首页|Late Jurassic oceanic plateau subduction in the Bangong-Nujiang Tethyan Ocean of northern Tibet

Late Jurassic oceanic plateau subduction in the Bangong-Nujiang Tethyan Ocean of northern Tibet

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Oceanic plateau accretion and subsequent flat-slab subduction in modern convergent settings have pro-foundly influenced the nature of subduction and mantle dynamics.However,evaluating similar impacts in ancient convergent settings,where oceanic plateaus have been subducted but geological records are limited,remains challenging.In this study,we present geochronological and geochemical data for a suite of ore-associated plutonic rocks from the Gaobaoyue area of northern Tibet.These rocks have zircon U-Pb ages of 152-146 Ma,with high Sr contents and Sr/Y and La/Yb ratios,low MgO,Yb,and Y contents,and depleted Sr-Nd-Hf isotopic compositions,consistent with an adakitic affinity that was generated by the partial melting of subducting oceanic crust.We compare the Late Jurassic adakitic magmatism with the spatiotemporal evolution of magmatism in northern Tibet to infer oceanic plateau subduction and sub-sequent flat-slab subduction in the Bangong-Nujiang Tethyan Ocean.This tectonic model explains(ⅰ)slab-derived adakitic magmatism,(ⅱ)the observed lull in magmatic activity,(ⅲ)intraplate compression and uplift,and(ⅳ)subduction jump and initiation.We also propose that the subduction of heteroge-neous oceanic crust(i.e.,buoyant oceanic plateau subduction)provided favorable conditions for tectonic exhumation,vertical slab tearing,and the formation of Cu-Au deposits.Our findings not only have impli-cations for establishing the fundamental process of oceanic plateau accretion in ancient subduction zones but also provide an alternative explanation for Late Jurassic complex tectonomagmatic activity in north-ern Tibet.

Northern TibetAdakitic magmaOceanic plateauFlat-slab subductionVertical slab tearing

Hao Wu、Haiyong Liu、Yu Wang、Xijun Liu、Qinggao Zeng、Panxi Wang

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Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration & Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources on Guangxi,Guilin University of Technology,Guilin 541006,China

Tibet Geological Survey,Lhasa 850000,China

Tibet Bureau of Geological and Mineral Exploration and Development,Lhasa 850000,China

Second Tibetan Plateau Scientific Expedition and Research(STEP)ProgramNational Natural Science Foundation of ChinaNational Natural Science Foundation of ChinaNatural Science Foundation of Guangxi,ChinaShandong Provincial Natural Science FoundationChina Geological Survey

2019QZKK07029205520842174080AD21220033ZR2020QD045DD20190167

2024

10.1016/j.gsf.2024.101813

地学前缘(英文版)
中国地质大学（北京） 北京大学

地学前缘(英文版)

CSTPCD
影响因子：0.576
ISSN：1674-9871
年,卷(期)：2024.15(4)
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