黔中猫场铝土矿地球化学研究

Geochemistry of bauxite in the Maochang deposit,central Guizhou

猫场铝土矿位于黔中清镇—修文铝土矿区,矿体产于下石炭统九架炉组,上覆摆佐组白云岩,下伏中上寒武统娄山关群白云岩,矿床成因类型为古风化壳沉积型。为了探讨猫场铝土矿成矿环境和成矿物质来源,为猫场矿区乃至黔中地区铝土矿资源的开发利用提供基础研究资料,我们对矿区铝土矿、顶底板铝土岩或粘土岩及围岩白云岩进行了主量元素、微量元素和稀土元素地球化学研究。结果显示,矿石成分主要为Al_(2)O_(3)、SiO_(2)、Fe_(2)O_(3)和TiO_(2),含矿岩系富集Li、V、Ga、Sc、Nb、Ta、Th、Hf、Zr、Y和REE等微量元素。微量元素含量和比值(Th、Sr/Ba、Th/U)分析表明,矿区铝土矿形成于海陆交替的沉积环境,以陆相沉积为主,成矿过程为氧化还原交替的沉积环境。通过稳定元素(Al_(2)O_(3)/TiO_(2)、Al_(2)O_(3)/Zr、TiO_(2)/Nb、Zr/Nb、Zr/Ta、Zr/Hf和Ta/Nb)相关性分析和稀土球粒陨石标准化配分模式判断,矿区物源可能为下伏中上寒武统娄山关群白云岩。

The Maochang bauxite deposit is located in the Xiuwen-Qingzhen area,central Guizhou Province.The ore body lies in the Lower Carboniferous Jiujialu Formation,under the dolomite of the Lower Carboniferous Baizuo Formation,and above the dolomite of the Middle-Upper Cambrian Loushanguan Formation.The genetic type of the deposit is an ancient weathering crust depositional type.The geochemical characteristics of major elements,trace elements and rare earth elements in bauxite,bauxitic clay and dolomite were studied.The results show that the bauxite is mainly composed of Al_(2)O_(3),SiO_(2),Fe_(2)O_(3) and TiO_(2),whereas the ore-bearing rock series are rich in trace elements such as Li,V,Ga,Sc,Nb,Ta,Th,Hf,Zr,Y and rare earth elements.The content and ratios of sensitive elements(Th,Sr/Ba,Th/U)indicate that the Maochang bauxite deposit was mainly formed in a land-sea interactive setting dominated by continental sedimentary setting,and the ore-forming process was mainly an alternating redox setting.The correlation of stable elements(Al_(2)O_(3)/TiO_(2),Al_(2)O_(3)/Zr,TiO_(2)/Nb,Zr/Nb,Zr/Ta,Zr/Hf and Ta/Nb)and the chondrite-normalized REE pattern were used to discuss that the materials of ore-forming could be sourced from the dolomite of the Middle-Upper Cambrian Loushanguan Formation.