Non-Synchroneity of Late Precambrian Glaciations in Africa

A review of presently available age and stratigraphic data on the Late Preeambrian glaeiogenie deposits of Africa provides compelling evidence for two major widespread glacial events, one between about 740 m.y. and 1,000 m.y. ago and the other between about 630 m.y. and 720 m.y. ago. It is proposed that the centers of glacial activity developed and shifted due to an increased obliquity of the Earth's ecliptic and the rapid movement of the African plate or the Late Precambrian paleopoles. There is no evidence to support the model of a severe Infracambrian ice age of global dimensions and non-synchroneity of the glacial sequences as well as stratigraphic relationships do not favour the hypothesis that such glaciation was triggered by a worldwide fall of temperature following the locking up of CO₂ in carbonate rocks preceding tillite deposition. Carbonate rocks seem to follow rather than precede the glacial strata and certain characteristic sedimentary associations found in many Late Precambrian glaeiogenie rocks of Africa may perhaps be used for continent - wide litho-stratigraphic correlation. An increased obliquity of the ecliptic as well as the arrangement of continental masses and continental drift are seen as the main causes of the Late Precambrian glaciations and a possible relationship with continental breakup and dispersal during the Pan-African teetono-thermal event is suspected.