Ore Prognosis By Litho-and Pedogeochemical Survey For A Polymetallic Deposit In Taliabu,Indonesia

Litho-and Pedogeochemical survey was adopted to study the distribution regularity of trace elements in a newly discovered skarn-type polymetallic ore area in Taliabu Island,Indonesia.In combination with the geochemical survey data,denudation degree analysis was carried out on the newly discovered orebodies,and the results were applied to deep prospecting.Based on the geological exploration in this ore area and the surrounding deposits,regional metallogenic comparative analysis was carried out,so as to predict the metallogenic prospects.The research shows that,in the tropical rainforest,pedogeochemical survey combined with lithogeochemical survey can effectively guide the polymetallic deposit prospecting.The main conclusions and ore-prospecting achievements are as follows:1.The orebodies mainly occur in the contact parts between granite and marble,inside the fissures of Pzmm2-4 slate,as well as in the interlayer of Pzmm2-4 slate and Pzmm2-5 marble.Through the study on mineral assemblages and geochemistry,in the contact zones there are Fe-Zn-Cu-Pb orebodies with certain zonation that is Fe-Zn-Cu?Zn-Cu?Pb-Zn-Cu from the rock body to the outer edge of the contact zone.While the intersected and interlayer orebodies in the surrounding rocks are Pb-Zn-Ag-Cu polymetallic orebodies.2.Lithogeochemical study shows that in the studied area,compared with the abundance of elements in upper crust,Cu,Pb,Zn,Mo,Bi,As,Sb,Hg,Cd,W,Sn and Ag of various rocks are commonly enriched,furthermore,Pb,Bi,Cd,As and Ag are strongly enriched(K>10),forming the primary halos.However,there is no Au enrichment.The enrichment degrees of Pb,Zn,Bi,Cd,As,Ag,W and Sn are increased significantly with the sequence of marble?skarnized marble?skarn.The main ore-forming elements,including Cu,Pb,Zn and Ag,with their associated elements,were enriched evidently in the forming process of skarn by contact metasomatism between rock bodies and carbonatite.3.A total of 12 Cu-Pb-Zn-Ag composite anomalies were delineated through the pedogeochemical survey.After anomaly follow-up and engineering verification,ores have been found in 6 anomalies,effectively expanding the scale of the known orebody,and a new orebody No.? was found;2 anomalies are of significant prospecting potentials and 3 anomalies may be the prospecting potentials which can be considered as prospecting prospects for further work.4.Denudation degree analysis revealed that the deposit has experienced uplift-denudation,but there still remains orebody with a certain economic significance,and deep orebodies can be explored near the contact zones of anomalies.