--> Abstract: Paleosols, Pedosedimentary History and Paleolandscape Evolution: Practical Tools for Nonmarine Sequence Stratigraphy and Basin Analysis, by Paul J. McCarthy; #90039 (2005)

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Paleosols, Pedosedimentary History and Paleolandscape Evolution: Practical Tools for Nonmarine Sequence Stratigraphy and Basin Analysis

Paul J. McCarthy
University of Alaska, Fairbanks, AK

Paleosols are useful for identifying erosional discontinuities and major pauses in sedimentation that allow us to recognize and map stratigraphically important surfaces, and for recognizing changing rates of accommodation, both in outcrop and subsurface. Many significant nonmarine surfaces may be apparent on the basis of sedimentology and regional stratigraphy alone; however, their appearance can change markedly across a study area, making correlation difficult. These difficulties can be at least partly resolved by utilizing a pedosedimentary approach in order to reconstruct local and regional paleolandscape evolution. A pedosedimentary approach has been utilized to reconstruct the sequence of pedogenic and sedimentary events recorded by mid-Cretaceous paleosols from different settings in the Western Canada Foreland Basin. This pedosedimentary approach provides a means of deciphering the development of paleosols based upon detailed microstratigraphic associations and depth functions of their pedogenic features, in conjunction with ancilliary geochemical, mineralogical, sedimentological and stratigraphic evidence. Paleosol micromorphology, field morphology and major physicochemical characteristics of both floodplain and interfluve paleosols reveal complex sequences of soil development that can be related to paleosol-landscape models that reflect differences in ancient hydrology, topography, parent material composition, surface stability and rates of aggradation across an individual landscape that vary both spatially and temporally. This permits both sequence boundaries and varying rates of accommodation to be identified with a high degree of confidence on the basis of intrinsic evidence derived from the record of ancient soil and landscape processes preserved within the paleosols themselves that is invaluable for regional correlation and terrestrial basin analysis.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005