峡东南华纪—震旦纪碎屑岩Ce同位素组成及地质意义  

Cerium isotopic compositions of Nanhuan to Sinian clastic rocks in Eastern Three Gorges,South China,and their geological significance

作　　者：高永娟[1,2] 凌文黎[2] 陈子万[2] 白晓[2] 邱啸飞[3] 段瑞春[3] 杨红梅[3] 卢山松[3] 

机构地区：[1]中国地质调查局成都地质调查中心,四川成都610081 [2]中国地质大学地质过程与矿产资源国家重点实验室,湖北武汉430074 [3]中国地质调查局武汉地质调查中心,湖北武汉430205

出　　处：《地学前缘》2015年第2期214-220,共7页Earth Science Frontiers

基　　金：国家自然科学基金项目(40873017)

摘　　要：元素La和Ce同属低活动性的稀土元素,能够对碎屑岩物源进行示踪。但目前尚缺乏对碎屑岩LaCe同位素体系的研究。本文以峡东泗溪南华纪—震旦纪碎屑岩为研究对象,进行了Ce同位素组成分析。结果显示：这些碎屑岩的138 Ce/142 Ce比值为0.022 583 2~0.022 587 8,εCe（t）值变化于1.06~6.13,整体上呈逐渐升高的演化特征,并与εNd（t）值呈耦合关系。结合碎屑岩Nd同位素分析结果认为,峡东南华纪—震旦纪碎屑岩的主要来源,以古元古代—中元古代甚至更老的地壳岩石为主,并存在幔源初生地壳物质加入。Lanthanum and cerium are low mobile rare earth elements, which can be used to trace the provenance of elastics, but there is tack of systematic research on the La-Ce isotopes of elastics. This paper reports the Ce isotopic compositions of Nanhuan-Sinian elastic rocks in Sixi, Eastern Three Gorges. These elastic rocks have 138Ce/142 Ce values of 0. 0225832 to 0. 0225878, and show an increasing trend of Ce （t） values from 1.06 to 6. 13, which coupled with the end （t） values. Combined with Nd isotopec compositions of the elastic rocks, it is suggested that the main provenance of Nanhuan-Sinian elastic rocks in Sixi, Eastern Three Gorges were from the Paleoproterozoic - Middle Proterozoic and even older crustal rocks and mixing with juvenile crustal rocks in different degrees.

关 键 词：峡东地区 碎屑岩 Ce同位素 沉积物源 

分 类 号：P597[天文地球—地球化学] P588.21[天文地球—地质学]