Semi-arid soils from a topolithosequence at James Ross Island, Weddell Sea region, Antarctica: Chemistry, mineralogy, genesis and classification

Abstract

Climate and parent material have a significant impact on the development of Antarctic soils, and areas dominated by basaltic-andesitic volcanic rocks, sedimentary rocks, and metamorphic rocks have been widely studied. James Ross Island, located in the semi-arid transition between East Antarctic Peninsula/Weddell Sea sector, receives both continental and maritime climatic influences, resulting in distinct, transitional soil formation process. In Antarctica, there is little research on semi-arid soils formed on volcano-sedimentary rocks, as well as their pedogenetic processes. In this study, a topolithosequence of volcanic and sedimentary rocks in this semi-arid transitional climate was investigated. Nine profiles, three on marine terraces, four on sedimentary rocks, and two on volcanic rocks were described, sampled, and analyzed for morphological, physical, chemical, and mineralogical properties. Soils are predominantly Gelisols/Cryosols and present cryoturbation features despite the current dry climate. Vegetation is scarce and nesting birds are absent, so that most soils can be characterized as ahumic. All profiles have a skeletic character, with a high percentage of coarse materials. The soil pH varied from neutral to alkaline and the potential acidity values were null. The mineralogy of the clay fraction presented kaolinite, which was likely inherited from warmer and wetter paleoclimatic conditions during sedimentation. The soils have intergrade properties between maritime and continental Antarctic, such as cryoturbation and redoximorphism, side-by-side with desert pavements and ahumic character. Soil properties were more sensitive to the variations in parent material than to the topographic position in the landscape.