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611.
Yannick Thomas Bruno Marsset Stéphane Didailler Jean-Pierre Regnault Sandie Le Conte Dominique Le Roux Patrick Farcy Maurice Magueur Pascal Viollette Jacques Herveou Jean-Charles Guedes Bernard Jegot Gilles Gascon Christian Prudhomme Hervé Nouze Estelle Thereau Isabelle Contrucci Jean-Paul Foucher 《Comptes Rendus Geoscience》2004,336(6):579-585
This note presents the first results of the development of 3D high-resolution marine seismic method designed for scientific application. A particular attention was paid to the realisation of an operational system to be in agreement with the expected goals in term of acquisition and processing. To cite this article: Y. Thomas et al., C. R. Geoscience 336 (2004). 相似文献
612.
Olivier Lacombe Jacques Angelier Frédéric Mouthereau Hao-Tsu Chu Benoı̂t Deffontaines Jian-Cheng Lee Muriel Rocher Rou-Fei Chen Lionel Siame 《Comptes Rendus Geoscience》2004,336(9):815-825
A structural and microtectonic analysis performed in the Liuchiu Hsu island demonstrates that its Plio-Pleistocene tectonic evolution was dominated by alternating NW–SE shortening and local radial extension caused by mud diapirism. Previous models based on seismic data considering both the formation of the Liuchiu Hsu island and the fold development in SW Taiwan as mainly driven by mud diapirism, fail to account for both the asymmetry of the west vergent thrust-related anticlines onshore and the elongated character of the ridges formed by diapir alignments offshore, which rather argue in favour of a tectonic origin. To cite this article: O. Lacombe et al., C. R. Geoscience 336 (2004). 相似文献
613.
SHU Liangshu CHARVET Jacques GUO Lingzhi LU Huafu LAURENT-CHARVET Sebastien 《《地质学报》英文版》1999,73(2):148-162
The nearly E-W-trending Aqqikkudug-Weiya zone, more than 1000 km long and about 30 km wide, is an important segment in the Central Asian tectonic framework. It is distributed along the northern margin of the Central Tianshan belt in Xinjiang, NW China and is composed of mylonitized Early Palaeozoic greywacke, volcanic rocks, ophiolitic blocks as a mélange complex, HP/LT-type bleuschist blocks and mylonitized Neoproterozoic schist, gneiss and orthogneiss. Nearly vertical mylonitic foliation and sub-horizontal stretching lineation define its strike-slip feature; various kinematic indicators, such as asymmetric folds, non-coaxial asymmetric macro- to micro-structures and C-axis fabrics of quartz grains of mylonites, suggest that it is a dextral strike-slip ductile shear zone oriented in a nearly E-W direction characterized by "flower" strusture with thrusting or extruding across the zone toward the two sides and upright folds with gently plunging hinges. The Aqqikkudug-Weiya zone experienced at least two stages of ductile shear tectonic evolution: Early Palaeozoic north vergent thrusting ductile shear and Late Carboniferous-Early Permian strike-slip deformation. The strike-slip ductile shear likely took place during Late Palaeozoic time, dated at 269(5 Ma by the40Ar/39Ar analysis on neo-muscovites. The strike-slip deformation was followed by the Hercynian violent S-type granitic magmatism. Geodynamical analysis suggests that the large-scale dextral strike-slip ductile shearing is likely the result of intracontinental adjustment deformation after the collision of the Siberian continental plate towards the northern margin of the Tarim continental plate during the Late Carboniferous. The Himalayan tectonism locally deformed the zone, marked by final uplift, brittle layer-slip and step-type thrust faults, transcurrent faults and E-W-elongated Mesozoic-Cenozoic basins. 相似文献
614.
Geochemistry of an oceanite-ankaramite-basalt suite from East Island,Crozet Archipelago 总被引:1,自引:0,他引:1
Bernard M. Gunn Ramon Coy-Yll Norman D. Watkins Christian E. Abranson Jacques Nougier 《Contributions to Mineralogy and Petrology》1970,28(4):319-339
The petrology and geochemistry of East Island have been investigated for the first time. The island is a deeply dissected remnant of a Pleistocene shield volcano, one of several emerging from an oceanic rise forming part of the southwest branch of the Indian Ocean ridge system. The lavas form a flat-lying sequence of oceanites, ankaramites, olivine basalts and feldsparphyric basalts, the ankaramites containing 1 cm phenocrysts of diopsidic clinopyroxene. X-Ray fluorescence analyses were made of 43 lavas for the major elements plus Cr, Ni, Rb, Sr, Ba, Pb, and Th and the minerals were analysed by electron microprobe. The elements Mg, Cr, and Ni are strongly concentrated in spinel, olivine and clinopyroxene phases and in the ankaramites and oceanite lavas with maximum concentrations of 18% MgO, 1,000 ppm Cr, 380 ppm Ni, while Al, Ti, K, Rb, Ba, Th, Na, P, Sr concentrate in the groundmass and in the feldspathic and aphyric basalts. The elements Si, Ca, Fe and Mn remain virtually constant throughout the series.Correlations of +0.95 or better exist between the concentrations of elements within the two groups given above, and negative correlations between elements in different groups. The fractionation trends are unique with respect to the constant Al/Ti ratio and K/Sr ratio, but all trends may be reproduced by calculating the effect of subtraction of suitable amounts of chromite, olivine and low Ti clinopyroxene from an alkaline olivine basalt parent. Either fractionation has taken place involving these three phases under low pressure conditions or it is the result of different degrees of partial melting of mantle material.A complex magnesian chrome spinel is found in the ankaramites and is often jacketed by a chromian titanomagnetite. A complete series of intermediate compositions appears to exist between the two end members. 相似文献
615.
Jacques Touret 《Lithos》1971,4(3):239-249
The basement of Southern Norway is a genetically homogeneous migmatite complex in which old supracrustals produced granitic and granodioritic ‘neosome’ during a late Precambrian (109 years ago) regional metamorphism. Observed isograds of critical minerals: muscovite, cordierite, orthopyroxene indicate that the Telemark amphibolite facies in the North passes into the coastal Bamble granulite facies in the South. The data of expeimental petrology suggest that the transition, which took place at temperatures of 700–800°C, is essentially due to a decrease of the partial water pressure. PH2O was equal to total pressure Ps in the amphibolite facies and lower than 2 kb in the granulite facies. 相似文献
616.
Prof. Georges Millot Prof. Jacques Lucas Hélène Paquet 《International Journal of Earth Sciences》1966,55(1):1-20
Résumé Les dégradations des minéraux argileux sont fréquentes dans les altérations. Elles comportent une évolution des réseaux cristallins depuis les micas et chlorites jusqu'aux minéraux ouverts comme les vermiculites et les montmorillonites par l'intermédiaire d'édifices interstratifiés. Les agradations constituent le mécanisme réciproque et sont fréquentes dans la sédimentation et la diagenèse. Elles régénèrent par cicatrisation, construction et croissance, les phyllites caractéristiques du prémétamorphisme: illite et chlorite. Ces transformations minérales dépendant des milieux naturels sont un chapitre important de la Géochimie des silicates de l'Hydrosphère.
The clay mineral degradations are frequent during weathering. They involve an evolution of the crystal lattices, from the micas and the chlorites to the open-minerals, through the mixed-layers. The aggradations constitute the reciprocal mechanism and they are frequent during sedimentation and diagenesis. Through cicatrization, construction and growth, they regenerate the phyllites typical of premetamorphism: illite and chlorite. These mineral transformations, subject to the natural environments, are an important chapter of the Geochemistry of Hydrosphere silicates.
Zusammenfassung Während der Verwitterungen kommt oft ein Abbau der Tonminerale vor, der sich durch die Entwicklung des Gitters von Glimmer und Chlorit, über ein Zwischenstadium von Wechsellagertonen, zu offenen Mineralen wie Vermiculit und Montmorillonit kennzeichnet. Der entgegengesetzte Vorgang spielt sich in dem, in Ablagerung und Diagenese häufigen Aufbau ab. So werden die charakteristischen Phyllosilikate der Vormetamorphose: Illit und Chlorit, durch Vernarbung, Aufbau und Anwachsen der Gitter wieder hergestellt. Diese Veränderungen, die von den Bedingungen der natürlichen Milieus abhängen, stellen ein wichtiges Kapitel der Geochemie der Hydrosphärensilikate dar.
. .相似文献
617.
The level fluctuations of Lake Ilay, Jura (France) during the last three millennia are reconstructed from sedimentological and malacological analyses of a core that is well-dated by tree-ring, radiocarbon and pollen datings. Changes in sediment facies, in carbonate concretion assemblages and in mollusc assemblages highlight a major lowering phase atc. 1550 BP and minor lowering phases atc. 2800 BP and shortly before AD 1394. Rises in lake level developed during the early Subatlantic and betweenc. 1500 and 1000 BP. These data are in good agreement with other proxy data from higher European and American latitudes. These correlations support the climatic origin of the level fluctuations of the Lake Ilay during the late Holocene. They suggest that the mediaeval climatic optimum is centred rather in the early than the late Middle Age. 相似文献
618.
619.
The Dog Creek archaeological site (NcVi‐3), located in the northern Yukon, provides evidence of complex site transformational processes related to microclimatic conditions occurring since the mid‐Holocene. Geoarchaeological research at Dog Creek sought to interpret site formation processes in order to understand the relationship between surficial artifacts, buried artifacts, and stratified sediments. It also attempted to reconstruct the periglacial processes that were active in transforming the site and their relationships to microclimatic conditions. Sedimentology and fabric analysis show that artifacts were buried by solifluction and disturbed by frost heave and cryoturbation. Radiocarbon dating and pollen analysis demonstrated that solifluction took place approximately 5200–2000 years ago when a spruce forest existed at the site. This evidence suggests an onset of cooling conditions that continues to the present. After the mid‐Holocene, the spruce treeline began to move south toward its present position. © 2001 John Wiley & Sons, Inc. 相似文献
620.