华北克拉通北缘白云鄂博矿区尖山组沉积源区、时代及其地质意义

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中文摘要：白云鄂博矿床位于华北克拉通北缘,其围岩尖山组为一套绿片岩相硅质碎屑岩组合,尖山组的形成时代及物源研究对于理解区域大地构造演化和成矿过程具有重要意义.采用LA-ICP-MS方法对矿区尖山组的变质砂岩及变质细砂岩进行了锆石U-Pb年代学研究.变质细砂岩样品Z5246的锆石年龄为2 645～1 147 Ma,包含两个主峰值年龄,分别为2 510和1 390 Ma;变质砂岩样品By23281锆石年龄为2 722～1 847 Ma,包含3个主峰值年龄,分别为2 487、1 925和1 859 Ma.结合锆石稀土元素特征,认为变质砂岩样品By23281中2 722～1 847 Ma的锆石属于未受热液改造的碎屑锆石,尖山组的形成时代应晚于1 847 Ma;而结合野外特征、锆石形貌及稀土元素特征,认为变质细砂岩样品Z5246中1 761～1 147 Ma的年龄反映了后期热液改造的过程,也进一步佐证了白云石碳酸岩的岩浆成因.结合矿区及周边已有的年代学数据,认为矿区尖山组物源主要来自华北克拉通北缘太古宙基底和古元古代晚期的变质岩,最终形成于中元古代,之后受到白云石碳酸岩岩浆期热液的明显改造.矿区尖山组碎屑岩的年龄数据记录了华北克拉通北缘太古代—元古代的陆壳增生、碰撞及裂解事件,为研究太古代—元古代区域构造演化提供了有力证据.

外文标题：Sedimentary Provenance and Geochronology of Jianshan Formation in Bayan Obo Ore District,the Northern Margin of North China Craton and Their Geological Significance

外文摘要：The Bayan Obo ore deposit is located in the northern margin of North China Craton,and its country rock,Jianshan Formation,is a set of greenschist facies rocks formed by regional metamorphism.The study on its formation age and provenance is of great significance for understanding the regional tectonic evolution.LA-ICP-MS zircon U-Pb geochronology was conducted on the metasandstone and metamorphic fine sandstone within Jianshan Formation.The zircon ages from metamorphic fine sandstone range from 2 645 Ma to 1 147 Ma,including two main peak ages of 2 510 Ma and 1 390 Ma,respectively.The zircon ages from metasandstone range from 2 722 Ma to 1 847 Ma,including three main peak ages of 2 487 Ma,1 925 Ma,and 1 859 Ma,respectively.Based on the REE characteristics of zircons,it is believed that zircons of sample By23281 displaying ages from 2 722 Ma to 1 847 Ma belong to typical detrital zircons and the formation age of Jianshan Formation should be later than 1 847 Ma.Based on the field characteristics,REE and morphology of zircons,the 1 761-1 147 Ma age of sample Z5246 represents the process of subsequent hydrothermal alteration,further confirming the magmatic origin of dolomitic carbonate.Based on the previous chronological data in the ore district and its periphery,it is advocated that Jianshan Formation is ultimately formed in the Mesoproterozoic,with its material sources coming from the Archean basement on the northern margin of North China Craton and metamorphic rocks from the Late Paleoproterozoic.In the Mesoproterozoic,Jianshan Formation is significantly altered by post-magmatic hydrothermal alteration of dolomitic carbonate.The ages of the clastic rocks in Bayan Obo ore district record the crustal accretion,collision and break-up events at the northern margin of North China Craton,providing powerful evidence for the study on the regional tectonic evolution during Archean-Proterozoic.

外文关键词：

meta-sedimentary rockzircon U-Pb ageArchean-Proterozoicsedimentary provenancehydrothermal alterationJianshan FormationNorth China Craton

作者：

杨建军、王东升、佘宏全、李以科、杨月后、柯昌辉、张丽、赵剑、赵阳、郭宾

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作者单位：

内蒙古自治区地质调查研究院内蒙古自治区岩浆活动成矿与找矿重点实验室,内蒙古呼和浩特 010020

中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室,北京 100037

包钢(集团)公司白云鄂博铁矿,内蒙古包头 014080

内蒙古包钢钢联股份有限公司巴润矿业分公司,内蒙古包头 014080

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关键词：

变沉积岩锆石U-Pb年龄太古代—元古代沉积源区热液改造尖山组华北克拉通

基金：

国家重点研发计划项目内蒙古自治区自然资源厅项目国家自然科学基金项目中国地质科学院矿产资源研究所科技成果转化项目中国地质科学院矿产资源研究所科技成果转化项目中国地质科学院矿产资源研究所科技成果转化项目中国地质科学院矿产资源研究所科技成果转化项目

项目编号：

2022YFC290530115000023505321000020342072114HE2224HE2228HE2313HE2333

出版年：

2024

DOI：

10.19814/j.jese.2024.03004

地球科学与环境学报

长安大学

地球科学与环境学报

CSTPCD北大核心

影响因子：1.422

ISSN：1672-6561

年,卷(期)：2024.46(5)