A Lithological Mapping Test Based On 3D Inversion Of Gravity And Magnetic In Lu-zong Ore Concentration District

Mineral resources play an irreplaceable important role in the human economic and social development.With the deepening of the resources exploitation,many mines in Lujiang(Lu)-Zongyang(zong) ore concentration district fall into a crisis of exhaustion of resources.Lu-zong ore concentration district is one of the Ore Belt of the Middle and Lower Reach of the Yangtze River.To expand the deep prospecting space and to dig deep resource potential has become a strategic choice for the sustainable development of resources in China. By using geological, geophysical and geochemical detection technology, and combining with the geophysical inversion technique and 3-d visualization technology,to reveal the spatial morphology of the structure,rock and fracture within a certain depth,and track the extension of known deposits,or predict and locate the mineralization, though lithologic mapping to achieve Lu-zong ore concentration district transparent within 5km depth is the main way to realize deep fine structures study,to explore deep mineral resources and to reveal metallogenic regularity of large-scale ore district.In this paper,we took Lu-zong ore concentration district as an example,proposed lithologic mapping based 3D inversion of gravity and magnetic,and then carried out the lithologic mapping test. Based on the analysis of the relationship between lithology and density and magnetic susceptibility, 3D inversion with prior information of high-precision gravity and aeromagnetic data were carried out.Then,used logical topology operations between density 3D model and susceptibility 3D model obtained three-dimensional distribution of five main type lithologies in the Lu-zong ore concentration district within 5km depth. This paper includes following parts:(1)According to the current research result,analyzed the regional geology Lu-zong ore concentration district.(2)Summarized the integrated geophysical characteristics of Lu-zong ore concentration district,and made a research of the property.(3)Acording to the workflow of 3d inversion of gravity and magnetic,and the prior information of this research area,we carry out a 3D inversion of gravity and magnetic with the priori information’s constraints,and then analyzed the distribution of rock bodys according to the results of the inversion.(4) This study introduced the theories and methods of lithological mapping test based on three-dimensional inversion of gravity and magnetic inversion,and given the workflow of lithological mapping. Combining the study actual conditions, then transformed the lithological units in geological maps into properties unit,the property data was given to the grid mesh of 3D inversion,in order th to create the reference model,boundary model and smooth weights model.Through the inversion we obtained the 3D distribution model of the density difference and magnetic susceptibility,combined the research of properties data of Lu-zong ore concentration district,obtained the the relationship between physical properties and lithology,the lithologic mapping test was carried out.The results of 3D lithologic mapping test are as follows:①The distribution of high magnetic and high density rocks is limited,it reflects the ultrabasic rocks and magnetite;②Acid rock and syenites are widely distributed in the Luzong Basin,speculate there is a concealed acid rock zone hidden under the Quaternary,on the eastern side of the basin;③The diorite and complex rock distributed in Shaxi and other places,diorite porphyrite distributed more widely in Lu-zong basin;④Limestones distributed mainly in the east,north and south Lu-zong basin.The lithologic mapping results show that the characteristics of shallow agree the surface geological mapping results well.More importantly,the lithologic mapping results reflects the changes deep lithology units,this makes up for the deficiency of the surface geological mapping. The lithological mapping results of Lu-zong ore concentration district show that 3D lithologic mapping test based on 3D inversion of gravity and magnetic is an effective method of understanding the lithological characteristics of the lithology in deep ore concentration area and finding the deep mineral.