地质学报2025，Vol.99Issue(5)：1589-1605,17.DOI:10.19762/j.cnki.dizhixuebao.2024195
阿拉善北部珠斯楞地区古硐井群的厘定及其地质意义
Determination and geological implication of the Gudongjing Group in the Zhusileng area,northern Alxa
摘要
Abstract
The distribution and formation age of Precambrian strata are crucial for understanding tectonic divisions,stratigraphic sequences,and fundamental geological research.The Gudongjing Group,traditionally considered the first sedimentary cover on the Precambrian basement of the Beishan Orogenic Belt,is mainly distributed in the Beishan area.However,its distribution and formation age in the northern Alxa area,north of the Enger Us ophiolitic mélange belt and south of the Sino-Mongolia border,have not been identified,which hinders the understanding of this geological body and the tectonic evolution of the northern Alxa.This study focuses on metasedimentary rocks of the Jixianian System in the Zhusileng area of the northern Alxa,in which field surveys,zircon geochronology,and Lu-Hf isotopic analyses were carried out.It is found that detrital zircon ages range from 2621 Ma to 291 Ma,mainly clustered in the Mesoproterozoic to Paleoproterozoic period.εHf(t)values are mainly concentrated in the range from-7.5 to+5.4,with crustal model ages TCDM plotting between 3.29 Ga and 1.69 Ga.These data indicate that the provenance underwent crustal remelting from the Neoarchaean to Early Paleoproterozoic and subsequent crustal growth during the mid-to late Paleoproterozoic.A maximum depositional age is constrained as 1240 Ma based on rock assemblages,metamorphism and deformation,and detrital zircon age spectra characteristics.Comparative analysis of the Jixianian System metasedimentary rocks in the Zhusileng area and the Gudongjing Group in the Beishan area reveals similarities in rock assemblages,ages,and Hf isotopic signatures.This suggests that the metasedimentary rocks from the Jixianian System can be classified as the Gudongjing Group.Based on previous work,it is confirmed that the northern Alxa,north of the Enger Us ophiolitic mélange belt,has a similar Precambrian basement,sedimentary cover,and age features of provenance to the Beishan Orogenic Belt.This suggests that the northern Alxa and the Beishan Orogenic Belt might experience a comparable Precambrian evolutionary history.关键词
阿拉善北部地区/古硐井群/前寒武纪/锆石U-Pb-Hf/地层对比Key words
northern Alxa/Gudongjing Group/Precambrian/zircon U-Pb-Hf/strata correlation引用本文复制引用
王振义,郑荣国,张进,刘建峰,曲军锋,赵衡,张北航,杨亚琦,赵硕,吴春娇..阿拉善北部珠斯楞地区古硐井群的厘定及其地质意义[J].地质学报,2025,99(5):1589-1605,17.基金项目
本文为中国地质科学院基本科研业务费专项(编号JKYZD202309)、中国地质调查局项目(编号DD20240075、DD20230217)、国家自然科学基金项目(编号U2344215)、内蒙古自治区自然科学基金(编号2024QN04021)和自然资源综合调查指挥中心科技创新基金(编号KC20240005)联合资助的成果. （编号JKYZD202309）
