Study On Sinian Phosphorus Ore Type And Sedimentary Environment In Wengfu Area,Guizhou

Guided by the theories of modern sedimentary geology and deposit geology,based on the systematic collection of basic geology and phosphate exploration results in the study area,supplemented by field geological survey and sampling test,and with the solution of key problems as the main research content,this study aims to solve the main ore types,metallogenic geological processes,sedimentary paleogeographic conditions,metallogenic laws and to delineate the prospecting target area.Through the research,the following knowledge and conclusions are obtained:Wengfu Phosphate Mine is located in the middle of Guizhou Province,about 20 km long from south to North and 3.8 km wide from east to west.The area is distributed on the Baiyan-Gaoping anticline in the near north-south direction.In recent years,all kinds of exploration have been carried out,and the total amount of various types of phosphate resources has been proved to be nearly 4 billion tons,which has become a world-class giant phosphate deposit.This paper mainly divides the structural and genetic types of phosphorite in the study area.On the basis of previous studies,it makes a more detailed and theoretical division.Because of the complex structure and various types of phosphorites in Wengfu area,their genesis and sedimentary environment are different.Based on the analysis of this study,combined with the former scholars' classification principle of genetic type of phosphorite,the phosphorite in Wengfu area is preliminarily divided into two types: primary sedimentary genesis and reconstructed sedimentary genesis.Among them,the primary sedimentary phosphorites include biochemically sedimentary phosphorites(banded sand detritus phosphorites,carbonaceous argillaceous phosphorites)and biogenetic phosphorites with fossils(multicellular algal phosphorites,biospheric phosphorites).The reconstructed phosphorites are mainly intraclast phosphorites.The phosphorus accumulation events in Doushantuo period are closely related to the paleogeographic environment and sea level rise and fall in Central Guizhou.The phosphorus coastal environment in Wengfu area provides favorable paleogeographic conditions for the enrichment,deposition and mineralization of phosphorus.The Doushantuo period in Wengfu area is located in the northeast margin of the middle ancient land of Guizhou Province,which connects the Yangtze platform and the open sea in the northeast.The Neoproterozoic global ice age made the deep sea water rich in phosphorus.After the ice age,the rising ocean current carried the phosphorus rich sea water into the shallow water transparent layer,and further enriched the phosphorus under the influence of biological action,which provided a rich source of ore-forming materials for the deposition of phosphorus ore.The frequent sea level fluctuation in Doushantuo period made the phosphorus ore exposed,leached,scoured,reconsolidated and redeposited for many times,and influenced by the further ore enrichment in the later period,forming a phosphorus deposit with large thickness and high grade.Based on the comprehensive analysis of various types of phosphate rocks in Wengfu area,the paper studies the ore-forming source,geological characteristics and sedimentary paleogeographic characteristics of Wengfu phosphate rock as a whole,explains the mineralization and geological conditions of phosphate rock,delineates the dominant metallogenic belt,and provides a theoretical basis for prospecting.