渣尔泰山群及宝音图群大理岩古沉积环境研究——以内蒙古霍各乞地区为例  

Research on the Paleosedimentary Environments of Marble in the Zhaertai and Buyant Groups:A case study of Huogeqi area,Inner Mongolia

作　　者：赵伟光 夏楚林[2] 陈磊 ZHAO WeiGuang;XIA ChuLin;CHEN Lei(BGRIMM Technology Group,State Key Laboratory of Mineral Processing Science and Technology,Beijing 102628,China;Qinghai University,Xining 810016,China;Drilling and Production Engineering Technology Institute of CCDC,Xi’an 710018,China)

机构地区：[1]矿冶科技集团有限公司,矿物加工科学与技术国家重点实验室,北京102628 [2]青海大学,西宁810016 [3]中国石油川庆钻探工程有限公司工程技术研究院,西安710018

出　　处：《沉积学报》2022年第6期1660-1675,共16页Acta Sedimentologica Sinica

基　　金：青海省科技计划项目(2020-ZJ-762)。

摘　　要：内蒙古霍各乞位于华北地台北缘西段,区内出露的渣尔泰山群和宝音图群对于揭示中—新元古代时期华北地台北缘的古沉积环境具有重要的科学意义,且这两个岩群均含有大理岩为其研究提供了可能。在对该地区渣尔泰山群和宝音图群大理岩进行详细的野外地质工作的基础上,进一步选取有代表性的大理岩样品做C、O同位素分析。结果显示,内蒙古霍各乞渣尔泰山群大理岩δ^(13)C_(V-PDB)值为-2.4‰~4.3‰,δ^(18)O_(V-PDB)值为-39.0‰~-15.3‰,δ^(18)O_(V-SMOW)值为-8.2‰~15.2‰,宝音图群大理岩δ^(13)C_(V-PDB)值为-1.1‰~5.9‰,δ^(18)O_(V-PDB)值为-18.5‰~-7.8‰,δ^(18)O_(V-SMOW)值为12.0‰~22.7‰,两者的C同位素均具有显著的正漂移特征,O同位素均发生了强烈的亏损。结合地质、地球化学特征综合分析认为:1)霍各乞渣尔泰山群大理岩原岩的古沉积环境为缺氧的浅海相环境,沉积期接受了丰富的陆源碎屑物质的混染,沉积期后发生了明显的碳酸盐溶解作用,大理岩C同位素正漂移与华北克拉通北缘裂解作用关系密切。2)霍各乞宝音图群大理岩原岩形成于相对闭塞的浅海相环境,沉积期受陆源碎屑物质的混染程度相对较小,沉积期后发生了明显的碳酸盐溶解作用,大理岩C同位素正漂移可能与沉积盆地的闭塞性有一定的关系。3)霍各乞渣尔泰山群和宝音图群大理岩原岩具有类似的古沉积环境。Huogeqi,Inner Mongolia,is located in the western region of the northern margin of the North China Plat⁃form.The marble content of both the Zhaertai Group and the Buyant Group in this area is significant for revealing the paleosedimentary environment of the northern margin of the North China Platform in the Meso-to Neoproterozoic.Fol⁃lowing detailed geological fieldwork,representative samples of marble from both groups were selected for C and O iso⁃topic analysis.Zhaertai Group marble samples containedδ^(13)C_(V-PDB)values between-2.4‰and 4.3‰;δ^(18)O_(V-PDB)values between-39.0‰and-15.3‰;andδ^(18)O_(V-SMOW)values between-8.2‰and 15.2‰.Buyant Group marble samples con⁃tainedδ^(13)C_(V-PDB)values from-1.1‰to 5.9‰;δ^(18)O_(V-PDB)values from-18.5‰to-7.8‰;andδ^(18)O_(V-SMOW)values from 12.0‰to 22.7‰.The C isotopes in both groups display an apparent positive drift,and their O isotopes are strongly depleted.A comprehensive analysis of geological and geochemical characteristics indicated that:(1)The protolith of Zhaertai Group marble was formed in a shallow anoxic marine environment.It was contaminated by abundant terrige⁃nous clastic materials during the depositional stage,and obvious carbonate dissolution occurred after deposition.The positive drift of the C isotope is closely related to the break-up of the northern margin of the North China Platform.(2)The protolith of Buyant Group marble was formed in a relatively closed shallow marine environment,and under⁃went somewhat less contamination by terrigenous clastic materials during deposition.After the deposition stage,obvi⁃ous carbonate dissolution occurred.The positive drift of C isotopes may be related to occlusion of the sedimentary ba⁃sin.(3)The protoliths of the marble in the Zhaertai Group and Buyant Group experienced similar paleosedimentary environments.

关 键 词：大理岩 C、O同位素 沉积环境 渣尔泰山群 宝音图群 华北地台北缘 

分 类 号：P534.3[天文地球—古生物学与地层学]