Haloclasty on the bed of the Lake Gairdner Salina, South Australia

Abstract

Lake Gairdner occupies a blocked valley system within the Gawler Ranges consisting of Mesoproterozoic dacitic rocks physically hard with low porosity and permeability. Haloclasty is developed on the lake and the precipitation of halite causes rock disintegration on the large blocks and boulders that have tumbled from columnar jointed dacite. Some are excessively notched producing mushroom rocks. Occasional wave action during short-lived lake phases carries the detritus away from the sites. The ages of the salina and of the salt crust are not known but are in the order of millennia and centuries rather than millions of years.