Petrogenesis of Oligocene Granitoids and its Implications on Beryllium Mineralization at Pagele,Nianqingtanggula Mountain(Central Tibet)  

作　　者：ZHANG Linyuan YANG Zhusen HOU Zengqian WU Changda LIU Chang XU Peiyan XIE Lankui 

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]Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China [4]School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China [5]Institute of Geology and Mineral Resources,Chengdu Center,China Geological Survey,Chengdu 610081,China

出　　处：《Acta Geologica Sinica(English Edition)》2024年第5期1202-1225,共24页地质学报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Grant Nos.92062105,91855214);the National Key Research and Development Program of China(Grant Nos.2021YFC2901905,2016YFC0600306)。

摘　　要：The newly discovered Oligocene granitoids(33.1-28.7 Ma)at Pagele are magmatic rocks related to beryllium mineralization during the India-Asia late-collisional stage.This discovery provides an ideal example to study the latecollisional orogeny and beryllium prospecting in the Lhasa terrane.The Oligocene granitoids include porphyritic granodiorite,StageⅠ,ⅡandⅢgranites,and granitic pegmatite.Geochemical analysis shows that the porphyritic granodiorite is characterized by high SiO_(2),K_(2)O,totalΣREE contents,and(La/Yb)N ratios;while the latter two by higher SiO_(2),lowerΣREE and(La/Yb)N ratios.Notably,the granitic pegmatite has extremely high Y/Ho,low K/Rb and Zr/Hf,and distinct REE tetrad effect(1.14-1.21).This study suggests that the porphyritic granodiorite may be derived from partial melting of beryllium-rich materials composed of Lhasa ancient crust(70%-80%)and enriched Lhasa lithospheric mantle(20%-30%)under the tearing subduction of Indian slab.The three-stage granites and granitic pegmatite,which contain higher beryllium contents or beryls,were likely generated by highly fractionation of the porphyritic granodioritic magma or other homologous magma.Considering the possible genetic and spatial link between Indian slab tear and rifts,we suggest that highly-fractionated granites in rifting systems represent important Be prospecting targets in the Lhasa terrane.

关 键 词：enriched Lhasa lithospheric mantle beryllium mineralization Oligocene granitoids Lhasa ancient crust central Lhasa subterrane 

分 类 号：P588.121[天文地球—岩石学] P618.72[天文地球—地质学]