中国东部地幔橄榄岩捕虏体的Re-Os同位素地球化学:岩石圈地幔的形成年龄和减薄作用的制约  

Re-Os isotope geochemistry of mantle-derived peridotite xenoliths from eastern China: constraints on the age and thinning of lithosphere mantle.

作　　者：支霞臣[1] 秦协[1] 

机构地区：[1]中国科学技术大学地球和空间科学学院,合肥230026

出　　处：《岩石学报》2004年第5期989-998,共10页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(编号:40173009;49873005);科技部国家重点基础研究发展规划项目(编号:C1999075503) ;中国科学院知识创新工程项目(编号:KZCX2-107)

摘　　要：我国东部新生代玄武岩中包含丰富的地幔橄榄岩捕虏体,近年来一些研究者对兴蒙造山带的双辽、汪清,华北克拉通的龙岗、汉诺坝、栖霞、女山和扬子克拉通的盘石山、练山等地8个新生代玄武岩区近百个地幔橄榄岩捕虏体全岩粉末样品获得了Re-Os同位素数据,对澎湖列岛新生代玄武岩的地幔橄榄岩捕虏体中不同产状的硫化物包裹体作了原位的Re-Os同位素体系分析,此外,对辽宁复县和山东蒙阴古生代金伯利岩中的3个地幔橄榄岩捕虏体全岩粉末样品作了Re-Os分析。本文综合了文献中已有的数据,采用Re-Os同位素体系常用的方法,如Os同位素代理等时线年龄和Re亏损模式年龄,计算了SCLM的年龄。结果表明这些地区SCLM的形成年龄主要为早-中元古代,局部地区如辽宁复县有更老的年龄。我国东部新生代玄武岩中的尖晶石相地慢橄榄岩代表的SCLM主体上是元古代SCLM经过显生宙减薄作用后的残余部分,它对我国东部SCLM减薄作用在纵向上的规模和强度提供了制约。There are abundant mantle-derived peridotite xenoliths in Cenozoic alkaline basalts distributed over eastern China. In recent years the Re-Os isotopic data for the whole rock powder of peridotite xenoliths contained in Cenozoic basalts from Shuangliao, and Wangqing in Xin-Meng Orogenic Belt, Longgang, Hannuoba, Qixia and Nushan in North China Craton and Pangshishan, and Lianshan in Yangtz Craton are reported in literature. Also the Re-Os isotope data in situ for different sulfide inclusions in peridotite xenoliths contained in Cenozoic basalts from Penghu Islands,, Taiwan Strait are reported. In addition a few Re-Os isotope data for whole rock powder of peridotite xenoliths in Paleozoic kimberlite from Fuxian and Mengying in North China Craton are reported too. All available data are synthesized and applied to determination of the age of SCLM beneath these areas by the techniques of Os isotope proxy isochron and Re depletion model age in this paper. The results indicate the age of SCLM beneath these areas is mainly Early-Middle Proterozoic. The present SCLM beneath eastern China is the remnant of Proterozoic analogue survived thinning during Phanerozoic.

关 键 词：RE-OS同位素体系 岩石圈地幔 形成年龄 中国东部 元古代 减薄作用 

分 类 号：P588.125[天文地球—岩石学] P597.3[天文地球—地质学]