南阿尔金古生代花岗岩U-Pb定年及岩浆活动对造山带构造演化的响应  

Zircon U-Pb Dating of Paleozoic Granites From South Altun and Response of the Magmatic Activity to the Tectonic Evolution of the Altun Orogenic Belt

作　　者：吴才来[1] 雷敏[1] 吴迪[2] 张昕[1] 陈红杰[1] 李天啸 

机构地区：[1]大陆动力学研究中心中国地质科学院地质所,北京100037 [2]中国地质大学(北京),北京100083

出　　处：《地质学报》2016年第9期2276-2315,共40页Acta Geologica Sinica

基　　金：地质调查项目(编号:12120115027001;12120114079901;1212010918007;1212010818090;1212010611803);国家自然科学基金项目(编号:41472063;40672049;40472034);创新研究群体科学基金项目(编号:40921001)联合资助

摘　　要：南阿尔金花岗岩锆石UPb定年结果表明，西部的且末县南依干村花岗岩体年龄分别为352SymbolqB@4Ma、349SymbolqB@2Ma、343SymbolqB@3Ma，东部的白干湖村北花岗岩体的年龄分别为447SymbolqB@4Ma、444SymbolqB@5Ma、448SymbolqB@2Ma，茫崖镇西花岗岩为444SymbolqB@6Ma、435SymbolqB@4Ma，阿克提山花岗岩为265SymbolqB@2M，柴水沟花岗岩为406SymbolqB@5Ma，常春沟石英闪长岩为469SymbolqB@3Ma，茫崖镇北花岗岩为462SymbolqB@8Ma。根据花岗岩的定年结果，结合岩石地球化学研究，本文将南阿尔金花岗岩类划分出为五期：第1期岩石组合为石英闪长岩＋花岗闪长岩＋二长花岗岩，具有Ⅰ型花岗岩的属性，时代〉460Ma；第2期岩石组合为石英二长岩＋正长花岗岩＋碱长花岗岩，具有S型号花岗岩的特征，时代为435~450Ma；第3期岩石组合为花岗闪长岩＋二长花岗岩＋正长花岗岩，具有A型花岗岩的属性，时代为404~411Ma；第4期花岗岩组合为花岗闪长岩＋二长花岗岩，时代为343~352Ma，具有S型花岗岩的地球化学属性；第5期花岗岩组合为石英闪长岩＋花岗闪长岩＋花岗岩，具有Ⅰ型花岗岩的地球化学特征，时代为265Ma。根据年代学和岩石地球化学研究结果，结合区域地质特征，我们认为第1期（465~469Ma）花岗岩浆活动可能与洋壳的俯冲作用有关；第2期（435~450Ma）岩浆活动可能属碰撞后岩浆活动；第3期（404~411Ma）岩浆活动可能与板块碰撞后造山带块体均衡调整有关，第4期（343~352Ma）岩浆活动可能与特提斯构造活动有关，第5期（265Ma）岩浆活动可能与阿尔金断裂的活动有关。Zircon U Pb dating of the South Altun granites shows that, in the western segment of the South Altun, granite plutons at Yigan Village south of Qiemo County are aged 352±4, 349±2, and 343±3 Ma; while in the eastern segment of the South Altun, granite plutons north of Baiganhu Village are aged 447±4, 444±5, and 448±2 Ma, granites west of Mangya Town are aged 444±6 and 435±4 Ma, the granite from the Aketi Mountains is aged 265±2 Ma, Chaishuigou granite is aged 406±5 Ma, Changchungou quartz diorite is aged 469±3 Ma, and the granite north of Mangya Town is aged 462±8 Ma. Based on previous studies in conjunction with granite dating and geochemical study results in this paper, the South Altun granite can be divided into five episodes： episode 1, characterized by the granite association of quartz diorite＋granodiorite＋monzogranite, with affinities of I type granite and an age of＞460 Ma; episode 2, characterized by the granite association of granodiorite＋monzogranite＋syenogranite, with geochemical affinities of I type granite and an age of 435-450 Ma; episode 3, characterized by the granite association of quartz monzonite＋syenogranite＋alkali feldspar granite, with affinities of A type granite and an age of 385-411 Ma; episode 4, characterized by the granite association of granodiorite＋monzogranite with an age of 343-352 Ma, with geochemical affinities of S type granite; and episode 5, characterized by the granite association of quartz diorite＋monzogranite, with geochemical affinities of I type granite and an age of 265 Ma. Based on the results of the above studies in conjunction with regional geological characteristics, it is considered that episode 1 granitic magma activity might be related to the subduction of oceanic crust, episode 2 magma activity might belong to post collisional magma activity, episode 3 magma activity might be related to the isostatic adjustment of orogen blocks after plate collision, episode 4 magma activity might be related to Tethyan tectonic activity, and episode

关 键 词：锆石U Pb定年 花岗质岩浆活动期次 岩石成因 南阿尔金 

分 类 号：P597.3[天文地球—地球化学] P588.121[天文地球—地质学] P542