| As one of the dominant minerals in Yunnan province,phosphate ore is the basic raw material for the development of phosphorus chemical industry and the production of phosphate fertilizer.However,excessive exploration has already led to a rapid decline in the phosphate ore resource in Yunnan province.At present,prospecting for phosphate ores plays an important role in the exploration,mining and processing of the phosphate ore resource in Yunnan province.The study area lies between the Dongchuan and Xundian country,Kunming.An important copper reserve is developed in the adjacent area.Due to the depletion of copper resource,the Dongchuan mining bureau declares bankruptcy,as a result,the Dongchuan city faces with many development problems.At present,although the circumstance is improved,but the situation is still very grim.Phosphate ore resource is widely distributed in the study area,but in most cases engineers paid no attention to this because of the copper exploration of Kunyang.As a result,the research relevant to phosphate ore resource is lacking and the exploration-degree is low.However,so it is necessary to carry out exploration for phosphate ore resource in this area.This paper is based mainly on the program of phosphate ore resource exploration in Bailongtan,Xundian.For the purpose of providing thoughts for future mineral exploration,we take phosphate deposits in Heishan-Bailongtan which mainly formed in Meishicun group,early Precambrian as example,and combine the earlier and present relevant research results to study the characteristics of deposits and phosphate ores.Achievements and cognitions obtained in this Paper are as follows:(1)The phosphate deposits in the study area are mainly ancient marine stratiform phosphorite deposits.Phosphorite bearing strata in early Cambrian directly overlies the strata in late Sinian,which consists mainly of carbonate rocks,phosphate rocks and siliceous rocks.According to the study on P-bearing characteristics,siliceous rocks and the small shell fossil assemblage of the strata in regions,we suggest that the Xiaowaitoushan,Zhongyicun and Dahai members in the early Precambrian Meishicun group are the main P-bearing strata.(2)Based on the research on phosphate ore characteristic in the study area,the main minerals are cellophane and apatite with clastic structure,oolitic structure,bone chip structure,massi-ve structure and banded structure.The main rock types are siliceous phosphorite,massive phosphorite and banded phosphorite.(3)Field research on the ore bodies reveals the characteristics of the ore bed and its top and bottom.Combining with the research on ore weathering/oxidation feature,we clarify the ore-controlling factors,metallogenic regularity and spatial characteristics of the main ore beds.Finally,we establish indicators for phosphate ore exploration.(4)On the basis of geochemistry characteristics of phosphate deposits,we summarize the geochemistry characteristics of the study area,which appears to be that the chemical compositions of the phosphate deposits are simple,and there is some variation in the characteristics of main elements with certain regularity.(5)Metallogenic regularity is summarized through the investigation of regional metallogenic characteristics,ore-controlling factors,sedimentary facies characteristics,P-bearing rock formation characteristics,and geology and geochemistry characteristics of the phosphate deposits.(6)The rocks in the strata can be regarded as indicator for the P prospecting area,and alteration associated with mineralization and secondary changes as direct and indirect prospecting indicators for the phosphate deposits,respectively.(7)We preliminary study the P prospecting areas including the distribution regularity and characteristics of ore-bearing horizons,which are similar to those of this region.The P-bearing rock formations have great resource potential,and strongly mineralized,thick and stably extend phosphate ore formations occurs.Further work is worthy to be carried out. |
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