| The Keluohe gold deposit is located in suture zone between Great Xing’an Range and Songnen Massif for Xing’an-Mongolian orogenic belt. Multistage tectonic superimposed transformation, magmatism and hydrothermal activity have provided favorable conditions for the mineralization of gold in this area. In this paper, we select Keluohe gold deposit as research focus. According to systematic collection of geophysical and geochemical prospecting from prerequisite, we studied geological characters and ore genesis of Keluohe deposit, analysed ore-forming geological conditions, summarize prospecting indicator and establish comprehensive prospecting model. Accrodign to ore-forming prediction studies to existing geological, geophysical, geochemical data, we delineated 4 ore-forming prognosi and provide the basis for following prospecting work.The orebodies for Keluohe gold deposit mainly host in the mylonitize granite, which controlled by NE ductile shear zone. The ore minerals are dominated by sulfides, metallic minerals mainly are composed of pyrite, chalcopyrite, pyrrhotite, sphalerite, galena. The main textures of ores are composed of euhedral-subhedral granular texture, xenomorphic granular texture, fillign texture, crush texture. The main structure of ores are composed of banded-ribbon structure, disseminated structure and veinlet structure.The wall rock alteration mainly contain silicification, pyritization, chloritization and serecitization, and obviously controlled by the orebody with plane-type alteration. According to geological observation and desk research, metallogenesis of the deposit can be devided into following four stages:(I) pyrite-quartz stage,(II) gold-polymetallic sulfide stage,(III) quartz-carbonate stage,and(IV) hydrothermal superimposed stage.(I) and(II) are main mineralization stages. The ore genesis is a typical ductile shear type deposit.The fluid inclusions show the type of fluid inclusions of main mineralizing stages for Keluohe deposit are gas-lwiquid two-phase inclusions. The ore-forming fluid is NaCl-H2O-CO2 system, homogenization temperatures is range from 181.9℃ to 285.3 ℃with an average of 247.44℃. The salinity is range from 4.17 to 9.72wt%(NaCleqv). The density is range from 0.78 to 0.92 g/cm3, homogenization pressures is range from 14.48 to 27.99 MPa and the mineralization depth is range from 1.45 to 2.79 km with an average of 2.23 km. The ore forming fluid of main mineralizing stage has the characteristics of middle hydrothermal solution, rich in water and low salinity, which is forming in lower metallogenic pressure and middle-shallow setting.The mylonitize granite from Keluohe gold deposit belongs to calc-alkaline series. It is characterized by relative enrichment in LREE, relative losses in HREE, obvious differentiation of light and heavy rare earth elements with negative Eu anomaly. The trace elements are characterized by enrichment in large ion lithophile elements(LILE), loss in high field strength elements(HFSE). Rb/Ba, Zr/Hf and Nb/Ta shows characteristics of crust source. The diorite in mining area belongs to metaluminous high potassium calc-alkali series, relative enrichment in LREE, relative loss in HREE, Eu anomaly is not obvious. enrichment in large ion lithophile elements(LILE), loss in high field strength elements(HFSE). Zr/Hf, Nb/Ta implied that it had been contaminated by the composition of curst in the process of its formation. In tectonic discrimination diagrams, the mylonitization granite and diorite shows characteristics of volcanic arc granite.According to research on typical ore deposit, we establish comprehensive prospecting indicator for Keluohe gold deposit. Dawangzi Group is main ore source bed and important strata indicator. The overprinted part of Late Devonian mylonitiation granite, granitic mylonite and Late Jurassic intermediate rock is an important sign of magmatic rocks. NE-trendign ductile shear tectonic belt is favorable for mineralization space. The contacting belt of potitive and negative mangetic prospecting is the sigb of magnetic anomaly of gold deposit. More than 4% of polarizaility, greater than 1400?m of resistivity value is the important electrical method of exploration. Large area, high anomaly, obvious accumulation centers are the direct geochemical prospecting of gold, As, Sb anomaly can also be used as the indirect sign of gold prospecting.According to process of existing geological, geophysical and geochemical data from Keluohe area, we delineated frou ore-froming prognosis area, such as Erdui, Jiudui, Beihe-386 Gaodi, 365 Gaodi, and provide the basis for following prospecting work. |
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