ABSTRACT

This study presents a lithology-based sequence-stratigraphic framework and depositional model for Lower Cretaceous, mixed siliciclastic-carbonate sediments of the Mid-Atlantic coastal plain (eastern United States). Lithologic data from cores and cuttings were integrated with wireline logs and two-dimensional seismic data to document lithofacies variability and stacking patterns across the Albemarle Basin of eastern North Carolina. Ten facies associations are defined, which are variably present within siliciclastic- and carbonate-dominated depositional profiles interpreted to extend from onshore lowland coastal plain to deep-shelf depositional environments.

Three depositional sequences (0, 1, 2) were identified, each with component upward-shoaling parasequences. Seismic reflectors typically coincided with key sequence-stratigraphic surfaces, which guided correlations between wells. Parasequences are grouped into parasequence sets with progressive progradational or retrogradational (highstand and transgressive systems tracts, respectively) stacking patterns. Transgressive parasequences are thinner, uniform in thickness, and tend to be more dominated by molluskan carbonate facies. Highstand parasequences have more variable thickness, are siliciclastic dominated, and tend to be progradational on seismic data. Late highstand deposits of sequence 1 are dominated by restricted carbonate facies that likely reflect increased aridity. Lowstand deposits were not recognized from onshore well and seismic data.

The sequence-stratigraphic framework developed documents the complex spatial and temporal facies relationships within a wave-dominated, mixed carbonate-siliciclastic passive-margin succession. The strata studied document the complex interplay of lithofacies within a transition zone between near-shore carbonate-dominated strata to the south (Southeast Georgia Embayment) and siliciclastic-dominated marginal-marine successions to the north (Baltimore Canyon Trough). It also provides a useful stratigraphic calibration set for coeval offshore sediments that have been identified as potential areas for hydrocarbon exploration.

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