Silcrete in Western Australia: geomorphological settings, textures, structures, and their genetic implications

Abstract

Summary Tertiary silcrete and laterite are extensively preserved in Western Australia in low-relief landscapes. Silcrete is best developed on topographic highs developed on fluviatile sands which overly radiolarites or deeply kaolinised claystones. Laterite occurs topographically lower and is generally developed on fine-grained bed rock. Lateral transition of silcrete to laterite indicates that these duricrusts form a soil catena. Cone structures in the silcretes indicate strongly evaporitic, dry conditions, whereas solution pipes in duricrust profiles indicate humid conditions. The silcrete/laterite catena thus indicates a strongly seasonal, hot, and humid climate, with rainfall probably in excess of 1000 mm yr −1 .