豫西偃龙地区本溪组含铝岩系的原岩恢复及其地质意义  

Protolith restoration and its geological significance of the aluminiferous rock series of the Benxi Formation in the Yanlong area,Western Henan

作　　者：刘恩法[1] 曹高社[2] 邢舟[2] 孙凤余[2] 杜欣 周红春[1] 陈永才[1] LIU Enfa;CAO Gaoshe;XING Zhou;SUN Fengyu;DU Xin;ZHOU Hongchun;CHEN Yongcai(The Fourth Geological Exploration Institute,Henan Geology and Mineral Bureau,Zhengzhou 450001,Henan,China;Institute of Resources&Environment,Henan Polytechnic University,Jiaozuo 454000,Henan,China)

机构地区：[1]河南省地质矿产勘查开发局第四地质勘查院,河南郑州450001 [2]河南理工大学资源环境学院,河南焦作454000

出　　处：《河南理工大学学报（自然科学版）》2022年第3期57-65,共9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项目(1211302108023-2);河南省两权价款项目(20111-36-8)。

摘　　要：为了揭示华北陆块上古生界最底部上石炭统-下二叠统本溪组含铝岩系承载的地质信息,以华北陆块南部豫西偃龙地区ZK0008钻孔为研究对象,系统采集本溪组含铝岩系样品,利用多种测试方法,确定含铝岩系矿物成分、矿物赋存状态、元素含量及其垂向变化,并依据土壤化学基本原理,分析本溪组含铝岩系矿物成因及矿物垂向变化的原因,进而恢复该区含铝岩系的原岩并讨论其地质意义。结果表明:该区本溪组含铝岩系矿物成分主要为硬水铝石矿物和黏土矿物,多为隐晶质集合体;相对难迁移元素主要富集在豆鲕状铝土矿中,相对易迁移元素主要富集在铝土质泥岩中;含铝岩系中矿物成分垂向上的变化是原岩不同程度富铁铝化的结果,原岩主要为来自北秦岭造山带、成分成熟度很低的长石和/或岩屑粉砂岩;本溪组原岩沉积时,海平面抬升可抵达北秦岭造山带的山前地区,可能由突发式的快速海侵引起,缓慢的海退可将来自北秦岭造山带的长石和/或岩屑带到离物源区较远的区域沉积;湿热多雨气候条件下,本溪组原始沉积物暴露地表时迅速彻底富铁铝化,形成一个典型的富铁铝化剖面,海平面多次升降旋回造成本溪组含铝岩系多个富铁铝化剖面叠置。The aluminiferous rock series of the late Carboniferous-early Permian Benxi Formation,as the base of the Upper Paleozoic in North China Block,are of great geological significance once their original rocks are restored.For this purpose,the borehole ZK0008,located at the Yanshi-Longmen region(abbreviated as the Yanlong area)in southern North China Block,was selected to determine the mineral compositions and their existing status,and the elemental contents and their vertical change of the aluminiferous rock series,by means of X-ray diffraction,scanning electron microscopy with energy spectrum,as well as geochemical analysis.On these bases,mineral genesis and the mechanism behind vertical mineral variation were analyzed,then the original rocks of the aluminiferous rock series were restored,and their geological significance was discussed.The results showed that the aluminiferous rock series of the Benxi Formation in the Yanlong area are mainly formed by diaspore and clay minerals,mostly cryptocrystalline aggregates.Inactive elements mainly exist in the pisolitic bauxite,whereas the active ones are mainly concentrated in the aluminous mudstones.Vertical variation in mineral compositions in the aluminiferous series was proposed to result from different degrees of ferrallitization with low maturity of the original siltstones,which mainly consisted of fine feldspar and/or lithoclasts from the North Qinling Orogenic Belt.During the original rocks of the Benxi Formation were deposited,rapid transgression might have made sea level reach the piedmont area of the North Qinling Orogenic Belt,and subsequently slow regression might have resulted in the diffusion of the feldspar and/or lithoclasts far from the source area.The original sediments of the Benxi Formation,once exposed to the surface,would have experienced rapid ferrallitization under humid,hot,and rainy climate conditions.Frequent sea-level fluctuations might have led to the superposition of several ferrallitization profiles,forming the aluminiferous rock series of the

关 键 词：本溪组 含铝岩系 原岩 华北陆块 豫西 

分 类 号：P228[天文地球—大地测量学与测量工程]