西北地质2026，Vol.59Issue(5)：86-102,17.DOI:10.12401/j.nwg.2025085
东昆仑东段沟里地区洪水川组火山岩夹层锆石U-Pb年代学、岩石成因及对古特提斯洋演化的制约
Zircon U-Pb Geochronology and Petrogenesis of Volcanic Interlayers in the Hongshuichuan Formation:Insights into the Evolution of Paleo-Tethys Ocean in the Gouli Area of the Eastern Section of East Kunlun
摘要
Abstract
The East Kunlun Orogenic Belt is an important part of the Paleo-Tethys domain,and there are still disagreements regarding the closure time limit of the Paleo-Tethys Ocean in this area.Volcanic rock interlayers in the Hongshuichuan Formation in the Gouli area of the eastern segment of this region were selected for zircon U-Pb isotopic age and petrogeochemical studies.The results show that this suite of volcanic rocks is composed of basaltic andesite,dacite,and rhyolite.The selected zircons in the dacite and rhyolite samples all exhibit mag-matic rhythmic zoning,and most of them have a high Th/U ratio,indicating that they are of magmatic origin.The LA-ICP-MS zircon U-Pb ages are(250±2.1)Ma(MSWD=4.9)and(248±4.5)Ma(MSWD=1.2),represent-ing that the volcanic rocks were formed during the Olenekian period of the Early Triassic.Petrogeochemical analysis shows that this suite of volcanic rock interlayers belongs to the calc-alkaline series,showing the charac-teristics of enrichment in large ion lithophile elements(LILE)such as Rb,Ba,Th,and U,depletion in high field strength elements(HFSE)such as Nb,Ta,P,and Ti,and no obvious anomalies in Zr and Hf,exhibiting the char-acteristics of arc magmatic rocks related to the subduction zone.The basaltic andesite is a magma from the man-tle source area metasomatized by subduction fluids,formed through later crystallization differentiation and crustal material contamination;the dacite and rhyolite have a homologous evolutionary relationship and are products of crustal melting induced by the upwelling of mantle-derived magma,formed in the environment of northward subduction of the Paleo-Tethys Ocean.The study on the age and sedimentary environment of the vol-canic rock interlayers in the Hongshuichuan Formation limits that the closure time of the Paleo-Tethys Ocean in the East Kunlun area is not earlier than 248 Ma.关键词
东昆仑东段/洪水川组火山岩夹层/锆石U-Pb定年/岩石成因/构造环境Key words
eastern section of the East Kunlun/volcanic rock interlayers in Hongshuichuan Formation/zir-con U-Pb dating/petrogenesis/tectonic environment分类
天文与地球科学引用本文复制引用
祁尧刚,孟勇,李佐臣,许星辰,张吉廷,王鹏,朱兴明,周霖..东昆仑东段沟里地区洪水川组火山岩夹层锆石U-Pb年代学、岩石成因及对古特提斯洋演化的制约[J].西北地质,2026,59(5):86-102,17.基金项目
中国地质调查局项目"青海省格尔木市纳赤台西地区小南川等2幅1∶5万区域地质调查"(DD20250103002),"东昆仑成矿带金矿资源潜力动态评价"(DD20220978),"祁连成矿带金矿资源潜力动态评价"(DD20220979),陕西高校青年创新团队联合资助. （DD20250103002）
