Добрый день, Коллеги. Важное сообщение, просьба принять участие. Музей Ферсмана ищет помощь для реставрационных работ в помещении. Подробности по ссылке
В монографии на основе оригинальных исследований автора и обширного опубликованного отечественного и зарубежного материалов рассматриваются теоретические и практические аспекты оползневедения с акцентом на ключевую проблему — методологию геодезического обес печения мониторинга деформационных процессов склоновых систем для нового решения актуальной научной проблемы — оценки степени оползневого риска и уровня безопасности склоновых систем.
На основе изучения морфологии, геологин, геометрии и ориентировки складчатых форм и структурных элементов в книге излагается методика исследования наложенных деформаций. В первом разделе рассматриваются структурные элементы метаморфических горных пород и их значение при изучении наложенной складчатости (первично-осадочные текстуры, полосчатость, сланцеватость, складки, линейность). Второй раздел посвящен геометрическому анализу. Сформулированы задачи, решаемые с помощью геометрического анализа, дано их решение. Рассмотрена стереогеометрия цилиндрических и конических складок, геометрический анализ структурных данных на площади и др. В третьем разделе излагаются особенности наложенных складчатых структур. Рассматриваются признаки наложенных деформаций, методические приемы установления последовательности деформаций, возрастные взаимоотношения складок между собой, складок и сланцеватости, линейности, даек, жил, метаморфогенного минералообразования и ультраметаморфизма
Martin Casey, who died on the 10 June 2008 after a short illness, was a structural geologist of world renown. He led numerical approaches to understanding rock deformation and the development of tectonic structures, pioneering the quantitative analysis of rock fabrics, textures and folds. These researches now underpin diverse areas of geology, such as quantifying the strength of rocks in the crust which leads to calibrations of the seismic properties of the minerals in continents and the prediction of the fine-scale structure of hydrocarbon reservoirs. This Special Publication is dedicated to his memory not only for his fundamental contribution to science but also as a mentor, colleague and friend. <...>
It is my great pleasure to introduce this volume dedicated to my long-standing colleague and friend, Henk Zwart; the more so since I missed the opportunity of addressing him on the occasion of his retirement from the chair of structural and applied geology in the State University at Utrecht in 1988.
Традиционный подход наблюдений за деформациями оснований зданий и сооружений или земной поверхности в районе предполагаемых сдвижении грунта предусматривает размещение геодезических знаков с наличием опорных пунктов (реперов), которые исполняют роль точек отсчета. При этом возникает необходимость оценки устойчивости самих опорных реперов. Существует целый ряд способов оценки их устойчивости. Однако их анализ показывает, что для определенных условий, например, когда все марки имеют один знак смешений, практически все они не дают правильного результата. Кроме того, зачастую в городских условиях или в промышленных зонах просто невозможно найти неподвижные участки для закладки опорных реперов. Известны случаи, когда из-за подвижности опорных реперов забраковывалась вся деформационная сеть, вследствие недостоверности получаемых результатов. Огромный труд н затраты уходили впустую. В этой связи и в России. и особенно во Вьетнаме остро стоит вопрос о создании надежных способов оценки в целом деформационных процессов и в частности вертикальных смешений оснований здании и сооружений.
Zoning patterns and zoning truncations in metamorphic minerals in a granodioritic orthogneiss indicate that strain and S-C fabrics in these rocks were produced by dissolution, precipitation, and replacement processes, even at epidote-amphibolite fades metamorphic conditions. The metamorphic fabric is defined by alternating layers and folia dominated by quartz, feldspars, and biotite + epidote. Zoning patterns in most metamorphic plagioclase, orthoclase, epidote, and sphene are truncated at boundaries normal to the shortening direction, suggesting dissolution. Interfaces of relict igneous orthoclase phenocrysts that face the shortening direction are embayed and replaced by biotite, epidote, and myrmekitic intergrowths of plagioclase and quartz. Metamorphic plagioclase grains are also replaced by epidote. We interpret these microstractures to reflect strain-enhanced dissolution. The cores of many grains show asymmetric overgrowths with at least two generations of beards, all oriented on the ends of grains that face the extension direction. We interpret these textures to reflect precipitation of components dissolved by deformation-enhanced dissolution. While biotite and quartz probably deformed by dislocation creep, the overall deformation was accommodated by dissolution perpendicular to the shortening direction, and precipitation parallel to it. These chemical processes must have been activated at lower stresses than the dislocation creep predicted from extrapolations of data from experiments in dry rocks. Thus wet crust is likely to be weaker than calculated from these experimental studies
In a well stratified flysch in the French Pyrenees, the offset of layers along a fault zone provide good data of relative displacement. It is shown that the fault surface is composed of three right-stepping fractures that opened tensile bridges along small left-stepping fractures. Translation on the fault zone is parallel to the fault surface. The displacement vector field shows that the movement between the two blocks was not a rigid body translation and that deformation in the hanging wall is greater than that in the foot wall. Volume loss within the rock is compensated by volume increase close to the fault surface.
Calcite dissolution and reprecipitation by pressure solution is indicated by the occurrence of stylolites and numerous calcite-filled veins around the fault. Calcite dissolution is more important in the hanging wall, especially in layers where the calcite content is close to 60%. Both cathodoluminescence observations and rare-earths element patterns are in favour of calcite in veins and dominos coming from units adjacent to the fault. There is no evidence that some calcite coming from farther distance could have entered in the system.
The deformation mechanisms and controls that operate in the mylonite/ultramylonite transition are interpreted from microstructural observation. The investigated mylonites and ultramylonites were derived from a granitic protolith which was deformed under greenschist facies conditions, and in the presence of fluid, in a regional-scale shear zone from northwest Argentina. Several deformation mechanisms were recognized to operate simultaneously in different domains of the microstructure at each particular stage of the microstructural evolution. This continuously mobile deformation partitioning, present throughout the microstructural evolution, ceases abruptly in the ultramylonite stage, where a stable-state microstructure is achieved. Domainal quartz c-axis fabrics indicate that quartz deforms by crystal-plastic processes at the initial and intermediate stages of deformation, but solution-transfer processes become predominant in the ultramylonite stage. Plagio-clase is progressively transformed into muscovite through retrograde softening reactions. K-feldspar is progressively transformed into fine-grade aggregates via cataclastic flow and incipient recrystallization. Mica deforms by kinking and basal slip, with progressive development of fine-grained, morphologically oriented aggregates. Plagioclase disappearance as well as the development of intrafolial microfolds characterize the transition between the mylonitic and ultramylonitic domains. Disruption of these microfolds is interpreted to represent the ultimate control on the localization of the ultramylonite bands, с 1998 Elsevier Science Ltd. All rights reserved
Fractal geometry allows the description of natural patterns and the establishment and testing of models of pattern formation. In particular, it is a tool for geoscientists. The aim of this volume is to give an overview of the applications of fractal geometry and the theory of dynamic systems in the geosciences. The state of the art is presented and the reader obtains an impression of the variety of fields for which fractal geometry is a useful tool and of the different methods of fractal geometry which can be applied. In addition to specific information about new applications of fractal geometry in structural geology, physics of the solid earth, and mineralogy, proposals and ideas about how fractal geometry can be applied in the reader's field of studies will be put forward.
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