Exploring the effects of cell size in geochemical mapping

Abstract

One ore-forming element (Cu) and one rock-forming element (SiO 2) from stream sediment dataset in Tibet (China) are selected to explore the effects of cell size in geochemical mapping using fractal and multifractal models. Five raster maps for Cu and SiO 2 are obtained by the IDW method with the cell sizes of 300 m, 500 m, 700 m, 900 m, and 1100 m. The results show that (1) whereas raster maps interpolated at different cell sizes have average and standard deviation values similar to those of the original data, their maximum values are lower and their minimum values are higher, indicating that the cell size slightly affects the concentration frequency distribution of geochemical patterns, and that the IDW method smoothens the original data to some extent; (2) the mean absolute error increases as the cell size increases, indicating that the cell size affects the accuracy of prediction; (3) the spatial patterns obtained with different cell sizes have different textures as indicated by different values of multifractal parameters, implying that the cell size affects the spatial texture of geochemical patterns; and (4) different Cu thresholds obtained by C-A fractal model indicates that the cell size slightly affects the delineation of geochemical anomalies.