An investigation into the sedimentary laminations at West Basin Lake, Victoria: Are they varves?

Abstract

West Basin Lake, in the Western Victorian Volcanic Region, has characteristics conducive to deposition of annually laminated sediments known as varves. The uppermost 50 cm of lake sediment consists of finely laminated, organic-carbonate sediments of a size and frequency that are typically associated with varved lake sediments. Varves hold tremendous potential as palaeoclimate indicators, allowing for the development of precise chronologies and annual scale climate reconstructions. Through detailed micro-facies analysis and counting of the West Basin lake sediments, the study found that the number of laminations was in good agreement with radiometric depth age modelling, suggesting annual deposition. It was concluded that although seasonal lamina were unable to be classified by the scope of this study, good agreement with radiometric depth-age modelling in conjunction with meromixis of West Basin Lake, its sheltered nature and sediment-water interface anoxia, suggest the laminations more likely represent varves than non-annual laminations and should warrant further investigation.