Study On Geochemistry Characteristics Of Rongxiang Bauxite Deposit In Qingzhen,Guizhou Province

Bauxite is one of the most scarce mineral resources in China.In recent ten years,the consumption of bauxite is high in the world.In 2016,52.0534 million tons of bauxite was imported,and the demand for aluminum resources is still very high.In terms of the reserves of aluminum resources,China is the second largest country after Australia.The two countries account for about half of the world's reserves.The contradiction between supply and demand of resources is prominent,which affects the safety of national aluminum resources and the sustainable development of aluminum industry.Therefore,to perfect the ore forming theory and to realize the breakthrough of prospecting is very urgent.The Rongxiang bauxite deposit in Qingzhen,Guizhou Province,located in the southern margin of the Yangtze block is an important part of the bauxite forming belt in Yunan-Qianzhong(Yunan refers to the southern part of Chongqing and Qianzhong refers to the center of Guizhou).The ore-forming conditions are superior,but the degree of study on the genesis and forming regularity of the deposit is low,and the ore-prospecting effect is not ideal.On the basis of summarizing the previous research results,this paper discusses the ore forming geological conditions,environment of bauxite and source of ore-forming materials through systematic studies on mineralogy,ore deposit geology and ore deposit geochemistry.The formation process of the ore deposit is revealed,which has some instructive significance for finding similar sedimentary bauxite deposits in the future.Through the above work,this paper has obtained the following understanding and conclusion:1.The ore body is deposited in the nine furnace formation under the carboniferous system and is stratified.The structure of ore mainly consists of grain-mud structure,mud-grain structure,mud-grain-microcrystalline structure and so on.The ore structure includes soil-shaped,semi-soil-like,clastic and compact structure,but the oolitic structure is rare.The quality of ore is best in clastic structure,followed by soil and semi-soil structure,and oolitic structure is the worst.2.The geochemical characteristics of principal elements,trace elements and rare earth elements are studied.The results show that the ore-bearing beds are closely related to the underlying strata,but not to the dolomite of the baizuo formation.Itindicates that the deposit of bauxite series is mainly formed in the continental environment.During the ore forming of bauxite in this area,the main components Al,Si and Fe are provided by the calcareous laterite and lateritization of the floor rock of the continental and ore-bearing rock series,as well as the terrestrial source.3.The formation time is determined by stratigraphic factors,and the formation of orebody is restricted by lithofacies and paleogeography.The shallow lake facies is favorable environment for ore forming.The distribution and lithologic assemblage of bauxite are strictly restricted by tectonic location and paleogeomorphology.4.The Rongxiang bauxite deposit belongs to the sedimentary type of paleo-weathering crust,which is the "initial enrichment" formed by the lateritization of the carbonate rocks in the basement,and then settled by microchip and colloidal chemistry after being transformed by hydrolysis.The deposit of bauxite in karst basin is mainly formed by kaolinite through desilication,and then after diagenesis period to weathering and leaching,rich to form high grade bauxite.The ore deposit is formed because the paleo-weathering crust has repeatedly deposited and reformed the deposit.