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711.
This study is devoted to the first French determinations of absolute gravity in the Antarctic (Dumont-d'Urville, Terre Adélie) and Arctic (Ny-Alesund, Spitsbergen) polar regions. The measurements in Dumont-d'Urville were performed in 2000 with the help of the FG5#206 absolute gravimeter belonging to the French geodetic community since beginning 1997; they show a strong noise that causes an uncertainty close to 11 μGal in the determination of the mean gravity value, which will be compared, to a new determination planned for 2005. The Ny-Alesund measurements show on the contrary a noise that, although very variable in time, leads to a gravity determination of better than 5 μGal. The comparison of our value with a previous one two years before suggests a gravity decrease of about 4 μGal which is related to the vertical uplift measured by Very Large Baseline Interferometry (VLBI) at the same site. However, the uncertainty does not allow discriminating between height-to-gravity conversion factors originating from different models. To cite this article: J. Hinderer et al., C. R. Geoscience 334 (2002) 819–826. 相似文献
712.
New data about the ‘Sables fauves’ clearly show two different kinds of organisations: stratigraphic superposition of Langhian and Serravallian units to the south and embankment of Serravallian sediments in Langhian deposits to the north. The result consists in two different palaeogeographic schemes. The Langhian Sea is widely extended, forming the ‘Lectoure Gulf’, whereas the Serravallian Sea is much more reduced, with valleys fillings to the north and a little gulf to the south. This involves a tectonic activity along a structure which orientation is N120°E (‘flexure de la Douze’) and a relative rising of the northern part, of about 30 m. To cite this article: P. Gardère et al., C. R. Geoscience 334 (2002) 987–994. 相似文献
713.
The singular evolutive extended Kalman (SEEK) filter has been proposed recently by Pham et al. (1997) for data assimilation into numerical oceanic models. This filter has been applied in different realistic ocean frameworks and has provided satisfactory results ( Pham et al., 1997; Verron et al., 1998). However, the SEEK filter remains expensive in real operational assimilation. To reduce cost and obtain a better representativity, we introduce the idea ‘local correction basis'. Such basis however cannot be made to evolve according to the model without destroying its locality property. Therefore we shall keep this basis fixed and we augment it by a few global basis vectors which evolve. The resulting semi-evolutive partially local filter is much less costly to implement than the SEEK filter and yet can yield better results. In the first application, validation twin experiments are conducted in a realistic setting of the OPA model over the tropical Pacific Ocean. 相似文献
714.
新疆北部古生代大陆增生构造 总被引:35,自引:2,他引:35
古生代亚洲中部是一幅两陆夹一洋、洋中多地体的构造图案,大地构造框架与现代西南太平洋格局十分相似。中亚造山带是晚古生代复杂地体的拼贴带。新疆北部古生代存在4类成因的8个地体构造。它们以裂解陆块地层块体、海山和火山弧的形式散布在中蒙大洋中,诸地体间是一系列的小洋盆。晚古生代,这些地体开始彼此拼贴并导致强烈推覆作用。石炭纪末-二叠纪初,中蒙大洋闭合,散布其中的诸地体分别增生到塔里木大陆北缘和西伯利亚大陆南缘。北天山-准噶尔地区6条蛇绿岩带记录了诸地体间碰撞事件。 相似文献
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Lucien Leclaire Yannis Bassias Micheline Denis-Clocchiatti Hugh Davies Isabelle Gautier Bernard Gensous Pierre-Jean Giannesini Philippe Patriat Jacques Segoufin Michel Tesson Jacques Wannesson 《Geo-Marine Letters》1987,7(4):169-176
Geological samples from the southern Kerguelen Plateau include Lower Cretaceous basalt and lava breccia, probable Lower Cretaceous conglomerate and shelf limestone, Upper Cretaceous chert with dolomite, Upper Cretaceous-Eocene ooze, and Tertiary conglomerate. Neogene sediments are only a few hundred m thick, and include foraminiferal and diatomaceous ooze, and ice-rafted debris. In conjunction with seismic reflection profiles, the samples indicate Early Cretaceous near-shore volcanism, followed by erosion, sedimentation, and subsidence through Cretaceous; arching of the plateau at the end of Cretaceous; subsidence through Paleogene; widespread emergence in mid-Tertiary; and slow subsidence through Neogene. 相似文献