摘要
谢米斯台增生杂岩带位于西准噶尔造山带西南缘,记录了晚石炭世至早二叠世的岩浆活动,反映了古亚洲洋的俯冲和闭合过程,但是该地区俯冲开始的时间仍存在诸多争议。谢米斯台地区广泛分布的辉绿岩墙,为追索俯冲的开始时间提供了重要线索。本研究对谢米斯台地区的辉绿岩墙进行了U-Pb定年,获得了343 Ma、314 Ma、221 Ma和198 Ma的岩浆结晶年龄。进一步分析西准噶尔地区基性岩的测年结果,发现岩浆活动的高峰期在310~300 Ma,而基性岩的侵位年龄自南西向北东逐渐变年轻。同时,该地区还发育有大量组分复杂的花岗岩类,其同位素特征显示了巨量的新生物质的加入,符合洋脊俯冲的地球化学特征。综合分析已发表的辉绿岩锆石U-Pb年龄显示西准噶尔地区南西—北东有逐渐变年轻的趋势,可能指示了西准噶尔地区在晚石炭世开始发生古亚洲洋岩石圈的俯冲。
The Xiemisitai Accretionary Complex is located on the southwestern margin of the Western Junggar Orogenic Belt,recording magmatism from the Late Carboniferous to the Early Permian and reflecting the subduction and closure processes of the PaleoAsian Ocean.However,there is still considerable debate regarding the timing of the onset of subduction in this region.The widely distributed diabase dykes in the Xiemisitai area provide important clues for tracing the onset time of subduction.This study performed UPb dating on the diabase dykes in the Xiemisitai area,obtaining magmatic crystallization ages of 343 Ma,314 Ma,221 Ma,and 198Ma.Further analysis of the results of mafic rocks in the Western Junggar region reveals that the peak period of magmatic activity occurred from 310 Ma to 300 Ma,and the emplacement age of basic rocks gradually becomes younger from the southwest(SW)to the northeast(NE).At the same time,the area also hosts a large number of compositionally complex granitoids,whose isotopic characteristics indicate the addition of a substantial amount of juvenile material,consistent with the geochemical characteristics of oceanic ridge subduction.Comprehensive analysis of published UPb dating results of zircons from diabase indicates a gradual younging trend of the ages from the SW to the NE in the Western Junggar region,which may indicate that the subduction of the PaleoAsian Ocean lithosphere began in the Western Junggar region during the Late Carboniferous.
作者
杨伟
邱亮
木红旭
颜丹平
童英
刘章鹏
张海华
张蕊
成橙
YANG Wei;QIU Liang;MU Hongxu;YAN Danping;TONG Ying;LIU Zhangpeng;ZHANG Haihua;ZHANG Rui;CHENG Cheng(School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China;Beijing Research Institute of Uranium Geology,Beijing 100029,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Shenyang Center,China Geological Survey,Shenyang,Liaoning 110034,China;School of Geophysics and Information Technology,China University of Geosciences(Beijing),Beijing 100083,China)
出处
《现代地质》
北大核心
2025年第6期1461-1482,共22页
Geoscience
基金
地球深部探测与矿产资源勘查国家科技重大专项(2025 ZD1006500)
中核集团铀矿地质勘查项目(遥D2411)
中核集团集中研发“四代”铀矿勘查(第一阶段)项目(SD02-03-3)。
关键词
洋脊俯冲
中亚造山带
西准噶尔
谢米斯台
锆石U-PB年代学
ocean ridge subduction
Central Asian Orogenic Belt
Western Junggar
Xiemisitai
zircon UPb geochronology
