Geogas Anomaly Charateristics And Deep Prospecting In Dashui Gold Deposit Gansu Province

The research area DaShui Gold Deposit is in the Qin-Qi-Kun Central OrogenicBelts of West qinling fold belt west-middle section.The south boundary isMaqu-Nanping-Lveyang major fracture,border on Songpan-Garz bow area of northedge of Zoige plot,where is the two big tectonic units binlding site, bleak structure isgrowth,especially the NWW structure dominate the site of regional ore deposits or orebody.This deposit has been mined more than20years,and now is critical mine,need tofind concealed deposits outside. At present,a low exploration area between Geerkeand Gongbei mining area,have metallogenic prospecting.With the development ofprospecting method,Geogas method was born,which characteristic is take effectquickly,easy operating,and reflecting deep abnormal,so is fit for prospecting in thisarea.In this study,first,we analyze the characteristics of rocks of tarce elements andrare-earth elements,and find the elements which can indicate gold mineralization;findthe characteristics of trace elements and rare-earth elements of4exploratoryline;Third,compare rock elements charateristics with exploratory line’s,chooseelements which can indicate gold mineralization in geogs;Last,use the indicatorelements to guide exploration.According to research,the mian point is bellow:1.Ore sample of Au, Sb and Cs, Ba, and Bi, and other13kinds of trace elementswere significantly enriched as indicator elements of gold mine. But elements like Sc,Sr, Th, Pb, and Sn were enriched in non-ore samples. The total content rare earthelements in the ore samples are greater than it’s in total non-ore samples. The ratio ofLa/Yb, La/Sm and LREE/HREE in ore samples is generally higher than it is in thosenon-ore samples.2.There are abnormalities of the elements Au, Ag and Cs, Cu and Co., of Bi, Ni ineach four experimental profiles, which are more accurate reflection of the deepunderground mineralized body characteristics and anomalies brought by the drilling. REE of ore samples is greater than non-ore samples in each four experimental profiles.Both kinds of samples are rich LEE, and the ratio of La/Sm and La/Yb in ore samplesis higher than non-ore samples, only samples in lines74and76are excepted.3.It is determined that the14kinds of Au, Cs, Ba, Ag, Cu, U, and Ni elements areused as indicator elements through combing with both trace element characteristics ofore samples and those four profile samples.4.Elements as Au、As、Cu、Zn、Cr、Sr、Mo are abnormal from point3to point10in5survey lines with170m width. Elements as Au、Cu、Cr、Sr、Ni、Pb、Mo areabnormal from point19to point23with100m width. Elements as Ag、As、Bi、U、Cu、Cr are abnormal in point31with25m width. Elements as Cu、Pb、Zn、Ni、Mo、Cr、Sr are abnormal from point31to point44with260m width. It isapproximately inferred three major ore-bearing structure in the area throughconnecting these points. The ratio of La/Sm and La/Yb in ore samples of3surveylines is higher than non-ore samples. There are anomalies of Eu and Ce both in someore and non-ore samples, but Eu and Ce are poor overall except in non-ore samples,and so does REE.5.It is suggested that abnormalities area is6.65square kilometers by the abnormaldistribution characteristics of Au、Sr、Cu、Pb、Cr、Co、Ag、Ni、Zn. It is dividedinto5areas; the first area is1.65square kilometers which located as the center ofpoint27in line C, the second one is2.6square kilometers which located as the centerof point33in line B, the third one is0.9square kilometers which located as the centerof point12in line A, the fourth one is1.1square kilometers which located as thecenter of point23in line E, and the fifth one is0.4square kilometers which located asthe center of point39and43in line E.