Geophysical And Geochemical Analysis For Copper Polymetallic Ore Deposits,Northern Namibia And Their Origin

Namibia is a country with richful mineral resources.After studying and analyzing the existing achievements in metallogenic prediction at home and abroad,and combing with the project of Namibia's northern copper polymetallic ore prediction,the author discussed systematically the application of the three methods---geological,aeromagnetic and geochemical in forecastig the copper polymetallic ore target area.In the thesis,the author researched the sphere,the tabular body and other forward models in the Southern Hemisphere,and discussed the magnetic anomalies in the southern hemisphere.On the basis of this theory,the author analyzed and interpreted the aeromagnetic data,including the preprocessing,conventional data processing and 2.5D Profile forward and inversion processing on the ? T data of the aeromagnetic anomalies in northern Namibia.The routine data processing system,which used RGIS and other gravity and magnetic softwares in frequency and spatial domain,includes the potential field conversion of the pole,reduction to the pole,upward continuation,regularization filter,vertical second derivative and so on.After analyzed the abnormal data,the author delineated multiple faults roughly,and deduced that there are three major faults,which was named as F1,F2 and F3,that provide the important evidence for the later geological prospecting.On the basis of geochemical interpretation for 12 elements,the author delineated 153(numbered)single element anomalies,9 comprehensive anomalies,which include 1 class A anomaly,2 class B anomalies,and 6 class C anomalies.In the research area,the main anomaly elements are Cu,Au,Pb,Zn,As,Co,etc.,and the anomaly area of Cu extents most widely.Besides,the anomalies of Bi,Cr,Fe,Mn,Ni,and Mo are weaker.The distribution of the elements'anomalies presents generally north-east direction.According to the geological map the author found that most of the anomaly areaS located in the North East-Central Abenab subgroup formations.A few located in the southwest corner of the second paragraph of Nosib group formations.According with the two points above,combing with the detail data of stratigraphy,structure,physical properties of rocks and minerals and distribution characteristics,the author analyzed the causes of the copper polymetallic ore deposits in northern Namibia.The author deduced that the Cause of the three mineral occurrences of 7200Cu,OkarikwaCu and 3200Cu in this area should belong to the Mississippi Valley-type,and the source of minerals came from the layer under the Otavi group layer,and the mineral deposit located in carbonate rocks,shale and siltstone layers of Abenab subsets,and the capacity of the mine is configured to construct broken fracture zone.By the aeromagnetic anomalies,the author deduced the buried fault structure,and considered that the northwest buried fault zone provided a channel and storage space for the formation of metal deposits.he extracted information about distributional characteristics of the elements with geochemical anomalies reflected.That the northwest fracture is also the ore-controlling structure in the region.After the research for Mississippi Valley-type(MVT)deposits in this area,the author believes it's better to use aeromagnetic method to narrow the prospecting targets within the target range,and more geochemical and geophysical exploration(electrical method)are needed to narrowThe target area futher,then the researchers can delineate the orebody range,and reduce the input of manpower,material and other resources.According to the similar analogy principle,on the basis of the mineralization law of the copper polymetallic ore in this area,which is summarized above,the author found the anomaly area which has the similar geological environment,similar information of magnetic anomalies with the copper polymetallic mine,it is useful for predicting more copper multi-metal mineral resources.