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Cristallochimie Des Elements Traces Dans Les Phases Du Manteau Terrestre
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Book Synopsis Cristallochimie des éléments traces dans les phases du manteau terrestre by : Gilles Quérel
Download or read book Cristallochimie des éléments traces dans les phases du manteau terrestre written by Gilles Quérel and published by . This book was released on 1998 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: La connaissance des coefficients de partage des éléments traces à haute pression et haute température est aujourd'hui requise afin de tester les différents modèles géochimiques d'évolution du manteau terrestre. Etant données les difficultés inhérentes à l'évaluation de ces coefficients de partage lors d'expériences d'équilibre dans différentes conditions (pression, température, composition chimique, ... ), la modélisation de la distribution de ces éléments traces est nécessaire. Cependant, celle-ci passe par la compréhension des phénomènes microscopiques qui contrôlent l'incorporation de l'élément. Ce travail a porté sur la détermination des différents sites d'accueil du chrome trivalent dans des minéraux du manteau à partir de l'étude de sa luminescence. Cette spectroscopie de luminescence, mise en oeuvre à haute pression en cellule à enclumes de diamant, permet de suivre l'évolution des niveaux d'énergie du cr3+ en fonction de la pression. Nous avons ainsi acquis des données de luminescence sur plusieurs phases cristallines de basse pression (spinelles, pyroxènes, forstérite), de haute pression (grenats, ilménite, pérovskites), et sur des verres silicatés de composition chimique simple. Les résultats obtenus sur les minéraux montrent que le Cr3+ s'incorporent majoritairement dans les sites octaédriques, nécessitant, dans certains cas, une compensation locale des charges. Les mécanismes de substitution, mais aussi l'énergie de stabilisation de l'élément trace dans la structure, dépendent alors fortement de la nature des cations disponibles pour assurer l'équilibre électrostatique. Dans les verres, nous mettons en évidence des variations importantes de la distribution de sites d'accueil en fonction de la composition chimique. La modélisation des paramètres thermodynamiques qui participent au partage du chrome à partir de nos données de haute pression est alors discutée
Book Synopsis Behaviour of the Sm-Nd Isotopic System During Metamorphism by : Valérie Chavagnac
Download or read book Behaviour of the Sm-Nd Isotopic System During Metamorphism written by Valérie Chavagnac and published by . This book was released on 1999 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aims of this Ph.D. Thesis were to decipher whether the use of Nd model ages are reliable constraints for the crustal evolution on Proterozoic migmatized terrane (example of the Limpopo Belt in South Africa) and to examine the consistency between Sm-Nd gamet and V-Pb zircon ages on eclogites (example of the VHPM Dabieshan in Central China). The Central Zone of the Limpopo Belt which is mainly composed of orthogneisses and paragneisses underwent granulite facies metamorphism followed by decompression metamorphic conditions (clockwise P-T loop) at 2.0 Ga. We have performed Sm-Nd and U-Pb work associated with major and trace element analyses on three examples of migmatites generated at 2.0 Ga to study the chemical and isotopic fractionation which may occur during migmatization. Partial melting following the Bt dehydration reaction did lead to different behaviour of Sm-Nd systematics for metagreywacke and metapelite. ln the first case, chemical equilibrium and full Nd isotope exchanges were not reached due to the incrongruent Pl melting and to the effect of accessory mineraIs (Mnz and Ap) on the compositions of the partial melt. Monazite entered the melt in prefarence to apatite, either by dissolution or by entrainment, and its unradiogenic Nd isotope signature dominates the leucosome. The Nd model ages on partial melt are up to 400 Ma older than those on paleosomes. The Nd model ages of these rocks cannot be used in a simple way to cons train the evolution of Southern Africa. ln the second case, incongruent Pl melting influenced the distribution of major, LILE and also REE between the partial melts and the paleosomes. Full Nd isotope exchange was nearly achieved while Pb-Pb systematics were not fully resetted. Incomplete exchange for both Nd and Pb for two leucosomes is also argued. It appears that the accessory minerals were chemically and isotopically equilibrated with the partial melt and the paleosome. The Nd model ages can be used to constrain the crustal growth of the Limpopo Central Zone. Finally, in migmatites formed by metamorphic segregation at subsolidus conditions on orthogneiss, chemical equilibrium and Nd isotope exchange were not reached during migmatization. The distributions of the elements are related to the proportional amounts of each mineraI in the migmatitic components. However, full Pb isotope exchange is reached here as highlighted by a Pb-Pb WR isochron yielding 2.0 Ga. ln addition, the geochemical characteristics combined with REE modelling provided arguments for closed system behaviour of the whole rock during migmatization. The isotopic compositions of the protolith obtained via mass balance calculations can be used to cons train crustal evolution. The UHPM Dabieshan is characterized by the occurrence of coesite and its quartz pseudomorph as inclusions in eclogites of basaltic composition but also of undoubted metasedimentary origin. Sm.-Nd garnet-omphacite-whole rock isochrons on the coesite-bearing eclogites of the Bixiling Complex gave ages at 210 ± 9 to 218 ± 4 Ma which are similar to 218.4 ± 1.8 Ma and 218.4 ± 2.5 Ma ages obtained by V-Pb zircon data. At the Shuanghe locality, Sm-Nd gamet-kyanite-whole rock isochron on a retrogressed eclogite gave an age at 231 ± 35 Ma in line with the U-Pb zircon data at 233 ± 21 Ma (lower intercept in the concordia diagram). ln addition, Ar-Ar and Rb-Sr phengite ages performed on the eclogite host gneisses (Bixilingg locality) yield 198 ± 4 Ma to 212 ± 2 Ma ages, overlapping the previous Sm-Nd and V-Pb zircon ages on the coesite-bearing eclogites. Consequently, the Sm-Nd garnet dating provide ages in agreement with V-Pb zircon ages and the quartzo-feldspathic gneisses underwent an event coeval to VHP on eclogites. Nd isotope equilibration at the VHP metamorphism appears to have been complete
Book Synopsis Evolution cénozoïque du bassin de Magellan et tectonique des Andes australes by : Marc Diraison
Download or read book Evolution cénozoïque du bassin de Magellan et tectonique des Andes australes written by Marc Diraison and published by . This book was released on 1998 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: L'extrémité australe de l'Amérique du Sud se situe actuellement dans un contexte cinématique complexe impliquant les plaques Nazca, Antarctique et Scotia. Dans ce secteur, l'histoire compressive andine débute au Crétacé supérieur avec pour conséquences le soulèvement de la cordillère et le développement du bassin, d'avant-pays de Magellan. L'arcature actuelle des Andes australes résulte du développement progressif de l'orocline patagonien associé au fonctionnement d'un décrochement senestre le long de la bordure sud du continent depuis le Crétacé supérieur. A partir de 30 Ma, l'ouverture du passage de Drake entre le continent Sud-américain et la Péninsule Antarctique conduit à la croissance de la plaque Scotia. La subduction de la dorsale du Chili débute à 14 Ma au niveau de la Terre de Feu. Le point triple migre progressivement jusqu'à sa position actuelle à 46°30'S. L'étude structurale et cinématique de la région (analyse de populations de failles) a été réalisée principalement à la transition cordillère/bassin. Elle est complétée par l'analyse de l'imagerie satellitaire et de la topographie numérique, l'interprétation de données de sismique réflexion pétrolière, une étude paléomagnétique, et de la modélisation analogique. Cette étude met en évidence (1) des directions principales de raccourcissement subperpendiculaires à la cordillère tout le long de l'orocline, (2) des composantes décrochantes dextres et senestres le long des secteurs de la cordillère orientés respectivement N-S et E-O, et (3) des rifts néogènes disposés radialement affectant principalement la zone axiale du bassin de Magellan. Ce champ de déformation, compatible avec le contexte actuel, a été comparé à celui obtenu par modélisation analogique d'un orocline simple. Le passage progressif entre la zone de subduction à l'ouest et le décrochement au sud du continent (appelé effet de coin) semble être une condition suffisante au développement de l'essentiel des structures observées
Book Synopsis Soils and Sediments by : Helene Paquet
Download or read book Soils and Sediments written by Helene Paquet and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 523 pages. Available in PDF, EPUB and Kindle. Book excerpt: Clays and soils are of great importance in various scientific fields, such as agriculture and environmental science, and in mineral deposits. Students and close collaborators of Georges Millot, the eminent French clay sedimentologist, have put together a book with topics ranging from weathering processes and diagenetic evalution of sediments to sedimentary mineral deposits. The book is of interest to practitioners, advanced students as well as teachers in the above fields.
Book Synopsis Dynamique de l'érosion continentale aux grandes échelles de temps et d'espace by : Dimitri Lague
Download or read book Dynamique de l'érosion continentale aux grandes échelles de temps et d'espace written by Dimitri Lague and published by . This book was released on 2003 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: L'évolution à long terme des reliefs continentaux résulte de couplages complexes entre processus d'érosion et mouvements tectoniques qui tendent à s'équilibrer pour atteindre éventuellement un état stationnaire. La partie érosion de ces couplages est gouvernée par l'interaction entre des processus élémentaires de versant et de rivière, étroitement couplés, qui contrôlent l'organisation spatiale du réseau de drainage. Ces processus sont caractérisés par des vitesses d'érosion et de transport lentes sur les versants et très rapides dans les rivières, et dépendent souvent non-linéairement de la pente topographique et du flux d'eau. Il en résulte une dynamique complexe à l'échelle locale dont les conséquences à l'échelle continentale sur la vitesse et les volumes de matière transportés ne sont pas encore comprises. L'objectif de cette thèse a été de comprendre et modéliser cette dynamique à l'échelle des temps géologiques, dans le cadre de perturbations tectoniques simples, et pour des conditions climatiques constantes. Nous utilisons un modèle numérique permettant de simuler l'interaction de différents processus d'érosion de versant et de transport fluvial. Les solutions hors équilibre prédites par ce modèle ne pouvant être validées analytiquement ou à partir de données naturelles, une approche expérimentale inédite a été développée. Elle permet d'étudier précisément l'évolution d'une topographie soumise à l'action simultanée d'une surrection simple et de processus d'érosion et de transport par ruissellement. Au cours d'une expérience, la surface s'auto organise d'abord en une série de bassins versants de géométrie similaire aux systèmes naturels, puis l'altitude moyenne du système s'approche quasi-exponentiellement d'une valeur constante, traduisant un état d'équilibre macroscopique. L'analyse couplée des expériences et des simulations numériques montre que cette dynamique dépend fortement de la présence de zones de drainage internes non-connectées aux conditions limites du système, du degré de non-linéarité entre érosion et pente topographique et de l'existence d'un seuil d'érosion. A partir de l'analyse de systèmes naturels, via le formalisme de la relation pente-aire drainée, nous mettons en évidence l'existence d'un tel seuil dans les systèmes naturels. Pour ce faire nous avons développé un nouveau critère morphologique permettant de caractériser l'état dynamique des reliefs naturels. L'hypothèse d'équilibre dynamique entre érosion et tectonique, nécessaire à l'interprétation correcte des relations entre formes topographiques et processus d'érosion, peut être ainsi (in)validée. Ces résultats suggèrent que le seuil d'érosion habituellement négligé dans le calibrage des lois d'érosion élémentaires doit être explicitement pris en compte pour prédire correctement les formes topographiques naturelles, la dynamique de la croissance des réseaux de drainage et les relations à l'échelle continentale entre taux de dénudation et paramètres topographiques.
Book Synopsis Mineral Deposits of North Africa by : Mohammed Bouabdellah
Download or read book Mineral Deposits of North Africa written by Mohammed Bouabdellah and published by Springer. This book was released on 2016-06-21 with total page 585 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents an exhaustive overview of major orebodies and mineral deposits of North Africa. It is intended both for academic researchers and especially for exploration geologists interested in mineral exploration in the northern part of the African continent. Recent changes in the mining laws of most countries in this region have encouraged international mining companies to invest in local mineral industries. Accordingly, this volume will be very useful for these professionals, as well as for researchers in the field of economic geology.
Book Synopsis Metamorphic Rocks and Their Geodynamic Significance by : Jacques Kornprobst
Download or read book Metamorphic Rocks and Their Geodynamic Significance written by Jacques Kornprobst and published by Springer Science & Business Media. This book was released on 2002-10-31 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes metamorphic rock formation mechanisms in a simplified form. It presents the geometrical rules which control mineral assemblages as a function of rock composition, and provides the basis of a thermodynamical approach used for equilibrium slope calculations as well as for the evaluation of P, T stability fields of mineral associations. On the basis of several examples from the literature, the author emphasizes the relations between different metamorphic gradients and different geodynamic situations. Associated P-T-t paths are examined from several points of view including the respective roles of heat conduction and convection. Audience: This textbook will be useful to undergraduate students in geology, but also to research students and scientists needing to rapidly update their knowledge of metamorphism. It is also accessible to anybody interested in geosciences wanting to acquire a basic knowledge of the close relationships that exist between geodynamics and metamorphic processes.
Book Synopsis Multilingual Thesaurus of Geosciences by : J. Gravesteijn
Download or read book Multilingual Thesaurus of Geosciences written by J. Gravesteijn and published by . This book was released on 1995 with total page 698 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Caledonia written by P. Maurizot and published by Geological Society of London. This book was released on 2020-07-09 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: This memoir summarizes the current knowledge of New Caledonia’s geology, geodynamic evolution, and mineral resources, based on published and unpublished information. It comprises 10 research papers, each addressing a particular geological assemblage or topic. After an introductory chapter, and a review of the published geodynamic models of evolution of the SW Pacific, chapters 3 to 5 focus on the main geological assemblages of Grande Terre: the Pre-Late Cretaceous basement terranes, the Late Cretaceous to Eocene cover, and the Eocene subduction-obduction complex, one of the largest and best-preserved in the world. Chapter 6 is devoted to the Loyalty Islands and Ridge. Chapter 7 deals with the mostly terrestrial post-obduction units including regolith. Chapter 8 deals with palaeobiogeography and discuss plausible scenarios of biotic evolution. Chapters 9 and 10 provide an comprehensive review of New Caledonia’s mineral resources. The volume will interest stratigraphers, sedimentologists, marine geologists, palaeontologists, palaeogeographers, igneous and metamorphic petrologists, geochemists, geochronologists, and specialists in tectonics, geodynamic evolution, regolith, ophiolites, and economic geology.
Book Synopsis Thermodynamics in Geology by : D.G. Fraser
Download or read book Thermodynamics in Geology written by D.G. Fraser and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: It has long been realized that the mineral assemblages of igneous and metamorphic rocks may reflect the approach of a rock to chemical eCluilibrium during its formation. However progress in the application of chemical thermodynamics to geological systems has been hindered since the time of Bowen and the other early physical-chemical petrologists by the recurring Cluandary of the experimental geologist. His systems are complex and are experimentally intractable, but if they were not so refractory they would not be there to study at all. It is only recently that accurate measurements of the thermodynamic properties of pure, or at least well-defined minerals, melts and volatile fluid phases, combined with experimental and theoretical studies of their mixing properties, have made it possible to calculate the eCluilibrium conditions for particular rock systems. Much work is now in progress to extend the ranges of com position and conditions for which sufficient data exist to enable such calculations to be made. Moreover the routine availability of the electron microprobe will ensure that the demand for such information will continue to increase. The thermodynamic techniClues reCluired to apply these data to geological problems are intrinsically simple and merely involve the combination of appropriate standard state data together with corrections for the effects of solution in natural minerals, melts or volatile fluids.
Book Synopsis International Laterite Symposium by : David J. I. Evans
Download or read book International Laterite Symposium written by David J. I. Evans and published by . This book was released on 1979 with total page 730 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Biomineralization: From Fundamentals to Biomaterials & Environmental Issues by : Frédéric Marin
Download or read book Biomineralization: From Fundamentals to Biomaterials & Environmental Issues written by Frédéric Marin and published by Trans Tech Publications Ltd. This book was released on 2016-01-15 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: Special topic volume with invited peer reviewed papers only.
Book Synopsis Dictionnaire des termes de médecine by : Henry Eugène de Méric
Download or read book Dictionnaire des termes de médecine written by Henry Eugène de Méric and published by . This book was released on 1899 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Handbook of Biomineralization by : Peter Behrens
Download or read book Handbook of Biomineralization written by Peter Behrens and published by John Wiley & Sons. This book was released on 2009-09-28 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: This first comprehensive overview of the modern aspects of biomineralization represents life and materials science at its best: Bioinspired pathways are the hot topics in many disciplines and this holds especially true for biomineralization. Here, the editors -- well-known members of associations and prestigious institutes -- have assembled an international team of renowned authors to provide first-hand research results. This second volume deals with biometic model systems in biomineralization, including the biomineral approach to bionics, bioinspired materials synthesis and bio-supported materials chemistry, encapsulation and the imaging of internal nanostructures of biominerals. An interdisciplinary must-have account, for biochemists, bioinorganic chemists, lecturers in chemistry and biochemistry, materials scientists, biologists, and solid state physicists.
Book Synopsis Gardner's Photographic Sketchbook of the Civil War by : Alexander Gardner
Download or read book Gardner's Photographic Sketchbook of the Civil War written by Alexander Gardner and published by Ravenio Books. This book was released on with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: In presenting the Photographic Sketch Book of the War to the attention of the public, it is designed that it shall speak for itself. The omission, therefore, of any remarks by way of preface might well be justified; and yet, perhaps, a few introductory words may not be amiss. As mementoes of the fearful struggle through which the country has just passed, it is confidently hoped that the following pages will possess an enduring interest. Localities that would scarcely have been known, and probably never remembered, save in their immediate vicinity, have become celebrated, and will ever be held sacred as memorable fields, where thousands of brave men yielded up their lives a willing sacrifice for the cause they had espoused. Verbal representations of such places, or scenes, may or may not have the merit of accuracy; but photographic presentments of them will be accepted by posterity with an undoubting faith. During the four years of the war, almost every point of importance has been photographed, and the collection from which these views have been selected amounts to nearly three thousand.
Book Synopsis Molecular Biomineralization by : Werner E. G. Müller
Download or read book Molecular Biomineralization written by Werner E. G. Müller and published by Springer Science & Business Media. This book was released on 2011-08-30 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: The concept of ‘biomineralization’ signifies mineralization processes that take place in close association with organic molecules or matrices. The awareness that mineral formation can be guided by organic molecules notably contributed to the understanding of the formation of the inorganic skeletons of living organisms. Modern electron microscopic and spectroscopic analyses have successfully demonstrated the participation of biological systems in several mineralization processes, and prominent examples include the formation of bio-silica in diatoms and sponges. This insight has already made the application of recombinant technology for the production of valuable inorganic polymers, such as bio-silica, possible. This polymer can be formed by silicatein under conditions that cannot be matched by chemical means. Similarly, the efforts described in this book have elucidated that certain organisms, bacteria in deep-sea polymetallic nodules and coccoliths in seamount crusts, are involved in the deposition of marine minerals. Strategies have already been developed to utilize such microorganisms for the biosynthesis and bioleaching of marine deposits. Moreover, studies reveal that bio-polymers enhance the hydroxyapatite formation of bone-forming cells and alter the expression of important regulators of bone resorption, suggesting a potential for bone regeneration and treatment / prevention of osteoporosis.
Book Synopsis Geology of Clays by : Georges Millot
Download or read book Geology of Clays written by Georges Millot and published by Springer Science & Business Media. This book was released on 2013-12-11 with total page 443 pages. Available in PDF, EPUB and Kindle. Book excerpt:
