A Sequence
Stratigraphic Framework for the Lower Cretaceous North Carolina Coastal Plain,
Southeastern U.S.A
Sunde, Richard1, Brian P.
Coffey2 (1) Simon Fraser University,
Burnaby, BC (2)
Simon Fraser University, Vancouver
A lithology-based sequence stratigraphic
framework for the little studied Lower Cretaceous mixed carbonate-siliciclastic
sediments of the subsurface Albemarle Basin is presented. Thin
sections produced of well cuttings from exploration wells were analyzed to
characterize lithology, fossil components, depositional facies, and diagenetic
events, because the study interval is entirely confined to the deep subsurface
in a basin lacking core control. Data was then used in conjunction with
wireline logs to document the facies abundance and stacking patterns.
Integration of 2D seismic data and biostratigraphic control allowed regional
correlation of major transgressive-regressive events between wells, resulting
in the generation of a sequence stratigraphic framework for the onshore basin.
Results show the following dominant
lithofacies (listed from shallow to deep): sandstone, skeletal sandstone;
variably sandy mollusk packstone/grainstone; siltstone; unfossiliferous and
diatomaceous shales; skeletal wackestone; variably sandy (quartz and glaucony)
lime mudstone, and marl.
Comparison of observed facies with cores
and wireline logs from the Baltimore Canyon and S.E. Georgia
Embayment confirms the sequences consist of upward shoaling siliciclastic
shorefaces, with basal open shelf mollusk-rich carbonates often marking
transgressive events. Basin-scale depositional trends indicate greater
accumulation of the carbonate facies in the southern basin, with increased fine
siliciclastic material to the north. This trend may reflect a major
siliciclastic point-source in the vicinity of the ancestral Chesapeake region.
The depositional and diagenetic models
generated from this research provide valuable insight into the facies and
reservoir properties in coeval offshore units comprising frontier exploration
targets along the Atlantic coast of the U.S. and Canada.