Clay minerals in Lake Frome sediments of Australia and their paleoclimatic implications

Abstract

Clay minerals in 32 samples collected from the upper 6 meters of drill core LF 82/1-3 in Lake Frome, Australia have been examined using X-ray powder diffraction techniques. The results show that the clay mineral species are predominated by illite, kaolinite and a small amount of montmorillonite. Minor chlorite and vermiculite can also be identified in some of the samples. In terms of clay mineral species, crystallinity and other characteristics, the upper 6-m core can be divided into 3 sections, the boundaries of which are marked at depths of about 125–150 cm and 415–455 cm with ages of 14 and 19 thousand years B.P., respectively. The middle section at a burial depth of 150–415 cm may have been deposited under moist conditions while the other two under relatively dry conditions. Additionally, some slight climatic fluctuations seem possible in different stages.