Geochemistry of semi-arid Cryosols on volcanic and sedimentary materials from James Ross Island, Antarctica

Abstract

In most parts of Antarctica, specifically in arid and semi-arid condition, soils are the results of weak weathering and little pedogenic processes. There, the use of geochemical data is considered an important tool to interpret possible pedological processes through the changing molecular ratios of elements with depth. The semi-arid soils of Antarctica remains little explored. In this study, the geochemistry of soils developed on different parent materials under a typical semi-arid climate was investigated, based on the quantification of the elements by various methods. Based on the major and trace elements geochemistry, the soil types are clearly differentiated by their geochemical composition, and highly affected by their parent materials. Based on the major elements abundances, chemical weathering is very limited. Using geochemical parameters to identify lithologic discontinuities, five profiles showed this characteristic. The apparent high chemical index of alteration and mineralogical composition, with kaolinite in the clay fraction, soils developed on the marine sedimentary rocks showed a pre-weathered nature, related to the ancient inheritance of Cretaceous paleoclimates, during which warmer climate led to intense weathering under subtropical conditions. Therefore, pre-weathering has a role in the mineralogical composition of Antarctic soils on sedimentary rocks.