地质通报2023，Vol.42Issue(12)：2037-2059,23.DOI:10.12097/j.issn.1671-2552.2023.12.003
辽宁弓长岭鞍山群时代与物源
Depositional age and provenance of the Anshan Group in the Gongchangling area,Liaoning Province:Constraints from detrital zircon U-Pb-Hf isotopic and rare earth element composition in the garnet-staurolite-mica-quartz schist
摘要
Abstract
The Anshan Group,which has undergone greenschist to amphibolite facies metamorphism and polyphase deformation,is one of the most important banded iron formation(BIF)-bearing meta-supracrustal rocks in the Eastern Block of the North China Craton.Depositional age and provenance of the Anshan Group are vital for understanding the tectonic setting of the BIF in the North China Craton.In this study,LA-MC-ICP-MS(laser ablation inductively coupled plasma mass spectrometry)was employed to analyze detrital zircon U-Pb-Hf isotope and rare earth element compositions of garnet-staurolite-mica-quartz schist from the Anshan Group in the Gongchangling area.Based on the internal structure,and U-Pb ages of detrital zircons,the peak age of 2528 Ma recorded by the youngest group of detrital zircons is chosen as the maximal depositional age of the Anshan Group,coupled with the geological relationship which the Anshan Group was intruded by the ca.2500 Ma Qidashan K-rich granites and 2510～2470 Ma metamorphic age of the Anshan Group,suggest that the Anshan Group was deposited between 2528 Ma and 2510 Ma,late Neoarchean.The 207Pb/206Pb ages of the detrital zircons from the studied sample is between 2931 Ma and 2454 Ma,and detrital zircon age patterns of the studied sample is characterized by the major peak of 2528 Ma.Combined with the internal structure of the detrital zircons,our new U-Pb ages reveal that the main provenance of Anshan Group is the late Neoarchean acid magmatic rocks.The two-stage Hf model ages of the typical detrital zircons are 3532～2711 Ma with a peak age of 2830 Ma,which further reveals that the intensive crustal growth in the Anshan-Benxi area was concentrated in Late Middle Archean.Integrated with previous geochemical data from Anshan Group in the Anshan-Benxi area,it is speculated that the Gongchangling BIF-bearing meta-supracrustal rocks of Anshan Group were probably deposited in a back-arc basin on the ancient continental margin.关键词
华北克拉通/弓长岭/鞍山群/石榴十字黑云母片岩/碎屑锆石/地质调查工程Key words
North China Craton/Gongchangling/Anshan Group/garnet-staurolite-mica-quartz schist/detrital zircon/geological survey engineering分类
天文与地球科学引用本文复制引用
陈丽梅,刘平华,杜利林,杨崇辉,张文,周万蓬..辽宁弓长岭鞍山群时代与物源[J].地质通报,2023,42(12):2037-2059,23.基金项目
中国地质调查局项目《华北陆块赞皇地区专题地质填图》(编号:DD20230209)、《华北陆块中部与东部前寒武纪基础地质调查》(编号:DD20190003)、《华北克拉通及周缘关键地质问题调查与变质岩试点填图》(编号:DD20160121)和国家自然科学基金项目《薄片原位独居石LASS与石榴子石微钻取样精细年代学研究:以弓长岭和鲁西孟家屯新太古代变质表壳岩为例》(批准号:41972205)、《内蒙古西部东阿拉善-狼山前寒武纪变质杂岩多期变质事件》(批准号:41672191)、《胶北莱阳地区～2.9Ga岩浆作用的多样性及其对中太古代壳幔作用过程的指示》(批准号:42272232)、中国地质科学院地质研究所基本科研业务费(编号:J2303) （编号:DD20230209）
