Application Of Gravity Inversion For Spatial Geological Mapping

This topic is in the field of gravity,geology and engineering. Though an example,this article has shown the concrete value and the effect of application by combining with the information of geologic and geophysical.Spatial geological mapping is a effective way, which is used for searching ores, finding out the characteristic and information about basal structure,shape,mate-rial composition and structure configuration of basin etc.. The spatial geological mapping exploiting the information offered by geophysical methods is one of the methods in geological mapping. It can improve the accuracy of geological mapping by processing and applying the materials of geology, geophysics and drilling.gravity and magnetic are referred to Field methods in the field of geophysics, their quantitative interpretation depends on accurate forward calculation, the researchers can chooses the model of two- dimensional, 2.5-dimensional or three-dimensional to simulate and calculate the body below the observer. This article uses 2.5D model (a prismatic body which has a polygonal cross-sections and terminated a finite distance along ) to discusse the theory, implementation method and visualizations to express about gravity 2.5 D inversions.And we take this model as the foundation, compute the gravity anomoly of a body below the observer. and regard 2.5D model as the besic cell of spatial geological mapping, produce dimensional geological model,depicte geologic structure and fracture ,etc. by changing the density contrast and shape of the body.The author combined with the information of drilling,geologic and geophysical .Putting forward the work-flow and implementation method of the gravity inversion method in spatial geological mapping.This article take the Tongling ore district as an example, illustrate the Application Of Gravity Inversion For Spatial Geological Mapping through many points such as the data processing, the collection and classification of about geology and drilling, the model establishment and revises, and so on. And has given the detailed inversion model. The model have shown the effects of application of gravity for spatial geological mapping. On the basic of understanding the geological data and stratum parameter about Tongling ore district, do some detailed inversion in the relevant regional. First of all, establish the preliminary 2.5D model of stratum and structure distribution according to the drilling information and related geological material. Secondly, based on the actual gravity data to modify the model. through human-computer interaction method, modify the model to make the curve, which produced by the 2.5D model, maximum limit similar with the survey anomaly curve. The primary data that we used is high precision gravity survey data, the scale is 1:50000. In the survey data processing, we have supplemented the gravity data, smooth and different depth analytic continuation as well as each kind of filter to the survey gravity anomaly in order to select the best data as the basis of gravity inversion. Understanding the related geological and drilling data mainly by surveying the drilling rock samples and reading the literature of the former work's research. In the article author carried on a detailed elaboration. The model is established and modified by using the three-dimensional gravity and magnetic inversion software—ModelVision Pro, which was produced in Australia.This article also has discussed some questions, which meets in the inversion process, such as multi-solution question, the boundary problem and the visualization question and propose some corresponding solution. Among them, the multi-solution question has been one of the difficulties in gravity inversion. Lots of scholars has carried on the detailed analysis and elaboration in view of this question. The author ues the way of combining many kinds of materials together in the example(including geologic structure material, rock properties material, physical prospecting material, drill bore material and so on)to restraint, and used the advance software of data processing to establish the model, though this way, we have a good result in reducing the influence of the multi-solution question. Finally, author have set up the geological models which vividly show the distributed characteristic of the formations, controlled the ore structure and the three-dimensional configuration related with mineralization as well as the distributed characteristic of the body. At the same time, this research is the first spatial geological mapping by combining kinds of materials together in the large ore district, and has exemplary role for others area like Tongling ore district.