赣南安远下坑仔岩体地质特征及锆石Pb-Pb法同位素年龄的地质意义  

GEOLOGIC FEATURE OF XIAKENGZI PLUTON OF ANYUAN,SOUTH JIANGXI AND THE GEOLOGIC SIGNIFICANCE OF Pb-Pb ISOTOPIC AGE OF ZIRCON

作　　者：谢明明 刘春根 李珊[2] 

机构地区：[1]江西省地质调查院,江西南昌330201 [2]江西省地质矿产勘查开发局赣西地质调查大队,江西南昌330201

出　　处：《江西地质》2001年第4期256-259,共4页Jiangxi Geology

摘　　要：赣南安远下坑仔岩体,前人将其划归为九曲—孔带混合岩带中的混合岩,在进行1∶5万鹤仔圩、隘高圩幅区调工作中,通过对其地质学、岩石学、岩石地球化学特征的研究,确认下坑仔岩体为岩浆结晶成因;成岩环境为板块碰撞抬升造山过程、岛弧或者活动陆缘的环境。根据在其中获取的结晶锆石Pb-Pb同位素年龄值996±29Ma,认为其成岩时代属晋宁期,这一结论对赣南地区古老结晶基底的存在提供了新的地质依据。The Xiakengzi rock mass of Anyuan,South Jiangxi had been classified as magmatite of the Qiuqu-Kongdai magmatitic zone by previous workers.However,based on a study on the geological,petrological and geo-chemical features during a1:50000regional geological survey program carried out for the Wankezi Fair and Aigao Fair map-sheet area,the authors have determined that this Xiakengzi rock mass is derived from magmatic crystallization and was formed in either an island arc or a mobile continental margin environment during uplift and mountain-building process due to collision of plates.Measurement of Pb-Pb isotopic age made on crystalline zircon from this rock mass gives(996±29)Ma,suggesting that it can be attributed to Jinningean Period in age.This provides a new geological evidence for the existence of old crystalline basement in the South Jiangxi area.

关 键 词：锆石 同位素年龄 晋宁期 结晶基底 下坑仔岩体 江西 铅-铅法 

分 类 号：P597[天文地球—地球化学]