地质学报2025，Vol.99Issue(6)：1993-2008,中插3-中插10,24.DOI:10.19762/j.cnki.dizhixuebao.2025150
内蒙古东部地区林西组碎屑锆石U-Pb年代学:对古亚洲洋闭合时间的约束
Detrital zircon U-Pb geochronology of the Linxi Formation in eastern Inner Mongolia:Constraints on closure timing of the Paleo-Asian Ocean
摘要
Abstract
The eastern Inner Mongolia region,located in the southeastern segment of the Central Asian Orogenic Belt(CAOB),is critical for understanding the closure of the Paleo-Asian Ocean(PAO),as recorded by the Upper Permian Linxi Formation.Establishing the provenance of the Linxi Formation is challenging due to potential multiple source regions and inconsistencies in detrital zircon age distributions within the unit,leading to two contrasting models:a bidirectional(north-south)mixed-source and a unidirectional northern provenance.To address this,we present new detrital zircon U-Pb ages from three sandstone samples of the Linxi Formation from the Taohaiyingzi area,Inner Mongolia.Our analyses yielded concordant detrital zircon ages ranging from 1647 Ma to 251 Ma.The maximum depositional age,calculated using the weighted mean of the youngest zircon grain cluster at the 2σ confidence level(YGC 2σmethod),is 257.7+0.7 Ma.This age,combined with a published zircon U-Pb age of 251.5+2.2 Ma from an overlying tuff in the Laolongtou Formation,confirms a Late Permian depositional age for the Linxi Formation.All samples exhibit consistent detrital zircon age distributions,indicating no significant variations in provenance throughout the studied section of the Linxi Formation.Regional detrital zircon age data reveal spatial provenance variations for the Linxi Formation across the southeastern CAOB:the northern segment received sediments from north of the suture zone;the central segment exhibits a bidirectional(north-south)mixed-source signature;and the southern segment was derived from sources south of the suture zone.Based on previous research,we propose that the PAO,which underwent bidirectional subduction during the Late Paleozoic,was ultimately closed through a"soft collision"along the Solonker-Xar Moron Suture Zone in the Late Permian.关键词
中亚造山带/上二叠统林西组/碎屑锆石U-Pb年龄/物源分析Key words
Central Asian Orogenic Belt/Upper Permian Linxi Formation/detrital zircon U-Pb dating/provenance analysis引用本文复制引用
李文强,王涛,贾建亮,蔡芃睿..内蒙古东部地区林西组碎屑锆石U-Pb年代学:对古亚洲洋闭合时间的约束[J].地质学报,2025,99(6):1993-2008,中插3-中插10,24.基金项目
本文为国家科技部重点研发项目(编号 2023YFC2906701)、国家自然科学基金项目(编号 42372138)和中国地质调查局项目(编号 DD20221817)联合资助的成果. （编号 2023YFC2906701）
