青海沱沱河地区夏里组砂岩形成时代及物源区构造环境判别  

Geochronology and tectonic environment of the provenance for Xiali formation sandstone in Tuotuohe area,Qinghai province

作　　者：李焕纪 孙永刚 郑近龙 董峻麟 张徐平 LI Huanji;SUN Yonggang;ZHENG Jinlong;DONG Junlin;ZHANG Xuping(School of Resources and Civil Engineering,Suzhou University,Suzhou 234000,China;No.5 Geological Survey Institute of Qinghai Province,Xining 810028,China;The Eleventh Geological Survey Institute of Heilongjiang Province,Harbin 150028,China)

机构地区：[1]宿州学院资源与土木工程学院,安徽宿州234000 [2]青海省第五地质勘查院,青海西宁810028 [3]黑龙江省第十一地质勘查院,黑龙江哈尔滨150028

出　　处：《世界核地质科学》2024年第5期875-887,共13页World Nuclear Geoscience

基　　金：安徽省教育厅高校自然科学重点科研项目(编号:2024AH051826);宿州学院资助2024年国家级大学生创新创业训练计划项目(项目名称:吉林省中部地区早中侏罗世花岗岩成因及构造背景研究)。

摘　　要：青海沱沱河地区位于青藏高原北部的北羌塘盆地内,该地区中-晚侏罗世地层发育广泛,但相关物源和构造背景的研究相对薄弱,这在一定程度上制约研究区铀矿找矿的深入。通过LA-ICP-MS对夏里组碎屑锆石进行U-Pb定年,从而限定夏里组细粒长石石英砂岩的形成时代,并结合长石石英砂岩主量-微量分析结果来探讨其沉积物的来源和物源区构造背景。夏里组砂岩碎屑锆石年代学研究表明,层段内砂岩主要有3个年龄区间:1805~1760 Ma、454~418 Ma和191~173 Ma,即夏里组砂岩沉积年龄下限为173 Ma。物源区判别图解显示夏里组沉积物主要来源于长英质沉积岩物源区,夏里组物源区构造背景以大陆岛弧为主,同时存在少量活动大陆边缘的源区。综合前人研究成果,认为北羌塘盆地夏里组具有良好的砂岩型铀矿找矿潜力。The Tuotuohe area in Qinghai is located within the North Qiangtang basin on the northern Tibetan Plateau,where Middle to Late Jurassic strata are extensively developed.However,the research on its provenance and tectonic background remains relatively weak,which constrains the exploration level of uranium deposits in the study area.This study conducted LA-ICP-MS U-Pb dating of detrital zircons in Xiali formation to define the formation age of the fine-grained feldspar quartz sandstone and discussed the provenance and its tectonic setting by analyzing the major and trace element composition of the feldspar quartz sandstone.The geochronological study of detrital zircons from the sandstone of Xiali formation indicated three main age intervals:1805~1760 Ma,454~418 Ma,and 191~173 Ma,with the lower limit of the sedimentary age of Xiali formation being 173 Ma.Provenance discrimination diagrams reveal that the sediments of Xiali formation primarily originated from felsic sedimentary rocks.The tectonic setting of the provenance area was mainly characterized by a continental island arc,with minor contributions from active continental margins.Integrating previous research found that Xiali formation in the North Qiangtang Basin was of good potential for sandstone-type uranium deposit exploration.

关 键 词：沱沱河 夏里组 碎屑锆石 U-PB定年 物源分析 砂岩型铀矿 

分 类 号：P595[天文地球—地球化学] P597[天文地球—地质学]