Petrogenesis of the Late Eocene to Early Oligocene Yao'an Shoshonitic Complex,Southeastern Tibet:Partial Melting of an Ancient Continental Lithospheric Mantle beneath the Yangtze Block  

作　　者：DONG Mengmeng YANG Tiannan XUE Chuandong XIN Di LIANG Mingjuan YAN Qinggao 

机构地区：[1]Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China [2]School of Earth and Space Sciences,Peking University,Beijing 100871,China [3]Department of Earth Sciences,Kunming University of Science and Technology,Kunming 650093,China [4]Geological Museum of Guizhou,Guiyang 550081,China [5]Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China

出　　处：《Acta Geologica Sinica(English Edition)》2023年第6期1657-1670,共14页地质学报（英文版）

基　　金：financially supported by the Ministry of Sciences and Technology of China(Grant No.2022YFF0800901);the Natural Science Foundation of China(Grant Nos.92055206 and 42163007)。

摘　　要：Cenozoic potassic-ultrapotassic igneous rocks are widespread in the southeastern Tibetan Plateau.Their petrogenesis and magmatic processes remain subject to debate in spite of numerous publications.Almost all of the Cenozoic extrusive and intrusive rocks in the Yao’an area,western Yunnan Province,SW China,are geochemically shoshonitic,collectively termed here the Yao’an Shoshonitic Complex(YSC).The YSC is located in the(south)easternmost part of the ENE-WSW-trending,~550 km-long and~250 km-wide Cenozoic magmatic zone;the latter separates the orthogonal and oblique collision belts of the India-Eurasia collision orogen.Previously published geochronological and thermochronological data revealed that the rocks of the YSC were emplaced over a short timespan of 34-32 Ma.This and our new data suggest that the primary magma of the YSC likely was formed by partial melting of ancient continental lithospheric mantle beneath the Yangtze Block.This part of the continental lithospheric mantle had likely not been modified by any oceanic subduction.Fractionation crystallization of an Mg-and Ca-bearing mineral and TiFe oxides during the magmatic evolution probably account for the variable lithologies of the YSC.

关 键 词：Ancient continental lithospheric mantle Partial melting Yao’an Shoshonitic Complex Late Eocene to early Oligocene SE Tibetan Plateau 

分 类 号：P588.1[天文地球—岩石学] P542.5[天文地球—地质学]