Skip to Main Content
Book Chapter

A Pedostratigraphic Approach to Nonmarine Sequence Stratigraphy: A Three-Dimensional Paleosol-Landscape Model from the Cretaceous (Cenomanian) Dunvegan Formation, Alberta and British Columbia, Canada

By
Paul J. McCarthy
Paul J. McCarthy
Department of Geology & Geophysics and Geophysical Institute, University of Alaska, Fairbanks, Alaska 99775-5780 pjmccarthy@alaska.edu
Search for other works by this author on:
A. Guy Plint
A. Guy Plint
Department of Earth Sciences, The University of Western Ontario, London, Ontario, N6A 5B7, Canada
Search for other works by this author on:
Published:
January 01, 2013

Abstract

A basin-scale pedostratigraphic model that focuses on paleosols and their pedostratigraphic relationships has been established for the Cenomanian Dunvegan Formation, a unit that represents a large delta complex. A detailed sequence stratigraphic and paleogeographic framework permits analysis of paleosol development with respect to distance from marine shorelines and coeval valleys. Paleosols that bracket sequence boundaries vary depending upon their paleo-landscape position. The sequence-bounding package of paleosols can be partitioned into three spatial zones based upon both the degree of development and the architecture of the paleosols. Zone 1 occurs in seaward localities near the maximum regressive shoreline and is characterized by hydromorphic, weakly developed paleosols typical of a poorly drained, progradational, and aggradational coastal plain. Zone 2 occurs in an intermediate location and is characterized by well-developed Alfisol-like welded paleosols that record a complex architecture indicating (i) an aggradational phase; (ii) a subsequent static and/or degradational phase related to valley incision, nondeposition, and soil thickening; and (iii) a final aggradational phase related to valley filling and renewed sedimentation across the coastal plain. Zone 3 occurs in more up-dip settings and is characterized by compound and complex Inceptisol-like paleosols that developed as the result of a reduced aggradation rate when valleys were being incised further down-dip. Because accommodation, sediment supply, and hydrological conditions vary in both dip and strike directions, the three zones represent lateral soil facies equivalents. The soil-forming interval bracketing the sequence boundary comprises a geosol composed of welded paleosols that subdivide both up-dip and down-dip into more weakly developed aggradational paleosol complexes. Above the sequence boundary, a high accommodation phase (equivalent to the Transgressive Systems Tract) is represented by widespread lacustrine and poorly drained floodplain facies and weakly developed hydromorphic paleosols. As accommodation rate decreases (late Highstand Systems Tract time) the alluvial succession becomes paleosol dominated, comprising floodplain pedocomplexes that record a regional decrease in the accommodation/sediment supply ratio. Up-dip variability along the sequence boundary and within sequences is controlled primarily by variations in the accommodation/sediment supply ratio, by hydrological variations associated with floodplain incision during valley formation, and by tectonic subsidence rates that vary in space and in time.

You do not currently have access to this article.

Figures & Tables

Contents

SEPM Special Publication

New Frontiers in Paleopedology and Terrestrial Paleoclimatology: Paleosols and Soil Surface Analog Systems

Steven G. Driese
Steven G. Driese
Search for other works by this author on:
Lee C. Nordt
Lee C. Nordt
Department of Geology, Baylor University, One Bear Place #97354, Waco, Texas 76798-7354, USA
Search for other works by this author on:
SEPM Society for Sedimentary Geology
Volume
104
ISBN electronic:
9781565763036
Publication date:
January 01, 2013

GeoRef

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal