of sulfides is consistent with the derivation of the oreforming fluids from the reduced basal layer of a stratified basin. The study area represents only a small part of the United Verde circulation cell. Increased δ¹⁸O values of the fluid, and the need for a source of Mg, Fe and other metals suggest that the fluids may have circulated into the Shea Basalt.
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Volkmann, Renate. "Planktic foraminifer ecology and stable isotope geochemistry in the Arctic Ocean : implications from water column and sediment surface studies for quantitative reconstructions of oceanic parameters = Ökologie planktischer Foraminiferen und stabile Isotope im Arktischen Ozean /." Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung, 2000. http://www.gbv.de/dms/bs/toc/315939354.pdf.
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Payne, Caldwell Robert. "Alteration, Mineralization, and Stable Isotope Geochemistry of the Wind Mountain and Willard-Colado Epithermal Deposits, Nevada: Implications for Amagmatic Hydrothermal Activity." OpenSIUC, 2014. https://opensiuc.lib.siu.edu/theses/1396.
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The Wind Mountain (WM) and Willard-Colado (WC) deposits, respectively of Washoe and Pershing Counties, Nevada, represent recent episodes of low-sulfidation, epithermal gold-silver mineralization. They have the principal features of amagmatic epithermal deposits including 1) young ages (<7 Ma), with Willard-Colado at 6.03 ± 0.04 Ma and Wind Mountain at a Pliocene or younger age, 2) absence of associated coeval igneous rocks, 3) development along range-front fault zones, and 4) proximity to modern geothermal systems. Such deposits in the Great Basin are generated by deeply convecting meteoric hydrothermal fluids that derive their thermal energy from the region's high heat flow and metals and volatiles from the traversed rock packages or shallow mantle. Hydrothermal alteration assemblages at both WM and WC are zoned outward from controlling structures along stratigraphic horizons and subsidiary structures, grading through silica, silica-kaolinite, kaolinite, and hematite-rich zones. Silicic and argillic alteration represents main stage hydrothermal activity; significant steam-heated alteration lithocaps are absent. Weathering-related, acid-sulfate fluids overprinted mineralized rocks at both deposits, oxidizing pyrite, remobilizing Au, and producing widespread hematite-goethite-kaolinite-alunite alteration. Gold mineralization is unique at each deposit but formed in several general paragenetic stages. Element maps generated by laser ablation-inductively coupled plasma-mass spectrometry demonstrate that primary Au is in solid solution with pyrite or arsenian pyrite forming patchy concentrations and enriched rims. Secondary and possibly remobilized Au occurs as disseminated electrum and native gold along fractures in silicified rocks. Elevated concentrations of Ag, As and Sb spatially correlate with primary and secondary Au. A final stage is represented by gold in Fe-oxide/hydroxide rims on pyrite crystals or aggregates. The hydrothermal fluids at WM and WC dominantly consisted of meteoric water, based on their low δ18OH2O and δDH2O values calculated from quartz δ18O, kaolinite δ18O and δD, and calcite δ18O data and assumed temperatures characteristic of the epithermal environment. Black calcite prominently fills the range-front faults where at WM it displays a banded texture and contains acicular Mn-oxide inclusions and at Colado is part of a vein sequence grading from centrally distributed quartz, through quartz-calcite and calcite to distal gypsum. Calcite δ13C values are similar to those of igneous and some sedimentary carbon but distinct from values for tufas along the WM range-front fault and at Pyramid Lake. Alunite and gypsum have negative δ34S values indistinguishable from those of pyrite, as well as from H2S in the San Emidio geothermal fluids near WM. This isotopic correspondence results from kinetically inhibited, nonequilibrium isotopic exchange during the low temperature oxidation of reduced sulfur species. It is consistent with the surficial and near surface formation of gypsum, particularly at WM where lenticular gypsum beds are in stratigraphic proximity to sinter containing reed casts. Alunite δ34S values, combined with a psuedocubic habit and association with quartz, support an origin by weathering rather than steam-heated processes. The absence of steam-heated alteration at both deposits is likely related to a high water table during hydrothermal activity, which at WM was expressed by springs depositing sinter or gypsum. Collectively, the data for Wind Mountain and Willard-Colado are consistent with the amagmatic genetic model. Meteoric hydrothermal fluids circulating along range front faults assimilated C, S and potentially Au and other metals from organic bearing sedimentary±volcaniclastic and metasedimentary host rock packages and (or) sediments in adjoining Cenozoic basins. Although they lack a steam-heated alteration lithocap, such as those prominently displayed at the Hycroft and Florida Canyon amagmatic deposits, weathering pervasively altered the tops of the deposits following a substantial drop in the water table due to a change to a drier climate or uplift of the ranges due to local tectonism.
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Moores, John, Robert Brown, Dante Lauretta, and Peter Smith. "Experimental and theoretical simulation of sublimating dusty water ice with implications for D/H ratios of water ice on Comets and Mars." BioMed Central, 2012. http://hdl.handle.net/10150/610231.
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Sublimation experiments have been carried out to determine the effect of the mineral dust content of porous ices on the isotopic composition of the sublimate gas over medium (days to weeks) timescales. Whenever mineral dust of any kind was present, the D/H ratio of the sublimated gas was seen to decrease with time from the bulk ratio. Fractionations of up to 2.5 were observed for dust mixing ratios of 9 wt% and higher of JSC MARS-1 regolith simulant 1-10 mum crushed and sieved fraction. These favored the presence of the light isotope, H2O, in the gas phase. The more dust was added to the mixture, the more pronounced was this effect. Theoretical modeling of gas migration within the porous samples and adsorption on the excavated dust grains was undertaken to explain the results. Adsorption onto the dust grains is able to explain the low D/H ratios in the sublimate gas if adsorption favors retention of HDO over H2O. This leads to significant isotopic enrichment of HDO on the dust over time and depletion in the amount of HDO escaping the system as sublimate gas. This effect is significant for planetary bodies on which water moves mainly through the gas phase and a significant surface reservoir of dust may be found, such as on Comets and Mars. For each of these, inferences about the bulk water D/H ratio as inferred from gas phase measurements needs to be reassessed in light of the volatile cycling history of each body.PACS CODES:98.80.Ft Isotopes, abundances and evolution (astronomy)], 64.70.Hz Sublimation], 68.43.-h Adsorption at solid surfaces]
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Heinemann, Niklas. "Physical and chemical effects of CO2 storage in saline aquifers of the southern North Sea." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/9686.
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One of the most promising mitigation strategies for greenhouse gas accumulation in the atmosphere is carbon capture and storage (CCS). Deep saline aquifers are seen as the most efficient carbon dioxide (CO2) storage sites, mainly because of their vast size and worldwide distribution. Injecting CO2 into brine filled media will cause a physical and chemical disequilibrium in the formation. This PhD thesis documents the investigation of some of the resulting effects which occur at the beginning of the injection, during the injection period and millions of years after injection. When CO2 is injected into a brine filled reservoir, large amounts of in situ brine will be displaced away from the injection well. This causes a pressure increase in the vicinity of the well which may compromise the injection process. The simulation of this pressure increase was performed with the black-oil simulator Eclipse10 (Schlumberger) while using a number of recent formulas to predict the mutual dissolution and the fluid properties of CO2 and brine. The results show that the pressure increase can exceed the maximum sustainable pore pressure and will cause fracturing of the reservoir formation. The pore pressure increase is dependent on parameters such as temperature and salinity because they change the fluid properties of the CO2 and brine, but also the capability of the fluids to dissolve mutually. The mutual dissolution has generally a pressure reducing effect although its impact is regarded to be overestimated. This is mainly because reservoir engineering software cannot simulate the shock front realistically. Undulations, which appear on the injection pressure profile are not a result of model instabilities but can either be related to enhanced mutual dissolution due to grid effects, or to the software which may overestimate or underestimate the pressure and dissolution. A detailed investigation of those undulations is vital for the interpretation of the injection pressure. High fluid pressure can be an important parameter for the estimation of the CO2 storage capacity of saline aquifers such as the offshore Bunter Sandstone Formation, in the UK southern North Sea. Based on fluid pressure, the 1 storage capacity was calculated using the ECLIPSE compositional simulation package and a simple analytical equation. The estimated storage capacity is 6.55 to 7.17 Gt of CO2 calculated with the analytical and the numerical approach respectively. By comparing the results, the differences are relatively moderate and therefore the application of the numerical simulator is not regarded as necessary. This is mainly due to the effective pressure flow which prevents pressure accumulations underneath the cap rock. Although the CO2 storage capacity of the Bunter Sandstone Formation remains high, a previous survey, which was not based on fluid pressure, calculated a storage capacity approximately twice as high as the results presented here. In theory, due to the increase in CO2 concentration, CO2 bearing carbonate minerals could precipitate when CO2 is injected into an aquifer such as the Rotliegend aquifer in the southern North Sea. Geochemical models often predict a relatively rapid growth of carbonate minerals as the most secure form of long term engineered CO2 storage. But validation of model-results remains difficult due to the long periods of time involved. Natural analogue studies can bridge the gap between experiments and real-world storage. The Fizzy field, a southern North Sea (UK) gas accumulation with a high natural CO2 content (c. 50%) provides an ideal opportunity to study the long term effect of CO2 related mineral reaction. However all such reservoirs contain ‘normal’ diagenetic dolomite, so that distinguishing sequestration related dolomite is a challenge. CO2 was stepwise extracted from dolomite from both the Fizzy field and the Orwell Rotliegend sandstone in order to reveal any zonation of the crystals which could be related to enhanced dolomite precipitation due to the high CO2 concentration. According to the method between 0 and 22 % of the dolomite in the Fizzy field precipitated due to the high CO2 concentration. Therefore, between 0 and 19 % of the CO2, which is related to the relatively recent high CO2 concentration, is ‘trapped’ in the ‘sequestration dolomite’. The wide range of this estimate is mainly related to rock heterogeneity.
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Reis, Alex J. "A MULTI-INDICATOR APPROACH TO UNDERSTANDING THE DIAGENESIS OF CARBONATES IN PENNSYLVANIAN MUDROCKS OF THE MIDLAND BASIN." UKnowledge, 2018. https://uknowledge.uky.edu/ees_etds/56.
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The Late Pennsylvanian was a time of frequent, rapid glacioeustatic sea-level changes. These changes were recorded in the Wolfcamp D Formation of the Midland Basin as a series of cyclothems similar to those studied in the Midcontinent region (e.g., Algeo and Heckel, 2008). This study focuses on identifying the mechanisms and controls on carbonate deposition and diagenesis through the Upper Pennsylvanian Wolfcamp D Formation and evaluating the potential for these layers to be stratigraphically significant. A stepwise progression of diagenetic processes was identified through the use of δ13Ccarb and δ18Ocarb, bulk geochemical and petrographic analysis, and scanning electron microscopy. Carbonate deposition and early-burial diagenesis appears to be strongly influenced by frequent changes in sea-level and benthic redox conditions. The transition to deep-burial diagenesis was controlled by the thermal gradient in the basin and the extent of diagenesis by the amount of clays and organic matter in the surrounding mudrocks. Further diagenesis was induced through interactions with a brine following clay diagenesis. The presence of multiple phases of diagenesis in this system further highlights the need for several lines of inquiry when evaluating the post-depositional evolution of carbonates in a mud-rich setting.
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Tamakloe, Frank. "A JOINT XRF-δ13Ccarb CHEMOSTRATIGRAPHIC APPROACH FOR CHARACTERIZING PALEO-ENVIRONMENTAL PROCESSES IN THE MUDSTONE-DOMINATED WOLFCAMP FORMATION OF WEST TEXAS". UKnowledge, 2019. https://uknowledge.uky.edu/ees_etds/69.
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The Late Paleozoic Ice Age represents a dynamic period in Earth system history recording a shift from icehouse to greenhouse conditions. Concomitant with this change was a series high-frequency, high-amplitude sea level fluctuations leading to the deposition of “Kansas type” cyclothems in the Mid-Continent, and a similar rhythmic expression of interbedded shales and carbonates in the Midland Basin. Stable isotope geochemistry is a particularly powerful tool when examining these mud-rich successions because changes in organic matter partitioning may be recorded first in δ13CDIC of sea-water and consequently in δ13Ccarb of marine rocks. The δ13Ccarb record may also illuminate early and late-stage diagenetic processes and associated destruction of organic matter.
This study used high-resolution x-ray fluorescence (XRF) and δ13Ccarb measurements to analyze paleo-environmental conditions in two cores within the Midland Basin Wolfcamp Formation. Using this approach, the combination of more positive δ13Ccarb measurements and enrichment of redox-sensitive elements reflect conditions more favorable for organic matter enrichment in the distal core. Additionally, four (< 6 in.) early-diagenetic intervals have been identified representing prolonged periods of reduced or non-deposition based on sharp negative δ13Ccarb excursions. These horizons are proposed as potential chronostratigraphic tie-points between the two core localities.
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Singh, Updesh. "Late Precambrian and Cambrian carbonates of the Adelaidean in the Flinders Ranges, South Australia : a petrographic, electron microprobe and stable isotope study /." Title page, abstract and contents only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phs1792.pdf.
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Harke, Ryan Michael. "Stable Isotope Analysis of Busycon sinistrum to Determine Fort Walton-Period Seasonality at St. Joseph Bay, Northwest Florida." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4328.
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ABSTRACT
Recent archaeological investigations indicate that coastal Fort Walton cultures in the St. Joseph Bay region of northwest Florida emphasized marine and estuarine foraging. These late prehistoric (A.D. 1000-1500) peoples collected fish, shellfish, and other aquatic resources. At the Richardson's Hammock site (8Gu10), radiocarbon-dated to about A.D. 1300, as at dozens of other shell middens around this salty bay, large gastropods were a major subsistence component. This adaptation is in sharp contrast with that of contemporaneous inland Fort Walton societies, who relied on maize agriculture. It is unknown whether coastal groups represent separate hunter-gatherer-fisher populations or seasonal migrations by inland farming villagers. This thesis research uses stable oxygen and carbon isotope analysis on lightning whelks (Busycon sinistrum) to determine the seasonality of Fort Walton foraging, and compares the environment of prehistoric St. Joseph Bay with that of the modern bay. Oxygen isotope profiles suggest that shellfish collecting was relegated primarily to the summer months, producing a scheduling conflict with the primary growing season for maize in northwest Florida. Thus, it is argued that coastal and inland Fort Walton probably represent separate culture groups. The relationship between d18Oshell and d13Cshell indicates similar environmental and climatic conditions between prehistoric St. Joseph Bay and today. However, modern whelks are depleted in d13C compared to Fort Walton whelks, which reflects both twentieth century CO2 emissions and years of dredging and wastewater pollution entering the bay.
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Regenberg, Marcus [Verfasser]. "Inorganic and stable isotope geochemistry of tropical Atlantic, Caribbean planktonic foraminifera : implications for the reconstruction of upper ocean temperatures and stratification / Marcus Regenberg." Kiel : Universitätsbibliothek Kiel, 2008. http://d-nb.info/1019553014/34.
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Cyr, Andrew J. "GEOCHEMICAL AND STABLE ISOTOPIC EVALUATION OF FENGHUOSHAN GROUP LACUSTRINE CARBONATES, NORTH-CENTRAL TIBET: IMPLICATIONS FOR THE PALEOALTIMETRY OF THE MID-TERTIARY TIBETAN PLATEAU." Connect to this document online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1080329128.
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Thesis (Master of Science)--Miami University, Dept. of Geology, 2004.<br>Title from first page of PDF document. Document formatted into pages; contains [1], v, 76 p. : ill. Includes bibliographical references (p. 42-50).
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Gerhardt, Angela Mae. "Carbon cycle changes during the end-Marjuman (Cambrian) extinction in the Southern Appalachians." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/48028.
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The late Cambrian-early Ordovician transition contains several trilobite extinctions. The first of these extinctions (the end-Marjuman) is thought to coincide with the Steptoean Positive Carbon Isotope Excursion or SPICE, a large and rapid excursion in the marine carbon isotope record. This excursion, which is expressed in sedimentary successions globally, is thought to represent a large perturbation to the carbon cycle during this time. Additionally, a limited amount of carbon isotope data from the Deadwood Formation in the Black Hills of South Dakota suggests the possibility of a small negative ẟ¹³C excursion near the extinction and preceding the SPICE. Previous high-resolution biostratigraphy has identified an expanded record of extinction event within the Nolichucky Formation of the Southern Appalachians making it an excellent candidate for the study of the precise relationship between the extinction and changes in the carbon cycle. This investigation confirms the onset of the SPICE occurs at the extinction boundary however no negative ẟ¹³C excursion occurs at the extinction boundary. Further there is no systematic relationship between local facies changes and ẟ¹³C or the extinction interval across the basin, which suggests that global environmental changes were responsible for both the ẟ¹³C record and the extinction event.<br>Master of Science
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Nitzsche, Kai. "Applying isotope geochemistry to identify mechanisms regulating the aquatic-terrestrial carbon and nitrogen dynamics across scales in a moraine landscape." Doctoral thesis, Humboldt-Universität zu Berlin, Lebenswissenschaftliche Fakultät, 2017. http://dx.doi.org/10.18452/17793.
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In dieser Studie wurden stabile Isotopenverhältnisse genutzt um die Mechanismen der aquatisch-terrestrischen C – und N-Dynamiken über verschiedene Skalenebenen hinweg in der Moränenlandschaft von Nordostdeutschland zu identifizieren; einer Landschaft, die stark landwirtschaftlich genutzt wird und in der es eine Vielzahl von kleinen Wasserkörpern (Sölle) gibt. Auf der regionalen Landschaftsskala spiegeln d13C-Isotopenkarten des org. Materials in Oberböden und von Pflanzenblättern eines 38.2 km2 großen Gebietes den Eintrag von org. Material von C3-Pflanzen, deren Wassernutzungseffizienz im org. Material des Bodens eingeprägt wurde, sowie den Eintrag von Mais (C4-Pflanze), wider. Die d15N-Isotopenkarte des org. Materials in Böden weist verschiedene Düngepraktiken hin. Auf der regionalen Sollskala deuten die d13C- und d15N-Isotopenwerte von Oberflächensedimenten von 51 Söllen auf kürzliche Einträge des org. Materials und Bewirtschaftungseffekte im Einzugsgebiet hin. Tiefere Sedimente sind durch die Ablagerung org. Materials von terrestrischen Pflanzen sowie dessen Umsetzungsgrad geprägt in Abhängigkeit von der Wasserführung. Auf der Transekt-Skala, d.h. entlang von Transekten von Erosions- zu Depositionsgebieten im Einzugsgebiet eines Solls, beeinflussen Erosion, Pflanzenproduktion, mikrobielle Umsetzung und Gülledüngung verschiedene Fraktionen des org. Materials. Auf der Aggregat-Skalenebene sind die Art und der Anteil spezifischer organo-mineral Assoziationen entlang des Transekts variabel. Bodenpartikel vom Feld und hereinwachsende Makrophyten sind die Quellen des org. Materials in Sedimenten. Diese Studie hat erfolgreich stabile Isotopenverhältnisse zur Identifikation von Mechanismen der C- und N-Dynamik auf individuellen Skalenebenen angewendet. Kleine Inlandwasserkörper sind Schlüsselelemente für die C- und N-Dynamik in landwirtschaftlich genutzten Moränenlandschaften.<br>In moraine landscapes, carbon (C) and nitrogen (N) dynamics can vary greatly across landscape structures and soil types especially when small water bodies are interspersed in the landscape. This study used stable isotope ratios to identify the mechanisms regulating the aquatic-terrestrial C and N dynamics across different scales in the young moraine landscape of NE Germany – a landscape intensively used for agriculture and interspersed with countless of small water bodies, the so-called kettle holes. At the regional landscape scale, d13C isoscapes of topsoil bulk soil organic matter (SOM) and plant leaves collected from a 38.2 km2 area revealed long-term inputs OM from C3 crops, which imprinted their water use efficiency status onto the soil, as well as short-term inputs from corn. The d15N SOM isoscape identified fertilization-induced impacts on the N dynamics of agricultural fields and grasslands. At the regional kettle hole scale, d13C and d15N of surface sediments of 51 kettle holes reflected recent OM inputs and management practices in the catchment. Deeper sediments recorded the degree to which the OM has been processed within the kettle hole depending on the water-logging period. At the transect scale, erosion, plant productivity, microbial decomposition and slurry fertilization affected OM fractions in topsoil along transects spanning erosional to depositional areas in the catchment of one arable kettle hole. At the aggregate scale, the pathway and magnitude of OM-mineral associations changed along the transect. OM in sediments was derived from clay- and silt-sized particles from the field, together with emergent macrophyte contributions. By means of stable isotopes techniques, different mechanisms were identified at the individual scales. Consideration of the spatial heterogeneity of all scales is essential to understand landscape C and N dynamics. Small inland water bodies are key constituents of C and N dynamics in moraine agricultural landscapes.
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Bonsall, Todd Andrew. "The geochemistry of carbonate-hosted Pb-Zn-Ag mineralization in the Lavrion District, Attica, Greece fluid inclusion, stable isotope, and rare earth element studies /." [Ames, Iowa : Iowa State University], 2008.
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