Metallogenic Geochemistry Study Of The Mn Deposit In Hougou-Dapingshan In Mianxian, Shanxi Province

The Hougou-Dapingshan three manganese (Mn) and phosphor (P) metallogenic belts, located in the middle east segment of the South Qinling Mn- P metallogenic zone, have been founded recently. The regional 3 high quality Mn orebodies are associated with carbonaceous argillaceous rock-carbonatite formation of Tananpo Formation ( Lower Cambrain), belonging to Mn deposit of sea facies sedimentary metamorphic/ reconstructed type.On survey of geology and ore deposits, the Hougou-Dapingshan manganese ore district, systematic sampling, microscopic observation, XRD and geochemical analyses have been conducted. Results were used to constrain formation of manganese deposits and the metallogenic forming condition. The controlling processing of high quality Mn ores are studied and presented, the prospecting indications for manganese deposits have been proposed and constrained. The conlcusions are as follow:1. The values of MnO/TiO2, Al/(Al+Fe+Mn), U/Th together with the discriminant diagrams of Na (Wt%) vs Mg(Wt%), Si(Wt%) vs Al(Wt%), Al-Fe-Mn, F2 vs F1 and lgw(U) vs lgw(Th) comprehensive analysis show that the Mn and P bearing ores were formed in the ocean hydrothermal sedimentary environment. Meanwhile the wall rocks were formed in a marginal marine sedimentary environment, sediments were maily derived from continent. The carbonaceous rocks had a close relationship with the Mn/P bearing ore formation.2. The trace element spider diagrams show that Mn bearing ores and wall rocks are depletion in Rb, K, Pb , and enrichments in Ba, U, Sr and the REE, these enrichments are more than average continental values. TheΣREE of samples varied from 24.26 ppm to 602.74 ppm with an average of 192.02 ppm. The LREE is much enrichments compared with thos of HREE. Apart from two samples, the value of LREE/HREE is greater than 1, varying from 0.41 to 18.27 with an average of 7.18. In the NASC Normalized REE patterns, both Mn bearing ores and wall rocks show nearly flat pattern distributions. Most samples show strong positive anomalies in Dy.3. The values of V/(V+Ni) vary from 0.45 to 0.99 with an average of 0.73, indicating that samples were formed in the anaerobic environment with features of ordinary stratified water bodies and a changed water depth and reduction. The values ofδU vary from 1.06 to 2.0 with an average of 1.46, indicating a anoxic sedimentary environment. It is inferred that Mn bearing rocks were formed in anoxic(reduction) sedimentary environment with stratified water bodies.4. The Mn metallogenic process has evident feature of basin-controlling, schistosity-controlling and single lithology. High quality Mn ores were controlled by Mn and P sediments and Mn metallogenic seam existing in the P metallogenic seam. Manganese limestone (including dolomite limestone) and pyritic charry schist are proposed as prospecting indications in this region.