Soil evolution on James Ross Island: evidence from geochronology, pedogeomorphology, and geochemistry

Abstract

Antarctic soils, forming under cold and aridity, preserve strong geochemical and mineralogical imprints of their parent material, offering a unique natural laboratory to study early-stage pedogenesis. James Ross Island (JRI), situated in the northeastern Antarctic Peninsula, presents a strategic setting due to its semiarid polar climate, diverse volcanic and sedimentary lithologies, and extensive deglaciated areas. Despite extensive research on soil genesis in Antarctica, critical knowledge gaps persist. These include: (1) insufficient understanding of how slope position and geomorphic processes modulate soil formation and spatial variability across contrasting lithologies on JRI; (2) a lack of detailed, quantitative analysis directly linking soil composition to specific parent rocks, limiting accurate quantification of weathering pathways and pedogenic transformations; and (3) an absence of a robust chronological framework for post-glacial landscape evolution and soil development, hindering the temporal contextualization of pedogenesis. This thesis addresses these gaps through three integrated studies. First, a detailed toposequence analysis evaluates how relief and slope processes (e.g., solifluction, aeolian redistribution) control soil morphology, chemistry, and spatial organization. Second, a comparative geochemical and mineralogical analysis of soils and their bedrock sources quantifies weathering intensity and pedogenic product formation in volcanic versus sedimentary settings. Third, Optically Stimulated Luminescence (OSL) dating of soils establishes a chronology of landscape exposure and stabilization, temporally contextualizing initial pedogenesis and periglacial activity. Together, these studies provide a comprehensive, process-based understanding of soil formation in a semiarid polar environment, contributing to refined pedogeomorphic models and insights into landscape sensitivity under changing climatic conditions. Keywords: Weathering; Periglacial Landscape; Deglaciation; Cryopedogenesis; Lithological controls.