Paleosols as Indicators of Paleoenvironment and Paleoclimate

Abstract

Paleosols are ancient soils that have been incorporated into the geological record. Soils form in response to interactions among the lithosphere, hydrosphere, biosphere, and atmosphere, so paleosols potentially record physical, biological, and chemical information about past conditions near Earth's surface. As a result, paleosols are an important resource for terrestrial environmental and climatic reconstructions. Long-standing paleosol research topics include morphology, classification, and clay mineralogy, all of which provide information about pedogenic processes and local paleoenvironments. Paleosols are also used to infer processes involved in the development of stratigraphic architecture and basin evolution. Recent paleosol research has introduced semiquantitative and quantitative measures for environmental and chronometric reconstructions that provide insight into major regional to global changes in temperature, precipitation, and atmospheric pCO2. These new proxies focus on morphological and chemical transfer functions and stable isotope geochemistry to provide estimates of precipitation, temperature, pCO2, and productivity, as well as chronometric estimates of mineral crystallization in deep-time pedogenic systems. Looking forward, consensus must be reached on terminology that most effectively communicates paleosol characteristics and implies important processes. Proxy development will continue to improve as data sets become available across greater ranges of environments and timescales.