Predicting Paleosol Distributions Using Paleoclimate Simulations: Results for the Late Devonian, Early Permian, Late Triassic, Late Jurassic, Late Cretaceous (Cenomanian), and Early Eocene

Different kinds of soils form in different climate regimes. For example organic-rich histosols often form in the low-lying, permanently waterlogged landscapes typical of tropical, everwet climates. Aridisols, as the name suggests are found in arid to semi-arid regions. Because soils so closely match climate regimes, they are one of the best indicators of past climates. In this paper we use the associations between modern soil types and modern climate to build a “paleosol prediction program”. There are two principal inputs for the paleosol prediction program 1) a present-day, digital map of the world's soil types, and 2) a digital map of global of modern seasonal rainfall and temperature patterns. Using a multivariate approach, the best fit between a given soil type and the range of rainfall and temperature was determined. Each major soil type has a unique climatic “fingerprint” or “climate envelop” defined by a range rainfall and temperature values. In the next step, a paleoclimate simulation using the Fast Ocean and Atmosphere Model (FOAM) was run for six time intervals: the Late Devonian, Early Permian, late Triassic, Late Jurassic, Late Cretaceous (Cenomanian), and early Eocene. 3D, paleotopographic maps for each of these time intervals was provided by the PALEOMAP Project. Using the climate envelops for each soil type, we were able to map out the predicted paleodistribution of each of these soil types on the paleogeographic maps. It is interesting to note that the extent and relative abundance of these soil types changes through time. The next step in the analysis will be to test the predicted paleosol locations using the database of climatically sensitive rock types compiled by Boucot, Chen and Scotese, and available paleosol information.