Geochronology and Geochemistry of the Permian Granitoids from the Alxa Area,Inner Mongolia,China:Constrains on the Permian Evolution of the Central Asian Orogenic Belt  

作　　者：HUANG Haibin SHI Yuruo Lawford JANDERSON KANG Yuelan 

机构地区：[1]SinoProbe Laboratory,Beijing SHRIMP Center,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China [2]Department of Earth and Environment,Boston University,Boston MA 02215,USA [3]National Natural History Museum of China,Beijing 100050,China

出　　处：《Acta Geologica Sinica(English Edition)》2025年第1期83-99,共17页地质学报(英文版)

基　　金：financially supported by the Geological Survey of China(Grant Nos.DD20240075,and DD20243516);the National Natural Science Foundation of China(Grant No.41872209);Basic Scientific Research Fund of the Institute of Geology,Chinese Academy of Geological Sciences(Grant No.J2314)。

摘　　要：We report new SHRIMP zircon U-Pb ages,zircon Lu-Hf isotopic and whole rock geochemical data from Permian granitoids located in the Alxa area of Inner Mongolia,China.In combination with published geochronological and geochemical data,the granitoids in the region can be divided into two age groups:ca.285 Ma and ca.269 Ma.The granitoids of the first group are mainly composed of calc-alkaline to high-K calc-alkaline,weakly peraluminous Ⅰ-type granodiorites with ε_(Hf)(t)values of-19.6 to-4.3,which demonstrates evidence of crustal reworking;the granitoids of the second group,however,mainly consist of A-type granites that are high-K calc-alkaline to shoshonite,metaluminous to weakly peraluminous,and have high 10,000×Ga/Al ratios(2.59-3.12)and ε_(Hf)(t)values ranging from-11.3 to-2.7,all of which demonstrates a mixed crust-mantle source.We interpret the granitoids of the first group to have formed during the subduction of Central Asian oceanic crust and the second group to have formed by the asthenospheric upwelling caused by the formation of slab windows during late ocean ridge subduction.

关 键 词：GEOCHRONOLOGY zircon Lu-Hf isotopes ridge subduction PERMIAN Central Asian Orogenic Belt 

分 类 号：P542.2[天文地球—构造地质学] P588.121[天文地球—地质学] P534.46