南天山造山带晚古生代构造属性及亲缘性:来自碎屑锆石U-Pb年代学的约束  

Late Paleozoic tectonic nature and affinity of the South Tianshan:Evidence from U‑Pb geochronology of detrital zircons

作　　者：尼加提·阿布都逊[1,2] 阿比旦·阿力木江 黄鹏 甘敬民[3] Nijiati Abuduxun;Abidan Alimujiang;Huang Peng;Gan Jingmin(Xinjiang Key Laboratory for Geodynamic Processes and Metallogenic Prognosis of the Central Asian Orogenic Belt,Xinjiang University,Ürümqi 830046;School of Geology and Mining Engineering,Xinjiang University,Ürümqi 830046;Xinjiang Research Centre for Mineral Resources,Chinese Academy of Sciences,Ürümqi 830011)

机构地区：[1]新疆大学中亚造山带大陆动力学与成矿预测自治区重点实验室,乌鲁木齐830046 [2]新疆大学地质与矿业工程学院,乌鲁木齐830046 [3]中国科学院新疆矿产资源研究中心,乌鲁木齐830011

出　　处：《地质科学》2025年第2期323-344,共22页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金项目(编号:42472279,41962013);新疆维吾尔自治区重点研发计划项目子课题(编号:2022B03015-2)资助。

摘　　要：南天山位于中亚造山带与塔里木克拉通的交界处,其构造属性及亲缘性长期存在争议。碎屑锆石U-Pb年代学在限定地层最大沉积年龄和鉴别古块体构造亲缘性等方面行之有效。本文对南天山乌什塔拉地区两件碎屑岩样品进行LA-ICP-MS锆石U-Pb年代学研究。依据3颗最小有效年龄的加权平均值,限定研究区砂岩和片岩的最大沉积年龄分别为312±1.4 Ma和373±1.7 Ma。与柯坪塔格构造带同时代地层对比,两件样品的碎屑锆石年龄谱均以古生代年龄峰值为主,且与伊犁—中天山地块岩浆弧年龄分布规律一致,但缺乏塔里木克拉通的标志性构造—热事件年龄信息,表明塔里木并非其物源区。在物源分析基础上,结合区域岩石组合及其构造样式,认为研究区碎屑岩是南天山增生杂岩的重要组成部分,是南天山古大洋岩石圈向北俯冲消减作用的物质记录。在晚古生代期间,南天山属于伊犁—中天山地块南缘汇聚板块边缘的一部分,而非塔里木克拉通北缘的被动大陆边缘。The South Tianshan is situated at the junction of the Central Asian Orogenic Belt and the Tarim Craton.There has been long a controversy regarding the tectonic attribute and affinity of the South Tianshan.Detrital zircon U‑Pb geochronology is effectively to delineate the maximum depositional age of strata and to discern the tectonic affinities of ancient blocks.This study reports LA‑ICP‑MS zircon U‑Pb geochronology of two samples from sedimentary rocks in the Wushitala area of the South Tianshan.Based on the weighted mean ages of the three youngest grains,the maximum depositional ages of the studied sandstone and schist are estimated at 312±1.4 Ma and 373±1.7 Ma,respectively.The detrital zircon age spectra of both studied samples are significantly different from those of coeval strata in the Kepingtagh belt,and predominantly display Paleozoic age peaks,closely overlapping with the age of arc‑related magmatism in the Yili‑central Tianshan.The samples lack the age information of typical tectono‑thermal events in the Tarim Craton,indicating that they were unlikely derived from the craton.Provenance analysis,integrated with regional lithological and structural data from literature,it is suggested that the sedimentary rocks in the study area constitute a significant component of the South Tianshan accretionary complex,recording the northward subduction of the South Tianshan oceanic plate.The South Tianshan was likely a part of the active margin of the southern Yili‑central Tianshan terrane,rather than the passive margin of the northern Tarim Craton.

关 键 词：碎屑锆石U-PB年龄 沉积物源 构造属性 增生杂岩 南天山 

分 类 号：P541[天文地球—构造地质学] P597.3[天文地球—地质学]