Study On Provenance, Sedimentary Facies And Geomorphology Of Pingguo Primary Bauxite In Guangxi

Previous investigations of provenance, sedimentary facies and geomorphology in primary bauxite of Pingguo don’t reveal the differences between different areas in Pingguo Mine, the patterns and evolutions of edimentary facies and geomorphology. The studies of provenance, sedimentary facies and geomorphology are significant for understanding mineralization mechanism and metallogenic prediction in primary bauxite of Pingguo.Based on the regional geological and geochemical background, the author carried out the research on field survey, cores observations, thin sections analyses, heavy minerals analyses, main elements and REE analyses, studied on variety of provenance, direction of ore-forming material transportation, patterns and evolutions of sedimentary facies and geomorphology, and sedimentary microfacie of Al enrichment. Some new understandings as follows:1. Variety of provenance and direction of ore-forming material transportation:Pingguo primary bauxite mineralized in Guizhou-Guangxi continental basin which was surrounded of magmatic rocks and metamorphic rocks what are the provenances of Pingguo primary bauxite. There is a large number of zircons in Pingguo primary bauxite ore, and the content of magmatic zircons is more than metamorphic zircons in primary bauxite ore of Pingguo. It indicates that the provenances of primary bauxite are diversiform, and predominantly magmatic with secondarily metamorphic rocks. The distribution patterns of the heavy minerals indicate that the ore-forming material in Guohua-Nadou Mine and Xin’an Mine were from SW to SE, in Taiping Mine from NW to SE, and the ore-forming materials transported for a relatively short distance.2. Patterns and evolutions of sedimentary facies:Based on the field survey, cores observations and thin sections analyses, the ore bearing formations can be divided into muddy, silty, sandy bauxite ore, shale and coal with differents components, structures, characteristics of REE. They are hallmarks of prodelta facies, delta front facies, delta plain facies(dam microfacies), delta plain facies(peat plains microfacies). The distribution patterns of these sedimentary subfacies indicates that Guohua-Xin’an-Nadou Mine and Jiaomei-Taiping Mine Belong to two different delta sedimentary systems, Yalang is prodelta, southwest(Guohua area), northwest(Baning area) and north(Dingjiangnan area) of Pingguo Mine are delta plains. In the process of mineralization, the coastline gradually moved to southeast, Najia, Tongmian and Poyan village changes from prodelta facies into delta front facies, and finally into delta plain facies.3. Pattern of geomorphology:Transport of ore-forming material and patterns of sedimentary subfacies indicate that north(Dingjiangnan area) and southwest(Guohua area) of Pingguo Mine are more higher than the southeast Yalang area).4. Sedimentary microfacie of Al enrichment:The analysis based on grade data of Pingguo primary bauxite and sedimentary microfacies shows that dam microfacie is the most conducive to the enrichment of Al, and its Al/Si is the most.5. The method of restoration palaeogeomorphology:It is feasible and effective that through an integrated provenance, direction of ore-forming material transportation and patterns of sedimentary facies of sediments to restore the palaeogeomorphology.