The Geological Features And 3 Demensional Modeling And Application In Luobusha Chromite Deposit, Tibet

The chromite deposit of Luobusa in Qusum County,Tibet, is the largest industrial chromite deposits in China, it is also one of the most typical mineralization conditions in the world. Chromite stone of its annual output accounting for about 80% of nation annual output. After 20 years of mining, the chromite deposit of Luobusa has consumed more than half of its proven reserves, its maintain reserves is less than 2 million tons, it will be mining out in next 10 years. So, searching for substitute resources has become one of the major problems that should be solved. we are still not clear about how the chromite body distribute in three dimensions, and what is the attitude of the chromite bodys, also the relationships between the chromite bodys up to now. The geological conditions is so complicated, the laws of the mineralization of deposit has not been understood fully, brings the mining and the prospecting to deep or surround much difficulty. Therefore,this article works on the 3-dimensional visual modeling for the deposit, hopefully we can explore and sum up the low of the distribution of the entire deposit, furthermore we can research on the metallogenic regularity and the features that controlled the chromite body.3-Dimensional modeling is a new method for researching on economic geology. After comparing the 3-Dimensional modeling softwares with each other,we finally chose MEMAPGIS, which has been developed by the Development Research Center of China Geological Survey, as the 3-Dimensional modeling platform for chromite deposit of Luobusa. After fullly collecting the basic geological data of the deposit,we use the software to build a drilling database,which include the information about the drilling location, the drilling suvey and the analysis of drilling samples.Based on the drilling database,we have made the drillings visualized in the 3-Dimensional space, and display the coordinates of the drill holes in three-dimensional space, and the information about how the drillings change in three-dimensional, also the spatial extension of the direction and the angle of the drillings,and also display the data of all kinds of the samples of drillings at different depth. We use the creating tools of the interactive 3D modeling software MEMAPGIS, base on the shape of the chromite body that projected on the sectiong plane,to construct the general occurrence of the chromite body in 3-Dimensional space. According to the topology theory, we built the solid model of the chromite deposit of Luobusa that can be saw from any angle in three-dimensional space.According to the display of the 3-Dimensional solid model, we conclude a feature that the distribution of the chromite body on the section plane occur like the imbrication,and pinch out to the side of reproduction. The chromite body generally south slope, Distributed along zones,appeared in groups, and concentrated on section. Based on this 3-Dimensional model, we preliminarily discuss the emplacement mechanisms of the Luobusha ultrabasic rocks and the formation model of the chromite body, and preliminarily predict the prospecting area that may have chromite bodys. This modeling is a successful attempt that using the modern information technology in mining geological work.