A Study On The Typical Mineral Typomorphic Characteristics Of Lailishan And Siguangping Tin Deposit In Yunnan Province And Its Significance

With its tectonic location at the south of Sanjiang metallogenic belt,Lailishan and Siguangping tin deposits are the well-known tin deposits in western Yunnan.With the application of theory and method of Genetic mineralogy and mineral prospecting,this paper have studied the typomorphic characteristics of same penetrating mineral,such as cassiterite,pyrite and quartz,in order to discuss the causes of minerals and deposits and ore-forming liquid source center,and provide reliable basis for prospecting.From the early mineralization to the late mineralization of Lailishan and Siguangping tin deposits,the crystallization habit of cassiterite transforms from cone development to the cylindrical developmental.Cassiterite in Lailishan and Siguangping tin deposit is relatively pure and have less impurity elements.Radial and spherical cassiterite have more impurity elements than granular and columnar cassiterite,that might be resulted from suddenly dropping of metallogenic temperature.The color of cassiterite band is positively correlated to the content of Nb,Ta and Fe,while the band in CL may be related to the content of U and Th.From the early mineralization to the late mineralization of Lailishan tin deposit,the cassiterite thermoelectricity type transforms from P-N type to N-P type,indicating that thermoelectric type of which formed in the relatively high or low temperature is N type or P type.In Lailishan and Siguangping tin deposits,pyrite belong to the sulfur rich type and(magma)htdrothermal genesis,and is produced in medium or partial shallow environment.The pyroelectric features of pyrite are relatively consistent,as namely along with the continuous mineralization,the appearance rate of N type pyrite is higher than the appearance rate of P type pyrite.The relative erosion degree of ore body of Lailishan and Siguangping tin deposit is medium,indicating under part having great potential.Pyrite thermal resistivity and impurity element contents show a negative correlation.The sulfur isotope frequency histogram of pyrite of Lailishan and Siguangping tin deposits shows the ore-forming fluid may be related to magmatic thermal fluid.The hermoluminescence glow curves of quartz of Lailishan tin deposit can be divided into three types: single-peak,double-peak and no-peak.The first and second stage mainly show single-peak,and the third and fourth stage mainly show double-peak,which may be resulted from a sudden change of metallogenic environment.However,the no-peak quartz may be caused by later tectonism,resulting in the sub-excited electrons in quartz crystal structure releasing ahead of time.Taojinchu block has obvious advantages than Laoxiongwo and Siguangping block in crystalline form,size,length-width ratio of cassiterite,and the band of cassiterite is best developed,the hermoelectricity of cassiterite mainly shows P-N type,the strength of total integral strength of quartz is greater.Those indicates that the mineralization temperature of Taojinchu block is generally higher than it of Laoxiongwo and Siguangping block,or further to say that Taojinchu block and its vicinity may be the ore-forming fluid source center.