Klusman R. Surface exploration Case Histories: Applications of Geochemistry, Magnetics and Remote Sensing

Article. — AAPG Studies in Geology. — 2002. — № 48. — p. 1-24.Areview of the methodology for interpretation and display of surface geochemical data is presented, and a discussion of direct and indirect methods for surface geochemistry is reviewed. The interpretation of surface geochemical data must initially focus on determining what is background, and which may be anomalous samples. The use of histograms and probability plots for this separation is illustrated. Because surface geochemical data are inherently noisy, a variety of smoothing techniques is used, including moving means for line plots and moving cell means for grid data. Adequacy of sampling density is assessed using an analysis of variance method. The data must be consistent with the geological evaluation and must aid in the assessment of petroleum potential, as well as being statistically significant.
Multivariate statistical methods, including ratios, crossplots, split-comparison plots, and ternary plots, are reviewed. More advanced multivariate techniques, such as principal components, factor and cluster analysis, and neural networks, are briefly described. The map display of surface geochemical data is frequently the final product. The various methods of generating a regular grid from irregularly spaced control points are described. Considerable discussion is given to geostatistical analysis and kriging for the estimation of grid point values. The limitations of detailed-contour and colored concentration-interval plotting are described.Direct Methods of Surface Geochemical Exploration
Indirect Methods of Surface Geochemical Exploration
Interpretation of surface geochemical data
Populations, Distributions, and Background
Reproducibility in Surface Geochemical Data
Empirical Corrections to Raw Surface Geochemical Measurements
Smoothing Surface Geochemical Data
Determination of Adequate Sampling Density
Multivariate Statistics, Exploratory Data Analysis, and Pattern Recognition
Map displays of surface geochemical data
Kriging and Other Interpolation Techniques in Contouring
Dot Maps and Color Displays
Summary and conclusionsReferences cited (86)