Abstract: Eustatically-Driven, Mississippi River Holocene Delta-Switching as Part of Global Highstand Process

LOWRIE, A.
Consultant, Picayune, MS;
S. J. MOFFETT
Consultant, Picayune, MS;
T. C. KLEKAMP
Elcon Exploration, Inc., Mandeville, LA;
R. HAMITER
Consultant, Lyman, MS.

Climatic and sea-level oscillations (of approximately one meter range and millennial periodicity) that influence deltaswitching are documented, especially for northern temperate latitudes. Proxies for climate include C¹⁴ fluxes, elevation of tree lines and archeological positions of seaports. Occurrence of the Little Ice Age, beginning in the early 1300s, is documented by historical records and by the commencement of the Belize Delta.

A complex of synergistic processes combine to create the existent Holocene sedimentation patterns. The processes include climate, rate and type of sediment inputs, sea-level position, sediment accommodation space, whether the continental margin is active or passive, oceanographic western boundary intensification occurrence and its impact on local meteorology and influence on vegetation and rates of weathering, and along which atmospheric cell (Hadley, Ferrel, or Polar) deposition is/has occurred. These ten inputs can impact Holocene transgressive and highstand deposition.

The intensity of these inputs varies with the strength of the climatic cycle, be it fifth order (~10³ yr), sixth order (~10² yr and multiples thereof, and seventh order (~10¹ yr and multiples thereof) oscillations. Each oscillation has impact on the erosion, transportation and deposition continuum.

The main objectives of this study include input description and quantification, as ranges, and delineation of process equations. The inputs provided by historical data such as river flow, rainfall, temperature and sea-level change yield a basis for extrapolating to prehistoric times. A Holocene description applies to similar highstand phases of the Plio-Pleistocene.

AAPG Search and Discovery Article #90932©1998 GCAGS/GCS-SEPM Meeting, Corpus Christi, Texas