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the palynofloras has been undertaken mainly by reviewing published sources from cretaceous basins but also with our own unpublished data.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.

Fossil seeds from the La Cantera Formation, Early Cretaceous, San Luis Province, Argentina

“…and Jugella spp. (Prámparo, 1990;Prámparo et al, 2018;Puebla et al, 2017). The abundant plicate pollen grains associated with the macrofossils confirm the strong representation of this group in the basin (Puebla et al, 2017).…”

“…This morphology is evident in seeds of some extant species of Ephedra (Section Alatae), which are wind-dispersed (Hollander and Wall, 2009;Hollander et al, 2010). The abundant record of Ephedra in the La Cantera Formation (indicative of dry, even arid conditions) suggests a marked arid season in the basin during the late Aptian (Puebla et al, 2017;Prámparo et al, 2018).…”

“…This family was a characteristic and abundant element of lowlatitude Cretaceous floras, mainly represented by Classopollis pollen (Alvin, 1982). It is also a frequent and abundant component of Early Cretaceous palynofloras of Argentina (Quattrocchio et al, 2011;Villar de Seoane and Archangelsky, 2014;Prámparo et al, 2018) and other high-latitude parts of Gondwana (Tosolini et al, 2015). Classopollis, together with pollen grains of Gnetales (mainly those with Ephedra and Welwitschia affinity), have been used as indicators of aridity in paleoclimatic reconstructions, mainly in low to middle latitudes (Herngreen, 1996;Mejia-Velasquez et al, 2012;Prámparo et al, 2018).…”

“…The La Cantera Formation yielded abundant pollen grains of Classopollis at some levels (Prámparo, 1989(Prámparo, , 1990(Prámparo, , 1994. The abundance of these pollen grains, together with Gnetalean pollen, both inferred to be droughtresistant, indicate an expanding hot arid climate during the Aptian-Albian in the middle and low latitudes of Argentina (Prámparo et al, 2018). However, there are no records of conifer macrofossils in the basin.…”

Laboratorio Y Museo De Dinosaurios De La Universidad Nacional De Cuyo: Fundación, Historia Y Descubrimientos Científicos

“…González Riga et al, 2015). Los estudios bioestratigráficos y paleoambientales indicaron que las huellas de Loncoche fueron producidas en llanuras deltaicas dominadas por mareas (Prámparo et al, 2006(Prámparo et al, , 2008. Por ello se realiza un seguimiento permanente que permite constatar que los morteros cementicios presentan mejor resistencia y adhesión al sustrato que los pegamentos de silicona (Coria et al, 2019).…”