Abstract: The Correlation Between Sequence Stratigraphy and Diagenesis in Quaternary to Neogene Carbonates, Subsurface Great Bahama Bank

Leslie A. Melim, Gregor P. Eberli, Peter K. Swart

Seismic sequences are commonly thought to represent significant changes in sedimentary facies due to changes in relative sea level. This study has also found a correlation between seismic sequences and diagenetic properties in two cores from the prograding western margin of the Great Bahama Bank.

Core Clino (677.27 m), the more distal core, penetrated a single shallowing upward succession from deeper slope facies through forereef, reef and platform top facies. Core Unda (452.94 m) includes three units of shallow water platform to reef facies separated by two intervals of deeper water proximal slope facies. Sequences identified on seismic have been correlated to these cores and show two kinds of association between diagenesis and sea level. Not only are the sequence boundaries defined by diagenetic horizons, (e.g., marine hardgrounds or subaerial exposure surfaces), but internally each seismic sequence has a characteristic set diagenetic properties. These properties include the amount and kinds of cementation, dissolution, recrystallization, and compaction as well as distributi n of dolomite and aragonite.

It is proposed that changing sea level not only controls the depositional facies, but also acts as the primary control on both near surface and shallow burial diagenesis. The initial diagenetic potential of the sediment (i.e., mineralogy combined with porosity/permeability) is only part of the story as sea level fluctuations also control variations of fluid flux into the platform (e.g. meteoric versus marine fluids). Thus, a careful analysis of seismic sequences and system tracts in the context of sea level history can be used to predict likely diagenetic patterns.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994