Numerical Simulation And Concealed-Ore Three-Dimensional Prospectivity In Northwestern Jiaodong Mining District,China

The northwest Jiaodong area is the largest gold accumulation area in China,which is located in the uplift metallogenic belt of the northwest Jiaodong Peninsula and occupies more than 90% of the gold reserves in jiaodong area.Although predecessors have carried out a lot of research on the structural characteristics,genesis and evolution of Northwest Jiaodong gold deposit,but the deep dynamic process and shallow structure-fluid coupling mineralization,have not formed a consistent understanding.In addition,the relationship between metallogenic structure characteristics and mineralization space is lack of quantitative expression,and the metallogenic dynamic environment plays a crucial role in the large-scale mineralization of Jiaodong gold deposit.In this paper,we selected the typical deposits in the Sanshandao,Jiaojia and Zhaoping faults in the northwest of Jiaodong to collect various exploration data and metallogenetic structural analysis data and to conduct 3D modeling of geological bodies and faults.We comprehensively carry out numerical simulation of metallogenic dynamics at regional scale,ore belt scale and ore deposit scale system to understand the characteristics of tectonic deformation and fluid activity in regional metallogenic period.This paper discusses the metallogenic evolution process of Northwest Jiaodong gold deposit from the force-heat-flow,and the control effect of tectonic deformation on the spatial distribution of ore deposits and orebodies.In addition,the extraction of numerical simulation metallogenic information and three-dimensional metallogenic prediction carried out to identify the deep mineralization potential area of typical deposits in northwest Jiaodong area,to improve the understanding of the genesis of northwest Jiaodong gold deposit,and provide theoretical support and prospecting ideas for the resource exploration in northwest Jiaodong area.The achievements and innovative of this paper are as follows:(1)Tectonic stress background is the key factor of gold deposit formation in jiaodong area.A series of stress tests carried out on the NE trending sanshandao,Jiaojia and Zhaoping ore-controlling faults in northwest Jiaodong.The result show that the stress background of NE-SW trending stretching and NW-SE trending compression during mineralization in northwest Jiaodong,which resulted in strike slip of local faults.The numerical simulation results show that the deformation has a good correspondence with the location of ore deposits.(2)Gold mineralization is the result of the coupling of mineralizing structures and hydrothermal activities.The driving force for the transport of mineralizing fluids comes from the fluid potential difference caused by regional tectonic stresses and brittle activity in fault zones.The regional tectonic stress background is consistent,and the fracture activity characteristics are the same.The structural control fluid transport provides favorable conditions for the precipitation of gold,forming a large-scale gold mineralization effect in northwestern Jiaodong area.(3)There are similarities and differences in mineralization in different fault zones in northwest Jiaodong.The fault zone features geometric morphology and distribution of rock mass,the spreading deformation and the distribution of ore deposits are similar,the regional tectonic stress background is consistent,the characteristics of fluid activity are similar,and the distribution of ore bodies has the rule of equal spacing occurrence.The occurrence and shape changes of faults control the distribution of ore deposits,and the stress direction and magnitude determine the degree of tectonic deformation,and then control the fluid migration mode,which results in the difference of mineralization depth and type between the first and second steps of Sanshandao and Jiaojia fault zones.(4)Multi-scale numerical simulation have carried out systematically and comprehensively in the same area.The results of large-scale numerical simulation provide constraints for small-scale numerical simulation,while small-scale numerical simulation provides local details for large-scale numerical simulation.It makes up for the limitation of imprecise large-scale simulation and lack of basis for small-scale simulation conditions,and provides a numerical simulation research method from whole to part,from fuzzy to clear,and from generalization to concrete.(5)Gold mineralization has strong correlation with volume strain,shear strain and discharge rate.According to the statistical analysis of mineralized units and forced-heat flow ore-forming elements,we identify the key factors of forced-heat-flow.The ore bodies mainly occurred in the parts where shear strain,volume strain and divergence of fluid flow converged(6)We have established a set of prediction ideas for deep concealed ore bodies based on mechanical-thermal-flow coupling quantitative analysis and multidimensional structural ore-control information integration.According to the northwest of Jiaodong gold deposit metallogenic regularities and ore prospecting marks,using 3d geological modeling method,set up three-dimensional structure of ore-controlling structure,numerical simulation for mineralization,and the results combined with structural ore-controlling geological index,the methods of random forest model,deep learning,three dimensional metallogenic prediction work,and delineated 2 target area.