首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 93 毫秒
1.
The statistical technique of discriminant analysis is used to define target areas for detailed general exploration given only general geological information and aeromagnetic anomaly blues. In the test area, located in Central Norway, on-going exploration surveys have revealed the presence of mineralization; however, it still has not been determined if any of the sites will beeconomically feasible. The area was divided into 1400 1-km × 1-km cells by superimposing square grid on 1:50,000-scale geological and geophysical maps. Later the area was divided into two subareas based on major differences in each area's geology. A number of geological natures and the aeromagnetic anomaly values were coded systematically in each cell. The cells representing an advanced degree of exploration were chosen as control cells in each of the subareas. The geological and geophysical parameters were transformed, by means of relatively simple transformations, to produce near-normal frequency distributions. A discriminant function was then obtained by discriminant analysis to divide the control data into two groups, cells with presence of mineral occurrence and cells without mineral occurrence. the discriminant function obtained for the control area proved to be relevant both geologically and statistically. Consequently, the discriminant equation was applied to cells outside the control area. The cells were assigned to one of the two groups by entering the geologic factors pleasured from the maps into the discriminant model. The exploration potential of a large number of cells was evaluated by this procedure. To test the results, field work including geochemical sampling was carried out in the cells with highest probability of mineral occurrance The field work results have shown that the application of discriminant analysis to geological information at 1:50,000 scale with 1-km × 1-km cells combined with a careful selection of techniques for transforming the variables is a feasible method for predicting gaeralization, and as such could become a valuable tool for mining exploration.This paper was presented at Symposium 116.3, Quantitative Strategy for Exploration, held as part of the 25th International Geological Congress, Sydney, Australia, August 1976.  相似文献   

2.
The known palaeontological and stratigraphical evidence is used as a basis for the construction of maps of the continents showing the extent of their inundation by the sea in Sakmarian time in the Upper Palaeozoic. In the northern hemisphere apart from India the evidence is sufficiently reliable to give reasonable maps, and the great extent of the inundations suggests that the climate would be considerably modified from that of today; no undoubted Sakmarian glacials occur there. In Southern continents and India, the Gondwana biogeographical province has made correlation with the northern continents controversial, but reasons are given for assuming that Gondwana glacial deposits were at least in part Sakmarian; the resultant maps show that the Gondwana land surfaces were but little reduced in area, and that the main glacials (except for India) lie within a belt between 40 S and 20 S. Present lack of knowledge of Sakmarian conditions in Antarctica makes reconstructions of climatic belts too hazardous for possible use in enunciating or checking hypotheses of continental drift and polar wandering.  相似文献   

3.
Multivariate statistical techniques have been widely utilized to assess water quality and evaluate aquatic ecosystem health. In this study, cluster analysis, discriminant analysis, and factor analysis techniques are applied to analyze the physical and chemical variables in order to evaluate water quality of the Jinshui River, a water source area for an interbasin water transfer project of China. Cluster analysis classifies 12 sampling sites with 22 variables into three clusters reflecting the geo-setting and different pollution levels. Discriminant analysis confirms the three clusters with nine discriminant variables including water temperature, total dissolved solids, dissolved oxygen, pH, ammoniacal nitrogen, nitrate nitrogen, turbidity, bicarbonate, and potassium. Factor analysis extracts five varifactors explaining 90.01% of the total variance and representing chemical component, oxide-related process, natural weathering and decomposition processes, nutrient process, and physical processes, respectively. The study demonstrates the capacity of multivariate statistical techniques for water quality assessment and pollution factors/sources identification for sustainable watershed management.  相似文献   

4.
Summary Rare garnet-spinel pyroxenite xenoliths occur in some basaltic tuff-breccia levels of Miocene age from the Valle Guffari (Hyblean Plateau, Sicily), together with a number of spinel-bearing mantle xenoliths. The garnet-bearing pyroxenites may be divided into two groups (a and b) on textural and mineralogical bases. Garnet-bearing spinel websterites with a fully recrystallized texture represent the first group (a). Here the garnet (Py54.5 A1m32 Gr13.5), with a diffuse kelyphitic alteration, forms a reaction corona between coarse spinel grains and the in contact pyroxenes. The transition from the spinel-pyroxenite to the garnet-pyroxenite field may depend on isobaric cooling from higher (magmatic?) temperatures. Garnet-pyroxene geothermometry indicates that the last equilibration most probably occurred at P = 1.0 GPa (ca.), T = 750 °C (ca).The second lithotype (b) is an orthopyroxene-bearing garnet-spinel clinopyroxenite, exhibiting a complex texture. It consists of zones of coarse clinopyroxene grains enclosing euhedral spinel passing to zones where tiny rounded crystals of the same pyroxene and spinel are enclosed in relatively large patches of extensively kelyphitisized garnet (Py64.8 Alm25.6 Gr9.6). Garnet also occurs as inclusion-free grains up to 4 mm in diameter. P-T calculations give significantly higher values than for the former case (a). The origin of the b-type garnet may also depend on subsolidus reaction of spinel and pyroxenes after an isobaric cooling from still higher temperatures, but a primary magrnatic origin might also be possible, especially for the granular garnets.P-T estimates for both the pyroxenite types closely match a steady geotherm for 100 mW/m2 surface heat flow. Such a relatively intense heat flow may suggest the occurrence of huge masses of hot magma intruding the Hyblean lithospheric mantle and lower crust at different levels.
Granat-Spinell-Pyroxenit-Xenolithe aus dem Iblei-Plateau (Südost-Sizilien, Italien)
Zusammenfassung Seltene Granat-Spinell-Pyroxenit-Xenolithe kommen in einigen basaltischen Tuff-Breckzien Horizonten miozänen Alters aus dem Valle Guffari (lblei-Plateau, Sizilien) zusammen mit einer Anzahl von Spinell-führenden Mantel-Xenolithen vor. Aufgrund textureller und mineralogischer Kriterien können die Granat-führenden Pyroxenite in zwei Gruppen (a und b) unterteilt werden. Granat-führende Spinell-Websterite mit vollkommen rekristallisierter Textur repräsentieren die erste Gruppe (a). Hier bildet Granat (Py54.5 Alm32 Gr13.5) mit einer diffusen kelyphitischen Umwandlung, einen Reaktionssaum zwischen grobkörnigem Spinell und Pyroxenen, mit denen er in Kontakt ist. Der übergang vom Spinell-Pyroxenit- zum Granat-Pyroxenit-Feld kann auf isobarische Abkühlung von höheren (magmatischen ?) Temperaturen zurückgehen. Granat-Pyroxen-Geothermometrie zeigt, dass die letzte Equilibrierung sehr wahrscheinlich bei P = 1.0 GPa (ca.), T = 750°C (ca.) erfolgte.Der zweite Typ von Granat-führenden Pyroxeniten ist ein (b) Orthopyroxenführender Granat-Spinell-Klinopyroxenit, der komplexe Texturen zeigt. Er besteht aus Zonen von grobkörnigem Klinopyroxen mit Einschlüssen von idiomorphem Spinell, der in Zonen übergeht, wo kleine gerundete Kristalle des gleichen Pyroxens und Spinells in relativ große Bereiche von extensiv kelyphitisiertem Granat (Py64,8 Alm25,6 Gr9,6) eingeschlossen sind. Granat kommt auch als einschlußfreie Körner mit bis zu 4 mm Durchmesser vor. P-T Berechnungen geben wesentlich höhere Werte als für die Gesteine des Types (a). Die Entstehung der b-Typ-Granaten kann auch durch Subsolidus-Reaktion von Spinell und Pyroxen nach isobarischer Abkühlung von noch höheren Temperaturen beeinflußt sein; ein primärer magmatischer Ursprung könnte auch möglich sein, besonders für die körnigen Granate.P-T Abschätzungen für beide Pyroxenit-Typen sind gut einer Geotherme für 100 mW/m2 Wärmefluß an der Oberfläche zuzuordnen. Ein solcher, relativ intensiver Wärmefluß könnte auf das Vorkommen von großen heißen Magmenkörpern hinweisen, die den lithosphärischen Mantel unter dem Iblei-Plateau und die untere Kruste in verschiedenen Niveaus intrudierten.

With 4 Figures  相似文献   

5.
Samples from hazardous waste site investigations frequently come from two or more statistical populations. Assessment of background levels of contaminants can be a significant problem. This problem is being investigated at the U.S. Environmental Protection Agency's Environmental Monitoring Systems Laboratory in Las Vegas. This paper describes a statistical approach for assessing background levels from a dataset. The elevated values that may be associated with a plume or contaminated area of the site are separated from lower values that are assumed to represent background levels. It would be desirable to separate the two populations either spatially by Kriging the data or chronologically by a time series analysis, provided an adequate number of samples were properly collected in space and/or time. Unfortunately, quite often the data are too few in number or too improperly designed to support either spatial or time series analysis. Regulations typically call for nothing more than the mean and standard deviation of the background distribution. This paper provides a robust probabilistic approach for gaining this information from poorly collected data that are not suitable for above-mentioned alternative approaches. We assume that the site has some areas unaffected by the industrial activity, and that a subset of the given sample is from this clean part of the site. We can think of this multivariate data set as coming from two or more populations: the background population, and the contaminated populations (with varying degrees of contamination). Using robust M-estimators, we develop a procedure to classify the sample into component populations. We derive robust simultaneous confidence ellipsoids to establish background contamination levels. Some simulated as well as real examples from Superfund site investigations are included to illustrate these procedures. The method presented here is quite general and is suitable for many geological and biological applications.  相似文献   

6.
Continental tholeiites cannot be identified using the Ti-Y-Zr diagram. Two-hundred and thirteen analyses from 16 localities representing 7 continental tholeiitic provinces all plot outside the within-plate basalt field of this diagram.Analyses representing about 50% of the population plot in the ocean-floor basalt field, the rest plots in the calc-alkali basalt field. Therefore problems might arise when attempts are made to classify ancient tectonomagmatic environments using the Ti-Y-Zr diagram.  相似文献   

7.
Xie  Mowen  Esaki  Tetsuro  Zhou  Guoyun 《Natural Hazards》2004,33(2):265-282
Based on a new Geographic Information Systems (GIS) grid-basedthree-dimensional (3-D) deterministic model and taking the slopeunit as the mapping unit, this study maps landslide hazard usingthe 3-D safety factor index and failure probability. Assuming theinitial slip to be the lower part of an ellipsoid, the 3-D critical slipsurface in the 3-D slope stability analysis is located by minimizingthe 3-D safety factor using the Monte Carlo random simulation.The failure probability of the landslide is calculated using anapproximate method in which the distributions of c, andthe 3-D safety factor are assumed to be in normal distribution.The method has been applied to a case study on three-dimensionallyand probabilistically mapping landslide hazard.  相似文献   

8.
Summary In this paper we present what is, to the best of our knowledge, the first comprehensive study of clinopyroxenes and plagioclases contained in the flows of the Grande Ronde Basalt member of the Columbia River Basalt Group (northwestern USA). The rocks have MgO(wt%)<6%, and trace amounts of Cr and Ni. About 56% of extracted solid containing normative clinopyroxene and plagioclase explains the liquid line of descent from the more mafic sample (MgO wt%=5.89) to the most evolved. The most ubiquitous phases in the basalts are plagioclase and augite. Ilmenite and magnetite are accessories in all rocks. Olivine is present in small amount only in one sample (RT 89-7). Based on principles of Ca–Na plagioclase–liquid exchange, estimates of pre-eruptive magmatic water are < 2.4wt%. From clinopyroxene–liquid equilibria, calculated pressures and temperatures of ascending magmas are between 1atm and 0.617GPa, and 1068°C and 1166°C, respectively. Compositions of magnetite–ilmenite pairs and olivine–clinopyroxene–oxide assemblages yield post-eruptive oxygen fugacities of NNO=–1.923, and one pre-eruptive value of NNO=– 2.455. A simple model of asthenospheric melting and magma ponding in the lower crust fits the physical parameters.Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1007/s00710-003-0017-1  相似文献   

9.
The Ejina Basin underlying complex aquifers is located in the lower reaches of the Heihe River with an arid climate and 40 mm mean annual precipitation. As the balance of the natural ecosystem in the Ejina Basin is fragile and easily upset, it is very important to estimate and rationally use the limited groundwater resources to maintain the balance. Water samples were collected from the Heihe River and wells for chemical and isotopic measurements across the basin. The Piper diagram gives two main types of hydrochemical features. Against the background of the regional geology, combining isotope 18O, tritium, and chemical analysis with groundwater flows indicated by a shallow groundwater level contour map, different kinds of groundwater sources and ways to replenish groundwater were discovered. North of the study area are artesian wells that are replenished by the mountainous area at the boundary between China and Mongolia. Replenishment for most of the groundwater resources of the Gurinai oasis comes from the Heihe River seepage flow of the highly conductive paleochannel, not from the Badain Jaran Desert as indicated by TDS and tritium analysis. The different groundwater ages which are younger than 35 years were approximately estimated by radioactive isotope tritium (T). By such efforts, groundwater resources can be effectively evaluated with the engineering impact of the Heihe River Project.  相似文献   

10.
Correlation coefficients of modal variables from several suites of granitic rocks have been calculated and tested for significance using the Chayes-Kruskal and Chayes methods. The results show that although Chayes' remaining-space transformation does, in general, weaken the original proportion correlations, the positive and low-negative original proportion correlations tend to increase in absolute value because of a tendency of positive increment of the covariance by such transformation. However, no satisfactory procedure for choosing the variable to be transformed (V2)could be determined, and testing of the significance of remaining-space correlations is found to be highly problematic. It is shown also that the Vistelius-Sarmanov procedure of calculation of correlation coefficients from closed-table data does not effectively eliminate the closure effect. It is concluded that assigning statistical significance to the correlation coefficients between modal variables is, in general, unsatisfactory, except where the number of variables 8,the sample size is large (say, 30),and there is no negative element in the variance vector of the corresponding open variables.  相似文献   

11.
In this study, the relation between ore grade and geological characteristic has been studied as a principle and also important conceptual in Zarshuran gold deposit in NW Iran. The main subject in this study was identifying a correlation among the ore grade populations and rock types which could be used in other steps of local estimation in the deposit concentration–number (C–N) fractal model and logratio matrix. The C–N log–log plot reveals six geochemical zones defined by Au?<?0.02 ppm as non-mineralized zone and Au?>?0.02 ppm as mineralized zones. According to geological logging and field geology inspection, black gauge, jasperoid, fault gauge and breccia, and carbonaceous rocks are considered as main rock types which contain major Au mineralized zones. The correlation between geological and fractal modeling by logratio matrix shows that there is a good correlation between geological assumed host rocks and C–N fractal modeling. Black gauge rock type with 93.48 % of overall accuracy shows a significant correlation with supergene zone of fractal model, and jasperoid with 92.5 % and carbonaceous rock type with 52.90 % have a decent correlation with highly and lowly mineralized zone of fractal model relatively. Black gauge, jasperoid, and fault gauge and breccia have an approximately near cooperation in this zone for mineralization.  相似文献   

12.
This paper deals with the quality of two multivariate statistical models based on the Geographical Information System for shallow landslide susceptibility assessment in a test area at La Pobla de Lillet (Eastern Pyrenees, Spain). The quality, which was guaranteed by a rigorous methodology based on a suitable diagnosis, validation, and evaluation of the models, ensured a reliable contrast of the final susceptibility maps. This enables us to transfer the best results to the end user. Landslide susceptibility models were carried out by logistic regression and discriminant analysis of the significant conditioning factors related to the characteristics of the slope and the upslope contributing area captured from the digital elevation model and landslide distribution. The explanatory variables were tested (KS test, principal components and one-way and T-test) to select the most statistically significant ones before being introduced into the logistic and discriminant analyses. Accuracy statistics and the receiver operating characteristic curve used for diagnosis and validation showed similar prediction skills and a good fit to the data with more than 85% of unfailed cells properly classified for the two models. The evaluation of the study area and the correlation function (R 2 = 0.83) between the models revealed that the discriminant model overestimated the susceptibility of the most stable zones with respect to the logistic model. Different methods of producing susceptibility maps showed marked differences in matching the models. Substantial spatial agreement (Kappa = 0.741) between binary maps produced by the standard cut-off value descended moderately (Kappa = 0.540) as a result of superimposing maps with five susceptibility levels defined by landslide percentage. Despite the fact that the two statistical models are similar in assessing susceptibility in the study area, the implications for hazard and risk management can be different because of the conservative nature of the discriminant model.  相似文献   

13.
Discusses the tragedy of the commons with regard to fish resources in the North Atlantic, and points to the fact that the Atlantic cod has now been so heavily exploited that a strong regulation of fisheries is needed to preserve an exploitable stock. The author argues for exclusive economic zones dividing up the remaining loopholes among coastal nations and individually transferable quotas.  相似文献   

14.
The economically important sulfide deposits of Precambrian age can be subdivided into two principal groups. The first group is represented by Ni- and Cu-bearing differentiates within either layered intrusions of the Sudbury-Bushveld type or within smaller ultramafic bodies (sometimes of greenstone belt association). The relatively narrow spread around the meteorite standard of the 34S values of these deposits suggests a mantle provenance of the sulfide sulfur.The second group (which is quantitatively more important) is represented by stratiform concentrations of base metal sulfides in sedimentary sequences lacking normally any ties to potentially ore-bearing magmas (Copper Belt, Broken Hill, Mount Isa, etc.). Although the problems related to the origin of such strata-bound deposits are rather complex, the majority of the latter probably formed as syngenetic sulfide precipitates in reducing aqueous environments characterized by the presence of bacteriogenic H2S. Sulfur isotope data furnished by some of the principal deposits actually suggest that hydrogen sulfide produced by bacterial sulfate reduction was instrumental in bringing about a precipitation of the metal sulfides, thus underlining the decisive role played by the biosphere in processes of supergene metal concentration.
Zusammenfassung Die wirtschaftlich wichtigen sulfidischen Metallkonzentrationen in präkambrischen Gesteinen lassen sich im wesentlichen zwei Lagerstättengruppen zuordnen. Die erste Gruppe bilden Ni- und Cu-führende sulfidische Differentiate in geschichteten Intrusionen vom Typ Sudbury-Bushveld oder innerhalb kleinerer ultrabasischer Komplexe. Die nur geringe Streubreite der 34S-Werte um den Meteoriten-Standard legt eine abyssische Herkunft des sulfidischen Materials (Magnetkies, Pentlandit, Kupferkies u. a.) derartiger Lagerstätten nahe.Die zweite und quantitativ wichtigere Gruppe bilden schichtige Anreicherungen von Buntmetallsulfiden in Sedimenten, die in der Regel keinerlei Beziehungen zu potentiell erzbringenden Magmatiten erkennen lassen (Copper Belt, Broken Hill, Mount Isa u. a.). Obwohl die beträchtlichen Probleme dieser stratiformen Sulfidlagerstätten eine genetische Deutung schwierig machen (und insbesondere die oft enorme Streubreite der Schwefelisotopen auf eine polygene Herkunft der Sulfide schließen läßt), dürfte es sich bei der Mehrzahl der Vorkommen um primär synsedimentäre Metallausfällungen in einem H2S-führenden reduzierenden Milieu handeln, wobei spätere tektonischmetamorphe Stoffmobilisierungen möglicherweise eine weitere Konzentration der Lagerstättensubstanz bewirkt haben. Die starke Beteiligung von bakteriogenem Schwefelwasserstoff bei der Ausfällung der Sulfide wird durch die Schwefelisotopen-Verteilung in verschiedenen derartigen Lagerstätten gestützt. Dieser Befund unterstreicht gleichzeitig die entscheidende Rolle der Biosphäre bei der Bildung von Metallanreicherungen im exogenen Zyklus.
Résumé Les concentrations de sulfures métalliques économiquement importantes dans les terrains précambriens peuvent essentiellement être subdivisées en deux groupes de gisements. Le premier groupe comprend les différenciats de sulfures nickelifères et cuprifères dans les intrusions litées du type Sudbury-Bushveld ou dans l'intérieur de complexes ultrabasiques plus petits. La faible distribution des valeurs du soufre 34 des météorites standard suggère une provenance abyssale des matériaux sulfurés de ces gisements (pyrrhotine, pentlandite, sulfures de Cu, etc.). Le deuxième groupe quantitativement plus important comprend les enrichissements «stratiformes »de sulfures métalliques dans les sédiments qui, en règle générale, ne montrent aucune liaison avec des magmatites potentiellement minéralisantes (Copper Belt, Broken Hill, Mount Isa, etc.). Quoique les problèmes importants relatifs à ces gisements sulfurés stratiformes rendent difficile une interprétation génétique (et en particulier la dispersion souvent énorme des isotopes du soufre qui permet de conclure à une provenance polygène des sulfures), il doit s'agir dans la plupart des cas de précipitations de métaux synsédimentaires primaires dans un milieu réducteur contenant H2S; à la suite de quoi une mobilisation ultérieure tectonico-métamorphique pourrait avoir exercé une nouvelle concentration de la matière du gisement. La forte participation d'H2S bactériogène au cours de la précipitation des sulfures est confirmée par la distribution des isotopes du soufre dans différents de ces gisements. Ce fait souligne simultanément le rôle décisif de la biosphère au cours de la formation des enrichissements métalliques dans le cycle exogène.
, . , . - , . 34S ( , , .. .) , , , (r Belt, Broken Hill, Mount Isa .). ( , ), , , , - , , , . . .
  相似文献   

15.
For the Swedish Deep Gas Project some 240 soil samples were collected and analyzed for trace metals and C. The data were determined to not be sufficient as anomalous patterns obtained were merely reflecting underlying crystalline or Palaeozoic bedrock. Any possible patterns related to a deep-seated gas source were completely swamped; in addition, glacial transport also presented a problem in interpretation. Therefore, the ARIADNE method was applied to the data set. ARIADNE is a pattern recognition system designed for use in a variety of exploration applications, ranging from geochemical regional surveys to detailed geophysical well logging. The system's core is a fuzzy classifier that can work both on differences in location and dispersion in variable space, either combined or separately. For unsupervised classification, a preprocessor, called NARCISSOS, is used, which, by using fuzzy principal components analysis, extracts a robust background and an appropriate number of anomalous populations. Mean vectors and covariance matrices of all populations are submitted to the ARIADNE classifier. By taking advantage of different patterns emerging by using mean vectors or variance-covariance matrices when classifying in the variable space, the relative influence of transport (e.g., glacial transport) can be estimated and probable source areas also can be established. When ARIADNE was applied to the Deep Gas Project data, two anomalous populations emerged. One was strongly tied, both geographically and chemically, to the Palaeozoic ring structure circumscribing the target area, and the background reflected general chemical features of granitic bedrocks inside and outside of that structure. The second anomaly, however, was not related to any bedrock composition, but rather to structural phenomena in the bedrock. It did not show any signs of glacial dispersions, as the other anomalous group did, and its chemical signture was more or less in concordance with what is found over oil or gas fields in other more traditional environments.This paper was presented at Emerging Concepts, MGUS-87, Redwood City, California, 13–15 April 1987.  相似文献   

16.
Chayes' t-test for closure correlations is developed from various approximations and assumptions. The empirical behavior of this test is observed through the use of random-sampling number matrices of order to thirteen. The experiments demonstrate a lower limit for the reliability of Chayes' model of about 91/100. That is, about one chance in ten remains that an error due to the statistical testing is committed on some product-moment correlations in a given matrix of correlation, given a confidence level of 90 percent. With increase in the number of variables, the test for departure from zero correlation can be used provided the sample size remains small.  相似文献   

17.
Geochemical and statistical analyses of 165 soil samples led to Cu-Au anomaly separation in Dalli-Northern Hill by using fractal geometry and U-spatial statistic. There was a good correlation between the anomaly areas and outcrops of quartz diorite porphyry (QDP) in the study area. Based on the interpretation of soil data and anomaly areas determination, one trench was suggested in NE-SW direction for follow-up exploration. Based on the rock sample analyses from the trenches in QDP rocks, the ratio of $ \frac{{{\mathrm{Ba}} \times {\mathrm{K}}}}{{{\mathrm{Ca}} \times {\mathrm{Zn}}}} $ clearly separated the mineralization area and considered as an index ratio for follow-up exploration stage. Dalli-Northern Hill anomaly includes pyrite/chalcopyrite/bornite, which is dominantly abundant in the ore body. Three IP profiles (IP04, IP05, and IP06) confirmed the conductivity of the sulfide zone. The background chargeability in the study area was about 5.4 mV/V and the average of maximum apparent chargeability in the study area was 44.4 mV/V, which could be related to the higher intensity of Cu-Fe sulfide minerals. The contact of andesite and quartz diorite has shown the strongest chargeability (71 mV/V) and high magnetic anomalies in the study area. DDH03 and DDH04 boreholes mostly confirmed that the IP/magnetic/geochemical anomalies were related to the contact of intrusive rocks and the wall rock of andesite. The combination of geochemical information from soil and rock together with geophysical data (induced polarization/resistivity) led to the subsurface geological cross sections and location of the mineralized zone enriched of sulfide. The mineralized zone in Dalli-Northern Hill distinct could be identified by potassic to weak sericitic and trace chloritic alteration, high values of the $ \frac{{{\mathrm{Ba}} \times {\mathrm{K}}}}{{{\mathrm{Ca}} \times {\mathrm{Zn}}}} $ ratio accompanied with high gold and copper values and enrichment from magnetite minerals. The high magnetic susceptibility, low resistivity, and high chargeability are considered as geophysical properties of the mineralized zones.  相似文献   

18.
Principal component analysis (PCA) is commonly applied without looking at the spatial support (size and shape, of the samples and the field), and the cross-covariance structure of the explored attributes. This paper shows that PCA can depend on such spatial features. If the spatial random functions for attributes correspond to largely dissimilar variograms and cross-variograms, the scale effect will increase as well. On the other hand, under conditions of proportional shape of the variograms and cross-variograms (i.e., intrinsic coregionalization), no scale effect may occur. The theoretical analysis leads to eigenvalue and eigenvector functions of the size of the domain and sample supports. We termed this analysis growing scale PCA, where spatial (or time) scale refers to the size and shape of the domain and samples. An example of silt, sand, and clay attributes for a second-order stationary vector random function shows the correlation matrix asymptotically approaches constants at two or three times the largest range of the spherical variogram used in the nested model. This is contrary to the common belief that the correlation structure between attributes become constant at the range value. Results of growing scale PCA illustrate the rotation of the orthogonal space of the eigenvectors as the size of the domain grows. PCA results are strongly controlled by the multivariate matrix variogram model. This approach is useful for exploratory data analysis of spatially autocorrelated vector random functions.  相似文献   

19.
In this experimental work I studied the correlation of the specific gravity and index of refraction at 19 moldavites from a finding place in Nchov. This place is in the south of Bohemia, in a district of eské Budjovice (Budweis). The reason for this work was the extraordinary declaration of the correlation of the specific gravity and index of refraction at one moldavite from Nchov that is: d=2,395 and n D =1,5033.These declarations were settled by Nováek. The results of these measurings have shown that the linear correlation of the specific gravity and index of refraction of the moldavites from other finding places are characteristic also for these ones. The definition of this correlation at 19 pieces of moldavites from Nchov shows also this linear character in the measuring of values d=2,355–2,395 and n D =1,4870–1,4950.In this work there were settled also some other dates of unity (so-called in couple-moldavites). But we must not oversee certain vaccilations of the declaration at the moldavites from Nchov, as at those from other finding places. The secularity of these declarations about the moldavites of Nchov lies also therein, that the avarage value of the correlation of specific gravity and index of refraction of this finding place is higher than those of other places.

Herrn Dr. Walter Weiskirchner, Dozent an der Universität Tübingen, danke ich herzlich für die freundliche Durchsicht der Arbeit.  相似文献   

20.
    
Patterns of inter-well correlations in map view can yield insight into the architecture of an area such as a petroleum reservoir. Preferred directions of fluid communications, discontinuities, and structural or depositional grain of an area often can be identified. In coherence mapping, large numbers of wells are compared in pairs, using a similarity coefficient. Sliding cross-correlation techniques of sections can be used to adjust for some normal stratigraphic inconsistencies. The calculated parameters are mapped as vector spider plots for each well, or as link-lines between well pairs with line thickness proportional to the strength of correlation. The resulting maps display areas of coherence and lines of discontinuities which can be interpreted according to the geologic style of the region. The method works best for areas with relatively great density of wells and uniform distribution. The database should contain logs digitized over the interval of interest and at least one stratigraphic marker. A pilot study of a carbonate reservoir with some 150 wells provided useful suggestions for reinterpretation of the field in terms of steeply dipping clinoforms of basin margin deposits.Paper presented at 15th Geochautauqua, Calgary, 4 October 1986.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号