Geochronology and Geochemistry of Early Cretaceous A-type Granites in Central-Eastern Inner Mongolia,China:Implications for Late Mesozoic Tectonic Evolution of the Southern Great Xing'an Range  

作　　者：ZHANG Yanwen ZHANG Xiaofei CHEN Lixin PANG Zhenshan CHEN Hui XUE Jianling ZHOU Yi TENG Chao CHEN Guochao 

机构地区：[1]School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China [2]Cores and Samples Center of Natural Resources,China Geological Survey,Yanjiao,Hebei 065201,China [3]Development and Research Centre,China Geological Survey,Beijing 100037,China [4]Mineral Exploration Technical Guidance Center,Ministry of Natural Resources,Beijing 100037,China [5]Chinese Academy of Natural Resources Economics,Beijing 100035,China [6]Nanyang Institutte of Technolog,Nanyang,Henan 473000,China [7]Hubei Key Laboratory of Resources and Eco-Environment Geology(Hubei Geological Bureau),Wuhan 430034,China

出　　处：《Acta Geologica Sinica(English Edition)》2023年第4期1094-1111,共18页地质学报（英文版）

基　　金：financial support from the National Natural Science Foundation of China(Grant Nos.41802222 and 42002102);the China Geological Survey Program(Grant Nos.1212011220453,DD20190570,DD20221692,DD20230053 and DD20230355);the Key R&D and Promotion Projects in Henan Province(Grant No.212102310030);the Open Fund of Hubei Key Laboratory of Resources and Eco-Environment Geology(Grant No.KJ2022-35)。

摘　　要：The southern Great Xing'an Range is the most critical Sn-polymetallic metallogenic belt in northeast China.However,the tectonic setting of the Early Cretaceous magmatic-metallogenic”flare-up“event remains uncertain.This paper presents an integrated study on the occurrence,petrology,zircon U-Pb ages,whole-rock geochemistry,and in situ zircon Hf isotopes for Wenduerchagan granites of Xi Ujimqin Banner,central-eastern Inner Mongolia.These granites consist primarily of granite porphyry(with ages of 137±1 Ma and 138±1 Ma)and(porphyritic)alkali feldspar granite(with an age of 141±2 Ma),corresponding to the early Early Cretaceous.They are A-type granites characterized by high silicon,alkali,and TFeO/MgO contents while being depleted of Ba,Nb,Ta,Sr,P,and Ti.They show right-dipping trend rare-earth element distribution characteristics with negative Eu anomalies(Eu/Eu^(*)=0.01-0.20)and weak heavy rare-earth element fractionation((Gd/Yb)_(N)=0.77-2.30).They demonstrate homogeneous zircon Hf isotopic compositions(positiveε_(Hf)(t)values from+5.3 to+7.1 and young two-stage Hf model ages of 851-742 Ma)and high zircon saturation temperatures(av.810℃).These geochemical characteristics indicate that Wenduerchagan granites originated from the partial melting of juvenile crust under high-temperature and low-pressure conditions.Wenduerchagan granites most likely formed in a post-collisional compression-extension transition regime caused by the closure of the Mongol-Okhotsk Ocean,when combined with regional geology.Such a transition regime can probably be attributed to the upwelling of the asthenospheric mantle caused by the break-off of a subducted Mongol-Okhotsk oceanic slab.Upwelling asthenospheric mantle provided sufficient energy and favorable tectonic conditions for magmatism and mineralization of the Early Cretaceous.

关 键 词：magmatism and mineralization A-type granite post-collisional environment Early Cretaceous southern Great Xing'an Range Mongol-Okhotsk Ocean 

分 类 号：P597.3[天文地球—地球化学] P534.53[天文地球—地质学] P588.121