岩石矿物学杂志2011，Vol.30Issue(3)：475-489,15.
青海玉树东莫扎抓和莫海拉亨铅锌矿床与逆冲推覆构造关系的确定——来自粗晶方解石Rb-Sr和Sm-Nd等时线年龄证据
Confirmation of connection between Dongmozhazhua and Mohailaheng Pb-Zn ore deposits and thrust nappe system in Yushu area,southern Qinghai: evidence from Rb-Sr and Sm-Nd isochron ages of macrocrystalline calcite
摘要
Abstract
Located in the northeast margin of Qiangtang terrane between Jinshajiang suture zone and Bangonghu-Nujiang suture zone, the Dongmozhazhua and Mohailaheng Pb-Zn deposits in Yushu area of Qinghai Province are typical Pb-Zn deposits in the Cu-Pb-Zn polymetallic mineralization belt within the northern part of the Nujiang-Lancangjiang-Jinshajiang area.Although these Pb-Zn deposits are in the front belt of Yushu thrust nappe system, the connection between Pb-Zn ore deposits and thrust nappe system remain unclear.Field investigations show that calcite is milk white in color, macrocrystalline, irregular and sack-like in form and is intersected by late mineralization.It was formed during the transitional stage from the compression stage (thrust nappe stage) to the extension stage (mineralization stage) and can be regarded as the link between Pb-Zn ore deposits and the thrust nappe system.Formation ages of the transitional stage in the Dongmozhazhua and Mohailaheng ore districts, determined by both Rb-Sr and Sm-Nd isochron methods for calcite, are 35.2～35.5 Ma with an average of 35.4 Ma and 34.0～34.6 Ma with an average of 34.3 Ma, respectively.Formation ages of such a transitional stage are synchronous with Pb-Zn mineralization epoch (35 Ma and 33 Ma, respectively).In combination with regional mineralization geological setting, the authors established a tentative tectonic model for metallogeny of the Pb-Zn deposits from the thrust nappe stage to the mineralization stage in Yushu area, i.e., India-Asian collision led to the lifting of the orogenic belt relative to the Tertiary foreland basins in the northern margins of the Qinghai-Tibetan plateau, and strong compression resulted in the thrusting of these basins (37～40 Ma).During the transitional stage from the compression stage to the extension stage (34～35 Ma), the mixing of early orogenic fluid and basin fluid resulted in the formation of macrocrystalline calcite.At last, fluids generated from the orogen migrated laterally along gently-dipping detachment faults of the thrust systems toward the basins and evolved into Pb-Zn ore-forming fluids through the interaction with country rocks and the mixture of early orogenic fluid.The ore-forming fluids migrated vertically along major thrust faults and finally accumulated in the back thrust induced by thrust-nappe structures at shallow levels to form Pb-Zn ore deposits.关键词
Rb-Sr等时线/Sm-Nd等时线/粗晶方解石/逆冲推覆构造/构造控矿模式/青海玉树东莫扎抓和莫海拉亨铅锌矿床Key words
Rb-Sr isochron/ Sm-Nd isochron/ calcite/ thrust nappe system/ tectonic model/ Dongmozhazhua and Mohailaheng Pb-Zn deposits in Yushu area, Qinghai Province分类
天文与地球科学引用本文复制引用
田世洪,于玉帅,王富春,薛万文,鲁海峰,张玉宝,朱田,俞长捷,杨竹森,侯增谦,杨天南,张洪瑞,刘燕学,宋玉财,刘英超,王银喜..青海玉树东莫扎抓和莫海拉亨铅锌矿床与逆冲推覆构造关系的确定——来自粗晶方解石Rb-Sr和Sm-Nd等时线年龄证据[J].岩石矿物学杂志,2011,30(3):475-489,15.基金项目
"十一五"国家科技支撑计划重大资助项目(2006BAB01A08) （2006BAB01A08）
国土资源大调查资助项目(1212010818096) （1212010818096）
国家973资助项目(2011CB403104,2009CB421007和2009CB421008) （2011CB403104,2009CB421007和2009CB421008）
国家自然科学联合基金资助项目(U09336051) （U09336051）
