Geochronology and geochemistry of Cretaceous-Eocene granites,Tengchong Block(SW China):Petrogenesis and implications for Mesozoic-Cenozoic tectonic evolution of Eastern Tethys  

作　　者：Yongqing Chen Guangjie Li Luxue Qin Yingxiang Lu Chengxing Jiang 

机构地区：[1]School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China [2]Yunnan Geological Survey,Kunming 650051,China

出　　处：《Geoscience Frontiers》2022年第2期214-236,共23页地学前缘（英文版）

基　　金：funded by the National Natural Science Foundation of China(Grant Nos.41972312,41672329,41272365);the National Key Research and Development Project of China(Grant No.2016YFC0600509)。

摘　　要：The Early Cretaceous-Early Eocene granitoids in the Tengchong Block record the evolutionary history of the Mesozoic-Cenozoic tectono-magmatic evolution of Eastern Tethys.(a)The Early Cretaceous granitoids with relatively low(^(87)Sr/^(86)Sr)iratios of 0.7090-0.7169 andε_(Nd)(t)values of-9.8 to-7.8 display metaluminous,calc-alkaline dominated by I-type granite affinity and hybrid mantle-crust geochemical signatures.They may have been derived from melting of the subducted Meso-Tethyan BangongNujiang oceanic crust with terrigenous sediments in an arc-continent collisional setting.(b)The Late Cretaceous-Paleocene granitoids with relatively high(^(87)Sr/^(86)Sr)iratios of 0.7109-0.7627,andε_(Nd)(t)values of-12.1 to-7.9 exhibit metaluminous to peraluminous,calc-alkaline dominated by S-type granite affinity and hybrid Lower-Upper crust geochemical signatures,which may be originated from partial melting of the Meso-Proterozoic continental crust in the collision setting between the Tengchong Block and Baoshan Block.(c)The Early Eocene granitoids have metaluminous,calc-alkaline I-type and S-type granites dual affinity,with relatively high(^(87)Sr/^(86)Sr)iratios of 0.711-0.736,ε_(Nd)(t)values of-9.4 to-4.7,showing crust-mantle mixing geochemical signatures.They may have been originated from partial melting of the late Meso-Proterozoic upper crustal components mixed with some upper mantle material during the ascent process of mantle magma caused by the subduction of the Neo-Tethyan Putao-Myitkyian oceanic crust,and collision between the Western Burma Block and the Tengchong Block.It is these multi-stage subductions and collisions that caused the spatial and temporal distribution of the granitic rocks in the Tengchong Block.

关 键 词：Zircon U-Pb geochronology Sr-Nd-Pb isotopes Granites in the Tengchong Block Tectono-magmatic evolution Eastern Tethys tectonic domain SW China 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学] P542