青海共和盆地三叠纪中酸性侵入岩中电气石化学组成、硼同位素特征及对岩浆-热液演化的启示  

Chemical and boron isotopic composition of tourmaline from the Gonghe Triassic intermediate-acid intrusive rocks,Qinghai and its implications for evolution of the magmatic-hydrothermal system

作　　者：陈希节 贠晓瑞[2,4,5] 雷敏 张盛生[6] 蔡志慧 刘若涵[2,7] 李振宇 何碧竹 CHEN XiJie;YUN XiaoRui;LEI Min;ZHANG ShengSheng;CAI ZhiHui;LIU RuoHan;LI ZhenYu;HE BiZhu(Development and Research Center of China Geological Survey,Beijing 100037,China;MNR Key Laboratory of Deep-Earth Dynamics,Institute of Geology,CAGS,Beijing 100037,China;State Key Laboratory for Mineral Deposits Research,Nanjing University,Nanjing 210046,China;Petroleum Exploration and Production Research Institute,Sinopec,Beijing 100083,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China;The Survey Institute of Hydrogeology,Engineering Geology and Environment Geology of Qinghai Province,Xining 810008,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;China University of Geosciences(Beijing),Beijing 100083,China)

机构地区：[1]中国地质调查局发展研究中心,北京100037 [2]自然资源部深地动力学重点实验室,中国地质科学院地质研究所,北京100037 [3]内生金属矿床成矿机制研究国家重点实验室,南京大学,南京210046 [4]中国石化石油勘探开发研究院,北京100083 [5]南方海洋科学与工程广东省实验室(广州),广州511458 [6]青海省水文地质工程地质环境地质调查院,西宁810008 [7]中国石油勘探开发研究院,北京100083 [8]中国地质大学(北京),北京100083

出　　处：《岩石学报》2022年第11期3359-3374,共16页Acta Petrologica Sinica

基　　金：中国地质科学院地质研究所先导研究项目(A1903);自然资源部深地动力学重点实验室开放基金(J1901-16、J1901-20-4);南京大学内生金属成矿机制国家重点实验室开放课题(2020-LAMD-K04);南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项(GML2019ZD0201);中国地质调查局项目(DD20221649、DD20221785、DD20190006);青海省重点研发计划(2018-SF-109)联合资助。

摘　　要：青海共和盆地干热岩经历的热历史过程、热源是了解干热岩地热藏形成亟待解决的难题,不同时期、不同类型的脉体可为其经历的热过程、热源提供证据。经调查发现,盆地东北当家寺岩体及井下干热岩中电气石脉体与该区后期断裂产状相近,是否代表后期热事件需要确定。本研究选择对GR1井、DR3井中酸性侵入岩岩芯和当家寺露头岩体中发现的电气石脉体开展了岩相学、锆石年代学、电子探针、LA-MC-ICPMS原位微量元素及B同位素分析,以约束电气石脉体的成因和源区。结果表明,GR1、DR3井岩芯及当家寺岩体含有电气石脉体的岩性分别是碱长花岗岩、高镁闪长岩及二长花岗岩;其中露头区花岗岩体中电气石脉的宽度约20cm,产状直立,其围岩的形成时代为239~241Ma。背散射及显微图像特征揭示,GR1井和DR3井下中酸性侵入岩及当家寺岩体中电气石为碱族的黑电气石和镁电气石,具有远近不同的多个流体来源。δ^(11)B分布在-11.50‰~-11.93‰,与大陆地壳平均的同位素组成δ^(11)B值(-10‰±3‰)相近。结合区域地质资料,认为在晚三叠世时期,该区域整体处于碰撞期或后碰撞期,陆壳加厚发生部分熔融形成S型花岗岩(~220Ma),其中含硼的热液流体侵位于早期具有俯冲背景的I型花岗岩(~240Ma)中形成电气石脉。The thermal history process and heat source experienced by the hot dry rock in the Gonghe basin of Qinghai is an urgent problem to be solved in understanding the formation of the hot dry rock geothermal reservoir.Different periods and different types of veins can provide evidence for the thermal process and heat source experienced by the hot dry rock.After investigation,it was found that the tourmaline veins in the Dangjiasi pluton in the northeast of the basin and the underground hot dry rock are similar to the later fault occurrence in the area.Whether it represents a later thermal event needs to be determined.This study selected the tourmaline from the cores in Well GR1 and Well DR3 and in Dangjiasi plutons are used as the key research objects to carry out petrographic,zircon U-Pb,electron probe analysis,LA-MC-ICPMS in-situ trace element and B isotope analysis to constrain the origin and source of tourmaline veins.The results show that the tourmaline-bearing cores in Wells GR1 and DR3 and the Dangjiasi granite are alkali feldspar granite,high-magnesium diorite and monzonite granite respectively;the tourmaline veins in the granite body in the outcrop area are about 20cm wide,and their occurrence is upright,the formation age of its surrounding rocks is 239~241Ma.Backscattering and microscopic image features reveal that the tourmaline in the hot dry rock Wells GR1 and DR3 and the Dangjiasi pluton are alkali-group schorl and magnesium tourmaline,with multiple fluid sources at different distances.The in-situ tourmaline δ^(11)B is distributed in the range of-11.50‰~-11.93‰,which is similar to the average δ^(11)B value of continental crust(-10‰±3‰);Combined with regional geological data,it is believed that in the Late Triassic,the region as a whole was in the collision period or post-collision period,and the continental crust was thickened and partially melted to form S-type granites(~220Ma).Meanwhile,the boron-containing fluids in the magma emplaced in the early I-type granites(~240Ma)with a subduction se

关 键 词：共和盆地 干热岩 中三叠世 花岗岩 电气石 硼同位素 壳源 

分 类 号：P578.953[天文地球—矿物学] P597.3[天文地球—地质学]