大兴安岭南段乌苏图如地区地球化学特征及找矿预测

Geochemical characteristics and prospecting prediction in the Wusuturu area,southern Daxinganling

乌苏图如地区位于大兴安岭南段,其相邻地区已发现多处重要矿床,找矿潜力巨大,但区内基础地质矿产调查程度总体较低。在对1∶5万水系沉积物测量5543件样品元素进行的相关性及因子分析等基础上,本文分析了元素的分布、分配、共生组合规律及主要地质单元的地球化学特征,结果表明:Ag、Sn、As、Sb、Bi、Pb等元素呈富集或强富集状态,特别是在下二叠统寿山沟组、大石寨组和晚侏罗世花岗岩背景区中含量较高,而Cu、Au、V相对贫化;区内各成矿元素均呈不均匀分布,且Sn、Ag、W、Mo、Pb、Zn、Cu等元素在二叠系寿山沟组、大石寨组和侏罗系满克头鄂博组、晚侏罗世花岗岩背景区中呈分异—极强分异分布,在局部区域存在富集甚至强烈富集,较为利于成矿。因此,可确定Cu、Pb、Zn、Ag、Sn、Au为区内主要成矿或伴生成矿元素,Mo、W、Bi、Sb、As、V等为成矿指示元素,并以与中酸性岩浆侵入有关的中高温热液成矿作用为主,主要成矿类型为热液型和接触交代型。依据成矿地质背景、地球化学综合异常及矿(化)点的空间分布情况,圈定出找矿预测远景区5处,并进行了工程验证。

Wusu Tulu area is located in the southern section of the Daxinganling,and many important deposits have been found in its adjacent areas,which has great prospecting potential,but the basic geological and mineral investigation degree in the area is generally low.On the basis of correlation and factor analysis of elements in 5543 samples of 1∶50000 stream sediment,the distribution,allocation,symbiotic association of elements and geochemical characteristics of main geological units are analyzed.The results show that:Ag,Sn,As,Sb,Bi,Pb and other elements are enriched or strongly enriched,especially in the Lower Permian Shushangou Formation,Dashizhai Formation and Late Jurassic granite area,while Cu,Au,V are relatively depleted.The ore-forming ele-ments in this area are unevenly distributed,and Sn,Ag,W,Mo,Pb,Zn,Cu and other elements in the Permian Shoushougou Formation,Dashizhai Formation,Jurassic Manketou Ebo Formation and Late Jurassic granite background area are differentiated to extremely differentiated distribution,and there are local areas of enrichment or even strong enrichment,which is more conducive to mineralization.Therefore,it can be determined that Cu,Pb,Zn,Ag,Sn and Au are the main ore-forming elements or associated ore-forming elements,Mo,W,Bi,Sb,As and V are the ore-forming indicator elements,and the main ore-forming types are hydrothermal type and contact metasomatism type,which are mainly related to medium-acidic magmatic intrusion.According to the metallogenic geological background,geochemical anomaly and the spatial distribution of mineralization(mineralization)points,5 prospective prospecting areas are delineated and verified by engineering.