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Accrétions contientales en Asie centro-orientale : évolution géodynamique et structurale du Tianshan et du Junggar oriental (nord-ouest Chine) au Paléozoïque.

Abstract : In eastern central Asia (north Xinjiang), the Paleozoic orogen of Tianshan separates the two blocks of Tarim and Junggar. It is divided into three units: the south Tianshan is composed of gneissic and Silurian ophiolitic nappes; in the central Tianshan, an Ordovician volcanic arc and Silurian flyschs overlay a Proterozoic basement; the north Tianshan is characterised by a Devonian to Carboniferous calc-alkaline volcanism.
The structural study of Tianshan and of the eastern border of Junggar provides new information on the chronology and kinematic of deformations which were responsible for the Palaeozoic structuration of this area. Except a pre-Sinian D1 deformation recognised in the Proterozoic substratum of Tianshan, three stages are distinguished. The first one, D2, is north-verging and coeval with the emplacement of the central Tianshan ophiolites of Mishigou and of the south Tianshan ophiolitic nappes of Kumux. The Middle to Late Devonian age of D2 is constrained by the Early Devonian age of ophiolites and the unconformity of Early Carboniferous conglomerates. A Middle to Late Carboniferous deformation D3 is divided into two stages: first, a southward shearing along the boundary between Junggar and Siberian blocks; second, a northward one which occurred in all the north Tianshan unit as folds and thrusts. D3 was coeval with the accretion of the Junggar block with the Tianshan. Finally, a double stage strike-slip deformation D4 dated at 290 and 245 Ma occurred all around the Junggar basin. It was dextral in whole Tianshan and roughly sinistral in Chinese Altay area.
In conclusion, the new structural and geochemical data are synthesised in a geodynamic model showing the Cambrian to Permian history of Tianshan and Junggar, marked by the successive accretion of the involved continental blocks and arcs.
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https://tel.archives-ouvertes.fr/tel-00001909
Contributor : Nathalie Pothier <>
Submitted on : Thursday, January 23, 2003 - 9:43:30 AM
Last modification on : Thursday, March 5, 2020 - 6:49:19 PM
Document(s) archivé(s) le : Friday, April 2, 2010 - 6:17:43 PM

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  • HAL Id : tel-00001909, version 1

Citation

Sébastien Laurent-Charvet. Accrétions contientales en Asie centro-orientale : évolution géodynamique et structurale du Tianshan et du Junggar oriental (nord-ouest Chine) au Paléozoïque.. Géologie appliquée. Université d'Orléans, 2001. Français. ⟨tel-00001909⟩

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