Reconstruction of a deep-time critical zone in southern patagonia (mid-high paleolatitude) during the mid-cretaceous greenhouse

Abstract

The mid-Cretaceous was a period characterized by a global greenhouse climate. Paleosols can be used to reconstruct Critical Zones of the Earth́s past and enhance our comprehension of such greenhouse conditions. Through macro- and micromorphological, clay-mineralogy, and bulk geochemical analyses of the paleosols, we conducted a deep-time Critical Zone reconstruction at mid-high paleolatitudes of the mid-Cretaceous Puesto El Moro Formation in the southern Patagonia (Austral-Magallanes Basin). Paleosols were classified as hydromorphic Histosol-like paleosols (Kachaike pedotype), Alfisols like-paleosols (La Lila pedotype), and Vertisol likepaleosols (La Bernarda pedotype). The analysis of these paleosols facilitated the reconstruction of the deeptime Critical Zone and enables us to infer the four scientific spheres (lithosphere, hydrosphere,biosphere, and atmosphere). Different types of paleosols developed under different parent materials with specific soil-moisture regime and drainage class. Overall, paleosols took place during temperate and humid conditions with a marked seasonality of the precipitations. The paleoclimate reconstruction obtained here provides new data from midhigh paleolatitudes and agrees with the current mid-Cretaceous climate reconstructions in the context of a greenhouse world.