Locating-Prediction Of Blinded Gold Ore Bodies Out Of Heilongjiang Wulaga Gold Deposit

The Wulaga gold deposit is located to the North Slope of the Xiao Xing'anling's East segment and the middle of Wulaga River of Heilongjiang water system. It belongs to Wulaga town, which is in the south of Jiayin County, YiChun, Heilongjiang Province. Geotectonically, the Deposit lies at the joint of Taipinggou upwarping and Jiayin down-warping belt that belong to the northern Jamusi up-warping belt.The Jamusi upheaval belt is located at JiLin-HeiLongJiang geosynclinal system which is in the east segment of Tianshan-Xing meng Hercynian fold belt. The basement of Taipinggou up-warping is occupied by old crystal rock system. There are linear structures which extend in N-S and E-W direction. However, the axes of folds in the basement are mainly in NE direction.The strata outcropping in the area include lately middle Proterozoic lower Heilongjiang group,early Cretaceous Ningyuancun group, Taoqihe group, late Cretaceous Yuliangzi group,Cenozoic Neogene Miocene- Pliocene Sunwu Group and Pleistocene-Holocene.The E-W extending structural breccia belt is the main ore-housing structure; N-W extending structure controls the pitch of ore bodies. The jointing of the structure in N-W direction with ones in E-W direction supplied abundant space for ore-forming hydrothermal solution. The industrial ore bodies are mainly distributed in E-W tectonic breccia belt between plagiogranite porphyry and lower Heilongjiang group. 90 percent of the gold ore bodies appear in the breccia belt in the inner contact belt, and the other appear in the interstratified fracture belt of schist which is in the north limb of Wulaga anticline. The volcano bodies intruding between lower Cretaceous Ningyuancun Group and middle proterozoic lower Heilongjiang group in the late middle Yanshan period control the deposit.The mineral combination is simple in the Wulaga gold deposit , the ore minerals are mainly composed of pyrite,marcasite,colloidal pyrite,colloidal marcasite and natural gold.Due to pulsing activities of ore-forming hydrothermal solution, there are such types of wall-rock alteration as potassic, kaolinization, chloritization and epidotization,berecitization,carbonatization,silicification;pyritization,Marcasitization ;pyrite-beresitization , propylitization. Mineralized silicification is linear distributed and controlled by structure. It is also filled with aplitic vein. Gray-black quartz of the chalcedony is closely related to gold mineralization.By analysesing and constracting on metallogenetic characteristics, geochemical and geophysical characters of Wulaga Gold Deposit, the author have summed up the geology ore-search indication, geochemical ore-search indication and geophysical re-search indication and set up the comprehensive information ore-search model.The geochemical ore-search indication: Geochemical anomaly reflects of the direct and indirect mineralization so that it is of importance in finding and predicting blinded gold ore bodies. Both secondary halo and primary halo in the Wulaga gold deposit indicate obvious element composite anomaly, and the most significant multi-element anomaly is Au, As, Sb. When the multi-element anomaly is consistent with wall rock alteration belt, this area will become direct information in locating-prediction of blinded gold ore bodies. Au,As,Sb element anomaly indicates linear distributing in the abnormity ichnography. The long axes of the anomalies in NWW (EW) direction are accord with ore-controlling and ore-housing structures The anomaly has been zoned in vertical,Head elements includ As,Sb,Hg; middle elements are composed of Au,Ag; tail elements compose of W,Mo,Bi.The geophysical re-search indication: The indication for geophysics shows that magnetism of the rock and the ore in the deposit is slight , magnetism of the tuff is the lowest one, granite porphyry and schist is secondly, basalt and veins rock are the highest ones. The chargeability of ore is as high as over fifteen percents, which is caused by the intensity of pyritization, is the mainly polar body in this area; schist is the second one, more than five percents; in tuff theηs value is about one percent And in granite porphyry is a little higher, almost three percents; high chargeability rocks in this ore deposit all are concerned with the pyritization and graphition. The electrical resistivity of rocks in the deposit is low especially the tuff. Anomaly is located at the metallogenetic location and the boundary of lithology by gamma spectrometry method. The content of the K spectrum and total spectrum increase, the content in K spectrum is more than 4%, the maximum value is over 5%; the content of the total spectrum is beyond 20×10-6. The U spectrum and Th spectrum have no obvious regularity,however, one of the spectrum increased. Three decreased and one increased or four-increased abnormity. Based on these abnormity, we can speculate the confine and strike of the anomaly.According to the ore-search model above, we have gained the locating-prediction of blinded gold ore bodies out of the deposit, Liushuhe and Shisangongli forecast sections, and gotten the results as follows:We used geological survey, ground gamma-ray spectrometry survey, lithogeochemical survey,trenching and induced polarization in Liushuhe forecast section and found out the structural crashing belts developing ,the abnormity of lithogeochemical distinct,the gold mineralization was contraled by structural crashing belts or structural breccia belts.The alterations of wall rocks included silicification;pyritization and carbonatization which showed the mineralization character of epithermal gold deposit.the north of the section where the NNW extending structure crossed with the NE extending structure is the most advancetangous district. We found gold orebody in two shallow bored wells and three drill holes and controlled a great dimension alteration ang mineralization breccia vein in which some sample arrived at industrial grade. The highest gold bearing was 54.6×10-6,and we gained the gold resource 2265kg total.In Shisangongli forecast section we confirmed the characters of synthesis exploring information according the geological information, high precision magnetic measurement, gamma-ray spectrum testing and soil geochemical information; and the blind gold ore bodies have been forecasted.Compared to the comprehensive information ore-search model of Wulaga gold deposit we selected the abnormity areas, and the checking engineering was actualized in the selected the target section. We found the gold ore both in exploratory trench and in shallow bored well, and gained 1500kg gold resource quantity.According to the results of this work, we can draw a conclusion that it is reasonable to predict blinded gold ore bodies out of the Wulaga Deposit by synthesized information method. Some abnormal areas has been confirmed by engineering and we have gained the anticipate purpose. This success approves the validity of the ore-search methods we choose,and points out the direction of the ore-search work out of Wulaga gold deposit for us.