Distribution of Late Carboniferous Bauxite Deposits in Western Henan, China
|School||Chinese Geology University (Beijing)|
|Course||Mineralogy,petrology, Mineral Deposit Geology|
|Keywords||bauxite deposit distribution ore-forming process multifract|
About1billion tons of bauxite has been explored in Western Henan. However the spatial distribution of orebodies, ore-forming process and ore-forming environment are not well understandable so far. Via a statistical approach on a collected in excess of2000drillcores, this paper aims to show the distribution of bauxite deposits, the statistical and spatial distribution of the orebody parameters and the controls of the physical parameters on the chemical content discussed.The orebody thickness is determined by two factors, the supply capacity and the weathering karst topography. So is there a supply difference between the deposits in the same district. Then the largest thickness in the less supply should be smaller than the smallest thickness in the deposit with more supply condition. The situation is not observed in all the deposits in the studied area. Besides, the great variance in such small area, i.e. in a single deposit, disapproved the orebody thickness is controlled by the material supply difference. This implies that the main controls on the thickness distribution are mainly the paleo-karst topography in this area. Thus the distribution can basically reflect the topographic information.The raw material supply for the bauxite in situ formation is adequate. The thickness and quality of bauxite orebody in West Henan is controlled both by the karst topography and local physicochemical conditions. From a view of whole west Henan, the greater the orebody thickness, the higher quality the bauxite ores, The thicker orebody is more preferentially contained in the deeper depressions. The diaspore is formed in an acid situation. The higher quality of bauxite, i.e., high diaspore content means a stable acid environment. The deeper one provides more suitable condition for AI2O3enrichment, more separation between the Al2O3-mineral (diaspore) and SiO2-minerals (clay), suggesting the deeper karst depression is more suitable to develop an acid condition facilitating the diaspore formation.The spatial change of orebody thickness and A/S value is random spatially, denoting a complex surface condition and environment. Nevertheless, the self-similar patterns of orebody thickness and A/S values are approximately analogue in various deposits, showing the ore-forming processes and mineralization intensity are consistent in the different area.