东昆仑三通沟锰矿成矿年代约束:碎屑锆石U-Pb和黑色页岩Re-Os年代学  

Constraints of Metallogenic Ages of Santonggou Manganese Deposit in East Kunlun,China:Detrital Zircons U-Pb and Black Shale Re-Os Chronology

作　　者：张琛明 于淼 代威 杨牧[1] 廖方周 张斌武 ZHANG Chen-ming;YU Miao;DAI Wei;YANG Mu;LIAO Fang-zhou;ZHANG Bin-wu(School of Geosciences and Info-physics,Central South University,Changsha 410012,Hunan,China;School of Earth and Space Sciences,Peking University,Beijing 100871,China;The Third Geological Exploration Institute of Qinghai Province,Xining 810008,Qinghai,China)

机构地区：[1]中南大学地球科学与信息物理学院,湖南长沙410012 [2]北京大学地球与空间科学学院,北京100871 [3]青海省第三地质勘查院,青海西宁810008

出　　处：《地球科学与环境学报》2023年第3期622-642,共21页Journal of Earth Sciences and Environment

基　　金：国家自然科学基金项目(41902074,41802080)。

摘　　要：三通沟海相沉积型锰矿是近年来东昆仑地区锰矿找矿工作的新突破。对三通沟锰矿中两件粉砂岩样品进行LA-ICP-MS碎屑锆石U-Pb定年,获得年龄为(1497±17)~(427±4)Ma,主要集中在441和473 Ma两个峰值附近,最年轻的碎屑锆石年龄为(427±4)Ma,表明其沉积时代晚于427 Ma,并且指示其沉积物质来源于纳赤台群中段。三通沟锰矿黑色页岩Re-Os等时线年龄为(387.4±6.2)Ma,表明其成矿作用中成岩转化过程的时间为中泥盆世,而锰质的初始沉淀早于这个时间。综合同位素定年结果,将三通沟锰矿的沉积时代限定在晚志留世—中泥盆世。结合早古生代海相沉积型锰矿矿床成因的主流观点,探讨三通沟锰矿的成矿作用与原特提斯洋俯冲作用之间的关系,认为早古生代原特提斯洋的俯冲闭合是三通沟锰矿成矿的主要原因,三通沟锰矿的成矿时代与原特提斯洋闭合时间基本一致。The discovery of Santonggou manganese deposit is an important breakthrough in manganese prospecting in East Kunlun.The detrital zircon from two siltstone samples of Santonggou manganese deposit were used for LA-ICP-MS U-Pb dating.The detrital zircon U-Pb ages are ranging from(1497±17)Ma to(427±4)Ma,with two peaks of 441 and 473 Ma,respectively.The youngest detrital zircon age is(427±4)Ma,indicating the age of Santonggou manganese deposit is later than 427 Ma.The age peaks of detrital zircon are consisting with Early Paleozoic Naji Tal Group,and indicate that the detritals provenance are the middle strata of Naji Tal Group.The Re-Os isochron age of black shale from Santonggou manganese deposits are(387.4±6.2)Ma,indicating that the age of burial diagenesis is Middle Devonian,and the initial precipitation of manganese is earlier.Based on isotopic dating results,the sedimentary age of Santonggou manganese deposit is limited in Late Silurian-Middle Devonian.The relationship between the mineralization of Santonggou manganese deposit and the subduction of Proto-Tethys ocean is discussed based on the main view about genesis of Early Paleozoic marine sedimentary manganese deposit.It is considered that the subduction and closure of Proto-Tethys ocean in Early Paleozoic is the main reason for the mineralization of Santonggou manganese deposit,and the metallogenic age of Santonggou manganese deposit is basically consistent with the closure time of Proto-Tethys ocean.

关 键 词：成矿年代学 物源 锰矿 RE-OS定年 U-Pb定年 原特提斯洋 构造演化 东昆仑 

分 类 号：P597[天文地球—地球化学] P618.32[天文地球—地质学]