黔中黑土田铝土矿床矿石矿物特征与成矿机制

摘要

黑土田铝土矿赋存于下石炭统九架炉组粘土岩、页岩中，矿石自然类型有碎屑状、致密状、土状3种，主要矿物有一水硬铝石、高岭石、白云母等。包括黑土田在内的黔中铝土矿床其成因：（1）致密块状铝土矿是地壳下降后，海水入侵，大量红土物质发生沉积成岩成矿的产物。（2）碎屑状铝土矿的形成可分为两种：一是在源岩中先形成的铝土矿（岩）在地壳短暂抬升期遭受风化剥蚀再分异沉积的产物；二是在大量红土物质发生沉积成岩成矿后，地壳上升海水退去后，经风化剥蚀残留下来的铝土矿。（3）土状铝土矿是在地壳再次上升，海水退去，沉积的铝土矿（岩）进一步遭受风化淋滤作用的产物。本矿区内矿石组合序列的多样性，是多次海进海退使红土化物质和先存铝土矿发生分异沉积成岩成矿的结果。%Heitutian bauxite deposit occurred in Jiujialu Formation of lower Carboniferous.The host rocks are claystone and shale.The ore types include clastic,dense massive and earthy aggregates.The main minerals are diasporite,kaolinite,muscovite etc.Ore genesis of bauxite deposit in central Guizhou can be summarized as followsing:(1 )Dense massive bauxite were formed by diagenesis of laterite after seawater invasion by crust subsidence.(2 ) Clastic bauxite,product of depositional fractionation of eroded preexisting bauxite during short-lived crust uplift,were weathering residue of bauxite which formed by diagenesis of laterite.(3 )The earthy bauxite are product of latest weathering and leaching of sedimentary bauxite in crust uplift again.The di-versity of ore combination sequences in this region can attribute to repeatedly sedimentary differentiation of later-ite and preexisting bauxite by several regression and transgression.