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1.
Statistical treatment of geochemical exploration data in the Ife-Ilesha area has not been fully utilized as a tool in their interpretation. The results of 176 stream sediment samples from an area of 1800 km2 analyzed for Cu, Zn, Mn, Ni, Co and Cr after hot extraction were treated with both simple and sophisticated (R-mode factor) statistical analytical methods. All the elements were found to have density distributions closely approaching lognormal or a mixture of two lognormal populations.They all show strong positive correlations with correlation coefficient values ranging from 0.5 between Mn and Ni to 0.84 between Mn and Co, all considered to be real at 5% level of significance.R-mode factor analysis produced a three-factor model which accounts for 82.0% of the total variance in the data. Factor 1 (Cu-Co-Ni) correlates spatially with the area underlain by the amphibolite complex, thus reflecting the parent rock as dominant influencing factor. Factor 2 (Mn-Co) and the strong positive correlation between Mn and Co are interpreted as resulting from the influence of Co-adsorption by Mn-oxides. Factor 3 (Zn) is probably a mineralization factor.  相似文献   

2.
Simulation experiments have been conducted to examine the potential usefulness of R-mode and Q-mode factor methods in the analysis and interpretation of geochemical data. The R-mode factor analysis experiment consisted of constructing a factor model, using the model to generate a correlation matrix, and attempting to recover the model by R-mode techniques. The techniques were successful in determining the number of factors in the model, but the factor loadings could not be estimated even approximately on the basis of mathematical procedures alone. Q-mode factor methods were successful in recovering all of the properties of a model used to generate hypothetical chemicaldata on olivinesamples, but it was necessary to use a correction previously regarded as unimportant.Publication approved by Director, U.S. Geological Survey.  相似文献   

3.
The application of R-mode principal components analysis to a set of closed chemical data is described using previously published chemical analyses of rocks from Gough Island. Different measures of similarity have been used and the results compared by calculating the correlation coefficients between each of the elements of the extracted eigenvectors and each of the original variables. These correlations provide a convenient measure of the contribution of each variable to each of the principal components. The choice of similarity measure (variance-covariance or correlation coefficient)should reflect the nature of the data and the view of the investigator as to which is the proper weighting of the variables—according to their sample variance or equally. If the data are appropriate for principal components analysis, then the Chayes and Kruskal concept of the hypothetical open and closed arrays and the expected closure correlations would seem to be useful in defining the structure to be expected in the absence of significant departures from randomness. If the data are not multivariate normally distributed, then it is possible that the principal components will not be independent. This may result in significant nonzero covariances between various pairs of principal components.  相似文献   

4.
Geochemical reconnaissance survey of Wadi Umm Khariga in the southern part of the Eastern Desert of Egypt was carried out in an area of 30 Km2. The results of 79 stream sediment samples analyzed for Co, Cr, Cu, Fe, K, Li, Mn, Ni, Pb, Rb, Ti, and Zn after hot extraction with aqua regia were treated with simple and multivariate statistical methods. Titanium, Cu, Co, Ni, and Cr show lognormal distribution, whereas the other elements are normally distributed. The correlation between Fe and Mn and most of the analyzed elements suggest coprecipitation process that could be significant in controlling the distribution of these elements. Regression analysis was effective in correcting the effects of Fe and Mn by calculating the residuals. R-mode factor analysis produced a four-factor model, which accounts for 79.1% of the total variance in the data. Factor 1 (rCr, rCo, Ni) scores are correlated spatially with the area underlain by the serpentinites, metarhyolites, and metadacites. Factor 2 (rLi, rZn, rTi, Rb, K) scores are correlated with the metarhyolites, metadacites, and metapyroclastics. Factor 3 (Cu, rTi, Pb) scores characterize the metabasalts, meta-andesites, metarhyolites, and metadacites, thus reflecting the parent rocks as dominant influencing factors. Factor 4 (Mn, Fe) scores reflect the secondary environment effects. Discriminant analysis delineated an anomalous area for Co, Ni, Cr, Cu, Ti, Mn, Pb, and Li with probable occurrence of economic mineral deposits.  相似文献   

5.
地球化学综合找矿隐蔽信息数据处理方法研究与应用   总被引：1，自引：0，他引：1  
本文认为:化探数据的正态变换是正确估计背景、异常,清晰反映元素间相关关系的基础;R型因子分析是揭示元素相关结构进行成因分类的有效方法;多层次拟合、插值是表征矿化因子得分空间分布规律正确圈定找矿靶区的可靠依据。以此种技术措施对某区1:5万水系沉积物测量520km2的面积和土壤测量12km2面积的实际资料进行数据处理,获得大量有用信息,新发现矿化异常多处,深化了对控矿条件的认识,为进一步找矿指出了方向。  相似文献   

6.
Insufficient knowledge of the hydrogeochemistry of aquifers in the Central Region of Ghana has necessitated a preliminary water quality assessment in some parts of the region. Major and minor ions, and trace metal compositions of groundwater have been studied with the aim of evaluating hydrogeochemical processes that are likely to impair the quality of water in the study area. The results show that groundwater in the area is weakly acidic with mean acidity being 5.83 pH units. The dominant cation in the area is Na, followed by K, Ca, and Mg, and the dominant anion is Cl?, followed by HCO3 ? and SO4 2?. Two major hydrochemical facies have been identified as Na–Cl and Na–HCO3, water types. Multivariate statistical techniques such as cluster analysis (CA) and factor analysis/principal component analysis (PCA), in R mode, were employed to examine the chemical compositions of groundwater and to identify factors that influenced each. Q-mode CA analysis resulted in two distinct water types as established by the hydrochemical facies. Cluster 1 waters contain predominantly Na–Cl. Cluster 2 waters contain Na–HCO3 and Na–Cl. Cluster 2 waters are fresher and of good quality than cluster 1. Factor analysis yielded five significant factors, explaining 86.56% of the total variance. PC1 explains 41.95% of the variance and is contributed by temperature, electrical conductivity, TDS, turbidity, SO4 2?, Cl?, Na, K, Ca, Mg, and Mn and influenced by geochemical processes such as weathering, mineral dissolution, cation exchange, and oxidation–reduction reactions. PC2 explains 16.43% of the total variance and is characterized by high positive loadings of pH and HCO3 ?. This results from biogenic activities taking place to generate gaseous carbon dioxide that reacts with infiltrating water to generate HCO3 ?, which intend affect the pH. PC3 explains 11.17% of the total variance and is negatively loaded on PO4 3? and NO3 ? indicating anthropogenic influence. The R-mode PCA, supported by R-mode CA, have revealed hydrogeochemical processes as the major sources of ions in the groundwater. Factor score plot revealed a possible flow direction from the northern sections of the study area, marked by higher topography, to the south. Compositional relations confirmed the predominant geochemical process responsible for the various ions in the groundwater as mineral dissolution and thus agree with the multivariate analysis.  相似文献   

7.
Currently popular line and ribbon methods yield grain counts that are differentially biassed in regard to sizes and orientations of the maximum projection diameter of the grains in the sample. Bias correction factors covering the entire range of counting situations are obtained using probability theory and coordinate geometry. The corrected numbers are true unbiassed Fleet counts that are suitable for estimating true statistical measures and for estimating economic potential of mineral(s). Irregular grains can be counted by classifying them into either elliptical or rectangular shapes by means of nondimensional discriminant equations based on area or length measurements. Wadell roundness (ρ) for elliptical and rectangular outlines shows inconsistency, but the modified Wadell roundness (ρ′) proposed herein is a consistent measure of roundness for all types of shapes, and hence the latter is recommended for use. Theoretically, roundness is linearly correlated with the form factor (B/A) for elliptical outlines and hence, a linear correlation of average roundness and average form factor in sediments is to be expected. The entire spectrum of shape comprising two continuous variables, form factor and modified Wadell roundness, may be classified into two discrete shape states (elliptical and rectangular) or into several discrete shape states having ranges of ρ′ and B/A values.  相似文献   

8.
The results of a multielemental biogeochemical orientation survey carried out in Calabria, southern Italy, are reported in this paper. Five plant species: three herbaceous species, Oenanthe pimpinelloides, Anthemis triumphetti, and a stonecrop (Sedum tenuifolium), a leguminous shrub, spanish broom (Spartium junceum) and laricio pine (Pinus nigra ssp laricio) were studied to determine which species is the most responsive to sulfide mineralization and which are the best indicator elements. Si, Fe, Ti, Mn, Zn, Mo, Cu, and Pb were determined in ashed material by X-ray fluorescence analysis. All the data were treated statistically and classified into geometrically increasing intervals, in order to discriminate anomalous from background values. In addition, an R-mode factor analysis and a correlation analysis were performed to find out whether any specific metal association that could characterize both the lithology and mineralization existed for each plant species. The herbaceous plants, particularly Oenanthe, were much more effective as indicators of mineralization compared with laricio pine. The elements that gave the best indication of sulfide mineralization were Zn and Pb, confirming the usefulness of biogeochemical methods as an additional prospecting tool in Calabria, where such exploration has never been attempted before. R-mode factor analysis was found to be extremely promising as a supplemental tool in the interpretation of results from this biogeochemical survey. Each plant species is always characterized by a metal association (predominantly Pb-Zn-Mn) whose high factor loading scores constantly show a close relationship with proven sulfide mineralization.  相似文献   

9.
A multivariate analytical strategy is proposed for aiding the investigator in extracting maximum information from environmental data. Data are carefully coded and scaled and are tested for redundancy using R-mode cluster analysis. The samples are partitioned into environmental classes using Q-mode cluster analysis. Q-mode ordination facilitates interpretations, which usually can be verified by comparison with field relationships. Discriminant analysis serves as an identification procedure for extending the classification to unknown samples. The strategy is demonstrated by application to Cape Hatteras microorganism distributions and Devonian sedimentary facies.  相似文献   

10.
Water quality data are required in order to compare chemical water analyses and identify water masses. R-mode factor analysis, a popular multivariate statistical tool, has been effectively used for groundwater quality studies. In this paper, the R-mode factor analysis was applied to 50 groundwater samples collected from pumping wells in the Sangan-Khaf basin which is located in the southeast of Mashhad, northeast Iran. The groundwater samples were analysed for chemical parameters. The factor analysis was then performed on the chemical data set. It can be suggested that four factors in R-mode analysis explain more than 94.31% of the total variance. The contribution of each factor at sample points, factor score, was calculated. The spatial distribution of the factor scores for each factor was mapped separately. Since the Sangan iron mine south of the study area probably affects groundwater aquifer, therefore, such studies can be used to manage the groundwater quality in the study area.  相似文献   

11.
Q- and R-mode factor analytical studies were made of 158 stream sediment samples from the Mount Nansen area, Yukon Territory, analyzed for Cu, Pb, Zn, Mo, Ni, Ag, and Sb. R-mode results were more clear-cut than were Q-mode in terms of ease of interpreting geological significance of individual factors, although results of both methods were very comparable. The 3-factor R-mode model accounted for 79.9 percent of the variation in the data. Factor 1, a Pb-Zn-(Ag) factor correlated with Mount Nansen volcanic rocks and particularly with known Pb-Zn-Ag-Au veins within those rocks. Factor 2, a Cu-Mo factor correlated with porphyric intrusions known to contain Cu-Mo mineralized zones. Factor 3, an Sb-(Ag) factor is, as yet, not adequately explained in terms of geology. The main additional contribution of the Q-mode study is the communalities. Samples that depart from the norm (i.e. do not agree well with the 3-factor model) are readily apparent because of low communalities and must be considered anomalous in the general sense until an adequate explanation for this difference is found.  相似文献   

12.
Relative growth of the Miocene pelecypod Glycymeris parilis (Conrad) was examined using allometric equations and principal components. Different parts of the shell showed contrasting growth strategies that were dictated by functional morphology and basic shell geometry. Despite the divergent developmental strategies, 93 percent of the correlation matrix variance is accounted for by overall size increase. The remaining variance mainly represents growth of the teeth, which differed considerably from other variables.  相似文献   

13.
R-mode factor analysis is used to describe the relationships among 18 remotely sensed and geochemical data sets (variables) for the Montrose 1° × 2° quadrangle, Colorado, a region that covers 19 000 km2. The data sets contain reconnaissance-scale information and include Landsat imagery, airborne geophysical information (eU, eTh, K40, aeromagnetics), elevation, and hydrogeochemical and stream sediment analyses. The elements U, K, Dy, Hf, V, Th, Ca and Ba in sediments and U in waters were selected.The results of the factor analysis for the entire quadrangle are compared to the results for a 50 km × 50 km test area containing several known uranium occurrences. Four factors account for 70.0% of the total variance in the data. These are interpreted as a felsic factor, Landsat factor, economic or mineralization factor (in terms of uranium mineralization and potential mineralized areas), and a volcanic factor.Graphical representations (maps) of the raw data, factor approximations, residuals for each data set, and the four-factor model greatly aid interpretation of the analytic results. We find that data integration techniques and R-mode factor analysis can be used with some success in uranium resource appraisal.  相似文献   

14.
The results of observations of a complete sample of radio sources with spectral indices α>?0.5 (S∝v α) are presented. The sample was selected from the Zelenchuk Survey at 3.9 GHz and contains all sources with declinations 4°–6°, Galactic latitudes |b|>10°, and 3.9-GHz fluxes >200 mJy. Spectra at 0.97–21.7 GHz were obtained for all 69 sample sources. The spectra were classified, and a correlation between variability amplitude and spectrum shape was found. The spectra were separated into extended and compact components. The distribution of spectral indices α for the extended components coincides with the distribution for sources with power-law spectra. The correlation between the luminosity and frequency of the peak flux density is confirmed. This correlation is due to the fact that the distribution of source linear dimensions does not depend on luminosity.  相似文献   

15.
Because of autocorrelation and spatial clustering, all data within a given dataset have not the same statistical weight for estimation of global statistics such mean, variance, or quantiles of the population distribution. A measure of redundancy (or nonredundancy) of any given regionalized random variable Z(uα)within any given set (of size N) of random variables is proposed. It is defined as the ratio of the determinant of the N X Ncorrelation matrix to the determinant of the (N - 1) X (N - 1)correlation matrix excluding random variable Z(uα).This ratio measures the increase in redundancy when adding the random variable Z(uα)to the (N - 1 )remainder. It can be used as declustering weight for any outcome (datum) z(uα). When the redundancy matrix is a kriging covariance matrix, the proposed ratio is the crossvalidation simple kriging variance. The covariance of the uniform scores of the clustered data is proposed as a redundancy measure robust with respect to data clustering.  相似文献   

16.
通过对南黄海295个站位沉积物样品的常量元素含量分析,研究了南黄海沉积物常量元素组成的R-型聚类分析、R-型因子分析及与物质来源的关系。南黄海沉积物常量元素Al2O3、MgO、K2O、Fe2O3分布基本相似;SiO2分布与Al2O3、MgO、K2O、Fe2O3分布相反;中、西部CaO、CaCO3分布与黄河、长江物源有明显关系;Na2O分布与黄河物质供给有关;TiO2分布反映了长江物质的运移方向。现代黄河物质及老黄河物质主要沉积于南黄海的西部、中部和东南部;海区东部物质反映来自朝鲜半岛物质的对南黄海东部的作用。长江物质主要局限于南黄海的西南和南部区域沉积;TiO2和Ti/Al分布反映了长江物质可能对南黄海中部区域也有所影响  相似文献   

17.
We obtained 503 photographic brightness estimates for the long-period classical Cepheid V396 Cyg (P = 33.3 days) from the plates of the Harvard Observatory and the Sternberg Astronomical Institute (SAI). Combined with published photoelectric observations, these data were used to plot an O-C diagram covering a time interval of 108 years. The O-C diagram is parabolic in shape, enabling the first determination of quadratic light elements and calculation of the evolutionary rate of decrease of the period, dP/dt = 14.1(±0.8) s per year (log(?/P) = ?6.35), in agreement with theoretical computations for the second crossing of the instability strip. The available data, reduced using the method introduced by Eddington and Plakidis, demonstrate the presence of small random period fluctuations that do not distort the evolutionary changes of the O-C residuals.  相似文献   

18.
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19.
Freshwater inflow is a driver of the functioning of estuaries, and average salinity is usually measured to identify the effects of inflow in salinity-zone habitats. However, salinity variability could act as a disturbance by producing unstable habitats, leading to the question: is salinity variance an indicator of benthic disturbance, and therefore a driver of community stability? The macrofauna communities of five estuaries that lie in a climatic gradient on the Texas coastline were analyzed using a 26-year data set. Comparisons within and between estuaries with different inflow regimes were used as a natural experiment to simulate press disturbance events (i.e., climatic inflow) and pulse disturbance (i.e., floods) in maintaining community stability. Salinity average and variance was compared with benthic community diversity, evenness, and species richness. Salinity variance was more correlated to benthic diversity for each estuarine system (r?=??0.6610; p?=?0.0015) than average salinity (r?=?0.3818; p?=?0.0967). As salinity variance decreased (i.e., stability increased), diversity levels of benthic communities increased, and areas with mgore freshwater inflow displayed lower levels of benthic diversity. These findings advance a component of the general theory of diversity maintenance that persistent stressors, such as salinity variability, can influence diversity.  相似文献   

20.
长江口外海域表层沉积物微量元素地球化学特征   总被引：1，自引：1，他引：0  
对采自长江口外海域187个表层沉积物的25个微量元素含量进行了标准差系数、相关分析及R型因子分析,探讨了微量元素的来源和分布特征。长江口外海域沉积物微量元素Li、V、Cr、Co、Ni、Ga、Cu、Zn、Th和Rb分布基本相似;Sr分布与Li、Cu、Pb、Zn、Th和Rb相反;研究区东南部Sr分布与生物作用有明显关系;Cd和Mo分布与粒度之间的相关性较差,主要受氧化还原环境的控制;Zr分布反映了长江物源的影响。相关分析和R型因子分析结果表明,沉积作用、粒度控制效应、海洋生物作用、氧化还原环境和源区地质背景等对长江口外海域表层沉积物中微量元素分布起着主要控制作用。  相似文献   

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