A Modified Graphic Correlation Method for the Plio-Pleistocene, Northern Gulf of Mexico: Implications for Sequence Stratigraphy
Claudia Arango, Tomas Villamil, Paul Weimer, and Art
Plio-Pleistocene biostratigraphic data from 60 wells in the Green Canyon area, northern Gulf of Mexico, were correlated using a modified version of Shaw's (1964) graphic correlation method. Our proposed modifications to this technique consist of (a) placing the origin of the graph at the present; i.e., at the sediment-water interface, allowing error bars to expand away from the origin of the graph as age increases; and (b) using multiple equations to establish the best-fitting line or curve of correlation.
Results from applying this method comprise the following: (1) a slightly modified biostratigraphy specific for the studied region, (2) a regional evaluation of the variability and range of biostratigraphic tops. This variability determines the reliability of biostratigraphic tops of taxa as proxy to time lines. The resulting distribution chart is specially important to seismic interpreters when evaluating the accuracy of regional chronostratigraphic correlations, (3) a sequence stratigraphic hypothesis tested against independently-derived seismic-stratigraphic interpretations. The slope of the line or curve of correlation is indicative of relative changes in sedimentation rate; steep curves represent condensation whereas gently sloping ones represent high sedimentation rates. Changes n the slope can be interpreted in terms of sequence stratigraphy: a change from gentle to steep represents the transgressive surface (the change from lowstand to transgressive-highstand), a change from steep to gentle represents the sequence. boundary (from highstand to lowstand). Basin-floor fans can be identified by abrupt changes in the slope, passing from very inclined to nearly horizontal and then to gentle.
AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California