河南省巩义地区本溪组铝土矿成矿物质来源——来自碎屑锆石LA-ICP-MS U-Pb年龄的证据  

Material sources analysis of Karstic bauxite of Benxi formation in Gongyi area,Henan Province:Evidences from LA-ICP-MS U-Pb dating of detrital zircons

作　　者：曹高社[1,2] 刘凌之 邢舟 孙凤余[1] 余爽杰[1] 方磅磅 杜欣 周红春 陈永才[3] CAO Gaoshe;LIU Lingzhi;XING Zhou;SUN Fengyu;YU Shuangjie;FANG Bangbang;DU Xin;ZHOU Hongchun;CHEN Yongcai(School of Resources&Environment,Henan Polytechnic University,Jiaozuo 454000,Henan,China;Collaborative Innovation Center of Coalbed Methane and Shale Gas for Central Plains Economic Region,Henan Province,Jiaozuo 454000,Henan,China;The Fourth Geolocgical Exploration Institute,Henan Bureau of Geo-Exploration&Mineral Development,Zhengzhou 450001,Henan,China)

机构地区：[1]河南理工大学资源环境学院,河南焦作454000 [2]中原经济区煤层(页岩)气河南省协同创新中心,河南焦作454000 [3]河南省地质矿产勘查开发局第四地质勘查院,河南郑州450001

出　　处：《河南理工大学学报（自然科学版）》2018年第6期55-65,共11页Journal of Henan Polytechnic University（Natural Science）

基　　金：全国油气资源战略选区调查与评价专项项目(1211302108023-2);河南省两权价款项目(20111-36-8)

摘　　要：巩义地区是河南省本溪组铝土矿发现最早的地区,也是豫西铝土矿成矿带的重要组成部分,但对其成矿物质来源尚不清晰。选取该区一个露天采坑内的豆鲕状铝土矿样品,进行岩石薄片观察、X衍射分析和LA-ICP-MS碎屑锆石U-Pb测年。结果表明,该区铝土矿主要矿物成分为硬水铝石、锐钛矿和伊利石;碎屑锆石年龄可以分成2组,第一组介于393—484 Ma间,峰值约为442 Ma,占86%,主要为早古生代岩浆锆石,第二组介于555—2 714 Ma间,具有约901 Ma,约1 718 Ma,约2 440 Ma的峰值年龄,占14%,主要为前寒武纪岩浆锆石或为岩浆成因的变质增生锆石;早古生代碎屑锆石主要来自于北秦岭造山带加里东期中-酸性花岗质侵入岩,前寒武纪碎屑锆石可能主要来源于北秦岭地区的变质地层,它们与侵入其中的加里东期岩浆岩一同被剥蚀,共同为研究区提供物源;该区铝土矿中缺少晚古生代碎屑锆石的原因可能与远离内蒙古隆起,靠近北秦岭造山带有关。Gongyi is the earlist discovered site of the karstic bauxite in Benxi formation in Henan province,and it is also the main component of bauxite metallogenic belt in West Henan.However,its bauxite material sources is not clear.In this study,samples from pisolitic-oolitic bauxite were selected.Petrographic observation,X-ray diffraction analysis and LA-ICP-MS detrital zircons U-Pb dating were conducted for data analysis.The results show that main mineral components of bauxite are diaspora,anatase and illite.The detrital zircon U-Pb ages of the sample can be divided into two groups.The first group mainly is early Paleozoic magmatic zircons(accounted for 86%)with the age ranges 393-484 Ma and the peak value is ca.442 Ma.The second group mainly is Precambrian magmatic zircons or metamorphic growth magmatic zircons(accounted for 14%)with the age ranges 555-2714 Ma and has three peaks,ca.901 Ma,ca.1 718 Ma and ca.2 440 Ma.The detrital zircons with early Paleozoic ages mainly derived from the Caledonian medium-acid granitic intrusive rocks of North Qinling orogeny.The detrital zircons with Precambrian ages might derive from metamorphic formations of North Qinling orogeny.The both types of aforesaid rocks were denuded together and provided sources for bauxite of Benxi formation in the study area.The reason for lack of late Paleozoic detrital zircon in bauxite of this area may be related to tectonic location which is far from Inner Mongolia uplift and close to North Qinling orogeny.

关 键 词：本溪组铝土矿 物质来源 碎屑锆石 LA-ICP-MSU-Pb测年 巩义地区 

分 类 号：P618.45[天文地球—矿床学] P536[天文地球—地质学]