摘要
河南铝土矿为上古生界石炭系本溪组的G层铝土矿,分布在三门峡—郑州—平顶山这个三角地带。底板为中奥陶统马家沟组或上寒武统的碳酸盐岩,为一水硬铝石型铝土矿床。化学成分以高铝、高硅、低铁、中低铝硅比为特征。全省平均Al2O365.28%,SiO211.57%,Fe2O34.14%,铝硅比5.64。总体上讲,化学成分比较稳定,(Al2O3+SiO2+Fe2O3)一般为80%~82%,铝土矿的形成明显受岩溶古地形的控制,矿体厚度变化很大。全省平均含铝岩系厚11.42m,铝土矿厚3.83m;但含铝岩系最大厚度为68.34m,铝土矿最大厚度为57.95m。溶斗中的厚大矿体一般铝硅比较高。在铝土矿的地质特征作了分区描述后,对铝土矿成矿地质条件,含铝岩系特征,矿床地质特征和铝土矿形成的岩相古地理环境做了总结归纳,并建立了成矿模式。作者认为:要把“G层”铝土矿归结为由某一种方式形成的意见是不可取的。铝土矿的成矿作用是多种多样的,既有残留下来的红土风化壳型,也有钙红土-沉积型、浊流堆积型和胶体化学沉积型。以钙红土-沉积型为主;钙红土风化壳形成之后,受到破坏经过短距离搬运再沉积下来。浊流堆积是钙红土-沉积型的一种特殊类型,胶体化学?
Henan bauxite, which belongs to G layer bauxite of Benxi Formation,Carboniferous, Upper Paleozoic, developed in Sanmenxia Zhengzhou Pingdingshan triangle belt. The floor is composed of Majiagou Formation of Middle Ordovician or carbonates of Upper Cambrian. They are monohydro diaspore type bauxite deposits, characterized by high Al,high Si, low Fe and mid low Al/Si ratio.In average, Al 2O 3 is 65 28%, SiO 2 11 57%,Fe 2O 3 4 14%,and Al/Si 5 64.In general,the chemical composition is stable.Al 2O 3+SiO 2+Fe 2O 3 is generally 80% ̄82%.The formation of bauxite is apparently controlled by the karst paleo topography.The thickness has big range. The average thickness of bauxite bearing series is 11 42 m and that of bauxite 3 83 m.The former has largest thickness 68 34 m and the latter 57 95 m.The thick ore body in cave has higher Al/Si ratio.The metallogenic model was established on the basis of geological division of bauxite. The author suggests that the metallogeny of bauxite is complicated. The deposits range from residual lateral weathered mantle type and terra rossa sedimentary type and alluvial accumulated type to colloid chemical deposit type. They are dominated by the terra rossa sedimentary type. After the formation of terra rossa weathered mantle, the materials were interupted and redeposited after a short distance transportation. The alluvial accumulated type is considered a special type of terra rossa sedimentary type. The colloid deposit is formed by the sedimentation in the deeper part of front water body of terra rossa sedimentary type. The source materials are from the weathered products of the above mentioned two kinds of rocks rather than the simple alumino silicates of paleo land or carbonates of basement. In general,basement carbonates are the main components though there is difference between different mining areas. The analysis of large materials suggest secondary ore enrichment plays an important role in the formation of rich ore bodies of bauxite and the structure geotopography unit where bauxite layers dipping gently and consistantly with geotopography is the favourable place for the formation of rich ore bodies, but that dose not mean that there is impossible for the existence of primary ore shoot.
关键词
铝土矿
铝矿床
地质特征
石炭纪
bauxite, genesis of deposit,metallogenic model,Carboniferous,Henan