TN369 : Modeling and interpretation of electrical soundings to determine the depth and thickness of the deposit and accurate recognition of karstic zone bedrock in one of Jajarm bauxite mines
Thesis > Central Library of Shahrood University > Mining, Petroleum & Geophysics Engineering > MSc > 2011
Authors:
F.momeni [Author], Abolghasem Kamkar Rouhani[Supervisor], Ali Reza Arab-Amiri[Supervisor]
Abstarct: Exploration methods are divided into two categories: direct and indirect methods. Direct methods such as exploration drilling are expensive, slow and possess high accuracy. However geophysical methods are among indirect methods that need low time and cost and also explanation and interpretation of their results are difficult. In this research, the efficiency of electrical sounding method to distinguish the ore or mineral laxyer in karstic bauxite deposit with rough topography of earth surface is investigated. For this purpose, in Taguee 4 & 5 bauxite mineral area, 82 electrical soundings on 3 lines have been planed and surveyed. Taguee region is one of the Jajarm bauxite mines, in which extraction activities have been carried out rarely and most drillings have been made for exploration purpose. In this work, Frist, the acquired data have been interpreted using standard curves and then, the obtained results have been modeled by IX1D, VES & IPI2WIN software packages. Thus, using IX1D software abilities, apparent resistivity data have been inverted directly by Occam and ridge regression methods. Comparison of the results of both methods shows that although ridge regression is superior in terms of fitting parameters to the model, but using this method for a ground with many laxyers results in very intense variations in resistivity of laxyers. On the other hands the inaccuracy to recognize the edge of laxyers by the Occam method and hiding some laxyers in this method cause difficulty in interpretation. Thus, it is preferred that depending on condition of actual earth model, either methods or both are used. The results of 1D modeling show at least, 4 geoelectrical laxyers in Taguee area that take place in the limits of Jajarm bauxite mines. For comprehensive understanding of the results, we have presented them in three 2D section and a 3D representation. In next phase, on the primary data, 2D smooth modeling have been made using Res2dinv software package. The obtained sections have been interpreted and compared with the results of 1D inversion.From investigation the results of 1D & 2D inversion, it is concluded that because of enough resistivity contact between the bauxite and dolomitic bed rock, the recognition of the baxsement is possible. Both bauxite and dolomite laxyer are This laxyer is steep and the bed rock possesses very rough topography, as the depth of lower edge of bauxite laxyer forecast between 20 to 70 meters. Despite this, due to the low resistivity contrast between the kaolinite bauxite and upper laxyers, the recognition of upper laxyers and thus, determination of the mineral laxyer thickness is difficult.
Keywords:
#Electrical sounding #2D smooth modeling #Inversion modeling #Occam method #Ridge regression #Bauxite. Link
Keeping place: Central Library of Shahrood University
Visitor: