河南新安县郁山铝土矿床地质特征、成矿规律及成矿物质来源

Geological Characteristics,Metallogenic Regularity,Sources of Ore-Forming Material of the Bauxite District,Yushan,Xin′an,Henan Province

河南郁山铝土矿区包括郁山、李村、杏树洼、煤窑洼4个铝土矿段。本溪组含铝岩系的分布、埋深及岩相特征直接控制铝土矿的赋存和空间特征。区内构造对含矿岩系的分布、产状、埋深及完整性等有重要的控制作用。含铝岩系厚度与铝土矿厚度及品位一般呈正变关系,即含铝岩系厚度大,铝土矿层厚而富。铝土矿物沉积于古地形中,大的凹陷沉积盆地控制着铝土矿带的分布范围和展布方向,其中小的洼地、溶洞、溶斗等具体控制铝土矿的矿体形态、产状、规模。河南郁山铝土矿为典型的喀斯特型铝土矿。铝土矿成矿物质均来自上地壳,为上地壳岩石经过风化而成,非花岗岩以及玄武岩等岩石类型;铝土矿物质来源与基底碳酸盐岩关系不大,具有一定距离的搬运,说明铝土矿物质来源非原地,而是异地来源;秦岭古陆提供了重要成矿物质。

Yushan bauxite district in Henan Province consists of Yushan deposit, Licun deposit, Xingshuwa deposit and Meiyaowa deposit. Distribution, depth and rock features of aluminum-containing rocks of Benxi Formation directly control the bauxite occurrence and spatial characteristics. The distribution, occurrence, depth and integrity of ore-bearing rock are controlled by tectonics in this district. There is a positive correlation between the thickness of the aluminum-containing rocks and thickness plus grade of bauxite, namely, the bauxite is thicker and richer while the thickness of the aluminum-containing rocks is bigger. Bauxite minerals were deposited in the ancient terrain, large sunken sedimentary basin dominated the distribution range and trend of bauxite belt, whereas, the shape, the occurrence and the scale of the bauxite ore bodies were restrained by small depressions, caverns, doline funnel and the like. The Yushan bauxite deposits are typically karst-type deposit. All ore-forming material comes from the weathering of the upper crust such as non-granitoid and basalt. Bauxite materials being transited for a distance suggests that bauxite material sources are not highly correlated to basement carbonate rocks and exterior instead of in situ. Qinling ancient land may be an important source for the ore-forming matter.