Could ‘Snowball Earth’ have left thick glaciomarine deposits?

Abstract

At least two of the Cryogenian (Neoproterozoic) glacials, viz. those of the Sturtian and the Marinoan, are said to have been so severe that the entire Earth was covered with ice (Snowball Earth). The most convincing evidence consists of diamicts with some glacial striae and of other glacial signatures (striated surfaces, polished rocks) that have been found in areas that are interpreted on the basis of paleomagnetic data as being positioned, at the time, at low latitudes. The extremely low temperatures must have contributed to entirely frozen oceans. Nevertheless, diamicts of exceptional thickness were formed in a marine environment. This cannot be explained satisfactorily, as icebergs cannot have floated in an entirely frozen ocean. It is suggested that at least a considerable part of the extremely thick Neoproterozoic ‘glaciomarine’ deposits represent syntectonic mass-flow deposits rather than glacial deposits. The existence of a huge mountain range between Eastern and Western Gondwanaland provided favourable conditions for such deposits.