Paleosols of Anacleto and Allen Formations (Argentina) and its relationship with Marília Formation and Urucuia Group (Brazil): Upper Cretaceous paleoenvironments in South America

Abstract

Paleosols are soils formed by the same processes we know today and that for some reason have been preserved. They may have been buried by later deposits on the surface or may be formed in different conditions from today.Especially since the 1980s, their importance had been recognized as they represent a mark in the depositional system since they indicate a lower sedimentation rate, preserving in it paleoenvironmental and stratigraphic information. In the past, paleosols were described by sedimentologists as massive lithofacies, but today is a source of complete and continuous information of different characteristics.This project aims to characterize the existing paleosols in Anacleto Formation (Neuquén Group) and in the Allen Formation (Group Malargue) in the provinces of Neuquén and Rio Negro, in Argentina in order to make the paleogeographic reconstruction based on their existing paleosols formed during the Upper Cretaceous, a period often characterized by significant green house effect, and unite the informations with those that were already collected over the past six years about the paleosols of Marilia Formation (19 ° to 23 ° S) and Group Urucuia (9 ° to 16 ° S ). These are located in a central and north area of the southern hemisphere, respectively. Together they build a large upper Cretaceous paleoenvironmental scenario for the South America area between latitudes 9 ° S and 40 ° S.The studies will envolve systematic field surveys, laboratory analysis (X-ray fluorescence spectroscopy, micromorphological description, X-ray diffraction), computerized processing of data and analysis of the existent phytoliths in paleosols of these formations.This study, together with parallel studies that have been made by the proponent since graduation, provides relevant information on global climate changes that occurred during the Cretaceous in South America during a time of significant increase in concentration of CO2 in the atmosphere of the planet.