| In western China, mineral resources potential is tremendous, but geological exploration is low. So the scientific potentiality assessment for the western China’s advantage mineral resources, can provide the basis for the scientific deployment of mineral exploration work. Some molybdenum deposits were found in East Tianshan mountain area. These molybdenum deposits are with porphyry type primarily. Therefore, through the potential resources evaluation and analysis of molybdenum deposits with porphyry type in East Tianshan mountain area, some decision supports can be provided further in order to look for some new deposits. At the same time, through this evaluation research work, some new nonlinear mathematical evaluation method can be introduced to provide new thoughts in the the mineral resources evaluation in the future. So, for riching mineral resources evaluation method system, this work plays a certain promoting role.This paper based on the national science and technology support project:the research of potential evaluation technology and application on western advantage mineral resource (2006BAB01A01), achieved multisource metallogenic prediction for molybdenum resources in East Tianshan mountain area. The main achievements and new cognition as follows:1. Collecting the data of geological, geophysical exploration, geochemical exploration and remote sensing systematically in East Tianshan mountain area. And the processing of comprehensive analysis and extraction for the collected data included that:(1) fundamental geological information:the information of all the known deposits and mineralization points, different levels of let ore and the ore-controlling structures, mineralization relevant magmatic rocks information, mineralization belt, alteration zones,contact zones, ductile shear belts, contained mineral rock, etc.(2) geochemical anomaly information:drawing the39elements in the geochemical anomaly and comprehensive anomalies map of the area, and extracting and analyzing the the anomaly information with the area.(3) remote sensing information:Application of man-computer interactive interpretation method to extract the geological structure; using the principal component analysis, membrane technology and frequency histogram to extract the alteration of remote sensing information and drawing the remote sensing anomaly information maps.2. East Tianshan mountain area, as the one of the16major mineralization zones about solid mineral resources, is the important China’s ore-forming belt of nonferrous metal and precious metals. From the metallogenic history, the metallogenesis have happened since the Precambrian metallogeny (heavenly lake iron deposits, etc) to Paleozoic (Tuwu and Huangshan copper deposits, etc) and since the Mesozoic (Huge south lake coal, etc) to the new generation (some salt deposits). From geological features perspective, East Tianshan mountain area has some characteristics:completely strata distribution, various sedimentary build, complex geological structure environment, frequently magma activities, obvious metamorphic deformation effect. So, the region ore-forming geological conditions are the superior. From geological work ways, in general, the current work level is still relatively low. So, in recent years, investigation of the resources in the area broke new ground, some new deposits found, such as Tuwu porphyry type copper deposits, Pobei Cu-Ni sulfide deposits, East gobi molybdenum deposits, etc. Therefore, in conclusion, it can be argued that, it is very likely to discover some large even superlarge deposits from geological exploration in the future.3. Through the analysis of the regional geological data, the following cognition can be concluded:(1) The endogenous metal deposits in the distribution were relatively concentrated in the area. General characteristic of present is south iron, middle gold, north copper nickel. From structural environment, endogenous mineral resources are mainly generated in Junggar plot and Tarim plot of the terrigenous Paleozoic activities belt. From the spatial distribution law, endogenous mineral resources are mainly controlled by tectonic environment and the corresponding mineralization in the evolution process of earth’s crust is with a certain stage.(2) From the ore control conditions of porphyry type molybdenum deposits, the ore-controlling factors of this deposits type including:the neuter and acidic intrusive rocks, deep fault that control acidic intrusive rocks, second-order faults that control the development of orebody in place. In addition, there is a stronger development of wall-rock alteration in this type of molybdenum deposits generally, and the favorable mineralization strata were mainly distributed in the carboniferous. Tectonically, the fracture is given priority to NNE, the magmatism in Variscan period is favorable ore-controlling for the deposits type.4. In multi-source information processing, this paper statistically analysed stream sediments geochemical data in this area. The results indicated that there is a complicated nonlinear relation between the geochemical elements such as the fractal characteristics. This paper extracted the East Tianshan mountain geochemical anomaly information to delineate the geochemical element anomalies areas. For making the work reasonable and effective, the paper take the lead in the two methods including traditional logarithmic normal distribution truncated method and nonlinear method C-A multiple fractal method for the determination of abnormal information. Comparison of the two methods, the results showed that the latter determine the result was more accurate and reasonable.The author delineated the Mo and Cu abnormal area on the basis of the above results. In addition, in the remote sensing information processing work, this paper extracted a batch of line and ring type faults and altered anomaly areas. And on the basis, it has come to some of the potential metallogenic concealed rock mass. From the multisource information, it is indicated that the molybdenum resources in this area was with a good metallogenic prospects.5. This paper taking the multisource information prospecting model to study the metallogenic prediction for porphyry type molybdenum deposits in East Tianshan mountain area. First of all, the genetic mode and the output mode for porphyry molybdenum deposits were analysed systematically, all kinds of information for mineralization, ore-prospecting criteria and comprehensive anomaly information in detail were concluded. The relationship between affecting factors such as the metallogenic and ore-control regularity for porphyry type molybdenum deposits was learned. The5prediction variables types (stratum, geological structure, magmatic rocks, geochemical exploration and remote sensing) are used to establish the model.Due to the less samples for the konwn molybdenum resources in East Tianshan mountain area, the traditional mineral resources prediction methods such as weights of evidence method, characteristics analysis method and nonlinear BP artificial neural network method are not fit for molybdenum resources prediction in the area. In view of this, the paper took the lead in using Kohonen nonlinear artificial neural network method for the the less models prediction worLThis method is not dependent on the sample numbers of forecast area, implementing the principle of unsupervised classification. Classification results show that two typical molybdenum deposits fall into "A" class of mineralization favorable area. It is supposed to the classification effect was more credible. Prediction results show that the method has characteristic of simple operation. It is a kind of relatively fast and effective forecast method.6. The latest China’s mineral resource reserve data was collected comprehensively. The grade-tonnage model of national78porphyry type molybdenum deposits was established. The resource was estimated by Monte Carlo simulation. The forecast results of the porphyry type molybdenum resources that the proportion accounts for43.5%compared with the discovered resources with90%probability. The forecast resources results of porphyry type molybdenum show that there is still some of the prospecting potential in East Tianshan mountain area. |
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