The Reseach Of Pyrite Typomorphic Characteristics And Deposit Genesis Of The Gangcha-Kemo Gold Deposit,Gansu Provice,China

Gangcha-Kemo gold field of Hezuo in Gansu province is located in Qinling overthrust structure on the north side, north is Gangcha gold field, south is Kemo 28 sign gold abnormal place. Gangcha gold deposit is newly discovered medium shallow near the north and south by faults controlled epithermal deposits Gansu Gannan region in recent years.The essay is based on theories and methods of genesis minerageny and prospecting mineralogy, further provide scientific foundation of the mineralization of Gangcha gold deposit, and provide scientific basis for deep mine mineralization to guide deep prospecting by studying of deposit geochronology, geochemical and quartz infrared spectroscopy, quartz thermoluminescence light, pyrite genesis mineralogy.The main research results are as follows:1.The andesite of main host rock of Gangcha gold field is rock of alc-alkalinemetaluminous Mg-rich, diorite is rock of Mg-rich calc-alkaline-potassium, diorite "extrusive phase" rock is Mg-rich calc-alkaline-metaluminous. These three types rocks are enriched in high field strength elements, have a deficit LILE,enrich LREE, have weakly defict HREE, Eu negative anomaly feeble.2.The volcanic of main host rocks of Gangcha gold deposit and intrusive rocks take shape from 242Ma-246 Ma, age of mineralization is 225 Ma, the former post-mineralization provide good metallogenic conditions and metallogenic environment for after mineralize, intrusion is important symbol for prospecting and prospecting significance to western Qinglin.3.The composition of Sulfur and plumbum isotopic indicates a common source of magma minerals(crust-mantle mixed source) and related with the deep intrusion, this type magma may form the upper crust delamination. Isotope of Hydrogen and oxygen indicates mineralization of magmatic hydrothermal fluids mainly water and mixed with a small amount of precipitation, reflecting Gangcha gold deposit has closer relationship with magmatic activity.4.Test Results of infrared spectra indicate that, the relative optical density value E1 of H2 O <2 is favor of mineralization, the relative optical density values of E2 of CO2 range from 0.3-0.5 is favor of mineralization; D2/D1 proportionality >0.2 is favor of mineralization. Most quartz sample of mining area exhibits thermoluminescence peak and non-peak blunt state, indicate that the area has been strong tectonic mineralization.5.Gangcha gold deposit is based on sulfur deficiency type, low temperature elements combination of(As+Sb) P-type pyrite, deposit erosion of from 25.5 to 38.5%, an average of 31.1%; Pyrite formation temperature is range from 84.4 ~ 386.6℃, mainly concentrated in the 200 ~ 280℃; The ω(Fe)/ω(S+As) values of Pyrite concentrated in 0.84-0.89, as a hypabyssal epithermal deposit; presume below 3000 m of 18-26 and 2-5 exploration line and below 2800 m of 5-23 exploration line of No. Au3 veins might have good prospecting potential.6.Based on field analysis of Geological Survey and indoor experiments presume: There may be porphyry deposit in deep of Gangcha gold field, and deep prospecting potential for greater.