黔中-渝南沉积型铝土矿区域成矿模式及找矿模型

Regional metallogenic model and prospecting criteria of sedimentary bauxite deposits in Central Guizhou-Southern Chongqing region

黔中—渝南沉积型铝土矿的区域成矿模式概括如下:志留纪末的广西运动和泥盆纪末的紫云运动等,可能都是在峨眉地幔柱演化的壳幔相互作用阶段,因地幔柱向地壳大量输送物质和辐射能量,从而引发的地壳升降运动,在此期间,全区大面积抬升,形成长期隆起区;泥盆纪末准平原化;早石炭世岩关期气候湿热,暴露地表的早古生代岩石全面红土化、钙红土化,形成的含三水铝石红土风化壳物质,为沉积型铝土矿提供了物源。修文及息烽—遵义沉积区,于早石炭世大塘期早—中期沉积了铝土矿含矿岩系—九架炉组。绥阳—正安—道真沉积区,在晚石炭世的黄龙组石灰岩沉积并钙红土化之后,于马平期沉积了铝土矿含矿岩系的大竹园组。3个沉积区的铝土矿含矿岩系,都是在以陆相为主的环境中沉积形成的。在成岩阶段,铝土矿中的三水铝石逐渐变质为硬水铝石。由于各沉积区形成含三水铝石红土风化壳的母岩不同,由此沉积而成的铝土矿及其含矿岩系,在化学成分和矿物成分上也就有所差异。

The metallogenic model and prospecting criteria of sedimentary bauxite deposits in Central Guizhou- South Chongqing region are summarized as follows： Guangxi movement took place at the end of the Silunian and Ziyun movement that occurred at the last stage of the Devonian period, which might both have been in the crust-mantle interaction phase of the E＇mei mantle plume evolution. The transportation of a large amount of materials and radiation energy from the mantle plume to the crust led to the rise- and-fall movement of the earth＇s crust. During this period, large area of the region was uplifted, leading to the formation of the long-term uplifted area. At the end of the Devonian, the pediplanation occured. In the Early Carboniferous Yanguanian period, the climate was humid and rainy. Exposed surface rock in the Lower Paleozoic experienced laterization and calc- laterization. Laterite weathering crust with gibbsite provided sources for the sedimentary bauxite. In Xiuwen and Xifeng-Zunyi sedimentary areas, the bauxite-beating rock series of Jiujialu Formation formed at the Early Carboniferous Datang Stage. Suiyang-Zheng＇ an-Daozhen sedimentary area deposited bauxite ore-bearing rock series of the Dazhuyuan Formation in the Maping period which, after the formation of the limestone of the Late Carboniferous Huanglong Formation, generated cale-laterization. As the deposition region formed different parent rocks containing gibbsite-laterite weathering crust, the deposited bauxite ore-bearing rock series have different chemical and mineral compositions.