河南省巩义铝土矿地球化学特征分析

GEOCHEMICAL CHARACTERISTICS OF THE GONGYI BAUXITE DEPOSIT IN HENAN PROVINCE

龙门-巩义地区是河南省铝土矿成矿带之一.通过对巩义铝土矿主要成分化学测试,研究分析铝土矿床化学元素变化规律.结果表明:铝土矿矿石主要矿物成分为一水硬铝石(含量45%~95%),其次为高岭石、伊利石等(含量4%~25%),含少量菱铁矿、黄铁矿、方解石、白云石等,微量矿物有锆石、磷灰石等.矿石的主要化学成分为Al_(2)O_(3)、SiO_(2)、Fe_(2)O_(3)、TiO_(2)、S,共占总成分的83.42%.其中,Al_(2)O_(3)含量40.46%~77.59%,平均60.68%;SiO_(2)1.00%~29.54%,平均14.07%;铝硅比值(A/S)1.8~65.1,平均4.3.在不同埋深条件下,相对深度越大,Al_(2)O_(3)的含量值及A/S值相对越大.该区域的化学风化指数(CIA)值可达到91.16,指示本区含铝岩系遭受了强烈的化学风化作用.

Longmen-Gongyi area is one of the bauxite metallogenic belts in Henan Province.Based on chemical test of the main compositions of Gongyi bauxite deposit,the paper analyzes the change rule of elements in the bauxite deposit.The results show that the major mineral compositions of bauxite ore is diaspore(45%-95%),followed by kaolinite and illite(4%-25%),with a small amount of siderite,pyrite,calcite and dolomite,and trace minerals such as zircon and apatite.The main chemical compositions of bauxite ore are Al_(2)O_(3),SiO_(2),Fe_(2)O_(3),TiO_(2)and S,accounting for 83.42%of the total,among which the Al_(2)O_(3)content is 40.46%-77.59%,averagely 60.68%,SiO_(2)1.00%-29.54%,averagely 14.07%,with the aluminum-silicon ratio(A/S)of 1.8-65.1,averagely 4.3.Under different burial depth conditions,the larger the relative depth is,the larger the Al_(2)O_(3)content and A/S ratio are.The chemical index of alteration(CIA)of the area is up to 91.16,indicating that the aluminum-bearing rock series in the area has undergone intense chemical weathering.