Neoproterozoic marine dolomite hardgrounds and their relationship to cap dolomites

Abstract

Neoproterozoic cap dolomites are unusual and distinctive marker units that occur after large Cryogenian glaciations. Several thin dolomite units that have features resembling cap dolomites occur within the Cryogenian-Ediacaran succession of the Adelaide Geosyncline. While each of these dolomite units has distinctive features, they also share many similarities with cap dolomites including: stratigraphic thickness ranging from several centimetres to several metres; impure dolomicrite composition; graded beds with a sharp top that become more dolomite-rich upwards; and evidence of volume expansion in the form of sheet cracks, tepees or other soft- sediment deformation structures. The carbon iso..