Pennsylvanian Glacial Cycles in Western Gondwana: an overview.

Abstract

The Pennsylvanian on the western rim of Gondwana can be considered a time of significant contrasts in terms of environments, revealing a unique translatitudinal disposition of the South American continent, where glaciomarine deposits and peat-forming environments, situated further south, coexisted with marine carbonate platforms and aeolian dune fields, in terrains further north. This peculiar record creates an opportunity to better understand the teleconnections of glaciation and deglaciation during the Late Paleozoic Ice Age (LPIA) between mid and low latitude regions. In the last decade, radiometric dating together with marine microfossils (mostly conodonts) has enabled a better understanding of the timing and duration of deposition of different sedimentary environments found in the climate belts that originated from a global ice-house regime. These advances in the chronostratigraphical positioning of sedimentary deposits also allow a more precise correlation between them, making it possible to estimate cause–effect patterns arising from the growth and decay of glaciers in this portion of Gondwana. This contribution aims to present an overview of the main climatic–environmental events that took place during the Pennsylvanian and to associate them with the floristic changes that occurred in the emergent lands based on palaeobotanic and palynological information. The record from the west rim of Gondwana could be roughly divided into Early, Middle and Late Pennsylvanian, exactly as proposed in the geological time-scale.