Luminescence dating, geochemistry, and analysis of Pleistocene sediments from Specimen Cave, Naracoorte, S.A.

Abstract

A digitised map was produced for Specimen Cave and used to indicate sediment sampling locations. Luminescence dating of the sediments provided constraints on the encompassed megafaunal inclusions to between 119.27±13.50 ka and 165.50±21.19 ka. Single-grain OSL method provided better results for the type of sediment accumulation than multi-grained analysis. The TT-OSL dating method provided better results for the age extent of sediment accumulation than single-grain OSL analysis. The most reliable OSL technique for Middle Pleistocene material was TT-OSL because SG-OSL had reached its limits of dating of the cave sediments due to grain saturation. Sediment morphology, through visual assessment and SEM images, displayed collisional wear patterns consistent with aeolian transport. Sediment input to the cave system was via pitfall entrances. Lithology was determined for 90 samples with characteristics used to compare provenance to known regional samples. Geochemical analysis of the cave sediments was used to assess; in-situ sediment similarities horizontally between cave areas; provenance related to nearby caves; and provenance to local area deposits with only minor similarities detected. Organic residue was determined in the sediment samples but no pollen was present for palaeoenvironment investigations. Deposition in the cave occurred during MIS 6 and MIS 5 in conditions of low ice volume and increased CO2, temperatures, and water table volumes, alongside decreased dust, sea level regression and continental uplift.