The Geochemistry And Sediment Environment Of Phosphate Deposits In Sinian System, Guizhou Province

Agricultural practices have proved that appropriate chemical fertilizers are the key in guaranteeing food production which demands not only the area under cultivation, but also fertilizer supply. Ministry of Agriculture's "948 "project predict that china will demand 11-12(106)tons of phosphate which requests 43-47(106) tons of phosphorite. It means that in the next 50 years the total of 18-20(108) tons of phosphorite will be requested. This high demand of phosphorite led to the dependence of mid-low grade phosphorite . based on distribution of phosphorite, the eastern and northern china have a limited supply of this resource ,additional phosphorite and phosphate fertilizer are forced to purchase. Some exports suggested that related department guide in production, storage and transportation to ensure timely requirement of fertilizer.On the basis of research and analysis in depositional environment forming phosphorite and geochemistry in Guizhou and Hubei region and the mineralization section in Kaiyang illustrates sedimentary rhythm of phosphate mine attributing to periodic transgression : massive bedding strata indicates subtidal deposit; thin bedding strata shows intertidal deposit; mud pellet bedding displays supratidal sedimentary. There are 5 transgressive and regressive sequences in each ore horizon.This tidal flat sedimentary environment is proved by sedimentary structure: scour mark, cross bedding, lenticular bedding, parallel bedding and wave bedding.The main research includes deposit types and distribution characteristics in Guizhou in sinian: the rock constituents, geochemical characteristics and size characteristics .Through identification of minerals , mineral composition is mainly for granular cellophane which is fluo calcium phosphase. according to analysis of chemical composition, its (CaO)7.6(P2O5)2.5(CaF2)0.9; and fluo apatite standard oxide molecular formulas are (CaO)9(CaF2)3(P2O5)1, more higher calcirm fluoride, (P2O5) slightly lower than the standard molecular formula. mineral composition is secondly for veined fill cellophane. Microscopically, it shows homogeneous mineral and zonal structure; Cellophane particles present layer and the massive structure. bearing phosphorus layer is marginal deposit in view of its surrounding rock which is high magnesian dolimite and rock chemicographic examining steady marginal deposit.