Study On Genesis Of Calcite Deposit From Ziyun County,Guizhou Province,China

The Ziyun calcite ore in south of Qian,is a newly discovered nonmentallic deposit in recent years.Tectonic location of the studying area wasin the southwestern Upper Yangtze platformal fold belt of the Yangtze paraplatform,which is adjacent from Shuicheng-Ziyun-Nandan aulacogen and located intersection part of structuraldeformation area of Guiding south-north in the Platform Collapse of South Guizhou and structuraldeformation area of north-western in Wangmo.Because of the time when was discovered is short,the exploration and the study and the scientific research of this calcite ore is relatively low,which is in mapping stage of field geological.Therefore,on the basis of the collection study of the early geological work,and by calcite deposit for main line,extensive field investigation,combing with geochemical data,polarization microscope testing methods are used.Analyzing geological characteristics,mineral composition,texture and structure,element geochemistry,Carbon and oxygen isotope geochemistry,fluid geochemical characteristics of Ziyun calcite ore.We preliminary ananlyse controled causes and metallogenic mechanism and establishedMineralization pattern.The purpose is to provides the important of theory basis for prospecting work of calcite deposit and give calcite Ore-prospecting Prospect for superior mineralization area.The artical made some achievements as follows:(1)Through the analysis of investigation of field geological background,Ziyun calcite deposit exists Carboniferous in the Baizuo formation,Huanglong formation,Maping formation and Permian in the Qixia formation,Maokou formation.Orebody were filled in the fracture structures and strata with occured as stratoid,lamellar and lenticular.Ziyun calcite deposits were formed 14 ore blocks and scale unequal size of ore,which were distribution for a total of 36 orebody.Orebody divided 6 from north-western and 30 from north-eastern.(2)The main minerals include calcite,which content in commonly is more than 95%,with a small amount of fluorite,and it is aggregation and rhombohedral in the shape.Calcite ore have widely distribution type of structure and texture.The calcite crystals are euhedral,subhedral and it shape,but mainly is euhedral.The ores revealed a variety of hydrothermal structures characteristics such as block structure,vein structure,drusy structure,brecciform structure,radiating structure,pectinate structure.(3)The characteristics of trace and REE element geochemical show that the content of trace elements in calcite ore and surrounding rocks is low,and besides the high content of Zn,Ni and Sr,the other elements are almost below the detection limitation,and the whole change is stable.The change of trace elements in calcite ore and surrounding rocks of the calcite deposits in Huoshanguan and other block from north-western is basically similar.While calcite ore and surrounding rocks in Dace block from north-eastern are obviously different,the trace element content of surrounding rocks is higher than calcite ore.Ore and surrounding rocks in Huoshanguan and other blocks from north-western both have the same REE pattern modelsand have regularity variation of ?REE.While REE in Dace block from north-eastern displayed distinctly different distribution patterns with surrounding rocks.This implies that the types of calcite mineralization are different.(4)Carbon and oxygen isotope geochemical show that the carbon isotopic compositions in the northeast Dace block is negative feature,while the carbon isotopes in the northwest Huoshanguan and other blocks from north-western are positive feature,it indicat that the calcite veins from northeast and northwest directions causes are different.Metallogenetic material source are form marine carbonate rock.Atmospheric water was joined formation high content of HCO3-Ore-forming fluid.Ore-forming fluid had not a lose relationship with magma.(5)Through the investigation of field,and according to the mineral composition,structure and tectoniccharacteristics,study area is mainly hydrothermal ore deposit.(6)According to the ore-controlling factors of the Ziyun calcite deposit,which is mainly controlled by stratum and tectonic.Ore body scale in the south is better than the north.It is predicted that large to medium calcite deposit can be found in Ziyun,Wangmo,Luodian,Zhenfeng.For the region and the outer draw out three ore-forming promising area,in order to find the direction of prospecting exploration of calcite deposit.