Academic literature on the topic 'Dissolution collapse'

The Regina Low is a collapse structure, formed as a result of dissolution of salt from the Middle Devonian Prairie Evaporite Formation. In this study, collapse has affected the Upper Cretaceous Pierre Shale and the Ardkenneth and Snakebite members of the Bearpaw Formation of the Montana Group; the Mennon, Dundurn, and Warman formations of the Sutherland Group; and the Floral and Battleford formations of the Saskatoon Group. A structural closure of 125–175 m approximates the thickness of the Middle Devonian Prairie Evaporite Formation. In the Early Pleistocene, about 54 m of collapse took place in eastern Regina accounting for the preservation of Snakebite Member. Major collapses of about 58 and 86 m took place in northern Regina during deposition of Middle Pleistocene, pre-Illinoian Dundurn Formation. The final major collapse of about 127 m took place in northeastern Regina between deposition of the lower and upper tills of the Floral Formation. Eighty-seven metres of this collapse took place during deposition of the Late Pleistocene, interglacial, Sangamon Pasqua Member of the Floral Formation. The Pleistocene fill in the Regina Low collapse structure suggests that collapse took place when dissolution of salt from the Prairie Evaporite Formation was accelerated by high hydraulic gradients created by the surcharge pressures of the glaciers.

Salt dissolution collapse-subsidence is proposed as the dominant tectono-stratigraphic control on the deposition of major sand trends across the northern Athabasca Oil Sands Deposit. Salt removal along linear dissolution trends 200 m below in the Prairie Evaporite (Middle Devonian) halite beds resulted in the collapse of the overlying Upper Devonian strata. The collapse-induced differential subsidence of the fault blocks formed the floor underlying the McMurray deposits in the 50 km long V-shaped Bitumount Trough extending across the northern area of the Athabasca Oil Sands Deposit. The lower and middle-upper McMurray sand trends filled the accommodation created by collapses of a linear chain of Upper Devonian fault blocks along the northern margin of the western Trough. A pair of tens-of-metres thick and 20–30 km long sand trends developed parallel in overlying accumulations of the lower and middle-upper McMurray Formation (Aptian). This half-graben tilted northward as the dissolution trend in the underlying Prairie Evaporite salt scarp widened, and the scarp margin was deeply embayed. Salt dissolution-induced structures were the principal control that located the large sand complexes exploited by bitumen mining projects. Earlier models of McMurray architecture interpreted the underlying karst collapse to have been largely pre-Cretaceous. This new architectural model reinterprets the spatio-temporal balance between erosion at the pre-Cretaceous surface and within the buried salt beds. Extensive salt removal resulted in collapse of the underlying hypogene karst during the late Aptian age. This resulted in the over-thickened multi-kilometres long McMurray sand trends. The underlying karst collapse resulted in unstable deposition surfaces along the sub-Cretaceous trough floors. This tectono-stratigraphic architecture, called the syndepositional model in this study, is proposed as an alternative to two other models, one of which proposes that deeply incised channel valleys and fills resulted from multiple significant sea-level fluctuations, while the other proposes that stacked parasequences accumulated along overlying shallow channels that meandered across a stable fluvio-estuarine coast.

Over the period of 30 years various scientists representing different fields have been studying disintegration of the USSR with unflagging interest. As of August 1, 2020, more than 300 books, 3000 articles, and 20 dissertations have been written in Russia alone. Generalization and critical analysis of this literature requires a monograph. But this task is so complex that for the time being the case is limited to historiographical articles. The purpose of this article is to identify the most popular points of view expressed by well-known experts on the problem of the disintegration of the Soviet Union. The analysis enables to draw the following conclusions. The existing explanations can be divided into two large groups. The first one includes works whose authors consider disintegration as the product of a combination of random circumstances, external causes, and mistakes of party and Soviet leaders, and therefore focus first on the study of the role of subjective and external factors, and, second, on the short period of time, 1985–1991, immediately preceding the disintegration. The second group includes works whose authors consider disintegration as a natural result of long-developed processes, search for its historical background, study trends in the development of the Soviet Union and the Union republics, and look at the disintegration systemically and comprehensively. In other words, the former consider disintegration to be a random phenomenon generated mainly by the events of 1985–1991, while the latter consider it to be a natural phenomenon with deep historical, economic, political, cultural, and social prerequisites and causes.

An advection–diffusion-limited dissolution model of an object being eroded by a two-dimensional potential flow is presented. By taking advantage of the conformal invariance of the model, a numerical method is introduced that tracks the evolution of the object boundary in terms of a time-dependent Laurent series. Simulations of a variety of dissolving objects are shown, which shrink and collapse to a single point in finite time. The simulations reveal a surprising exact relationship, whereby the collapse point is the root of a non-analytic function given in terms of the flow velocity and the Laurent series coefficients describing the initial shape. This result is subsequently derived using residue calculus. The structure of the non-analytic function is examined for three different test cases, and a practical approach to determine the collapse point using a generalized Newton–Raphson root-finding algorithm is outlined. These examples also illustrate the possibility that the model breaks down in finite time prior to complete collapse, due to a topological singularity, as the dissolving boundary overlaps itself rather than breaking up into multiple domains (analogous to droplet pinch-off in fluid mechanics). The model raises fundamental mathematical questions about broken symmetries in finite-time singularities of both continuous and stochastic dynamical systems.

AbstractThe dissolution of limestone and chalk (soluble carbonates) through geological time can lead to the creation of naturally formed cavities in the rock. The cavities can be air, water, rock or soil infilled and can occur at shallow levels within the carbonate rock surface or at deeper levels below. Depending upon the geological sequence, as the cavities break down and become unstable they can cause overlying rock strata to settle and tilt and also collapse of non-cemented strata and superficial deposits as voids migrate upwards to the surface. Natural cavities can be present in a stable or potentially unstable condition. The latter may be disturbed and triggered to cause ground instability by the action of percolating water, loading or vibration. The outcrops of various limestones and chalk occur widely across the UK, posing a significant subsidence hazard to existing and new land development and people. In addition to subsidence they can also create a variety of other problems such as slope instability, generate pathways for pollutants and soil gas to travel along and impact all manner of engineering works. Knowledge of natural cavities is essential for planning, development control and the construction of safe development.

ABSTRACTThe Spanish empire's vertiginous collapse in the first decades of the nineteenth century has long been a source of historiographical disputes. Historians seeking to explain the demise of Spain's dominion in the Americas and the emergence of independent nation-states have identified certain factors as decisive. Among these are: the coalescence of an anti-colonial, national consciousness among creoles; peninsular misrule and economic mismanagement; and the seismic effects of geopolitical upheaval, particularly the Napoleonic occupation of Spain. This historiographical review recapitulates established explanations, introduces a new wave of scholarship on the subject, and identifies topics that may be crucial for future research.

The Cambrian dolomite reservoir is an important target in oil and gas exploration. The Penglaiba section in the Keping area is typically examined in studies dealing with the Cambrian dolomite reservoirs of northwestern Tarim Basin. Based on sedimentological, petrographic, and geochemical data, lithofacies and fluids are identified as the major factors that control the dolomite reservoir in the study area. Lithoacies are fundamental to reservoir evolution because they provide suitable channels for dolomitization and dissolution of fluids that, in turn, facilitate the formation of high quality reservoirs. The lithofacies which could form high-quality reservoirs in the study area are: slope slip (collapse) facies, gypsum related facies, and algae dolomite facies. The sources of fluids include seawater, meteoric freshwater, diagenetic/hydrocarbon fluid, and hydrothermal fluid. These fluids lead to dolomitization, penecontemporaneous meteoric dissolution, hypergene dissolution, organic acid dissolution and hydrothermal dissolution that result in secondary porosity, and as such, they have a significant contribution to reservoir evolution.

The Onion Creek Diapir is one of many salt domes proximal to the Uncompahgre thrust front of the ancestral rockies in the Paradox Basin. It is comprised of Paradox Formation evaporites and large blocks of Honaker Trail Formation carbonates that were deformed by loading of Permian Cutler Formation progradational alluvial to fluvial fans. The history of salt movement in the Onion Creek Diapir is recorded in the near-salt strata. Large salt bodies and their adjacent mini-basins evolve conforming to a complex relationship between salt withdrawal, creating localized accommodation, and sediment deposition. Migrating mini-basin depo-centers, thinned and folded strata, and spatial facies trends reveal the relative rates of diapirism and sedimentation. The study area outcrop, north of the diapir, is divided by significant stratigraphic horizons that help define depositional periods. Six measured sections in the study area reveal higher preservation rates of fine grained floodplain deposits, typically destroyed in alluvial environments, than at locations correlating to stratigraphic levels high in the outcrop suggesting a low accommodation environment evolving into higher accommodation where stacked channel complexes are preserved. Preserved slump folding at the base of the outcrop reveals that although some salt emergence occurred in the earliest depositional period it was not significant enough to preclude sediment deposition or to divert the Cutler fluvial network and destroy floodplain facies. A 3-D digital outcrop, modeled from photogrammetric data, illustrates the development of localized accommodation, attracting fluvial channel in a near-salt, tight axial syncline during the later depositional period. These evidences suggest a greater emergence of the diapir and likely diversion of the Cutler channel complexes.

Introducció La Tesi és obra de l’esforç i dedicació compartit amb molts companys i col·laboradors al llarg de gairebé 22 anys ininterromputs i més de 1.000 dies d’immersions. L’objectiu general és realitzar l’estudi de les cavitats subaquàtiques costaneres del Llevant i Migjorn de Mallorca, és a dir, d’una part important del carst eogenètic litoral, concretament de l’endocarst inundat, al menys parcialment, per les aigües freàtiques litorals. La zona freàtica de l’endocarst, afectada per les variacions del nivell degudes a causes glacio-eustàtiques, és també la responsable de l’espeleogènesi de les mateixes cavitats. La franja costanera posseeix una amplària d’ordre quilomètric, ja que la influència de la mar a les poroses calcarenites amb permeabilitat primària i secundària determinen la penetració de les aigües marines terra endins i la disposició d’una zona de mescla, agressiva químicament. Contingut de la investigació S’ha estructurat la Tesi en 4 parts i 23 capítols: Part I: Introducció i marc metodològic; Part II: Antecedents; Part III: Cavitats litorals del Llevant i Migjorn de Mallorca amb continuacions subaquàtiques; Part IV: Discussió del carst costaner i Part V: Conclusions i bibliografia. S’han situat les cavitats investigades en relació amb les que es troben al litoral espanyol i al carst eogenètic mundial, amb l’evolució històrica de les exploracions. Per a les principals cavitats s’ha realitzat l’exploració, la topografia, la descripció, les característiques hidrològiques, l’estudi de les morfologies primàries o de dissolució, les morfologies secundàries o espeleotemes, la distribució de les sales d’esfondrament, l’espeleogènesi proposada, els sediments, les restes arqueològiques sota les aigües, la fauna anquihalina, els fòssils, la relació de la cavitat amb la superfície, la relació de les coves amb les cales i surgències submarines i els impactes que afecten a la cova, a més a més de la dificultosa documentació fotogràfica d’aquests ambients extrems. En darrer lloc, s’ha discutit de forma global per al conjunt de cavitats tots els aspectes mencionats abans i les seves interferències. Conclusions S’ha incrementat l’interès espeleomètric d’importants cavitats ja conegudes o fins i tot de cavitats inèdites i s’ha descobert la connexió entre coves abans considerades independents. La suma del recorregut explorat supera els 50 km de galeries subaquàtiques. S’ha contribuït a determinar el perfil hídric vertical de salinitat i temperatura i les característiques diferencials en els casos de la presència d’una connexió directa amb la mar. La troballa de cavitats dins materials del Pliocè i especialment del Pleistocè, a més a més del Miocè superior, suposa incrementar la distribució de les formacions endocàrstiques i representa que els mecanismes espeleogenètics que les han generat han actuat també dins el Pleistocè, un període d’activitat espeleogenètica fins ara no documentat per Mallorca. S’ha intentat establir un intent de classificació i sistematització de les morfologies de corrosió lligades a la zona de mescla d’aigües i de les morfologies hipogèniques trobades a les galeries sotaiguades. S’ha descrit i documentat els espeleotemes més freqüents i interessants que es troben a les galeries i sales sotaiguades. La presència de sediments a l’interior de les cavitats és prou important, amb gruix i tipologia extraordinàriament divers. L’anàlisi de les topografies, fotografies a més dels estudis de camp in situ, han permès delimitar les sales d'esfondrament. Les cavitats constitueixen en un sentit ecològic ambients anquihalins, amb algunes galeries amb corrents intensos per la proximitat a la mar, amb presència de comunitats d’organismes sèssils filtradors. S’han trobat nous gèneres i espècies i s’ha estudiat la distribució de la fauna. Algunes de les coves constitueixen importants jaciments paleontològics i arqueològics. Una part de les cavitats estudiades han estat declarades ZEC.
Introducción La Tesis es obra del esfuerzo y dedicación compartido con muchos compañeros y colaboradores a lo largo de casi 22 años ininterrumpidos y más de 1.000 días de inmersiones. El objetivo general es realizar el estudio de las cavidades subacuáticas costeras del Llevant y Migjorn de Mallorca, es decir, de una parte importante del karst eogenético litoral, concretamente del endokarst inundado, al menos parcialmente, por las aguas freáticas litorales. La zona freática del endokarst, afectada por las variaciones del nivel debidas a causas glacioeustáticas, es también la responsable de la espeleogénesis de las propias cavidades. La franja costera posee una anchura de orden quilométrico, ya que la influencia del mar en las porosas calcarenitas con permeabilidad primaria y secundaria determina la penetración de las aguas marinas tierra adentro y la disposición de la zona de mezcla, químicamente agresiva. Contenido de la investigación Se ha estructurado la Tesis en 4 partes y 23 capítulos: Parte I: Introducción y marco metodológico; Parte II: Antecedentes; Parte III: Cavidades litorales del Llevant y Migjorn de Mallorca con continuaciones subacuáticas; Parte IV: Discusión del karst costero y Parte V: Conclusiones y bibliografía. Se han ubicado las cavidades investigadas en relación con las que se encuentran en el litoral español y en el karst eogenético mundial, así como la evolución histórica de las exploraciones. Para las principales cavidades se ha realizado la exploración, la topografía, la descripción, las características hidrológicas, el estudio de las morfologías primarias o de disolución, las morfologías secundarias o espeleotemas, la distribución de las salas de hundimiento, la espeleogénesis propuesta, los sedimentos, los restos arqueológicos bajo las aguas, la fauna anquihalina, los fósiles, la relación de la cavidad con la superficie, la relación de las cuevas con las calas y surgencias submarinas y los impactos que afectan a la cueva, además de la documentación fotográfica de estos ambientes extremos. En último lugar, se ha discutido de forma global para el conjunto de cavidades todos los aspectos mencionados anteriormente y las interferencias entre diferentes apartados. Conclusiones Se ha incrementado el interés espeleométrico de importantes cavidades ya conocidas o incluso de cavidades inéditas y se ha descubierto la conexión entre cuevas antes consideradas independientes. La suma del recorrido explorado supera los 50 km de galerías subacuáticas. Se ha contribuido a determinar el perfil hídrico vertical de salinidad y temperatura y las características diferenciales en los casos de la presencia de una conexión directa con la mar. El hallazgo de cuevas en materiales del Plioceno y especialmente del Pleistoceno, además del Mioceno superior, supone incrementar la distribución de las formaciones endokársticas y representa que los mecanismos espeleogenéticos que las han generado han actuado también dentro del Pleistoceno, un periodo de actividad espeleogenética hasta ahora no documentado en Mallorca. Se ha intentado establecer una clasificación y sistematización de las morfologías de corrosión ligadas a la zona de mezcla de aguas y de las morfologías hipogénicas localizadas en las galerías subacuáticas. Se han descrito y documentado los espeleotemas más frecuentes e interesantes que se encuentran las galerías y salas bajo el agua. La presencia de sedimentos en el interior de las cavidades es bastante importante, con grosores y tipología extraordinariamente diversos. El análisis de las topografías, fotografías además de los estudios de campo in situ, han permitido delimitar las salas de hundimiento. Las cavidades constituyen en un sentido ecológico ambientes anquihalinos, con algunas galerías con corrientes intensas por la proximidad al mar, con presencia de comunidades de organismos sésiles filtradores. Se han descubierto nuevos géneros y especies y se ha estudiado la distribución de la fauna. Algunas de las cuevas constituyen importantes yacimientos paleontológicos y arqueológicos. Una parte de las cavidades estudiadas han sido declaradas ZEC.
Introduction This Ph.D. thesis is the result of the effort and dedication shared with many colleagues and caving companions for nearly 22 uninterrupted years of underwater explorations, totalizing more than 1,000 days of diving activities. The overall target is the study of the subaqueous coastal caves in the East and South of Mallorca, that is, an important part of the littoral eogenetic karst in the Island, specifically the endokarst drowned at least partially for coastal groundwater. The phreatic zone within the endokarst, which is affected by the sea-level variations due to glacial-eustatic causes, is also responsible for the speleogenesis of the littoral caves themselves. The coastal fringe has a width in the order of a few kilometres because the influence of the sea on the porous calcarenites ‒with high primary and secondary permeability‒ determines the penetration of sea water inland together with the establishment of a chemically aggressive mixing zone. Content of the research The Ph.D. dissertation is structured in 4 sections and 23 chapters: Section I: Introduction and methodological frame; Section II: Previous background; Section III: Coastal caves with underwater extensions in Eastern and Southern Mallorca; Section IV: Discussion on the coastal karst; and Section V: Conclusions and bibliography. The investigated caves have been placed in relation to those found along the Spanish coast and the eogenetic karst areas worldwide, taking into account the historical evolution of the explorations. In each of the investigated caves the following aspects have been dealt with in detail: the exploration, the topographical surveying, the description of the cavity, the hydrological characteristics, the study of the primary dissolution morphologies, the secondary morphologies or speleothems, the distribution of the breakdown chambers, the proposed speleogenetic processes, the sediments, the archaeological remains recovered underwater, the anchialine fauna, the paleontological remains, the relationship of the cave with the surface landscape, the relationship of the cavity with the coast-line morphology and the submarine springs, the anthropic impacts affecting the cave, and additionally the very difficult photographic documentation of these extreme environments. Finally, a comprehensive discussion of the whole caves is provided in which all aspects mentioned above and their interferences are addressed thoroughly. Conclusions The planimetric development of important already known caves ‒or even of some unknown cavities‒ has reached very relevant figures, being discovered at the same time the connection between caves before considered as independent phenomena. The accumulated length of the explored galleries and chambers totalizes over 50 km of underwater passages. Contributions have been made in order to determine the hydric vertical profile of temperature and salinity, and the distinctive features in the cases of the presence of a direct connection to the sea. The discovery of caves in Pliocene and especially Pleistocene rocks, in addition to Upper Miocene materials, results in an increase in the distribution of endokarstic formations and supports the fact that speleogenetic mechanisms having generated them have also acted in the Pleistocene, a period of speleogenetic activity not documented so far in Mallorca. An attempt has been made trying to establish a classification and systematization of solutional morphologies related to the phreatic waters in the coastal mixing zone, and the features of hypogenic origin observed in the subaqueous passages. The most frequent and interesting speleothems found in the underwater galleries and chambers have been extensively described and documented. Detrital sediments are present inside some caves as relatively important accumulations, showing very diverse thicknesses and typologies. The interpretation of topographical surveys, aerial photographs, as well as in situ field observations, have allowed a careful delimitation of the collapse chambers. In an ecological sense the caves are anchialine environments, that show some passages with strong water flows due to the proximity to the sea, with the presence of communities of sessile filtering organisms. The distribution of the aquatic fauna has been studied, with the discovery of new genus and species of stygobiontic organisms. A few caves are important paleontological and archaeological sites. Some of the investigated caves have been declared ZEC (Special Conservation Zone) by the regional environmental authorities.

El análisis de estructuras paleokársticas ha atraído, en los últimos años, el interés de numerosos investigadores a la información que aportan a la geología aplicada y la paleogeomorfología. Estudios recientes se han centrado en la aplicación de técnicas de exploración del subsuelo debido a la escasez de afloramientos. En la presente Memoria se analizan íntegramente las formas de hundimiento pretéritas que afloran discontinuamente con gran detalle, en los acantilados de las costas meridional (plataforma de Llucmajor) y oriental (plataforma de Santanyí) de Mallorca, a lo largo de más de 75 km de línea de costa, afectando a las rocas carbonáticas del Mioceno superior. El estudio se ha centrado en la distribución geográfica, evolución geológica y las características geomorfológicas de estos paleocolapsos, con especial énfasis en su génesis, su relación con la arquitectura y distribución de las facies, así como en las formas y productos asociados.

Los paleocolapsos han sido descritos en su contexto litoestratigráfico y estructural dentro de las mencionadas plataformas carbonáticas, siendo este trabajo una contribución al conocimiento del karst en estas unidades geológicas y su relación con las fluctuaciones marinas. La karstogénesis queda reflejada en estas formas pretéritas donde se han observado depósitos y formas de disolución ligadas a la dinámica kárstica controlada, en el caso que nos ocupa, por las fluctuaciones del nivel del mar: brechas, sedimentos detríticos, cementos, así como distintos tipos y volúmenes de porosidad. La mayor parte de estas formas (sobre un total de 177), cuyas dimensiones en sección varían desde pocos metros hasta afloramientos con 28 m de altura y más de 100 m en la horizontal, se ubican en la plataforma de Santanyí a excepción de dos estructuras ubicadas en la plataforma de Llucmajor.

El análisis geológico y su relación con los paleocolapsos muestra como en la plataforma de Llucmajor éstos afectan a las facies de la Unidad Complejo Arrecifal (facies de back reef y frente arrecifal). Sin embargo, en la plataforma de Santanyí, los paleocolapsos afectan tanto a parte del Complejo Arrecifal (facies de back reef), como a la totalidad de la Unidad Calizas de Santanyí. A partir del estudio de la arquitectura de facies del Complejo Arrecifal en la plataforma de Llucmajor se ha establecido el modelo deposicional en la plataforma de Santanyí. Sin embargo, ésta última se encuentra compartimentada como consecuencia del control de dos fallas en dirección de orientación E-O en S'Algar y Na Magrana, donde se localiza el contacto entre facies de lagoon externo y talud arrecifal. No obstante, la cartografía y análisis de los lineamientos en dicha plataforma ha permitido identificar dos familias principales con dos direcciones dominantes; NE-SO y NO-SE, siendo la dirección E-O menos representativa. Se han observado fracturas distensivas y pequeñas fallas inversas miocenas asociadas al proceso de colapso, así como fracturas y fallas postmiocenas, y fracturas cuaternarias.

El estudio de la geometría en sección de los paleocolapsos pone de relieve que la formas en "V", "U" y conoidales son las más comunes. Han sido identificadas dos partes diferentes en un paleocolapso tipo: una inferior donde se observa la paleocavidad ubicada en la base del paleocolapso (lagoon externo y/o frente arrecifal), con una geometría irregular de dimensiones entre 1 m y 9 m rellena por sedimentos adyacentes y suprayacentes a ésta; y una parte superior, coincidente con los bordes de la estructura (lagoon interno/Calizas de Santanyí) buzando con inflexión conoidal hacia la paleocavidad.

Se han identificado cuatro tipos de brechas (crackle, crackle-laminae-split, de mosaico y caótica) en las estructuras de paleocolapso asociadas cada una de ellas a distintos niveles estratigráficos y, en algunos paleocolapsos, con una gradación vertical y lateral. Son característicos de estos depósitos los sedimentos detríticos (matriz) y los cementos asociados (vadosos y freáticos). En general, el cemento domina sobre la matriz en la zona inferior del paleocolapso, mientras que por encima, es la matriz la que domina sobre el cemento. El análisis por difracción de Rayos X de la matriz indica para la muestra total que la calcita es el mineral principal y el cuarzo el mineral secundario. En la fracción arcilla, la moscovita, la illita y la caolinita son los minerales más comunes. De ello, junto con el estudio de láminas delgadas en estos depósitos, donde se han observado tamaños de grano en el cuarzo superior a 2 mm, se deduce un ambiente de sedimentación subsuperfical y otro subaéreo de lo que se extrae un origen, proceso de transporte y sedimentación diversos, así como la evolución cristaloquímica en determinados minerales. Los cementos son de naturaleza calcítica, con contenidos relativamente altos en magnesio para los freáticos y bajos para los vadosos. Para el estudio de la porosidad en los paleocolapsos se ha procedido a su clasificación en dos tipos principales, interclasto e intraclasto, a partir de las cuales se ha estudiado la macro y microporosidad. La brecha caótica de colapso es la que presenta volúmenes de porosidad más elevados y tipologías diversas.

El análisis de isótopos estables muestra una gran homogeneidad entre la composición isotópica de los cementos, con valores en δ18O y δ13C ligeros, lo que indica condiciones análogas de precipitación, con dominio de aguas dulces sobre las saladas. Tanto la marca del oxígeno como del carbono parecen indicar que los cementos se depositaron en un período interglaciar coincidente con algún estadio isotópico impar.

El estudio de la arquitectura de facies de la plataforma de Llucmajor ha permitido elaborar un modelo genético de ocurrencia para los paleocolapsos y su ubicación espacio-temporal. Dicho modelo, ha sido corroborado por la relación entre la distribución de facies y paleocolapsos en la plataforma de Santanyí, por la observación en algunos paleocolapsos de sedimentos a techo de la Unidad Calizas de Santanyí que sellan la estructura, así como por el tipo de brechas características de colapsos sinsedimentarios (brecha crackle-laminae-split), que muestran una deformación dúctil de los materiales cuando éstos no estaban completamente consolidados, dando lugar a formas laxas de bajo ángulo. Los procesos genéticos que dieron lugar a los paleocolapsos kársticos están directamente relacionados con la alta frecuencia de fluctuación del nivel del mar durante el Mioceno superior, la misma que controló la arquitectura de facies y la posición del nivel freático. Las oscilaciones del nivel freático causaron la alternancia de dominios freáticos y vadosos así como, de agua dulce y agua salada en la interfase, provocando la disolución de los parches coralinos y el posterior hundimiento del techo de las cavidades.

El estudio integral de todos estos aspectos junto con el análisis de una red de paleocauces y una playa fósil, ha permitido realizar una reconstrucción paleogeográfica desde el Messiniense en la plataforma de Santanyí e identificar estructuras de paleocolapso postmiocenas y cuaternarias. Con estos datos se ha procedido a la comparación de los paleocolapsos kársticos con otras estructuras similares en el País Vasco y Las Islas de Malta, de lo que se extraen analogías y diferencias, determinadas fundamentalmente por el orden de fluctuación del nivel del mar.

Por último, se discute el papel de los paleocolapsos kársticos como elementos que contribuyen en cierta medida a la ocurrencia de hidrocarburos en plataformas carbonáticas, pudiendo ser excelentes reservorios debido al gran número de afloramientos, el volumen de roca afectada y a su elevada porosidad y permeabilidad.
Paleokarst tend to differ from studies of recent and modern karst landforms though is important the genetic understanding of the karst processes for analysis a paleokarst structure. Paleokarst systems form an important class of carbonate record and they have a pronounced lateral and vertical spatial complexity that results from a complex history of formation. Most of the known karst systems are epigenetic and they are the result of near-surface karst processes during periods of subaerial exposure and latter burial compaction and diagénesis. Scale, porosity types and spatial complexities of these paleokarst systems depends on the carbonate rock solubility, paleoclimatic conditions, lowering of base level either by tectonic uplift or sea-level fall and time of subaerial exposure. Uplift, in addition, commonly induces fracturing and faulting that further control karst development. Ascertaining and predicting paleokarstic heterogeneities within carbonate rocks are strategic to fluids field development and optimum production. With current subsurface methods, however, most of the smaller-scale stratigraphic architecture and diagenetic facies are difficult to define. Predictive models for exploration and development are best made from outcrop studies of well-exposed examples. Accuracy for prediction of these models depends on the detailed understanding of the genetic factors controlling their geometries, scale, pore networks and spatial complexities of these potential karstic store. Miocene carbonates (Upper Tortonian-Lower Messinian) in Mallorca Island are composed of reefal (Reef Complex) and shallow water carbonates (Santanyí Limestone) that prograded across platforms surrounding paleoislands. The contact between the Reef Complex and the Santanyí Limestone is a subaerial erosion surface with paleokarst features. The shallow-water carbonates beds both the lagoonal beds of the Reef Complex and basal beds of the Santanyí Limestone, are affected by paleocollapse structures produced by roof collapse of caverns developed in the underlying Reefal Complex. These paleocollapse structures affecting to the carbonate platform allows to propose a genetic model to explain the origin of these paleosink, that are related to early diagenetic processes induced by high-frequency sea-level fluctuations, the same sea-level fluctuations that controlled the facies architecture of the carbonate platforms.

Cartography and study of lineaments and fractures on Santanyí Platform have permitted identified two principals groups with two main directions: NE-SO and NO-SE. Have been observed distensiva fractures and Miocene small inverse faults related with de breackdwon phenomena. Moreover, postmiocenes and quaternary faults and fractures have been recognized.

The geometry of paleocollapse structures is commonly (in section) as "V", "U" or funnel. The size is variable from few meters of long to thousands meters, and few meters of weigh to thirteen meters. Breccias has been classified as crackle, crackle-laminae-split, mosaic and chaotic types. Chaotic breccias grade from matrix-free, clasts-supported breccias to matrix-supported breccias. The matrix mineralogy is compose in the total sample for calcite in the major part and quartz in less quantity. However, same structures present quartz as principal mineral. To the clay fraction, caolinite, illite and moscovite are the most general mineral present.

The geochimical sediment (carbonate) are filling a part of interclaste breccias porosity. This is commonly phreatic speleothems. Isotopic studies of this sediments show δ18O and δ13C contents negatives. This fact could indicate a fresh water environment deposition

This chapter conceptualizes the end of Fascism and the beginning of the civil war, after the armistice of September 8, 1943, as the collapse of the markers of certainty and the beginning of a liminal period of chaos and political, as well as existential, uncertainty. It takes the reader for a ride in what was a confusing and bewildering scenario that followed the removal of the Duce, the collapse of the nation, the dissolution of the structure of power, and the disintegration of national unity. A situation of pure liminality and radical uncertainty, pulling and pushing, imbued with a deep sense of disorientation and confusion pervaded all sectors of Italian society: the governmental level, the army units inside and outside the country, as well as people in the cities and in the countryside. Yet, it was precisely this situation of uncertainty that paved the way for passage to democracy.

This book presents Central Europe as a key laboratory for the interwar international order. A new regional order of national states, ushered into being by the dissolution of the multinational Habsburg Empire in 1918, was born alongside a new framework for international governance. The region became the key test case for new international organizations like the League of Nations: problems of border drawing, financial collapse, endemic disease, national minorities, and humanitarian aid emerged as domains where the League’s identity and authority were defined and tested. The predicaments of post-imperial sovereignty, meanwhile, sparked supranational initiatives like international policing and treaties to protect the commercial rights of foreigners. These interactions shaped the successor states as well as institutions of international organization, offering unique insights into the relationship between nationalization and internationalization. Central Europe emerges as a crucible for forms and techniques of supranational governance. With chapters covering international health, international financial oversight, human trafficking, minority rights, scientific networks, technical expertise, passports, commercial treaties, borders and citizenship, and international policing, this book pioneers a regional approach to international order, and explores the origins of today’s global governance in the wake of imperial collapse.

In the various permutations of German Romanticism from its beginnings in the 1790s, two factors remain constant: a penchant for collaborative, transdisciplinary work, and the formation of small circles—often in university towns—whose particular character often depended upon and contributed to the prevailing intellectual discourse of that locale. For the four cities highlighted in the chapter heading, one further factor needs to be considered: the impact of the Napoleonic reorganization of central Europe. The breakup and dispersal of the Jena Romantics coincided with the collapse of the moribund Holy Roman Empire, which officially ended in 1806 but whose final dissolution began with the Treaty of Lunéville in 1801. This chapter looks at the interplay between history and creative collaboration, literary innovation and political aspiration or restraint, as the main energies of German Romanticism relocate themselves in these different cities at different times.

Lucretius, Vergil, and Ovid developed important conventions of the Western plague narrative as a response to the breakdown of the Roman res publica in the mid-first century CE and the reconstitution of stabilized government under the Augustan Principate (31 BCE–14 CE). Relying on the metaphoric relationship between the human body and the body politic, these authors use largely fictive representations of epidemic disease to address the collapse of the social order and suggest remedies for its recovery. Plague as such functions frequently in Roman texts to enact a drama in which the concerns of the individual must be weighed against those of the collective. In order to understand the figurative potential of plague, this book evaluates the reality of epidemic disease in Rome, in light of twentieth-century theories of plague discourse, those of Artaud, Foucault, Sontag, and Girard, in particular. Pestilence and the Body Politic in Latin Literature identifies consistent features of the outbreaks described by Roman epic poets, charting the emergence of Golden-Age imagery, emphasis on bodily dissolution, and poignant accounts of broken familial bonds. Such features are expressed through Roman idioms that provocatively recall the discourse of civil strife that characterized the last century of the Roman Republic. The final chapters examine key moments in the resurgence of Roman plague topoi, beginning with early imperial poets (Lucan, Seneca, and Silius Italicus), and concluding with discussion of late antique Christian poetry, paintings of the late Italian Renaissance, and Anglo-American novels and films.

This article looks at the mass destruction that raged Europe from 1914 to 1945. The trauma of 1918, Germany's defeat and dissolution, would not stop haunting nationalist Germans until the Third Reich collapsed; many Germans took the legend of the stab in the back as a matter of fact, according to which a Jewish-communist conspiracy had betrayed the national cause and sold out the otherwise victorious army. This article further traces the Holocaust that raged Europe and in particular Germany. The condition of the Jews and the treatment meted out to them by Hitler's forces is worth noting. The concentration camps to where most of the Jews were transported are vividly described in this article. It is impossible to estimate how many Germans, whether men or women, whether at the battle front or on the home front, knew about the Holocaust, and what exactly they knew.

The Armenian mandate debate is overlooked in studies of the fight over ratification of the Treaty of Versailles and membership of the League of Nations. This chapter emphasizes its significance to debates over US league membership and the United States’ postwar relationship with Britain. It explores the findings of the Harbord Commission, the investigative group that President Wilson sent to the Near East to ascertain whether the US should accept a mandate. It follows the American public debate over assuming the mandate in Congress and the national press, highlighting how it reveals the residual American mistrust of British imperialism, as well as the growing British disillusionment with American indecision over whether to make a commitment in the Near East. It explains how this aggravated tensions in Anglo-American relations, already evident in the clash between the two nations over access to the region’s oil resources. And it explores how the collapse of order in the Near East in 1922 led to Americans and Britons blaming each other for allowing the outbreak of renewed atrocities.

This chapter describes the extent and formation of karst in Kentucky: how the dissolution of limestone by water shapes the underground and surface of over half of Kentucky; the ways that hydro geologists map karst aquifers, including illustrative examples. The beauty of caving in the Mammoth Cave area and throughout Kentucky karst is illustrated. The special challenges of construction and development on karst are discussed: karst flooding, cover-collapse sinkholes, maintaining water quality in karst.

Abstract Complete mud loss is a severe costly drilling problem which increases drilling time and makes wells challenging to control. Such situation was encountered during drilling of three wells from a platform in an offshore field in Persian Gulf. This unexpected problem occurred while other wells from this platform were drilled and completed according to the routine plan. Further investigations using 3D seismic data showed that, these wells had penetrated through a massive collapse feature causing extended drilling times. Buried collapse features are developed as result of karstification due to dissolution of carbonate rocks. Although karstification may be evaluated as a disturbing parameter of reservoir properties, the most critical concern about this phenomenon is difficulties in forecasting drilling mud weight due to highly unpredictable fluid transmissibility. Collapse feature has different viscoelastic properties from its surrounding sediments, therefore, it generates different seismic responses in terms of amplitude and frequency. This aspect was utilized for identification of encountered collapse feature where, a practical semi-automated approach based on seismic derived multi-attributes cubes and neural network analysis was taken. Once a sinkhole cube was generated based on the above approach, geobody of the collapse feature was extracted. Results then were thoroughly validated by mud loss intervals at wells. Close investigation of the sinkhole cube revealed that seven collapse features exist in the area of study in which, problematic wells pass through one of them. It was discovered that all collapse features are interconnected with deep-seated faults which acted as hydrocarbon migration conduit. This incident obviously emphasizes role of geohazards analysis before any offshore drilling, even in a developed field with several number of wells. As experienced, a significant part of well non-productive time can be avoided if an integrated multi-disciplinary approach is taken. The authors will describe an effective proactive approach towards geohazards and present lessons learned in the case presented to address unexpected geo-drilling incidents.

From 1967 to 1978, about 125,800 barrels of low- and intermediate level waste were disposed of — nominally for research purposes — in the former “Asse” salt mine which had before been used for the production of potash for many years. Since 1988 an inflow of brine is being observed which will cause dangers of flooding and of a collapse due to salt weakening and dissolution if it should increase. Since several years the closure of the Asse repository is planned with the objective to prevent the flooding and collapse of the mine and the release of radioactive substances to the biosphere. The first concept that was presented by the former operator, however, seemed completely unacceptable to regional representatives from politics and NGOs. Their activities against these plans made the project a top issue on the political agenda from the federal to the local level. The paper traces the main reasons which lead to the severe safety problems in the past as well as relevant changes in the governance system today. A focus is put on the process for public involvement in which the Citizens’ Advisory Group “A2B” forms the core measure. Its structure and framework, experience and results, expectations from inside and outside perspectives are presented. Furthermore the question is tackled how far this process can serve as an example for a participatory approach in a siting process for a geological repository for high active waste which can be expected to be highly contested in the affected regions.

One of the biggest events in international political history at the end of the 20th century was end of the Cold War due to the dissolution of the Soviet Union. With the collapse of the Soviet Union in December 1991, the Cold War system, led by the US and the Soviet Union as the two main axes, disappeared into history, dramatically changing the international situation and creating new independent states in the international community. In the past, as the protagonist of the Silk Road civilization, it was a channel of trade and culture, linking the East and the West, but as members of the former Soviet Union, Central Asian countries whose importance and status were not well known have emerged on the international stage in the process of forming a new international order. After independence, Central Asia countries began to attract attention from the world as the rediscovery of the Silk Road, that is, the geopolitical importance of being the center of the Eurasian continent, and as a treasure trove of natural resources such as oil and gas increased.

In the event of a severe accident in a nuclear reactor, the oxidation, dissolution and collapse of fuel rods is likely to change dramatically the geometry of the core. A large part of the core would be damaged and would look like porous medium made of randomly distributed pellet fragments, broken claddings and relocated melts. Such a complex medium must be cooled in order to stop the accident progression. IRSN investigates the effectiveness of the water re-flooding mechanism in cooling this medium where complex two-phase flows are likely to exist. A macroscopic model for the prediction of the cooling sequence was developed for the ICARE/CATHARE code (IRSN mechanistic code for severe accidents). It still needs to be improved and assessed. It appears that a better understanding of the flow at the pore scale is necessary. As a result, a direct numerical simulation (DNS) code was developed to investigate the local features of a two-phase flow in complex geometries. In this paper, the Cahn-Hilliard model is used to simulate flows of two immiscible fluids in geometries representing a damaged core. These geometries are synthesized from experimental tomography images (PHEBUS-FP project) in order to study the effects of each degradation feature, such as displacement and fragmentation of the fuel rods and claddings, on the two-phase flow. For example, the presence of fragmented fuel claddings is likely to enhance the trapping of the residual phase (either steam or water) within the medium which leads to less flow fluctuations in the other phase. Such features are clearly shown by DNS calculations. From a series of calculations where the geometry of the porous medium is changed, conclusions are drawn for the impact of rods damage level on the characteristics of two-phase flow in the core.

Abstract Carbon sequestration is the process of capturing and storage of atmospheric carbon dioxide. The objective of any carbon sequestration project is to store CO2 safely for hundreds or thousands of years with a goal of reducing global climate change. A depleted hydrocarbon reservoir is one of the potential storage sites being considered for long-term CO2 storage. The dynamic, geochemical, and geomechanics changes that occur during CO2 injection are inter-related. For example, when injected CO2 causes dissolution of reservoir rock, on one hand, porosity increases while rock strength decreases. On the other hand, reduced rock strength could cause additional compaction thus reducing porosity, whereas increase in pressure due to injection could cause dilation. Hence, it is critical to have an integrated model that captures effect of all changes on the storage capacity and integrity of the reservoir. Three major depleted gas reservoirs in Central Luconia field, located offshore Sarawak, are being evaluated for future CO2 storage. A 3-way coupled modelling approach that integrates dynamic model, geochemistry model, and geomechanics model is utilized to obtain cumulative effect of all three changes. This integrated model provides a more accurate estimate of 1) CO2 storage capacity, 2) Caprock integrity evaluation, 3) CO2 plume migration path, and 4) Volume of CO2 stored through different storage mechanisms (viz. hydrodynamic trapping, capillary trapping, solubility trapping, and mineral trapping). Apart from providing storage capacity, this model also provides inputs for evaluating integrity of caprock, fault reactivation study, MMV (Measurement, Monitoring, and Verification) planning, and estimating potential leak rates through plugged and abandoned wells. Using a 3-way coupled model, it is estimated that there is an average reduction in porosity of 5-10% (of initial porosity). This translates to an equivalent reduction in CO2 storage capacity of 5-10% compared to dynamic model. It is observed that pore collapse as a result of pressure depletion is primarily responsible for this reduction in porosity. It has also been observed that the injection can be continued till initial reservoir pressure is reached without breaching caprock integrity. CO2 plume migration path significantly affects MMV planning. Potential leak rate estimation is critical in mitigation and contingency planning.