Inverse relation between ice extent and the late Paleozoic glacial record of Gondwana Available to Purchase

The late Carboniferous–earliest Permian age estimate (300–280 Ma) for maximum ice volume during late Paleozoic glaciation of Gondwana is challenged. Past estimates assume a direct relation between extent of depositional glacial record and former ice cover; this assumption cannot be sustained, given that the glacial record is composed predominantly of glacially influenced marine strata that accumulated on the margins of ice-covered areas. We argue that Gondwana ice cover expanded in the Early Carboniferous in response to polar position, availability of moisture from a mediterranean sea, and epeirogenic uplift of the Gondwana interior. In Namurian time (ca. 325 Ma), Gondwana ice cover attained a maximum extent of about 21 × 10⁶ km², nearly the area of maximum Pleistocene ice cover. Despite extensive ice cover, the depositional record is meager; continental glacial deposits are poorly preserved on a regional unconformity. Thereafter, extensional subsidence of intracratonic basins promoted marine flooding, fragmentation of the ice cover, and the accumulation of thick glacially influenced marine deposits. In Stephanian-Asselian time (ca. 285 Ma), ice cover had decreased to about 15 × 10⁶ km², but glacial marine strata were being deposited and preserved across a very large area of the Gondwana supercontinent.