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Stephen F. Pekar1, Michelle A. Kominz2
(1) Rutgers University, Piscataway, NJ
(2) Western Michigan University, Kalamazoo, MI

Abstract: Two-dimensional paleoslope modeling: a new method for estimating water depths for benthic foraminiferal biofacies, paleo shelf margins, and systems tracts

A new method developed for estimating water depths of benthic foraminifers was implemented for Oligocene foraminiferal biofacies from the New Jersey Coastal Plain. We combined foraminiferal biofacies and two-dimensional flexural backstripping results into a two-dimensional paleoslope model. The geometry of New Jersey Oligocene strata was reconstructed by calculating the effects of sediment accumulation and flexural loading. Water-depth estimates for benthic foraminiferal biofacies were calibrated to inner neritic facies along the resulting complex profile (nonlinear, e.g., with clinoforms). Water-depth estimates for ten foraminiferal biofacies ranged from 20±10 m to 110±30 m and were consistent with more qualitative estimates based on other methods (e.g., foraminiferal abundances, species diversity). Reconstructed stratal geometry allowed determination of water depths for the paleoshelf and system tracts. Clear distributional patterns of benthic foraminiferal biofacies allowed testing and calibrating of the sequence stratigraphic model. Water-depth estimates ranged from 20±10 m up to 85±25 m for the preserved sediments landward of the clinoform rollover and from middle neritic to outer neritic (50±15 m to over 100±30 m) for the slopes of the clinoforms. During lowstand systems tracts, water depths immediately seaward of the clinoform slope ranged from inner neriticat updip sites to outer neritic at downdip sites. During highstand systems tracts, water depths ranged from 25±10 to 85±25 m landward of the clinoform rollover to 85±25 m to over 100±30 m on the slope and seaward of the clinoform rollover.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana