首页|Late Cambrian Magmatic Events in SW Yunnan and Implications for the Tectonic Reconstruction of Northern Gondwana

Late Cambrian Magmatic Events in SW Yunnan and Implications for the Tectonic Reconstruction of Northern Gondwana

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In this study,we investigated Early Paleozoic magmatic rocks of the Manlai Formation exposed along the eastern margin of the Lancang terrane to better understand the tectonic history of the Proto-Tethys.We present petrological,geochemical and whole-rock Sr-Nd and zircon Hf isotopic data for basalts and gabbros sampled from the Qianmai mélange.Zircon grains from six basaltic and gabbroic samples yielded U-Pb ages of 495-482 Ma.These rocks are characterized by tholeiitic and Nb-enriched compositions,with Nb/La ratios in the range of 0.38-1.38,similar to the typical Nb-enriched basalts.All the mafic rocks show slightly negative to positive εNd(t)(-1.67 to+4.32)and zircon εHf(t)val-ues(-7.3 to+3.8).Elemental and isotopic data suggest that the Qianmai Nb-enriched mafic rocks were mainly derived from the mixing of an OIB-like source with a subduction-modified mantle wedge source.Together with magmatic and sedimentary records of similar ages in the Lancang terrane and the Baoshan Block,our results reveal Early Paleozoic magmatic and sedimentary sequences along an active margin of the Proto-Tethys.Taking into account the recently identified Early Paleozoic ophiolitic mélange in the Yunxian-Menghai belt,we consider the Qianmai magmatic rocks to represent the prod-ucts of early-stage subduction-related magmatism within a primitive island arc or fore-arc setting asso-ciated with the southward subduction of the Proto-Tethys.We infer that prolonged south-dipping sub-duction on the northern margin of Gondwana persisted from the Cambrian to the Late Ordovician.

Qianmai mélangeNb-enriched basaltsisland arcProto-Tethysnorthern margin of GondwanaSW Yunnantectonicsgeochemistry

Guichun Liu、Jianwei Zi、Xiaomei Nie、M.Santosh、Cai Zhu、Wei Wang、Tianyu Zhao、Guangyan Chen、Qinglai Feng

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Yunnan Institute of Geological Sciences,Kunming 650216,China

School of Earth Sciences,China University of Geosciences,Wuhan 430074,China

State Key Lab of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China

John de Laeter Centre State Key,Curtin University,Bentley 6102,Australia

School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China

Department of Earth Science,University of Adelaide,Adelaide SA5005,Australia

Yunnan Geotechnical Engineering Survey and Design Institute,Kunming 650214,China

Yunnan Exploration Institute of Geology and Mineral Resources,Kunming 650051,China

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the"Xingdian Talent"Youth Talent Program in Yunnan ProvinceNational Natural Science Foundation of ChinaNational Natural Science Foundation of ChinaNational Natural Science Foundation of ChinaState Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences in Wuhan

XDYC-QNRC-2022-0041421620204187306292055314MSFGPMR201702

2024

10.1007/s12583-022-1613-5

地球科学学刊(英文版)
中国地质大学

地球科学学刊(英文版)

CSTPCD
影响因子：0.724
ISSN：1674-487X
年,卷(期)：2024.35(5)