成果归属机构：

青藏高原研究中心

作者：

Hebert, R. ; Bezard, R. ; Guilmette, C. ; Dostal, J. ; Wang, C. S. ; Liu, Z. F.

单位：

Univ Laval, Dept Geol & Genie Geol, Quebec City, PQ G1V 0A6, Canada;St Marys Univ, Dept Geol, Halifax, NS B3H 3C3, Canada;China Univ Geosci, Res Ctr Tibetan Plateau Geol, Beijing 100083, Peoples R China;Tongji Univ, Sch Ocean & Earth Sci, Shanghai 200092, Peoples R China

关键词：

Ophiolite; Yarlung Zangbo Suture Zone; Suprasubduction; Geodynamics; Tibet

摘要：

The purpose of this first synthesis is to summarize findings on the Yarlung Zangbo Suture Zone (YZSZ) ophiolites and discuss still remaining problems. The YZSZ studied for almost 30 years and is the youngest of the sutures recognized on Tibet Plateau. It is now acknowledged that the YZSZ is a complex assemblage of sedimentary, metamorphic and igneous rocks created during and shortly after the collision between India and Eurasia. The ages of the various lithologies span a time interval from the Jurassic to the Middle Miocene, with some Permian and Devonian exotic blocks from melange zone. The YZSZ is characterized by ophiolitic complexes and ophiolitic melange. The ophiolites are of two types: non dismembered and dismembered sections. The non disturbed sections, although tectonically reworked, are observed along the segment from Dazhuqu to Jiding in Xigaze area and Spontang ophiolite. The dismembered sequences are found in various locations such as Nidar, Kiogar, Jungbwa, Saga, Sangsang, Xigugabu, and Luobusa. The incomplete stratigraphic log could be connected to intraoceanic or orogenetic origins. The ophiolites are distributed into two groups of ages: the Luobusa. Zedang and Kiogar sequences being Jurassic-Lower Cretaceous whereas all other sequences are of Lower Cretaceous age. Compilation of geochronological data suggest that some ophiolite sequences might have evolved for over more than 70 My from their initial genesis to obduction which occurred around 70-90 My ago. Ophiolites differ in terms of petrological and geochemical aspects however, they were all generated in suprasubduction zone and more specifically in arc (few fore-arc) and back-arc settings. Synthesis of more than 700 geochemical analyses show variable mixing of components from N-MORB-type to IAT-CAB and to OIB end-members. The Jurassic ophiolites show the maximum of arc component while the Lower Cretaceous ones show little to strong mixing. In addition, most ophiolites were created in short lived (30 My) basins and generated close to the Eurasiatic continental margin. We propose that Ladakh-Tibet ophiolites were generated in a suprasubduction context similar to Mariana arc, inter-arc and back-arc or Tonga-Lau system. The variable arc signature of these ophiolites is directly related to their initial position within the suprasubduction system. (c) 2011 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

基金：

National Research Council of Canada; China Research Council

语种：

英文

DOI：

10.1016/j.gr.2011.10.013

来源：

GONDWANA RESEARCH,2012(2):377-397.

出版日期：

2012-09

提交日期：

2017-12-14

引用参考：

Hebert, R.; Bezard, R.; Guilmette, C.; Dostal, J.; Wang, C. S.; Liu, Z. F.. The Indus-Yarlung Zangbo ophiolites from Nanga Parbat to Namche Barwa syntaxes, southern Tibet: First synthesis of petrology, geochemistry, and geochronology with incidences on geodynamic reconstructions of Neo-Tethys[J]. GONDWANA RESEARCH,2012(2):377-397.