Postglacial transgressions in late Paleozoic basins of western Argentina: a record of glacioeustatic sea level rise
The areas marginal to main glaciated centers are appropriate sites to distinguish the record of glacioeustatic sea level fluctuations. The Late Paleozoic basins of western Argentina show a marginal position with respect to the glaciated areas of eastern South America (Brazil). In three of these basins (Tarija, Calingasta-Uspallata and Central Patagonian) widespread glacial-marine diamictites and their gravity-reworked counterparts pass upward to open-marine fine clastics (mudstones, shales and scarce fine sandstones) with fossils of the Levipustula zone of Middle Carboniferous (Late Namurian-Westphalian) age. The presence of fine-grained marine sequences capping the diamictitic deposits is interpreted as the sedimentary response to a glacioeustatic sea level rise, expressed as a transgression in stratigraphic terms. The glacioeustatic nature of this sea level rise is confirmed by the interbasinal, facies-based correlation of the transgressive episode and the paleolatitudinal positioning of this portion of Gondwanaland during Carboniferous times.