重庆城口地区下寒武统黑色岩系元素地球化学特征及其成因  

ELEMENTAL CHARACTERISTICS OF THE LOWER CAMBRIAN BLACK ROCK SERIES IN CHENGKOU DISTRICT,CHONGQING AND THEIR GENETIC SIGNIFICANCES

作　　者：朱正杰[1,2] 朱长生[1,2] 程礼军[1] 李航[1,2] 双燕[1] 罗泰义[3] 杨洪永[1] 雷恩[1] 

机构地区：[1]外生成矿与矿山环境重庆市重点实验室,重庆地质矿产研究院,重庆400042 [2]煤炭资源与安全开采国家重点实验室重庆研究中心,重庆400042 [3]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵州贵阳550002

出　　处：《矿物岩石》2011年第2期66-72,共7页Mineralogy and Petrology

基　　金：环境地球化学国家重点实验室开放基金项目(HDH09001);重庆市国土资源和房屋管理局科研项目(CIGMR0905)

摘　　要：地区广泛发育有下寒武统。利用ICP-MS方法系统分析重庆城口地区下寒武统黑色岩系中多金属富集层、炭质粉砂岩以及硅质岩样品的微量元素、稀土元素组成。研究结果表明稀土总量为111.41×10-6~184.13×10-6,平均为138.83×10-6,相对其他地区黑色岩系较低;LREE/HREE=2.49~3.44,LREE相对富集,HREE亏损;δCe=0.39~0.46,Ce呈明显负异常;δEu=0.84~1.10,Eu异常不明显。δCe,δU,V/Cr,Ni/Cr,V/（V＋Ni）表明该区黑色岩系形成于缺氧环境;稀土元素地球化学特征及其相关图解、Cr,Sb,As,Bi的富集以及U/Th等反映本区黑色岩系非正常海水沉积产物,明显受热水沉积的影响,同时还存在火山活动的影响,火山活动可能为热水活动提供了动力及物质成分。The black rock series of Lower Cambrian are well developed in Chengkou district,Chongqing.ICP-MS techniques was used to analyze trace element contents in Lower Cambrian black rock series,including cherts,black siltstones and multi-elements concentrated layers.Compared to northern Guizhou and northwestern Hunan,the REE in these rocks is very low with the value ranging from 111.41×10-6 to 184.13×10-6,averaging 138.83×10-6.LREE/HREE ratios vary from 2.49 to 3.44,indicating that LREE is relative abundant.δCe values range from 0.39 to 0.46,showing almost negative anomaly,and the δEu shows unconspicuous anomaly,with the value between 0.84 and 1.10.The indicators of δCe,δU,V/Cr,Ni/Cr and V/（V＋Ni） demonstrated that these black rock series formed in the anoxic environment.REE geochemical characteristics and their diagrams,high enrichments of Cr,Sb,As,Bi and U/Th ratios indicated that black rock series mainly formed by hydrothermal deposition.Meanwhile,the petrogenesis of black rock series was associated with volcanism,which provided the composition and dynamics to the hydrothermal activity.

关 键 词：城口 下寒武统 黑色岩系 微量元素 热水沉积 

分 类 号：P595[天文地球—地球化学]