碎屑重矿物分析对内蒙古西乌旗早二叠世寿山沟组的物源指示及构造意义  

Detrital heavy minerals analysis of Early Permian Shoushangou Formation in the Xi Ujimqin, Inner Mongolia: Implications for provenance and tectonic setting

作　　者：张英利[1] 郭现轻[1] 孙立新 马收先[1] 施立志[1] ZHANG Ying-li;GUO Xian-qing;SUN Li-xin;MA Shou-xian;SHI Li-zhi(MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,CAGS,Beijing 100037,China;Tianjin Center of Geological Survey,CGS,Tianjin 300170,China)

机构地区：[1]中国地质科学院矿产资源研究所,自然资源部成矿作用与资源评价重点实验室,北京100037 [2]中国地质调查局天津地质调查中心,天津300170

出　　处：《岩石矿物学杂志》2021年第6期1155-1170,共16页Acta Petrologica et Mineralogica

基　　金：深地资源勘查开采项目(2019YFC0605202);中国地质调查项目(DD20201173,DD20190099)。

摘　　要：碎屑重矿物由于相对比较稳定,蕴含重要的成因信息,对其进行电子探针成分分析,能够还原岩石形成的物源区和盆地构造背景。内蒙古西乌旗早二叠世寿山沟组一段主要由砂岩夹砾岩等组成,二段主要由粉砂岩、泥岩等组成。重矿物分析表明,寿山沟组一段和二段砂岩重矿物主要有锆石、尖晶石和石榴子石等,指示其物源区为岩浆岩和变质岩。重矿物电子探针成分分析结果显示,电气石成分指示其具贫锂花岗岩和变沉积岩物源,尖晶石成分指示其具岛弧和洋中脊玄武岩类物源,石榴子石成分指示其具高级变质基性岩源区。综合物源分析显示,寿山沟组主要来源于迪彦庙蛇绿岩、锡林浩特杂岩和本巴图组玄武岩等。结合区域地质对比,认为寿山沟组形成于弧后盆地,古亚洲洋在早二叠世时期尚未闭合。The detrital heavy minerals are relatively stable and contain important genetic information. The EPMA composition analysis of them can provide the provenance and basin tectonic setting. The first member of Shoushangou Formation is mainly composed of sandstone and conglomerate, and the second member is mainly composed of siltstone and mudstone. The assemblages of heavy minerals in the sandstones are mainly composed of zircon, spinel and garnet, suggesting that the provenance rocks were magmatic and metamorphic rocks. The results of electron probe microanalysis show that tourmalines were derived mainly from lithium-poor granite and metasedimentary rocks, spinels were sourced from island arc basalts and mid ocean ridge basalts, and garnets from the source of high-grade metabasic rocks. Comprehensive provenance analysis shows that they were mainly derived from Diyanmiao ophiolite, Xilinhot complex and basalts of Benbatu Formation. Combined with regional geological correlation, the sediments of Shoushangou Formation were formed in a backarc basin, suggesting that the Paleo-Asian Ocean was not closed in the Early Permian.

关 键 词：兴蒙造山带 西乌旗 寿山沟组 物源分析 电子探针 弧后盆地 

分 类 号：P588.212[天文地球—岩石学] P574.2[天文地球—地质学]