中国地质2023，Vol.50Issue(6)：1788-1803,16.DOI:10.12029/gc20210110002
内蒙古白云鄂博地区识别出新火成碳酸岩
Identification of new igneous carbonatites in the Bayan Obo area,Inner Mongolia
摘要
Abstract
This paper is the result of mineral exploration engineering. [Objective]The formation of the giant Bayan Obo REE deposit is closely related to carbonatitic magmatism.Near the ore district,southwest of West Ore Body,there are carbonate rocks with a certain scale covered by Mesozoic-Cenozoic sediments,the genesis of which can indicate the formation process of the well-known Bayan Obo deposit.[Methods]This contribution demonstrates that these rocks are actually igneous by the detailed study on petrology and mineralogy.[Results]The rocks were little affected by fluid metasomatism and can be divided into dolomite type and calcite type according to their mineral compositions.Bulk rock analysis shows that these carbonatites are rich in Sr(>4940×10-6),Mn(>2150×10-6)and Ba(>106×10-6),and the average REE content are 938×10-6,much higher than that of sedimentary carbonates.The δ13CV-PDB and δ18OV-SMOWof the rock samples are-3.7‰--4.2‰and 6.7‰-7.7‰,respectively,typical of primary igneous carbonatite.They have relatively homogeneous Sr isotopic compositions(87Sr/86Sr=0.702815-0.703185),indicating the mantle-derived rocks were contaminated by the crust limitedly.In addition,the mineral chemical features of dolomite,calcite and apatite also indicate an igneous origin.[Conclusions]The identification of these carbonatites is of great significance for the comparative study on the Bayan Obo deposit and tectonic evolution of the area.关键词
岩石地球化学/矿物化学/C-O-Sr同位素/碳酸岩/矿产勘查工程/白云鄂博/内蒙古Key words
petrogeochemistry/mineral chemistry/C-O-Sr isotopes/carbonatite/mineral exploration engineering/Bayan Obo/Inner Mongolia分类
地质学引用本文复制引用
胡乐,李以科,孙盛,李瑞萍,柯昌辉,王安建..内蒙古白云鄂博地区识别出新火成碳酸岩[J].中国地质,2023,50(6):1788-1803,16.基金项目
国家自然科学基金项目(42072114)、中国地质调查局项目(DD20190828)和包钢集团科研项目(HE1918、HE1922)联合资助. Supported by the projects of National Natural Science Foundation of China(No.42072114),China Geology Survey(No.DD20190828)and Scientific Research Projects of Baogang Group(No.HE1918,No.HE1922). （42072114）
