陕西省渭北铝土矿地质特征及找矿前景分析

Geological Characteristics and Prospecting Perspective of Weibei Bauxite Deposits,Shaanxi Province

渭北铝土矿带是陕西省两大铝土矿带之一。矿床产于下古生界碳酸盐岩不整合面上,为岩溶型铝土矿。矿体形态有似层状、透镜状和漏斗状,空间展布严格受基底古岩溶地形的控制。矿石类型属于一水硬铝石型铝矿,主要呈碎屑状、豆鲕状和泥状结构,致密块状和层状构造。矿石主要化学成分有:Al2O3、SiO2、Fe2O3、TiO2,Al2O3平均含量为55.05%～64.97%,SiO2平均含量为12.44%～15.16%,A/S平均为3.63～5.22。矿床受沉积间断、古气候、古纬度和古地形等因素控制。与我国主要铝土矿成矿区——河南、山西相类比,渭北地区具有相似的成矿地质和古气候条件,找矿前景较好,但以低品位矿石为主。

Weibei bauxite belt is one of the two biggest bauxite belts in Shaanxi province.These deposits lying on the top of unconformity surface of Lower Paleozoic carbonate rocks are karst type bauxite deposits.Strictly controlled by basal ancient karst landform,the ore bodies generally show a stratiform-like,lenticular,and funnel-shaped pattern.The ore type is diasporic bauxite,mainly showing the clast,oolith,mud textures,and having a compact mass and stratiform structure.The main chemical compositions include Al2O3,SiO2,Fe2O3 and TiO2,with the average content of Al2O3 being 55.05%-64.97%,SiO2 12.44%-15.16%,and a A/S ratio of 3.63-5.22.The ore bodies are mainly controlled by hiatus,paleoclimate,paleolatitude,ancient landform,and so forth.Compared with the bauxite deposits in Henan and Shanxi provinces in which the bauxite ore bodies are mainly deposited,Weibei area has similar metallogenic geology and climate conditions,so it has a great prospecting perspective in Weibei area for exploring bauxite deposits,although the grade is somewhat low.