The Geochemical Characteristic Of 1:50000 Stream Sediment Survey Of Yulong Township,sichuan Province

The study area is located in the north part of the prospective area of Yanshanianauricupride at Manigango-Kanggayinzhi.Various mineral resources have already been found in this area including gold,copper and building ma terials,among which the gold mine and building sandstones have been exploited and utilized and generated good economic and social benefits.The first-order tectonic unit in the study area belongs to the Tibet-Sanjiang orogenic system,while the second-order tectonic unit is mainly Sanjiang arc basin that covers across Bayan Har Block in the north and east parts,the third-order tectonic unit includes Yidun-Shaluli island arc,Ganzi-Litangophiolitic mélange belt and Yajiang relict basin ranging from west to east.The study area has an excellent metallogenic background that spans over to the prospective area of Manigango-Kanggayinzhi and Yanshanianauricupride(IV level),the prospective area of Shiqu-Degeyinzhi and the Yanshanian copper,tin,silver,lead and zinc ore prospective area.On the whole,the elements are distributed mainly in the Ganzi-Litang combination zone,among which the element association anomaly of Au,Ag,Cu,Sb,W and Sn is clearer and has a relatively large anomaly dimension and good continuity.Most of the anomaly is distributed in a strip shape along with the direction from northwest – southeast,which is basically in accordance with the features of regional tectonic movement.The iron family elements are basically distributed merely in the combination zone,which is identical with the distribution pattern of the basic and ultrabasic rocks in the region.As and Sb in this region had great metallogenic potential.Additionally,although the coefficient of concentration of Au was not high,its coefficient of variation reached 6.82,presenting an uneven distribution,which suggested certain metallogenic potential.Dendrogram of R cluster analysis reflected good correlations between Au,As and Sb,with correlation coefficient of Au and Sb reaching 0.973 and correlation coefficient of As and Au reaching 0.874,which suggested obvious low-temperature hydrothermal activity in this region.The correlation coefficient of Bi and W was 0.6,indicating rock emplacement-associated high-temperature hydrothermal activity in this region.The correlation coefficients between each iron family element were all over 0.793,which was consistent with the emergence of a large number of basic volcanic rocks in this region.Research on the correlations of elements and formation rock revealed that the content of each element in the Yidun island arc showed no obvious variation trends(relatively gentle).Most elements were depleted;only Ag and Bi elements showed a certain enrichment trend between the Late Triassic and Paleogene.In the Xikang Group,all elements were depleted,and reached their maximum values in Lianghekou Formation,followed by a gradual depleted trend.In the Garbs-Litang junction,changes of various elements were obvious.According to the survey results of stream sediments,the gold and silver ore-prospecting target area in Madake,the gold and copper polymetallic prospecting target area in Tama-Malong area and the copper ore-prospecting area were selected in the study area,which has laid a good foundation for the geological prospecting work in this area.