地质通报2023，Vol.42Issue(11)：1875-1893,19.DOI:10.12097/j.issn.1671-2552.2023.11.007
内蒙古北山造山带圆包山—希热哈达地区白山组火山岩锆石U-Pb年龄、地球化学特征及对古亚洲洋俯冲作用的启示
Zircon U-Pb ages and geochemistry of volcanic rocks from the Baishan Formation in the Yuanbaoshan-Xirehada area in Beishan orogenic collage,Inner Mongolia,NW China,and implications for the subduction history of the Paleo-Asian Ocean
摘要
Abstract
Andesite and breccia-bearing granite porphyry samples were collected from the Baishan Formation in the Yuanbaoshan-Xirehada area of the northern Beishan orogenic collage in Inner Mongolia,NW China.Petrographic,LA-ICP-MS zircon U-Pb geochronology,and geochemical analyses were conducted to examine the Late Paleozoic tectonic evolution history in the Beishan area.The zircon U-Pb dating results suggest that the weighted mean ages of andesite and breccia-bearing granite porphyry are 300.0±2.5 Ma(MSWD=2.0,n=13)and 300.3±1.9 Ma(MSWD=1.9,n=23),respectively.These findings confirm that the stratigraphic age of Baishan Formation in the study area is Late Carboniferous.The volcanic rocks are relatively enriched in light rare earth elements and large ion lithophile elements(e.g.Rb,K,and Ba)and depleted in heavy rare earth elements and high field strength elements(e.g.Nb,P,and Ti).They exhibit geochemical characteristics related with active continental margin volcanic arcs,which indicate that the subduction history of the Paleo-Asian Ocean continued into the Late Carboniferous in the northern Beishan orogenic collage.Geochemical studies further suggest that the magma source of the andesite in the Carboniferous Baishan Formation is the middle-lower crust metasomatized by fluid in the subduction zone,and the breccia-bearing granite porphyry is mainly the product of the middle-lower crust melting,and the samples exhibit sediment incorporation.The volcanic rocks from the Baishan Formation changed from neutral and calc-alkalic rock series in the northern part to intermediate-acid or acid and high potassium calc-alkalic rock series in the southern part along the ophiolite mélange belt,indicating the southern subducted polarity of the Paleo-Asian Ocean plate.关键词
北山造山带/白山组/圆包山/中亚造山带/古亚洲洋Key words
Beishan orogenic collage/Baishan Formation/Yuanbaoshan area/Central Asian Orogenic Belt/Paleo-Asian Ocean分类
天文与地球科学引用本文复制引用
杜庆祥,伍赛男,张永,沈晓丽,韩金瑞..内蒙古北山造山带圆包山—希热哈达地区白山组火山岩锆石U-Pb年龄、地球化学特征及对古亚洲洋俯冲作用的启示[J].地质通报,2023,42(11):1875-1893,19.基金项目
国家自然科学基金项目《华北板块北缘东段石炭纪古亚洲洋俯冲起始的沉积记录》(批准号:42272120)、中国地质调查局项目《阴山成矿带小狐狸山和雅布赖地区地质矿产调查》(编号:DD20160039)、山东省高校科研计划《延边地区解放村组地层形成时代及构造意义》(编号:J18KA213)、山东省高校优秀青年创新团队《郯庐断裂带两侧恐龙动物群对比与启示》(编号:2019KJH004) （批准号:42272120）
