Combined effects of eustatism and isostasy on stable epicratonic platforms during glacial periods with the example of the late Proterozoic-glacial deposits in western Mali in West Africa

Abstract:

The combined effects of eustatically and isostatically driven sea-level changes are illustrated in the late Proterozoic glacial deposits of the West African craton (Bakoye Group, western Mali). The 500 metres thick alternation of marine and continental deposits of the Bakoye Group exhibits at a parasequential scale, anomalic features in such an intracratonic setting. These anomalous deposits occur within a strongly shallowing upward marine succession lying upon earlier fluviatile and eolian deposits. On epicratonic platforms during glaciation, eustatically and isostatically driven sea-level changes encompassed largely all other non glacially-related sea-level variations. Hence, these deposits are interpreted to have been emplaced by a glacioeustatic rise of sea-level overtaken by the isostatic rebound of the substrate responsible for the perturbated facies. This type of parasequence might be an "elementary icecap fluctuation event' which oocurs within a larger glacial event, the aggradational units. Three aggradational units built up the Bakoye Group. The questions yet remaining to be answered are the significance and timing of the parasequences, of the units, and of the glacial Bakoye Group during a glacial period. -from English summary

Año de publicación:

1990

Keywords:

Fuente:

scopus