The Cretaceous flora of the Neuquén Basin,its paleoenvironmental and paleoclimatic significance

Abstract

The paleoenvironmental and paleoclimaticsignificance of Cretaceous flora in the Neuquén Basin is summarized. Berriasian-Barremianterrestrial palynological assemblages are dominated by Araucariaceae andCheirolepidiaceae, with subordinated podopcarps, ferns, lycopsids andbryophytes that progressed in a mild and humid climate. Tithonian-Barremiandinoflagellates mostly possess Mediterranean affinities. Upper Barremianevaporitic strata represent the final cycle of marine deposition related to thePacific ocean in the basin. In the Aptian appear the first angiosperm pollengrains. Aptian- Cenomanian terrestrial palynological assemblages arecharacterized by the presence of northern Gondwana forms such as Afropollisand elaterate pollen grains. Tempskyaceae and Ginkgoales are also present inthe late Early Cretaceous. Turonian-lower Campanian continental strata mostlyinclude petrified wood and charophytes. Upper Campanian-Maastrichtian stratayield a rich terrestrial palynological assemblage composed by Nothofagaceae,Podocarpaceae, Cheirolepidiaceae, Araucariaceae, Salviniales and angiosperms,but also dinoflagellates that reflect the beginning of a marine transgressionrelated to the Atlantic ocean. The presence of locally abundant cycads andpalms suggests a warm and relatively humid climate towards the end of theCretaceous.