Cretaceous climatic reconstruction from Argentina based on palynological data

Abstract

Paleoclimatic reconstructions have used different proxies as climate indicators. In this context, palynomorphs play a crucial role for making inferences about past climate changes because of their presence and distribution during the geologic history in almost all types of environments. Argentina has a wide latitudinal range in South America, with diverse cretaceous units yielding palynomorphs that represent different climatic conditions. The Cretaceous was a time when climate conditions showed some special variations. Different theories about the climate conditions at this time were postulated. The main aim of this contribution is to understand climate trends during the Cretaceous, based on the quantitative analysis of selected pollen and spores, considered as climate indicators, from different geological units in Argentina. The evaluation of the palynofloras has been undertaken mainly by reviewing published sources from cretaceous basins but also with our own unpublished data. The climatic trend during the Cretaceous showed that the Early Cretaceous is marked by aridity episodes with high values of Classopollis and Gnetales. In contrast, the Late Cretaceous showed warmer and more humid conditions indicated by increasing values of free-sporing plants (especially Bryophytes and ferns) and palm pollen grains, and the decrease until their absence of the aridity indicators.