东昆仑东段巴隆地区变复成分砾岩层锆石U-Pb年龄及其地质意义  

Metamorphosed Polymictic Conglomerate Layer Zircon U-Pb Age and Its Geological Significance at Balong Area in East part of Eastern Kunlun Mountains

作　　者：李小兵[1] 裴先治[1,2] 陈有炘[1] 刘成军[1] 李瑞保[1,2] 李佐臣[1,2] 陈国超[1] 徐通[1] 杨杰[1] 胡楠[1] 

机构地区：[1]长安大学地球科学与资源学院,西安710054 [2]西部矿产资源与地质工程教育部重点实验室,西安710054

出　　处：《地质论评》2014年第6期1212-1230,共19页Geological Review

基　　金：国家自然科学基金项目(编号41172186;40972136;41472191);中央高校基本科研业务费专项资金项目(编号CHD2011TD020;2013G1271091;2013G1271092);青海省国土资源厅--中国铝业公司公益性区域地质矿产调查基金项目(中铝基金200801)的成果

摘　　要：东昆仑东段巴隆地区哈图沟出露—套变质—变形的沉积地层,其北部为变复成分砾岩段、南部为变细碎屑岩段.根据变复成分砾岩段砾石成分统计、砾石的分选系数（1.24～1.42）及砾石的砾度等粒性特征得出该套变复成分砾岩地层为近源快速堆积的产物.利用LA-MC-ICP-MS锆石U-Pb微区测年技术,对变复成分砾岩段绢云钠长石英片岩的碎屑锆石进行U-Pb同位素测年,测试结果表明,碎屑错石年龄谱可明显划分为6组：①南华纪—震旦纪年龄组,751 ～ 602Ma,峰值为674Ma,该组锆石年龄与东昆仑造山带新元古代中—晚期岩浆事件的年龄相对应,并且与Rodinia超大陆裂解事件相关,该组锆石中最小的年龄为602Ma,表明沉积地层形成时代应晚于602Ma;②中元古代晚期—新元古代中期年龄组,1146 ～ 783Ma,出现三个峰值,分别为788Ma、947Ma和1115Ma,该组锆石年龄与东昆仑造山带中元古代晚期—新元古代中期岩浆事件大致相对应,代表东昆仑地区响应了全球尺度的Rodinia超大陆的汇聚事件,且证实了柴达木—祁连—东昆仑等地（陆）块前寒武纪的演化特点与塔里木及扬子克拉通非常相似;③中元古代晚期年龄组,1399～1180Ma,峰值为1318Ma,该组锆石年龄可能与东昆仑构造带中元古代晚期岩浆事件相关;④中元古代早期年龄组,1712 ～ 1553Ma,峰值为1556Ma,该年龄谱段代表了源区在中元古代早期存在着一期热事件;⑤新太古代晚期—古元古代早期年龄组,2530～2347 Ma,峰值为2518Ma,该组锆石年龄与东昆仑造山带内新太古代晚期—古元古代早期岩浆事件年龄大致相对应,表明东昆仑造山带新太古代晚期—古元古代早期岩浆物质也为哈图沟变质地层提供了物源;⑥太古宙年龄组,3230～2763Ma,表明变复成分砾岩的物源区可能存在古太古代陆核.通过对变质岩系的碎屑锆石年龄和物源特征的分析研究,认为这套变质的沉积�There are a suit of metamorphosed-deformed sedimentary strata at Hatugou of Balong area in East part of eastern Kunlun Mountains,which northern for metamorphosed polymictic conglomerate segment,the southern for metamorphosed clastic section.Through this metamorphosed-deformed sedimentary gravel composition statistics,gravel sorting coefficient （1.24 ～ 1.42） and granulometric analysis of gravel,and show it is the product of near-source and rapidly accumulation.This article,get sericite—albite—quartz schist variant of polymictic conglomerate detrital zircon U-Pb isotopic ages by LA-MC-ICP-MS zircon U-Pb dating of micro-technology.The detrital zircon age spectra can be divided into 6 groups：① Nanhuan—Sinian age group,751 ～602 Ma,the peak value is 674 Ma.The age group corresponding to the Late Neoproterozoic magmatic events age in Eastern Kunlun Orogenic Belt （EKOB）,and associated with Rodinia supercontinent breakup event,The smallest zircon age of 602Ma,indicate sedimentary strata formed time should be later than 602 Ma.② Late Mesoproterozoic—MidNeoproterozoic age group,1146 ～783Ma,there are peak value is 788 Ma,947 Ma and 1115 Ma.The ages group can compare in Late Mesoproterozoic—Mid-Neoproterozoic magmatic events of EKOB,which represent the Eastern Kunlun area in response to the global scale convergence event of Rodinia,this confirmed that evolution characteristics of the Qaidam—Qilian—Eastern Kunlun in Precambrian is very similar to with the Tarim block and Yangtze block.③ Late Mesoproterozoic age group,1399 ～ 1180 Ma,the peak value is 1318 Ma.The age group may be related to the Eastern Kunlun tectonic belt Late Mesoproterozoic magmatic events.④ Early Mesoproterozoic age group,1712 ～ 1553 Ma,the peak value is 1556 Ma.The age group represents the source region thermal event in the Early Mesoproterozoic.⑤ Late Neoarchaean—Early Paleoproterozoic age group,2530 ～ 2347 Ma,the peak value is 2518 Ma.The age group with Late Neoarchaean—Early Palaeoproterozoic age of the s

关 键 词：东昆仑东段 巴隆地区 变复成分砾岩 LA-MC-ICP-MS锆石U-Pb定年 物源 

分 类 号：P597.3[天文地球—地球化学] P588.212.5[天文地球—地质学]