Critical Zone Studies of Soils and Weathering: Implications for Interpreting Climate and Landscapes of the Past: Overview

The National Academy of Sciences identified integrative studies of the "Critical Zone" (CZ) as one of the six compelling opportunities for earth scientists in the next decade. The CZ is defined as the near-surface environment in which complex interactions involving rock, soil, water, air and living organisms regulate the natural habitat.

Integrative studies of the surface- and near-surface environment are recognized as an important area of focus by scientific communities including geology, biology, pedology, and hydrology. Modern-ancient analog studies of the CZ relate the morphology, microscopy and chemistry of modern (i.e., surface) soils to interpreting the genesis and climate record of ancient buried soils known as paleosols. This session will focus on uniting the efforts of geoscientists studying ancient soil systems with those engaged in studies of modern surface soils and weathering processes. Research on modern systems currently conducted by invited speakers for this symposium focuses on: (1) climate- (rainfall amount, seasonality, temperature and drainage) and time-dependent controls on rates and processes of weathering and soil formation in modern systems, with application to both Earth and Mars, (2) isotope geochemistry of soils as a tool for understanding paleoclimate (precipitation, temperature and seasonality) and paleoecology, and (3) climate signals produced by organism (animal-plant) interactions with soil matrices. Research on ancient systems currently conducted by invited speakers for this symposium emphasizes development of an array of proxy estimates for paleoclimate and paleoecology reconstructions, including: (1) paleoprecipitation and paleotemperature from whole-rock geochemistry as well as from carbonate, siderite, goethite, and other pedogenic minerals, (2) paleobarometers for estimating paleo-atmospheric pCO₂ and other important gases, and (3) evaluating the modern/ancient analog potential of the Quaternary. Important limitations to the success of modern-ancient analog approaches are also identified and suggestions for future directions of research are proposed.