吉泰盆地石炭系黄龙组黑色碳质泥岩物源、构造背景与古风化作用:来自稳定元素地球化学的证据  

Provenance,Tectonic Setting and Palaeo-weathering of Black Carbonaceous Mudstones from Carboniferous Huanglong Formation in the Jitai Basin:Evidence from Stable Element Geochemistry

作　　者：颜开 王春连[1] 王九一 沈立建[1] 余小灿 孟令阳 YAN Kai;WANG Chun-lian;WANG Jiu-yi;SHEN Li-jian;YU Xiao-can;MENG Ling-yang(MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037;2902 Geological Brigade of Jiangxi Bureau of Exploration and Development for Geology and Mineral Resources,Xinyu,Jiangxi 338099)

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]江西省地质矿产勘查开发局902地质队,江西新余338099

出　　处：《地球学报》2022年第3期325-337,共13页Acta Geoscientica Sinica

基　　金：中央级公益性科研院所基本科研业务费专项(编号:KK2005,KK2016);国家973计划项目(编号:2011CB403007);中国地质调查局地质矿产调查评价专项项目(编号:DD20190437,DD20190606)联合资助。

摘　　要：吉泰盆地在白垩纪—古近纪时期,沉积了巨量的富锂钾卤水,同时富含硼、铷、铯、溴、碘等新兴矿产资源,综合利用价值高。本文采用X射线荧光光谱(XRF)和电感耦合等离子体质谱(ICP-MS)分析了吉泰盆地石炭系黄龙组黑色碳质泥岩的主、微量和稀土元素地球化学特征。通过对其物源、构造背景及古风化作用的详细分析,探讨了其对上覆卤水矿层的影响。吉泰盆地M2钻孔底部细碎屑岩具有LREE富集,HREE较平缓的特征,且均表现明显的Eu负异常,综合La/Th-Hf和Zr-TiO_(2)图解,认为其主要来自长英质/基性岩浆岩和古老沉积组分的混合源区,为卤水形成带来了丰富的深源物质。微量元素和稀土元素的含量和比值(La/Th、Cr/Th、Th/Sc),反映出被动大陆边缘的构造背景特征。通过计算化学风化指数(CIA、CIW、PIA和ICV)及Al_(2)O_(3)-(CaO+Na_(2)O)-K_(2)O图解,表明其化学风化程度较高,有利于元素的迁移和富集,为卤水矿床的形成提供了丰富的成矿元素。In the Cretaceous–Paleogene period,a huge amount of lithium-potassium rich brine was deposited in the Jitai Basin,which is rich in boron,rubidium,cesium,bromine,iodine and other emerging mineral resources,with high comprehensive utilization value.In this paper,the major,trace and rare earth element geochemical characteristics of Carboniferous Huanglong Formation black carbonaceous mudstone in the Jitai Basin were analyzed by X-ray fluorescence spectrometry(XRF)and inductively coupled plasma mass spectrometry(ICP-MS).Based on the detailed analysis of its provenance,tectonic setting and paleo-weathering,the influence of it on the overlying brine ore bed is discussed.The fine clastic rocks in the lower part of the M2 borehole in the Jitai Basin are characterized by LREE enrichment and gentle HREE,and they all show obvious negative Eu anomaly.Based on La/Th-HF and Zr-TiO_(2) diagram,they are mainly from the mixed source area of felsic/basic magmatic rocks and ancient sedimentary components,which brings abundant deep source materials for the formation of brine.The contents and ratios of trace elements and rare earth elements(La/Th,Cr/Th,Th/Sc)reflect the tectonic background characteristics of passive continental margin.The chemical weathering index(CIA,CIW,PIA and ICV)and the diagram of Al_(2)O_(3)-(CaO+Na_(2)O)-K_(2)O show that the chemical weathering degree is high,which is conducive to the migration and enrichment of elements,and provides rich ore-forming elements for the formation of brine deposits.

关 键 词：吉泰盆地 地球化学 物质来源 构造演化 风化作用 

分 类 号：P619.211[天文地球—矿床学]