青藏高原北羌塘盆地周琼玛鲁地区诺日巴尕日堡组上部岩石的地球化学特征及其成因  

Preliminary geochemical study on hydrothermal of the limestone hosted in Nuo Ribagaribao Formation in the Zhou Qiongmalu area,northern Qiangtang basin,Qinghai-Tibet Plateau.

作　　者：潘术娟[1,2] 李荣社[2] 计文化[2] 王根厚[1] 刘银[1,2] 时超[1,2] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中国地质调查局西安地质矿产研究所,陕西西安710054

出　　处：《地质通报》2010年第12期1863-1871,共9页Geological Bulletin of China

基　　金：中国地质调查局国土资源大调查项目《青藏高原前寒武纪地质、古生代构造-古地理综合研究》(编号:1212010610102)资助

摘　　要：青藏高原北羌塘周琼玛鲁一带中二叠世诺日巴尕日堡组上部层位纹层状灰岩与脉岩、沉凝灰岩共生。3件灰岩样品中有2件在Al-Fe-Mn判别图上投影点落于热水沉积物区内;Fe/Ti、(Fe+Mn)/Ti和Al/(Fe+Mn+Al)比值平均值分别为0.53、41.90和46.06。Ni/Co<3.6;U/Th<1;不同程度地富集金属元素Co、Cu、Zn、Pb和热液活动性元素As、Sb、Ba。岩石稀土元素配分曲线向右倾斜,具有弱的负Eu、负Ce异常。灰岩中Co、Ni、Fe和火山岩样品之间在Co/Y-P/Y、Ni/Y-P/Y和Fe/Y-P/Y的比值相关图上呈较好的线性相关性。综合分析表明,这些灰岩为热水沉积成因,形成于弧后盆地环境。这一发现对沱沱河上游一带大范围的Pb、Zn化探异常的成因研究和进一步的找矿工作具有一定的指示意义。The laminated limestone,dike rock and tuff are associated in the upper part of Middle Permian Nuo Ribagaribao Formation in the Zhou Qiongmalu area,northern Qiangtang.The plots of Al-Fe-Mn triangle diagram show that two limestones lay in the area of hydrothermal sediments.The average ratio of Fe/Ti、（Fe＋Mn）/Ti and Al/（Fe＋Mn＋Al） are 0.53,41.90 and 46.06,respectively;the rate of Ni /Co is less than 3.6 and U/Th is less than 1;These rocks are enriched in various degrees in metal elements（Co,Cu,Zn and Pb） and hydrothermal active elements（As,Sb and Ba）.The rare earth elements distribution patterns of these rocks show weak negative δCe and δEu,and skew to the right.Besides,the Co,Ni,Fe in limestones and the volcanic rocks on Co/Y-P/Y,Ni/Y-P/Y and Fe/Y-P/Y are present well linear dependence.Above all,those characteristics show that the limestones of Middle Permian Nuo Ribagaribao Formation are hydrothermal sedimentation and are formed in the environment of back-arc basin.This discovery has some indication meaning to the research of the large-scale Pb,Zn geochemical anomaly and the further ore-prospecting work in the upstream of the Tuotuohe area.

关 键 词：北羌塘盆地 中二叠世 诺日巴尕日堡组 热水沉积 弧后盆地 

分 类 号：P534.46[天文地球—古生物学与地层学] P595[天文地球—地质学]