Geochemical Characteristics And Ore-prospecting Prognosis Of The Stream Sediment Survey In The Jilongxiaogou-Beixili District,Heilongjiang Province

Jilongxiaogou-Beixili district is located in the north part of the Heilongjiang Province,the junction part of the northern margin of the Xingan-Mongolia Orognetic Belt and the E'erguna Block,and belongs to the E'erguna-Xingan Metallogenetic Belt and the subzone of the Walali-Beixili Fe-Au Metallogenetic Belt.The stratas of this district are dominated of the Paleozoic and Mesozoic stratas.There are many intrusions,and geological structures are significantly complex,which can provide the good metallogenic geological conditions.Based on the systematic study of the ore-forming geological characteristics,this study completed the geochemical measurement of 1:50000 stream sediments with twenty-three elements in the study area,delineated 315 places of the elemental abnormalities,and analyzed the distribution characteristics of the each single elements.Among all of the analyzed elements,the elemental abnormalities of Au,Ag,Sb,Mo,U,As,Cd,Hg,Ni,Cu,Cr,and W distribute in the large scale areas,show good concentration zonings and have certain geological significance,so these abnormalities are proposed to be related with mineralization.However,the elemental abnormalities of La,Bi,Co,and Pb show small scale of development and are scattered with few concentration zonings.The elemental abnormalities from Nb,Sn,Ti,V,Y,Zn,and Zr elements are sporadic in the study area,so these abnormalities has no guiding significance for exploration.Results of the systematic cluster analyses of 12 elements with abnormalities show that the three elemental assemblages,i.e.,As-Sb-Au-Cu-Hg,W-Mo-U,and Cr-Cd,have good internal correlations,which could reflect varies genetic significance.Among them,the AsSb-Au-Cu-Hg abnormal assemblage may be caused by mineralization.Combined with previous studies,Ag also serves as an abnormal element to carry out comprehensive anomaly delineation.Based on the characteristics of geochemical anomalies from the stream sediments,regional metallogenic geological settings,geological characteristics of the deposits and so on,five metallogenic prospective areas are restricted,including one of the I-level metallogenic prospective area and three of the II-level metallogenic prospective area,and one of the IIIlevel metallogenic prospective area.The results also point out that gold is the main exploration mineral species in the study area,followed by iron and polymetallic species.