Geochronological and geochemical constraints on the origin of the Yunzhug ophiolite in the Shiquanhe–Yunzhug–Namu Tso ophiolite belt, Lhasa Terrane, Tibetan Plateau
| Autor: | Jian-Lin Chen, Yun-Chuan Zeng, Ji-Feng Xu, Zhi-Qiang Kang, Bao-Di Wang, Feng Huang |
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| Rok vydání: | 2018 |
| Předmět: |
Dike
geography geography.geographical_feature_category Plateau 010504 meteorology & atmospheric sciences Geochemistry Geology Structural basin 010502 geochemistry & geophysics Ophiolite 01 natural sciences Tectonics Geochemistry and Petrology Mesozoic Mafic 0105 earth and related environmental sciences Terrane |
| Zdroj: | Lithos. :250-260 |
| ISSN: | 0024-4937 |
| Popis: | The formation of the Shiquanhe–Yunzhug–Namu Tso ophiolite melange zone (SNMZ) within the Lhasa Terrane, Tibetan Plateau, is key to understanding the Mesozoic tectonic evolution of this terrane, which remains controversial. We show that the Yunzhug ophiolite in the central segment of the SNMZ formed at ~ 150 Ma, based on U–Pb dating of zircons from a gabbroic sample in a well-developed sheeted dike complex. Geochemically, these mafic rocks are dominated by E-MORB-type compositions, along with minor amounts of rocks with P-MORB-type compositions. The samples also exhibit high eNd(t) values and lack negative Nb and Ta anomalies. Data for all the samples plot within the MORB array on a Th/Yb–Nb/Yb diagram. Therefore, these mafic rocks most likely formed in either a slow spreading oceanic setting or an embryonic ocean, and not in a back-arc basin as has been previously assumed. Taking into account the regional geology, we propose that the Yunzhug ophiolite is part of a distinct ophiolitic belt and represents material formed in an embryonic ocean within the Lhasa Terrane, which provides new insights into the Jurassic tectonic evolution of the Lhasa Terrane. |
| Databáze: | OpenAIRE |
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