沉积型铝土矿及其含矿岩系在溶蚀洼地中的沉积特征——以遵义后槽矿区为例

位于遵义铝土矿带中部的后槽矿区,受NE-SW向岩溶盆地控制,溶盆内分布有众多形态各异的中、小型溶洼、溶坑和溶沟,在这些溶蚀洼地中,沉积了下石炭统九架炉组的铝土矿含矿岩系。其中主要有似泥石流沉积、沼泽、泥炭沼泽沉积和洪泛漫流沉积。似泥石流沉积物与沼泽、泥炭沼泽沉积物多次交替重叠,构成了多个沉积旋回,表明沉积环境发生过多次周期性变化。似泥石流沉积和洪泛漫流沉积,是形成铝土矿的主要沉积作用。洪泛漫流沉积形成的、覆盖全区所有溶蚀洼地的铝土矿体最为重要,称为"主流面状矿体"。"主流面状矿体"形成之后,本区原始的红土风化壳物质向九架炉组铝土矿含矿岩系沉积物的转变阶段即告终结。铝土矿含矿岩系的形成,主要是在各种溶蚀洼地中陆相复合沉积作用的结果。

Sedimentary characteristics of sedimentary bauxite and ore-bearing rock series in corroded depression: A case study of the Houcao mining area in Zunyi

There are many medium and small karst depressions, karst pits and karst ditches with varied morphology in the NE-SW karst basin of the Houcao mining area in the middle of Zunyi bauxite belt. The bauxite-bearing rock series of Lower Carboniferous Jiujialu Formation was deposited in these corroded depressions. The sedimentary types were mainly debris flow-like deposition, swamp deposition, peat bog deposition and flooding sheetflood deposition. Sediments of these sedimentary types were alternatively deposited in multiple depositional cycles. This shows that the depositional environment changed repeatedly and periodically. Debris flow deposit and flooding sheetflood deposit seem to have been the main sedimentary types in the bauxite mineralization process. Bauxite orebodies were formed by flooding sheetflood deposition, called "mainstream planar orebodies", which constituted the main sedimentary type and covered all the corroded depressions in the mining area. After the formation of "mainstream planar orebodies", the conversion of the original laterite weathering crust material to the sediments of bauxite ore-bearing rock series in Jiujialu Formation drew to an end. The formation of bauxite-bearing rock series in corroded depressions was mainly affected by complex continental deposition.