The Rate of Tidal Channel Migration and the Response to Sea Level Change in Holocene Carbonate Muds of Northwest Andros Island, Bahamas

Maloof, Adam C.¹; Grotzinger, John P.^2
1 Geosciences, Princeton University, Princeton, NJ.
² Geological & Planetary Sciences, California Institute of Technology, Pasadena, CA.

Virtually all pre-Mesozoic records of changing ocean chemistry and temperature are derived from chemical sediments deposited on continental shelves. Stable isotope studies of these carbonate rocks have helped to correlate stratigraphic units from around the world and placed the evolution of life in the context of a variable and, at times, non-uniformitarian carbon cycle. However, in the absence of quantitative constraints on the rate and duration of geochemical variability, stable isotope data tell us little about the processes most important to the variable carbon cycle and the co-evolution of life and the surface environment.

Meter-scale upward-shallowing parasequences in platformal carbonates are ubiquitous and have been used to constrain depositional timescale when interpreted as the stratigraphic response to a periodic external driver such as the orbital forcing of sea level change. However stochastic internal drivers such as the avulsion and migration of meandering tidal channels also may exert important control on parasequence architecture and modify or obliterate the fingerprint of orbital forcing. We present a study of carbonate accumulation on northwest Andros Island under the influence of a known Holocene sea level forcing and determine the relative importance of channel avulsion and migration in controlling Holocene parasequence architecture.

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009