Mafic and felsic derived soils in the Georgia piedmont : parent material uniformity, reconstruction, and trace metal contents

Abstract

Felsic and mafic/ultamafic rocks will weather to form soils having different characteristics. Three pedons were chosen based on differing parent materials. Particle size and chemical properties were characterized by standard methods, and clay mineralogy was evaluated using x-ray diffraction. Sand Zr and whole soil trace metals were measured on the ICP-MS, using HF dissolution. Particle-size separates and trace metals were reconstructed using Zr as the immobile constituent. Soils developed from mafic/ultramafic parent materials had thinner sola and higher pH, CEC, and base saturation than the pedon developed from felsic rocks. 2:1 clays dominated the mafic/ultramafic sites and kaolinite dominated the felsic site. Parent material discontinuities were seen at the mafic/ultramafic sites using sand:silt and Ti:Zr ratios. Reconstruction analysis of the clays found that substantial clay neoformation occurred in the argillic horizons at all three sites, and trace metal reconstruction found that metals were residually accumulating at the mafic/ultramafic sites.