Study On The Mineralization And Prospecting Of DSO Type Iron Deposit In Labrador Metallogenic Belt,Canada

With the development of China's economy stepping into transition period,it is urgent to use high-quality iron ore resources at home and abroad in order to solve the problem of relative shortage of mineral resources.For this,DSO?Direct Shipping Ore?as the rich iron ore of full iron grade than 50%?sio2<18%?,has been received substantial attention because of its high grade and good economic value.The DSO iron deposit in Labrador Metallogenic Belt was the earliest large-scale developed deposit in the history of Canadian mining,but little research on its genesis and prospecting method had been done.In recent years,with the development of a series of exploration and research work,several DSO deposits have been discovered in the middle Labrador Metallogenic Belt–Schefferville area around.The specific study of these iron deposits not only helps to improve the theoretical research level of the iron deposits in the Labrador Metallogenic Belt,but also has some instructive significance for the prospecting of the DSO type iron ore in the Metallogenic belt.On the basis of the predecessors'study,this paper systematically analyzed the regional tectonic background,metallogenic characteristics and geophysical characteristics of the Labrador Metallogenic Belt in Canada,and summarized the deposit geological features of Joyce Lake,Red Dragon,Sawyer,Lac Lefer,Houston,etc.The DSO ore body occurs mainly as layered and lenticular.NW trend large faults,secondary extensional structures,the superposition of secondary folds controlled the deposit location.According to ore structure and hardness,DSO deposit can be divided into soft and hard DSO deposit.The soft type ore mainly contained hematite,martite and goethite,meanwhile the main gangue mineral is quartz,which the production of hematite is closely related to.And in the later period,the hematite replaced the quartz in iron-bearing construction of the early stage,so that there is a large amount of void in the ore,which shows the characteristics of deep hydrothermal-phenotypic transformation.The hard ore mainly contained blue hematite with very little quartz content.The overall performance is characterized by hydrothermal transformation.By conducting detailed field work and laboratory studies of mineralogy,geochemistry and ore-forming fluids,it was found that the orebody in the deep part has higher iron content than the shallow part.The LREE content of DSO ore is higher than that of Taconite Rock,which indicated that the ore body was more influenced by deep hydrothermal action in the formation process and the contribution of surface weathering to the enrichment of iron element is relatively weaker.At the same time,the?¹⁸ value of oxygen isotope in DSO ore is lower than that of Taconite Rock,which also illustrated the genesis of the deposit was related to hydrothermal fluid.On this basis,the Metallogenic model of the DSO-type iron deposit in the Labrador Metallogenic Belt was summarized,and the obvious hydrothermal action is taken in the formation of the orebody,Instead of the previous thought,only by the surface weathering-leaching effect.On the basis of fully summarizing the model of the DSO iron deposit in the Labrador Metallogenic Belt,the indicators of DSO deposit have been established.By analyzing and comparing the technical method of using gravity and magnetic data to interpret the DSO orebody,this paper putted forward wavelet analysis,matched filter and other gravity-magnetic data processing methods to separate Sokoman Formation and overlying strata.After that,the local gravity anomaly of the rich iron Body?or DSO?and Sokoman Formation could be identified and extracted,meanwhile based on the poisson formula,we could get the“fake gravity anomaly”from magnetic anomaly.Thus,the"residual gravity anomaly"caused by the DSO orebody was able to be calculated which could be used for prospecting the DSO deposit.We have obtained the good results in Joyce Lake,Lac Lefer,Hayot,Black Bird mining areas,and the considerable potential DSO resources,which has pointed out the direction of the DSO deposit exploration in the Labrador Metallogenic Belt.