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.