地质通报2018，Vol.37Issue(4)：545-558,14.
阿尔金造山带南缘中―晚奥陶世正长花岗岩的发现及其地质意义
The discovery of Middle-Late Ordovician syenogranite on the southern margin of Altun orogenic belt and its geological significance
摘要
Abstract
The syenogranite is located in the Paxialayidang ditch of the Altun Mountains.The U-Pb dating of zircons from the sye-nogranite using LA-ICP-MS yielded a group age of 455.1±3.6Ma, indicating that the crystallization of the intrusion occurred in Middle-Late Ordovician period. The geochemical analysis shows that major elements are characterized by high SiO2, Al2O3and K2O and low TiO2,CaO and MgO,which suggests that syenogranite belongs to the typical high-K calc-alkaline series with deeply peraluminous feature.In addition,the rocks are enriched in total REE.The samples are enriched in LREE(light rare earth elements)and depleted in HREE(heavy rare earth elements)with Eu anomalies.The chondrite-normalized REE patterns show right-oblique type.The syenogranite is enriched in large ion lithophile elements of Rb,Th,K and depleted in high field strength elements of Ba, Sr,Ti,with the characteristics of S-type granite.In combination with the diagrams for discriminating compositions of original rocks, the authors hold that the rocks were formed by the partial melting of meta-pelitic sedimentary rocks from the lower crust. Com-bined with the data of regional geological characteristics, the authors consider that the syenogranite was formed in the transitional tectonic setting from the compressional to the extensional regime, thus belonging to the post-collisional granites. It is shown that Azhong Block and Qaidam Block entered into a transformation period from compression to extension during Middle-Late Ordovi-cian period.关键词
阿尔金造山带/LA-ICP-MS锆石U-Pb测年/正长花岗岩/地球化学/岩石成因Key words
Altun orogenic belt/LA-ICP-MS zircon U-Pb dating/syenogranite/geochemistry/petrogenesis分类
天文与地球科学引用本文复制引用
张若愚,曾忠诚,陈宁,李琦,王天毅,赵江林..阿尔金造山带南缘中―晚奥陶世正长花岗岩的发现及其地质意义[J].地质通报,2018,37(4):545-558,14.基金项目
中国地质调查局项目《新疆阿尔金地区1:5万J45E010020等六幅区域地质矿产调查》(编号:12120114081901)、《新疆西昆仑1:5万喀英迪吉勒嘎等五幅区域地质调查》(编号:1212011120533) （编号:12120114081901）
