| Since the 21 st century,the economic development of China enters into a new norm of structural optimization,speed variation and dynamic transformation,which makes the mineral resources exploration facing unprecedented opportunities and challenges.On the one hand,with the rapid development of globalization,the economic development of China needs a lasting support for geological prospecting.On the other hand,with the global economic situation is complex and changeable,the mining market has been shrinking and the price of mineral resources has been decreasing,which needs more mineral resources.However,the surface mine,shallow mine and easily identifiable ore having been exhausted,the geological prospecting has been developing in the deep of earth,which forces the traditional methods to be updated effectively.To obtain the deep mineral resources,it needs new methods and techniques to mineral exploration urgently.Nowadays,the primary halo geochemistry is the important technology to mineral deposit prediction.The principle prospecting of primary halo geochemistry according to elements in the spatial distribution and assemblage characteristics can reflect the microscopic traces procession of hydrothermal ore-forming,such as the movement,migration,precipitation and enrichment,which is useful for the quantitative prediction.Identifying “anomaly” is important of mineral deposit prediction in primary halo geochemistry.Traditional identify anomaly methods with mean and variance Sanpei method,cumulative frequency method probability paper method and singularity theory,etc.However,each method has its own conditions to identifying geochemistry anomaly,it is necessary to select appropriate theoretical algorithm to identify anomaly in the different geological background.The observations of the geochemical anomalis are located in the tail of the samples,which are related to the random characters in theprocess of quantification at the very large or small level and estimate the probability of the extreme event in the existing observation levels—these characteristics are also the contents of the EVT.The EVT is a branch of statistics that studies the limiting distribution of the minimum and maximum value and evaluates the risk of extreme events.Therefore,the mathematical foundation of the geochemical anomaly is described by the EVT.So the new GPD model of geochemical anomaly is designed.The parameters and threshold of the model is demonstrated in the paper.Use the new GPD model to identify anomalies in the Jiguanzui Cu-Au mining area,the results show that the designed model can effectively identify the anomalies regions of elements,which is consistent with the ore body trend.The regions are also content with what the cumulative frequency method identifying.After the diagnostic test of the results,The results show that the theoretical distribution of the elements are consistent with the actual distribution of the elements,which shows the ability of the GPD model to identify the geochemical anomaly is feasible.In addition,the core hyperspectral prospecting is another important exploration technique to mineral deposit prediction.In the range of visible spectrum of near infrared and short wave infrared,the core hyperspectral technique can be got the pop curve of minerals by diagnosing minerals,then the mineral assemblage can be extracted,because the spectral curves characteristics of minerals have their own indicating information.Establishing the reasonable standard spectra and matching the mineral effectively are very important for mineral deposit prediction in core hyperspectral.Selecting standard spectrum must be combined with the actual geological conditions,USGS standard spectrum and the rock identification results by experts.In the PIMA View,it can be analysis the waveform,reflectivity,peak value,wavelength of the spectrum and standard spectrum.Then testing the calculation,classification,fitting,matching of spectral,it can be obtained the types of minerals.The matching results of minerals are consistent with the mineral cores of the original histogram and the rock identification results by experts,so the spectral curve matching method in this paper is accurate and reliable,and thus obtains the prospecting criteria of the core hyperspectral.The primary halo geochemistry and the core hyperspectral play an important role in the geological prospecting.However,each of them is single methods to mineral deposit prediction.The elements of primary halo geochemistry and the minerals of core hyperspectral have relationships,so the rough set model can be used to form an integrated information system or decision table of them.Then use the discernibility function to reduction of them,it can be got the association rules between elements and minerals,through analysing the mechanism of anomaly,it can be form a new quantitative method for deep ore prospecting.Coupling modeling with rough set,it can be determined the best prospecting indicators for deep mineral prediction,it can not only reduce the multi solution of the single ore prospecting method,but also supplement and perfect the representative and timeliness of lithologic identification.This paper takes the No.26 line,VII ore body at the Jiguanzui Cu-Au mining area in Hubei,China,as an example.Through coupling modeling with rough set,it has been gotten the association rules of elements and elements,elements and minerals,minerals and minerals.So the prospecting markas can be gotten as follows:(1)prospecting indicators of elements combination: {Cu?Au?Mo?Ba?Ag?Pb};(2)prospecting indicators of minerals assemblage: {Marble(calcite+dolomite),(chalcopyrite+Pyrite+Molybdenite),Chlorite,Plagioclase};(3)prospecting indicators of elements and minerals: {Cu,(chalcopyrite+Pyrite)};(4)prospecting indicators of elements and minerals: {Mo,Molybdenite}.Through the comprehensive information of primary halo data,the core spectrum interpretation and coupling prospecting indicators,we have predicted a molybdenum blind ore body,where it located in the-1100 m under the drilling KZK10 and KZK11 in the 26 exploration line. |
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