Quantitative Prediction Theory And Practice Of Seafloor Massive Sulfide Deposits

As the mineral resources on land growing exhausted and the mineral exploration becoming more and more difficult,seafloor polymetallic sulfide,to be a new part of mineral resources,gradually becomes the academic frontiers.It has a significant development potential,which makes it become a research hotspot at home and abroad.According to the constitution of the international seabed authority,a contract area should be applied for first before the exploiting of marine mineral resources.And it should be relinquished 50% and 75% area within 8 and 10 years,respectively.Therefore,how to determine the location of contract area based on such less data,and how to select out the prospecting targets and optimize the prospecting targets are the questions need to be solved.In view of the exploration situation of seafloor polymetallic sulfide,this paper systematically establishes a three-stage quantitative prediction process system,which is applied for the metallogenic prediction of seafloor polymetallic sulfides in the Indian Ocean Ridge.This process system gradually determines the location of prospecting target and narrows the scope of prospecting target.In the last stage,this paper selects Longqi hydrothermal area to be the typical study area and carry out a new prediction method called bidirectional prediction and evaluation.This new method combined with quantitative assessment and simulation analysis,which can delineate the most favorable metallogenic locations of the sulfide in prospecting targets.The prediction result will provide a basis for the exploration and exploitation of seafloor polymetallic sulfides.The paper mainly includes the following innovative results:(1)Based on the summary of mineralization geological background,ore-controlling factors and prospecting signs of seafloor polymetallic sulfide,this paper selects Indian Ocean Ridge and its surrounding to be the study area.Combined with the depth,gravity and magnetic anomaly,structural and some other kind of data,a prospecting model of sulfide deposits has been established.(2)This paper systematically establishes a three-stage quantitative prediction process system,and is applied for the prediction of seafloor polymetallic sulfide in the Indian Ocean Ridge.The method of weights-of-evidence has been used in the prediction,and the result makes a proposal for the block planning of China sulfide contract area.(3)In the last stage of the prediction process,Longqi hydrothermal area is selected as a typical study area.Bases on the collected geological and geophysical data,this paper uses Surpac software to build the a 3D geological model and achieves the 3D metallogenic prediction by using the "cube model" prospecting methods.(4)Based on the geological model of seafloor polymetallic sulfides in the Longqi hydrothermal area,this paper transforms the mineralization conditions to corresponding parameters in the FLAC3 D software,and achieves the simulation reappearance of polymetallic sulfide mineralization process.(5)Combined with quantitative assessment and simulation analysis,this paper carries out a new method to delineate the most favorable metallogenic locations of the sulfide in prospecting targets.It can reduce the multiple solutions of comprehensive quantitative prediction and decrease the uncertainty of metallogenic process simulation,and finally increase the probability of prospecting.