Geochemical element differentiation in serpentine soils from the ophiolite complexes, eastern Taiwan

The vertical distribution of 14 geochemical elements (Si, Al, Ti, K, Na, Ca, Mg, Fe, Mn, Cu, Cr, Ni, Pb, and Zn) in nine serpentine pedons for three ophiolite complexes was investigated. The pedons are located at Wu-Mau, Tong-An, and Shih-Tao mountains in the Coastal Range, eastern Taiwan. The objective of this study was to discriminate the parent material inheritance and pedogenic factors by comparison of the element concentrations based on principal component (PC) analysis. From the experimental results, the relative abundance of major elements was as follows: Si > Fe > Mg > Al, with lesser concentrations of Ti, K, Na, and Ca. In addition, Cr, Mn, and Ni contents in these soils were higher than in soils formed from other parent materials, with considerable variation between pedons on different landscapes, which reflected the ophiolite differences and degrees in chemical weathering of the associative serpentinitic rocks. The contents of pairs of Si-Fe, Si-Mn, Si-Pb, and Si-Zn showed significantly (P < 0.05) positive correlations. The close relations among contents of Fe, Mn, Cr, and Ni were observed herein. According to the eigenvalue in PC analysis, the elements most responsible for separation along the PC-1 axis were Si, Fe, Mn, Zn, Mg, and Ca, whereas Cr and Ni were the trace metals responsible for separation along the PC-2 axis. This result reflected the parent material differences in igneous rock composition and the degree of serpentinization between ophiolite complexes.