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2003 Vol. 14, No. 3

Display Method:
Past and Future of Mathematical Geology
Frederik P Agterberg
2003, 14(3): 191-198.

This is a brief review of alternative methods of problem-solving in geoscience with emphasis on the role of mathematical geology. It is desirable to maintain a clear-cut distinction between reliable facts which can be stored in data banks and concepts that can be incorporated in the specifications of statistical models designed for specific purposes. If possible, subjective probabilities should be incorporated in hypotheses that are to be tested by statistical inference. KEY WORDS: mathematical geology, history of geoscience, use of computers, conceptual models, probability, statistics.

Fractal and Multifractal Modeling of Hydrothermal Mineral Deposit Spectrum: Application to Gold Deposits in Abitibi Area, Ontario, Canada
Qiuming Cheng
2003, 14(3): 199-206.

A number of fractal/multifractal methods are introduced for quantifying the mineral deposit spectrum which include a number-size model, grade-tonnage model, power spectrum model, multifractal model and an eigenvalue spectrum model. The first two models characterize mineral deposits spectra based on relationships among the measures of mineral deposits. These include the number of deposits, size of deposits, concentration and volume of mineral deposits. The last three methods that deal with the spatial-temporal spectra of mineral deposit studies are all expected to be popularized in near future. A case study of hydrothermal gold deposits from the Abitibi area, a world-class mineral district, is used to demonstrate the principle as well as the applications of methods proposed in this paper. It has been shown that fractal and multifractal models are generally applicable to modeling of mineral deposits and occurrences. Clusters of mineral deposits were identified by several methods including the power spectral analysis, singularity analysis and the eigenvalue analysis. These clusters contain most of the known mineral deposits in the Timmins and Kirkland Lake camps.

Theory and Method of Mineral Resource Prediction Based on Synthetic Information
Shicheng Wang, Shuisheng Ye, Dongdai Zhou
2003, 14(3): 207-214.

Metallogenic prognosis of synthetic information uses the geological body and the mineral resource body as a statistical unit to interpret synthetically the information of geology, geophysics, geochemistry and remote sensing from the evolution of geology and puts all the information into one entire system by drawing up digitalized interpretation maps of the synthetic information. On such basis, different grades and types of mineral resource prospecting models and predictive models of synthetic information can be established. Hence, a new integrated prediction system will be formed of metallogenic prognosis (qualitative prediction), mineral resources statistic prediction (determining targets) and mineral resources prediction (determining resources amount).

Simulating Some Complex Phenomena in Hydrothermal Ore-Forming Processes by Reaction-Diffusion CNN
Deyi Xu, Chongwen Yu, Zhengyu Bao
2003, 14(3): 215-219.

Complexity phenomena like dynamic and static patterns, order from disorder, chaos and catastrophe were simulated by the application of 2-D reaction-diffusion CNN of two state variables and two diffusion coefficients transformed from Zhabotinksii model. They revealed somehow the mechanism of hydrothermal ore-forming processes, and answered several questions about the onset of ore forming.

Spatial Database of Geological Survey Extent in 20th Century in China
Quanming Wang, Tianzhu Ye, Yiping Fang, Jianguo Chen, Shuyu Li, Daquan Zhang
2003, 14(3): 220-226.

During the whole 20th century in China, especially the latest 50 years, we have gotten much geological information about geological mapping, geophysics, geochemistry, mineral exploration, remote sensing, environmental geology, hydrogeology, engineering geology and oceanic geology etc. by our geologists and explorers. All the information has been accumulated and can be used as a decisionmaking foundation for the future plan of geological survey. The spatial database of geological survey extents has been established by using computer technology. The database contained all kinds of exploration sections and collected about 160 000 records in this database. This paper introduces the data construction, contents and applying system of this database, and trys to let people know what kinds of geological survey were finished, when the exploration were carried out, and how and where you can get this information.

Theoretical Study on Stochastic Modeling of Combined Gravity-Magnetic-Electric-Seismic Inversion and Its Application
Hanjie Yan, Hong Yan, Yunping Li, Xiaofeng Zhang
2003, 14(3): 227-233.

As gravity field, magnetic field, electric field and seismic wave field are all physical fields, their object function, reverse function and compound function are certainly infinite continuously differentiable functions which can be expanded into Taylor (Fourier) series within domain of definition and be further reduced into solving stochastic distribution function of series and statistic inference of optimal approximation. This is the basis of combined gravity-magnetic-electric-seismic inversion of stochastic modeling. It is an uncertainty modeling technology of combining gravity-magnetic-electric-seismic inversion built on the basis of separation of field and source gravity-magnetic difference-value (D-value) trend surface, taking distribution-independent fault system as its unit, depths of seismic and electric interfaces of interests as its corresponding bivariate compound reverse function of gravity-magnetic anomalies and using high order polynomial (high order trigonometric function) approximating to its series distribution. The difference from current dominant inversion techniques is that, first, it does not respectively create gravity-seismic, magnetic-seismic deterministic inversion model from theoretical model, but combines gravity-magnetic-electric-seismic stochastic inversion model from stochastic model; second, after the concept of equivalent geological body being introduced, using feature of independent variable of gravity-magnetic field functions, taking density and susceptibility related to gravity-magnetic function as default parameters of model, the deterministic model is established owing tobetter solution to the contradiction of difficulty in identifying strata and less test analytical data for density and susceptibility in newly explored area; third, under assumption of independent parent distribution, a real modeling by strata, the problem of difficult plane closure arising in profile modeling is avoided. This technology has richer and more detailed fault and strata information than sparse pattern seismic data in newly explored area, successfully inverses and plots structural map of Indosinian discontinuity in Hefei basin with combined gravity-magnetic-electric-seismic inversion. With development of high precision gravity-magnetic and overall geophysical technology, it is certain for introducing new methods of stochastic modeling and computational intelligence and promoting the development of combined gravity-magnetic-electric-seismic inversion to open a new substantial path.

Application of GIS in Mineral Resource Prediction of Synthetic Information
Shuisheng Ye, Shicheng Wang, Deqiong Li
2003, 14(3): 234-241.

This paper introduces the formation mechanism and synthetic information prediction of large and superlarge deposits in Shandong Province by analyzing and studying on the GIS platform. The authors established a prospecting model of synthetic information from large and superlarge gold deposit concentration region, and the multi-source spatial database from concentration region of deposits and anomalies. On the basis of the spatial database, a target map layer, a model map layer and a predictive map layer were set up. Based on these map layers, geological variables of the model unit and predictive unit were extracted, then launched location and quantitative prediction of the gold deposit concentration region. The achievement of predicting large and superlarge deposits by the GIS platform has enabled the authors to design automation (or semi-automatic) interpretation subsystems, namely geophysics, geochemistry, geologic prospecting and comprehensive prognosis, and a set of the applicable GIS software for mineral resources prognosis of synthetic information.

An Improved Dynamic Programming Method for Automatic Stratigraphic Correlation
Hanjie Yan, Hong Yan, Zhucong Xiang, Yanjiang Wang
2003, 14(3): 242-244.

An improved dynamic programming algorithm is proposed for reducing the possible mismatching of layer in multi-well correlation. Compared with the standard dynamic programming algorithm, this method restricts the searching range during layer matching. It can not only avoid possible mismatching between sample and target layer, but also reduce the time spent on layer correlation. The result of applying the improved methods on the data processed by standard method before indicates that the improved one is more effective and timesaving for the multi-well correlation system than conventional dynamic programming algorithm.

Quantitative Prediction of Concentrated Regions of Large and Superlarge Deposits in China
Shicheng Wang, Zhenyu Zhao, Yutian Wang
2003, 14(3): 245-249.

Identification and quantitative prediction of large and superlarge mineral deposits of solid mineral resources using the mineral resource prediction theory and method with comprehensive information is carried out nationwide in China at a scale of 1∶5 000 000. Using deposit concentrated regions as the model units and concentrated mineralization anomaly regions as prediction units, the prediction is performed on GIS platform. The technical route and research method of locating large and superlarge mineral deposits and principle of compiling attribute table of independent variables and functional variables are proposed. Upon methodology study, the qualitative locating and quantitative predicting mineral deposits are carried out with quantitative theoryⅢ and characteristic analysis, respectively, and the advantage and disadvantage of two methods are discussed. This research is significant for mineral resource prediction in ten provinces of western China.

Spatial Database Management System of China Geological Survey Extent
Jianguo Chen, Zhijun Chen, Quanming Wang, Yiping Fang
2003, 14(3): 250-256.

The spatial database management system of China geological survey extent is a social service system. Its aim is to help the government and the whole social public to expediently use the spatial database, such as querying, indexing, mapping and product outputting. The management system has been developed based on MAPGIS6.x SDK and Visual C++, considering the spatial database contents and structure and the requirements of users. This paper introduces the software structure, the data flow chart and some key techniques of software development.

An Approach to Spectral Discrimination of Rocks Using ASAI and Rough Sets
Zhenfei Zhang, Guangdao Hu, Mingguo Yang, Xing Liu, Zhenhai Wang, Wenhui Li, Xiaobing Zhang, Li He
2003, 14(3): 257-260.

Field data of outcrop spectrums provide important basis for modeling of hyper-spectral remote sensing aiming at mineral prospecting. We make an approach to the application of rough set theory in spectral discrimination of rocks. We build a decision table with an adequate number of samples (outcrops) of known rock type (the universe), of which the conditional attributes are discretized 'area spectrum absorption indexes' (ASAI) corresponding to wavelength intervals, and the decision attribute is rock type. We search to obtain the exhaustive set of reducts of the table, each of which will serve as a variable number of deduction rules. Suppose we have n (usually a very big number) rules in total and there are m types of rocks in our universe, for any unknown sample, we judge its rock type by each of those rules. An unknown sample may be recognized as a different type by different rules because it is outside our universe, and we accept the most frequent judgment result and ignore the other m-1 types of results. Our ASAI is an improvement upon the traditional spectrum absorption index (SAI), better applicable to field spectrums: given a spectrum curve and a wavelength interval, we take the average reflectance within the interval as a base line and let ASAI=abelow/(aabove+abelow), where abelow and aabove stand for total areas, bounded by the curve, the base line and the borders of the intervalbelow and above the base line respectively. With the equipments of FieldSpectr Fr (made by ASD Co., US), we collected data from Baiya gold deposit, Yunnan, and applied the above method to discriminate altered rocks as an experiment. The results show satisfactory performance of the method.

Development of Geological Data Warehouse
Zhenhua Li, Guangdao Hu, Zhenfei Zhang
2003, 14(3): 261-264.

Data warehouse (DW), a new technology invented in 1990s, is more useful for integrating and analyzing massive data than traditional database. Its application in geology field can be divided into 3 phrases: 1992-1996, commercial data warehouse (CDW) appeared; 1996-1999, geological data warehouse (GDW) appeared and the geologists or geographers realized the importance of DW and began the studies on it, but the practical DW still followed the framework of DB; 2000 to present, geological data warehouse grows, and the theory of geo-spatial data warehouse (GSDW) has been developed but the research in geological area is still deficient except that in geography. Although some developments of GDW have been made, its core still follows the CDW-organizing data by time and brings about 3 problems: difficult to integrate the geological data, for the data feature more space than time; hard to store the massive data in different levels due to the same reason; hardly support the spatial analysis if the data are organized by time as CDW does. So the GDW should be redesigned by organizing data by scale in order to store mass data in different levels and synthesize the data in different granularities, and choosing space control points to replace the former time control points so as to integrate different types of data by the method of storing one type data as one layer and then to superpose the layers. In addition, data cube, a wide used technology in CDW, will be no use in GDW, for the causality among the geological data is not so obvious as commercial data, as the data are the mixed result of many complex rules, and their analysis always needs the special geological methods and software; on the other hand, data cube for mass and complex geo-data will devour too much store space to be practical. On this point, the main purpose of GDW may be fit for data integration unlike CDW for data analysis.

Accessing Multi-Source Geological Data through Network in MORPAS Software System
Hongbo Mei, Guangdao Hu, Jianguo Chen, Zhenhua Li
2003, 14(3): 265-268.

MORPAS is a special GIS (geographic information system) software system, based on the MAPGIS platform whose aim is to prospect and evaluate mineral resources quantificationally by synthesizing geological, geophysical, geochemical and remote sensing data. It overlays geological database management, geological background and geological abnormality analysis, image processing of remote sensing and comprehensive abnormality analysis, etc.. It puts forward an integrative solution for the application of GIS in basic-level units and the construction of information engineering in the geological field. As the popularization of computer networks and the request of data sharing, it is necessary to extend its functions in data management so that all its data files can be accessed in the network server. This paper utilizes some MAPGIS functions for the second development and ADO (access data object) technique to access multi-source geological data in SQL Server databases. Then remote visiting and congruous management will be realized in the MORPAS system.

Application of Weights of Evidence to Mineral Potential Mapping of Yujiacun Ore Field in Northwest Yunnan Province, China
Qinglin Xia, Pengda Zhao, Shouting Zhang
2003, 14(3): 269-273.

The multivariate information comprehensive processing technique is especially important at present to the digital mineral prospecting. However, the GIS-based weights of evidence have provided us with a powerful tool for the quantitative assessment of mineral resource potential. In this paper, the mineralization model is established, based on the achievements made by previous researchers, to mend such deficiencies as few references on ore fields in Yujiacun, Yunnan Province and the shortage of quantitative prediction and assessment of mineral resources. In addition, the weights of evidence are used to make a systematic quantitative prediction and assessment of mineral resources there, so that 2 mineral prospecting target areas of grade Ⅰand 8 mineral prospecting target areas of grade Ⅱ are delineated, providing the further mineral resource exploration with the basis for the selection of mineral deposits.

Grade-Tonnage Model of Porphyry Copper Deposits of China
Xueping Wang, Min Wei, Lipei Yang, Jingman Zhao
2003, 14(3): 274-277.

A grade-tonnage model is established according to the analysis of 72 porphyry copper deposits recorded in "The Mineral Resources Data Base of China". Based on the analysis of frequency histogram, the cumulative frequency distributing graph and the theoretical model with double logarithmic coordinates of copper deposits, the typical mathematical characteristics of grade-tonnage model of porphyry copper deposits are clarified.

Image Processing on Geological Data in Vector Format and Multi-Source Spatial Data Fusion
Xing Liu, Guangdao Hu, Yubao Qiu
2003, 14(3): 278-282.

The geological data are constructed in vector format in geographical information system (GIS) while other data such as remote sensing images, geographical data and geochemical data are saved in raster ones. This paper converts the vector data into 8 bit images according to their importance to mineralization each by programming. We can communicate the geological meaning with the raster images by this method. The paper also fuses geographical data and geochemical data with the programmed strata data. The result shows that image fusion can express different intensities effectively and visualize the structure characters in 2 dimensions. Furthermore, it also can produce optimized information from multi-source data and express them more directly.

GIS Predictive Model for Producing Hydrothermal Gold Potential Map Using Weights of Evidence Approach in Gengma Region, Sanjiang District, China
F Bassam, Al Bassam
2003, 14(3): 283-292.

Gengma region, Sanjiang district is known to have some large-scale gold deposits. GIS predictive model for hydrothermal gold potential was carried out in this region using weights of evidence modeling technique. Datasets used include large-scale hydrothermal gold deposit records, geological, geophysical and remote sensing imagery. Based on the geological and mineral characteristics of areas with known gold occurrences in Sanjiang, several geological features were thought to be indicative of areas with potential for the occurrence of hydrothermal gold deposits. Indicative features were extracted from geoexploration datasets for use as input in the predictive model. The features include host rock lithology, geologic structures, wallrock alteration and associated (volcanic-plutonic) igneous rocks. To determine which of the indicative geological features are important spatial predictors of area with potential for gold deposits, spatial analysis was done through the modeling method. The input maps were buffered and the optimum distance of spatial association for each geological feature was determined by calculating the contrast and studentized contrast. Five feature maps were converted to binary predictor patterns and used as evidential layers for predictive modeling. The binary patterns were integrated in two combinations, each of which consists of four patterns in order to avoid over prediction due to the effect of duplicate features in the two structural evidences. The two produced potential maps define almost similar favorable zones. Areas of intersections between these zones in the two potential maps placed the highest predictive favorable zones in the region.