Research On The Synthetic Metallogenic Information And The Positioning Location And Quantitative Prediction Of Resource Orientation For Lancang-Laochang Lead Zinc-polymetallic Deposit

The doctoral dessertation title of Research on the Synthetic Metallogenic Information and the positioning location and quantitative Prediction of Resources Targets for Lancang-Laochang Lead Zinc-polymetallic Deposit is selected based on the cooperative item of Yunnan province and China academy/university of research on the reserves increase and the stereo prediction of deposits of Lancang-Laochang Silver Lead Zinc-polymetallic Deposit (serial number: 2003ADBEA34A025) which I preside in.The research goal is to evaluate the metallogenic geological settings and study the metallogenic laws systematically with the purpose of mineral exploration prospect for Lancang-Laochang Lead Zinc-polymetallic Deposit. Based on the application of new technologies, new theories or disciplines such as Digital information and computer technology, Remote sensing for deposits, Paleotectonics and paleolithofaces, Geochemistry, Geophysics, Mathematical Geology, Geographic information system (GIS) etc., the author has analyzed the spatial information of geological information, geophysical information, geochemical information and remote sensing information wholly with the help of the second developing software desktop of GIS, studied the changeable law of variables, established the quantitative and stereo mineral prospecting modes, specified and optimized the quantitative Prediction of Resources Targets. From these research items, the following conclusions have been drawn:No.1 Metallogenic geotectonic environments: Through the analysis or differentiation of the tectonic geological structure environment which formed the deposit with the characteristics of the petrochemistry and petrogeochemistry of the volcanic rocks, the author concludes that the volcanic rocks in the Lancang-Laochang Lead Zinc-polymetallic Deposit district belong to the rock types of basalt-andesite series such as alkalescence basalt, coarse face basalt and so on. According to the geochemical characteristics such as high contents of TiO₂, right inclination type of rich LREE ration curve, right inclination type of primary mantle standardized curve of microelement, high content of Nb, Zr, Th, we can think the vocanic rocks have the continental features. And the illustration of the Th/Hf-Ta/Hf for tectonics environment judgement indicates that the basalts are formed in the condition of continental ridge. No.2 The relationship between vocanic rocks's lithofacies and orebodies: The lithofacies of the vocanic rocks can be divided into four types: eruption, overflow, eruption sediment and extrude, meanwhile eruption sediment is very closed to orebodies. There is a direct relationship between the eruption sediment face and the orebodies in C₁⁸. The orebodies are often found in the definite thickness ,usually over 5m, tuff which has formed in the condition of faults. The orebody of C₁⁷, with the only relationship to the eruption sediment face, lies on the top part of the eruption sediment face. It mostly relates to the light black, black tuff or hoar andesite-like tuff. The orebodies in C₁⁵⁺⁶ almost lie on the eruption sediment face. They mostly relate to the grey-black tuff, the hoar or grey-black andesite-like tuff and marble. So, there is a definite relationship between the orebodies and the eruption sediment face.No.3 Geochemistry deposit: The approximate mean content of Pb isotope in the ore and wallrocks (carbonate rocks, volcanic rocks and granite porphyry) indicates the sources of Pb from these types of rocks are inherently related. From the construct Pb mode map, we can see that the source of Pb in the ore is very complex and the Pb belong to crust-mantle admixture Pb. The Pb in the volcanic rocks, carbonate rocks and part ore may all be from wallrocks (strata bearing original minerals).The Pb in the granite porphyry comes from the crust and there may be definite genetic relationship between it and deposit. The fact that the content of S isotope is near zero, with the characteristic of the S in the meteorolite, indicates the contents of S are mainly from basalts and partly from biology. According to the analysis of the calcites, the apparent differences between the comtent of d¹³C_PDB, varying from -7.2ω‰to +2.8ω‰with the mean value of -2.06ω‰, the comtent of d¹⁸O, varying from -0.18ω‰to +10.5ω‰with the mean value of +5.72ω‰and the comtent of d¹³C, varying from -5ω‰to -8ω‰, the comtent of d¹⁸O, varying from +6ω‰to +8.5ω‰indicate the C from the calcites in the orebody originates from magma or strata or the admixture of magma, strata and seawater, and the apparent differences between the comtent of dD,varying from -69.86ω‰to -93ω‰with the mean value of -86.8ω‰as well as the comtent of d¹⁸O_H2O,varying from -1.53ω‰to +9.21ω‰with the mean value of +3.62ω‰in the liquid inclusion of Quartz and the comtent of dD,varying from -50ω‰to -80ω‰as wellas the comtent of d₁₈O, varying from +6ω‰to +9ω‰indicate that the metallogenic liquid may be water from magma and seawater or atmospheric precipitation.No.4 Geophysical information: Five abnormal TEM low resistance areas, two abnormal electricity areas and two abnormal magnetic areas have been gotten through adopting the effective geophysical prospecting techniques such as TEM, IP and high precision of magnetism and so on. Based on the comprehensively calculated output of electricity and resistance sound, which are combined with geological characteristics from earth surface and drills, the stratum C₁ interface contour map has been acquired. So, by means of systematically geophysical prospecting, a large quantity of useful geophysical prospecting information has been obtained.No.5 Geochemistry of elements: It can be found after analyzing the sample analysis results from wallrocks and ores that the high value abnormity of the main metallogenic elements composition concentrates on the crossing points of the different faults, appearing around the crater structure occasionally. This indicates the metallogenic temperature is a little high because of the volcano environment. So, there are two available prospecting areas which lie in the high value abnormity of the north part of Beixiang mountain and the southwest part of the Nanxiang mountain. From the matrix table of the variance maximum vertical rotation, we can deduce two research outcomes: F1 factor bearing the weight of Cu-Pb-Zn-As-Sb-Hg-Ag-Au stands for the massive pyrite exhaiative hydrothermal sedimentary mineralization epoch and F2 factor bearing the weight of Cu-Pb-Zn-As-Sb-Hg-Be-Sn-Mo-Y-Cr-Se-Yb-V-Nb-Ni-Ga implies the superimposed mineralization on the hydrothermal sedimentary deposit by the intrusion of deeply concealed basic igneous rocks and acidity igneous rocks. Therefore, there are two main metallogenic epoch of sedimentation, reconstruction and overlapping.No.6 Remote-sensing technology: After RS information interpretation on the seven wave bands of the regional 1;200000 LandsatTM and the Quickbird data, the author gives an explain to the line-ring structure qualitatively , analyzes the density ,number, quantative of optimize and benefits and the mean orientation of line structure and interprets the RS geological comprehensive digital information quantatively. Adopting the data amalgamation, the author manipulates the RS data, geophysical data, geochemical data by means of PCA and establishes a deposit RS comprehensive information prospecting modes for the purpose of RS metallogenic information prediction. The research results make it clear that there is a close relationship between the mineralization information and the linear geological structure, and most deposits lie in the crossing parts of line and ring geological structure.No.7 Quantitative prediction: With the help of prospecting signs, mine control factors, the grid cell (0.1Km×0.1Km) calculating methods, the author has established the prospecting information value modes and calculated the simple variable information value, the compound variable information value, the comprehensive information value and predicting information value. At last, the critical prospecting information value (2.5). Based on the critical value, four favourable prospecting prediction targets have been pointed out. Some of them are validated effectively.