| Guizhou bauxite is one of main minerals, concentrated in central-North of Guizhou Province. In recent years, in the Wu-Zheng-Dao area of north-Guizhou, geological exploration units carryed out comprehensive exploration, bauxite prospecting maded a major breakthrough. Had beening proven in large-scale, more than 10 large bauxite deposits.resource reserves of over 700 million tons.Among them, Daozhen-Xinmin bauxite deposit is one of the large deposits recently verified,The position of ore-bearing was the middle Permian Liangshan Formation,ore bodies produced in the lower middle Silurian Hanjiadian Formation mudstone or upper on the Carboniferous limestone erosion surface.The genetic type of the deposit belongs to the paleo weathering crust typical sedimentary ore deposit.From 2007 to 2011, the implementation of the ore deposit study, survey, detailed survey, the prospecting units mainly around the ore body spatial distribution and work for delineating resource, the main ore-controlling factors of the ore deposits, metallogenic regularities and ore mineralogy characteristics, deposits and roof and floor rocks, the element migration and enrichment regularity is lack of system researching,the current literature published only JIN zhongguo and Mo guangyuan (2013) on the ore-forming geological background, geological characteristics of Xinmin bauxite made preliminary analysis.In this paper, through a lot of field geological investigation, exploratory trench and drill core detailed observations, surface exposed in ore-bearing recourse, system integration of data sampling test, indoor arrangement,in order to comprehensively summarizes the metallogenic regularities and the main ore-controlling factors,revealing major and trace elements element in the migration and accumulation mechanism of sedimentary diagenesis,establishmenting the geochemical evolution model of ore deposits and prospecting research demonstration effect for the adjacent area.Obtained through the study of the following main results and awareness:(1) In the study area,from the Cambrian in Middle Upper to Jurassic Stratigraphic have developed completely. Among them, Middle Permian Liangshan Strata is the oriferous layer position.The Xinmin mining area, Ore-bearing rock series from top to bottom is divided roughly into three sections:upper, middle and lower section. The upper is a thin layer of gray-black-containing carbonaceous mudstone, shale, and thickness range of that is 0.3 m～1m,which is direct roof of seam. The middle is bauxite layer, compositing from light gray-gray bauxite (rock),and thickness range of that is 0.2～2.5m,which is the main ore occurrence segment, orebody layered,stratiform lenticular output. The lower section is gray-green, green chlorite, sometimes bauxite mixed green mudstone containing iron and direct bottom of seam.(2) Within the mining area, earthy-semi earthy structure, clastic structure, oolitic-bean oolitic structure mainly distributed in surface and shallow, compact shape structure mainly distributed in deep underground, ores of earthy-semi earthy and clastic structure produced in the fault structure developed zone. Ore structure is mainly beans oolitic structure, clastic structure, micro-clay crystal structure etc. Based on the ore structure, the structure characteristic and unify study to the decessorpre, Xinmin bauxite ore is divided into pisolitic bauxite, earthy-semi earthy bauxite, clastic bauxite, dense block four of the natural type bauxite. Sulfur content of ore ranged at 0.10%～7.00%, mean of that generally was less than 0.30%,iron content of ore ranged at 1.20%-26.00%, mainly ranged at 7% to 9%. Industrial type belongs to low iron sulfur type (44% of the total ore), containing iron low sulfur type (35.2 44% of the total ore) and middle iron low sulfur type (13.7% of the total ore).The sum of those types is 93.4%. Ore mineral composition mainly has diaspore, soft aluminum stone, kaolinite, in addition, little illite, chlorite, iron minerals, very small amount of quartz minerals.(3)Geochemical analysis showed that constant element mainly composed by Al3O2、SiO2 and Fe2O3、TiO2.There are differences in content between different ore samples. Al2O3 and TiO2 showed strong positive correlation. Al2O3 and SiO2 showed strong negative correlation. Al2O3 and Fe2O3 showed negative correlation. Ore sample enriched Gd、Li、Be、Sc、V、Cr、Ga ect. element. Slightly enriched elements of ore samples are Ba、Ni、Sr、Zn. Co is depleted element. Li,Ge and Ga have had a higher degree of enrichment in orebody, enrichment factor was respectively 36.60,5.97and 3.06. In the ore-bearing rock series,different space trace element enrichment patterns has different apparent behavior. There are some elements exhibit both lossed and enriched, the bottom seam richest REE, REE overall performanly have enricher LREE enrichment over HREE enrichment.Between light and heavy elements have had obvious fractionation, Ce of ore shows positive anomaly exception, Eu of ore shows negative anomaly exception.(4)Through stable element ratio, REE distribution patterns, provenance instruction sresearch thinking that Hanjiadian Stratum mudstone provided main source for Xinmin bauxite. By discussing the formation of sedimentary evolution of bauxite and discussing activity patterns of geochemical elements during the formation of bauxite. Geological and geochemical evolution model had been established,which of that is from mother rock (Hanjiadian Stratum mudstone) to intermediates (bauxitic rock) then to formation of bauxite. |
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