Study On The Late Permian Sedimentary Palaeogeography And Mineralization Of Bauxite Ores In Tianshengqiao Mining Area, Wenshan County, Yunnan Province

Based on comprehensive analyses of the data from outcrop, identification of rockslices and geochemical characteristics, this paper mainly studied the integratedstratigraphy, sedimentary palaeogeography, bauxite mineralization and metallogenicregularity，metallogenic prospects of bauxite. The main results as follows:1. High resolution stratigraphic framework of Tianshengqiao mining area,Wenshan County, in the major mineralization period, the Late Permian earlyWuchiaping period, was established by comprehensive studying of Petrology,Paleontology and Sequence stratigraphy.2. Through analyses of regional tectonic background and sedimentarycharacteristics, of mapping in terms of single factor analysis and multifactorcomprehensive theory, of integrating combination of rock types, and of verticalstratigraphic sequence and lateral facies changing, this paper divided the types ofsedimentary facies, draw the maps of lithofacies-paleogeography and depositionalsystem tracts, reestablished palaeogeographic pattern of Tianshengqiao mining area.Moreover, this study proposed that the sedimentary facies were coast facies andconfined shallow facies, including the sub-facies of marsh, tidal flat, the top ofconfined shallow sea, the bottom of confined shallow sea, and the micro-facies ofsupratidal zone, intertidal zone, subtidal zone, lagoon and uplift.3. This paper presented the sedimentary setting of Tianshengqiao area in theearly Wuchiapingian. This area was in low-energy muddy coast, which laid thefoundation for further in development of sedimentary facies model series, includinggentle slope low-energy muddy coast sedimentary facies mode, low-energy muddycoast sedimentary facies mode with depressions, and low-energy muddy coastsedimentary facies mode with uplifts.4. The paper emphasized that the relationship between sedimentarypalaeogeographic characteristics and metallogenic environment of bauxite, proposedthat the depositional environment formed in the intertidal zone to shallow sea,especially the subtidal zone and lagoon, which were beneficial to the formation of bauxites.5. The Tianshengqiao bauxite was a typical sedimentary deposit．The ore bodiesoccurred in the Longtan Formation of the Upper Permian．Studies of stable elementratios (such as Zr/Hf，Nb/Ta)，bivariate graph of lgNi and lgCr，and REE pattensuggested that the sources of bauxite deposits in this area came from differentmetallogenic materials. The basalt was one of the major sources of metallogenicmaterials for the bauxite formation. The carbonate rocks of the Upper Carboniferousand surrounding ancient kratons supposed to provide some of the material sources forthe bauxite as well.6. The main factors controlling the distribution of bauxite in the region weredepositional environment (facies control), the strata (stratum control) andmicrotopography (topography control). According to Bauxite ores isopleth maps ofthe highest and average grade by the actual data, this paper proposed the metallogenicprospect areas to support exploration and development by useful data.