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西藏冈底斯带昂仁县差绒—丁欧复式花岗岩的成因:锆石U-Pb年代学及地球化学制约
投稿时间:2018-01-09  修订日期:2018-08-08  点此下载全文
引用本文:秦臻,佘朋涛,易鹏飞,张继军,张若愚,于恒彬,姚肖博,康琴琴.2018.西藏冈底斯带昂仁县差绒—丁欧复式花岗岩的成因:锆石U-Pb年代学及地球化学制约[J].地质论评,64(6):1557-1574
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作者单位E-mail
秦臻 1)陕西省矿产地质调查中心西安710068
4)陕西省地质调查院西安710054 
qz05105135@163.com 
佘朋涛 2)陕西省水工环地质调查中心西安710068
4)陕西省地质调查院西安710054 
 
易鹏飞 1)陕西省矿产地质调查中心西安710068
4)陕西省地质调查院西安710054 
 
张继军 2)陕西省水工环地质调查中心西安710068
4)陕西省地质调查院西安710054 
 
张若愚 2)陕西省水工环地质调查中心西安710068
4)陕西省地质调查院西安710054 
 
于恒彬 2)陕西省水工环地质调查中心西安710068
4)陕西省地质调查院西安710054 
 
姚肖博 1)陕西省矿产地质调查中心西安710068
4)陕西省地质调查院西安710054 
 
康琴琴 3)陕西省地质调查实验中心, 西安710068
4)陕西省地质调查院西安710054 
 
基金项目:本文为西藏自治区1∶5万许如错东地区(H45E009012、H45E010012、H45E011012、H45E011011)区域地质矿产调查项目(编号:1212011221063) 的成果。
中文摘要:西藏冈底斯带昂仁县措迈乡差绒—丁欧复式花岗岩岩石类型为石英闪长岩、黑云二长花岗岩和二长花岗岩,各侵入体之间为突变接触关系,闪长岩U- Pb同位素年龄为155.4±2.7Ma;黑云二长花岗岩U- Pb同位素年龄为152.0±13Ma、153.96±0.92Ma,时代均为晚侏罗世。岩石地球化学显示三者均为高钾钙碱性系列岩石,石英闪长岩为弱铝质―准铝质;黑云二长花岗岩和二长花岗岩则为准铝质—过铝质。黑云二长花岗岩和二长花岗岩相比石英闪长岩表现为富硅、富碱、贫Ca、Ti、Mg,轻稀土元素更富集,轻稀土分馏程度更高,分异更加明显的特点,微量元素二长花岗岩Ba、Sr、P、Ti亏损最为明显,黑云二长花岗岩的Rb、Th、K富集最为明显,石英闪长岩相比黑云二长花岗岩和二长花岗岩的Rb/Sr(0.18~0.46)、Rb/Ba值(0.13~0.26)最低,指示其分异演化程度较低。差绒—丁欧花岗岩应是同时代不同期次侵入的复式岩体,早期为I型的石英闪长岩和黑云二长花岗岩,晚期为S型二长花岗岩,该复式岩体并非产出于单一的俯冲环境,二长花岗岩可能为弧陆碰撞时的产物。
中文关键词:冈底斯带  复式花岗岩  石英闪长岩  二长花岗岩  弧背断隆带  壳幔混合  弧陆碰撞
 
Petrogenesis of Charong—Ding’ou Composite Granites in Angren County,Gangdese Belt, Xizang (Tibet): Constraints from Geochemical Features and Zircon U-Pb Ages
NameInstitution
QIN Zhen1) Shaanxi Mineral Resources and Geological Survey, Xi’an, 710068;4) Shaanxi Institute of Geological Survey, Xi’an, 710054
SHE Pengtao2) Shaanxi Hydrogeology Environmental Geology and Engineering Gelogy Survery Center, Xi’an, 710068;4) Shaanxi Institute of Geological Survey, Xi’an, 710054
YI Pengfei1) Shaanxi Mineral Resources and Geological Survey, Xi’an, 710068;4) Shaanxi Institute of Geological Survey, Xi’an, 710054
ZHANG Jijun2) Shaanxi Hydrogeology Environmental Geology and Engineering Gelogy Survery Center, Xi’an, 710068;4) Shaanxi Institute of Geological Survey, Xi’an, 710054
ZHANG Ruoyu2) Shaanxi Hydrogeology Environmental Geology and Engineering Gelogy Survery Center, Xi’an, 710068;4) Shaanxi Institute of Geological Survey, Xi’an, 710054
YU Hengbin2) Shaanxi Hydrogeology Environmental Geology and Engineering Gelogy Survery Center, Xi’an, 710068;4) Shaanxi Institute of Geological Survey, Xi’an, 710054
YAO Xiaobo1) Shaanxi Mineral Resources and Geological Survey, Xi’an, 710068;4) Shaanxi Institute of Geological Survey, Xi’an, 710054
KANG Qinqin3) Shaanxi Experiment and Geological Survey, Xi’an, 710068;4) Shaanxi Institute of Geological Survey, Xi’an, 710054
Abstract:Objectives: The magmatic activity of the Gangdese granite belt has a very complicated history. This research studies the petrology, petrogeochemistry and zircon U- Pb isotopic chronology of the composite granites in Charong—Ding’ou, in order to provide constraints for the Jurassic tectonic magmatic evolution process in this area. Methods: On the basis of detailed field geological survey, the petrology, petrogeochemistry and zircon U- Pb dating , geochemistry and tectonic environment of the composite granites in Charong—Ding’ou were systematically studied. Results: The type of rock mass of the composite granites in Charong—Ding’ou is quartz diorite, bio adamellite and monzonitic granite, and there is a abrupt contact relationship between the intrusions. The U- Pb isotope age of diorite was 155.4±2.7Ma. The U- Pb isotopic age of the bio adamellite was 152.0±1.3Ma, all of which were late Jurassic. The rock geochemistry shows that all three are high- k and calc- alkaline series of rocks, the quartz diorite is weakly aluminum — quasi- aluminum,The bio- adamellite and monzonitic granite are aluminum — peraluminous. The bio- adamellite and monzonitic granite characterized by silicon—alkali enrichment and poor Ca, Mg, and Ti. The light rare earth elements more enrichment, light rare earth fractionating degree is higher,compared to quartz diorite。The differentiation characteristics of trace elements:the Ba, Sr, P Ti loss of monzonitic granite is obvious and The Rb, Th, K accumulation of bio adamellite is most obvious.The Rb/Sr (0.18~0.46) and Rb/Ba (0.13~0.26) of quartz diorite indicate their evolution differentiation degree is low,compared to bio adamellite and monzonitic granite.  Conclusions: Charong—Ding’ou composite granites should be the same age with different stages complex rock mass, and early state is Type I quartz diorite and bio adamellite with Type S monzonitic granite in late state. The compound rock mass is not from a single subduction environment and monzonitic granite may be from arc continental collision.
keywords:Gangdese belt  composite granites  quartz diorite  monzonitic granite  back arc fault uplift area  Crust—mantle mixing  arc—continent collision
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