河南省铝土矿床地质特征及成矿规律

河南省铝土矿资源丰富，查明资源储量居全国第二位。铝土矿成矿区在大地构造位置上处于华北陆块南缘的华熊台缘坳陷渑池—确山陷褶断束中西段、嵩萁台隆和山西台隆太行山拱断束南段。属豫北—豫西铝土矿成矿区（Ⅲ级区带），渑池—鲁山矿集区、嵩箕矿集区和南太行矿集区（IV级区带）。研究矿床地质特征、总结成矿规律、探讨矿床成因，对于成矿预测、找矿潜力评价和矿产开发利用至关重要。依托中国矿产地质志项目，重点对河南省铝土矿床的地质特征及成矿规律进行了研究。结果表明：①本溪组（C2b）为铝土矿的赋矿地层，含矿1~4层；有主矿一层，呈层状—似层状、透镜状和漏斗状，结构简单， “无矿天窗”和夹石少。②矿石自然类型为碎屑状铝土矿、豆鲕状铝土矿和层状铝土矿等，反映出有机械沉积和胶体化学沉积两种沉积方式。③矿石矿物为一水硬铝石，黏土矿物主要为高岭石和伊利石，其他矿物少量至微量。④矿石总体具有高铝、高硅、低铁、低硫的特点，伴生有Ga、Li及稀土元素。⑤铝土矿成矿规律可描述为，矿床在大地构造位置上均处于华北陆块南缘；矿床类型均为与古风化壳有关的海相沉积矿床，成矿时代均为晚石炭世；矿床均分布于古陆（岛）边部的潮间带—滨浅海环境；下伏地层均为寒武系或奥陶系碳酸盐岩，且岩溶漏斗发育的地带有利于优质铝土矿形成；铝土矿常与耐火黏土矿、山西式铁矿等共生，但与共生矿床规模多表现为负相关。

Geological Characteristics and Metallogenic Regularity of Bauxite Deposits in Henan Province

The bauxite resources are abundant in Henan Province， and its identified resource reserves rank second in China. The metallogenic area is tectonically located in the middle and western sections of Mianchi-Queshan collapsed fold fault bundle in Huaxiong platform marginal depression， the southern section of Taihangshan arch fault bundle of Songji and Shanxi platform uplifts in the southern margin of the North China Block. It belongs to northern and western Henan bauxite metallogenic area （grade III area）， Mianchi-Lushan， Songji and South Taihang ore concentration areas （grade IV area）. Based on the project of China Mineral Resources Geology，the geological characteristics of bauxite deposits in Henan Province was studied，and its metallogenic regularities and discussed the genesis were summarized. The study showed that:①the ore-host stratum is Benxi Formation （C2b）， which contains 1~4 ore-bearing layers， among of which there is one main layer with simple structures of bedded， lenticular， or funnel-shaped， and less “non-ore skylight” or gangue. ②The natural types of the bauxite ore are clastic， bean oolitic and layered， indicating mechanical and colloidal chemical deposition. ③The ore mineral is diaspore and the clay minerals are mainly kaolinite and illite， with minor to trace other minerals.④ The ore is generally characterized by high-aluminum， high silicon， low iron and low sulfur， accompanied with Ga， Li and rare earth elements. ⑤ The metallogenic regularity of bauxite deposit can be described as that all the bauxite deposits are the marine facies deposits related with Late Carboniferous paleo-weathering crust， tectonically located on the southern margin of the North China continental block， distributing along the intertidal zone-beach or shallow sea belt of the paleo-continent （island）. Underlying strata are Cambrian or Ordovician carbonate rocks， and the well-developed karst funnel is conducive to the high quality bauxite mineralization. The coexistence of bauxite with refractory clay ore， Shanxi-style iron ore and pyrites is usually found， but their deposits scales are often negatively correlated.