Locating-Prediction Of Blinded Gold Ore Bodies In Deep And Around Heilongjiang Wulaga Gold Deposit

The Wulaga gold deposit is located to the North Slope of the XiaoXing'anling's East segment and the middle of Wulaga River of Heilongjiangwater 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 andJiayin down-warping belt that belong to the northern Jamusi up-warping belt.The Jamusi upheaval belt is located at Jin-HeiLongJiang geosynclinal systemwhich is in the east segment of Tianshan-Xing meng Hercynian fold belt.The basement of Taipinggou up-warping is occupied by old crystal rocksystem. 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 E-W extending structural breccia belt is the main ore-housingstructure;N-W extending structure controls the pitch of ore bodies. The jointingof the structure in N-W direction with ones in E-W direction supplied abundantspace for ore-forming hydrothermal solution.The strata outcropping in the area include lately middle Proterozoic lowerHeilongjiang group,early Cretaceous Ningyuancun group, Taoqihe group, lateCretaceous Yuliangzi group,Cenozoic Neogene Miocene-Pliocene SunwuGroup and Pleistocene-Holocene.By studying on metallogenetic characteristics, geochemical andgeophysical characters of Wulaga Gold Deposit, the author have set up thedescriptive explorative model and forecast model by synthetical information.There are two sources of gold. One is that magma melting in the deep gains golddirectly from gold-bearing basement strata, the other is that the gold is gained from thegold-bearing basement strata during the magma eluviationThe industrial ore bodies are mainly distributed in E-W tectonic brecciabelt between plagiogranite porphyry and lower Heilongjiang group. 90 percentof the gold ore bodies appear in the breccia belt in the inner contact belt, and theother appear in the interstratified fracture belt of schist which is in the northlimb of Wulaga anticline. The volcano bodies intruding between lowerCretaceous Ningyuancun Group and middle proterozoic lower Heilongjianggroup 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 aresuch types of wall-rock alteration as potassic, kaolinization, chloritization andepidotization , berecitization , carbonatization , silicification;pyritization,Marcasitization;pyrite-beresitization , propylitization. Mineralizedsilicification is linear distributed and controlled by structure. It is also filledwith aplitic vein. Gray-black quartz of the chalcedony is closely related to goldmineralization.According to the analyzing of liquid component of fluid inclusions, thedeposit can be confirmed as typical epithermal ones with characteristics of lowsalt, low pressure, and mixture of meteoric water.Geochemical anomaly reflects of the direct and indirect mineralization sothat it is of importance in finding and predicting blinded gold ore bodies. Bothsecondary halo and primary halo in the Wulaga gold deposit indicate obviouselement composite anomaly, and the most significant multi-element anomaly isAu, As, Sb. When the multi-element anomaly is consistent with wall rockalteration belt, this area will become direct information in locating-prediction ofblinded gold ore bodies. Au,As,Sb element anomaly indicates lineardistributing in the abnormity ichnography. The long axes of the anomalies inNWW (EW) direction are accord with ore-controlling and ore-housingstructures 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 content of hydrargyrum in soil is closely related to the metallogenetictemperature in the endogenetic deposit. There are strong Hg anomalabove oreand alteration zones, and the width and scale of the anomaly belt have apositive correlation with the scale of the ore body.The indication for geophysics shows that magnetism of the rock and theore in the deposit is slight , magnetism of the tuff is the lowest one, graniteporphyry and schist is secondly, basalt and veins rock are the highest ones. Thechargeability of ore is as high as over fifteen percents, which is caused by theintensity of pyritization, is the mainly polar body in this area;schist is thesecond one, more than five percents;in tuff the ηs value is about one percentAnd in granite porphyry is a little higher, almost three percents;highchargeability rocks in this ore deposit all are concerned with the pyritizationand graphition. The electrical resistivity of rocks in the deposit is low especiallythe tuff.Anomaly is located at the metallogenetic location and the boundary oflithology by gamma spectrometry method. The content of the K spectrum andtotal spectrum increase, the content in K spectrum is more than 4%, themaximum value is over 5%;the content of the total spectrum is beyond20×10-6. The U spectrum and Th spectrum have no obvious regularity,however,one of the spectrum increased. Three decreased and one increased orfour-increased abnormity. Based on these abnormity, we can speculate theconfine and strike of the anomaly.According to the model above, we have gained the locating-prediction ofblinded gold ore bodies in diggings depth, Zhangcaigou and Hexi forecastsections, and gotten the results as follows:The data we get by the TEM and the shallow seism methods can reflect thedeep-seated tectonic feature and lithology. The MT method can show thedeep-seated tectonic features, and we can speculate that lower resistancebody(No.3 abnormal body) has correlation with ore-bearing structure orore-bearing blinded rock, we can guess that the granite porphyry vein is locatedbetween line 121 and 129.Depth is -200～-400 meter;the storage mine beltform is in -150～-300 meter .Seven anomalies in the zhangcaigou forecast area can be indicated by thegamma spectrometry method. Ⅰ andⅡ anomaly areas are the best mineralizearea , which are located in the intersection of three constitution. Ⅳ,Ⅶanomalylie in the south-north strap. There are 4 anomaly of low electrical resistrity andhigh chargeability in the electrical sounding of Ⅴ section , these anomalies areall located at the intersection of the Ⅰanomaly of gamma spectrometry andⅡ anomaly of the Hydrargyrum contend in soil. Blinded ore bodies may exist inthese abnormal areas. .Six abnormal sections have been confirmed in Hexi district. By syntheticalanalysis, we think No.1 anomaly and No.3 anomaly are the best sections ofform mine. And we should put more attention into the two areas.Based on the project checking, we can get some conclusions as followings:Based on the drill checking in the deep forecast area, a plagiograniteporphyry body is proved at the 682.7～685.2m in depth in the ZK123-3, whichis 2.5m in thickness, has a maximum gold content of 0.09×10-6 .In addition,samples from the schist with ectonization, silicification and pyritization et.al.have the maximum gold content of 1.36×10-6. Therefore, we should continuedesigned drills so that we can do the deeper estimation work for themineralization of the porphyry body.The width and the length of the mineralizing or alterating breccia blet inthe Zhangcaigou forecast area can be showed by the trenching method . Theaverage value of Au in the breccias was between (0.3～0.5)×10-6. the widthwhich is controlled by the mineralization alteration breccia zone is 40m,andalteration extensively developed. The first drill proves mineralization for thefirst time, and the 1049,1050,1051 contiguity samples had catched sight of themine ,average gold content is 20×10-6 ,the maximum value is 55.10×10-6 in the1051. The average value of 1056～1063 is about 1×10-6;there are 7mcontinuous mineralization in the ZK110—1,the gold contents in samples arefrom 0.5×10-6 to 1.15×10-6;there are three mineralization between 366.60～368.60m in the ZK100—1,the minimum gold content is 1.68×10-6;themaximum is 2.40×10-6. There are 2m mineralization between 366.60 ～368.60m,the average value reaches 2.00×10-6, which displays the mineralizationin the deeper area has enhance trend. These data can demonstrate the continuityand catholicity, which indicate industrial ore bodies in the deeper part.Six abnormal areas have been gotten in Hexi area. They are associatedwith the ore-forming structures.The further work should draw attention toconfirm them.According to the analysis, we can draw a conclusion that it is reasonable topredict blinded gold ore bodies in location in the Wulaga Deposit bysynthesized information. Some abnormal areas has been confirmed byengineering and we have gained the anticipate purpose.