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The AAPG/Datapages Combined Publications Database
AAPG Bulletin
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Analyses of stratigraphic correlation, reservoir distribution, and facies change in Mesozoic and Cenozoic sediments in the subsurface of the Salisbury embayment can be used as a model for stratigraphic projection into the submerged part of the geosyncline. The sediments studied are unlithified with a thickness greater than 7,700 ft near the coast. Onshore Cretaceous marine and nonmarine sand and clay correlate with a published geophysically identified semiconsolidated sediment unit as thick as 14,000 ft. Paleocene, Eocene, and Miocene sediments project into a zone of up to 5,000 ft of unconsolidated sediment. A thin veneer of Quaternary marine and nonmarine sediments covers almost the entire coastal plain-shelf area. Limited onshore evidence suggests that lithified Triass c or Jurassic sediments comprise a significant deeper part of the offshore basin.
Correlations range from simple, long-range correlations of widespread, uniform, marine units to difficult, short-distance correlations where abrupt facies changes in marine and nonmarine sediments take place. Identification of the Upper-Lower Cretaceous boundary is in doubt and previously has been placed at different levels within a stratigraphic interval 3,000 ft thick. The diversified and complex terminology applied to sediments on the northwest geosynclinal flank demonstrates the complexity of correlation in this area of abrupt facies change. Detailed geophysical log correlations also suggest the presence in the subsurface of this area of abrupt facies changes in marine and nonmarine stratigraphic units. Local minor unconformities may be common in the margin of the geosyncline.
A salt-water wedge protrudes to within 20 mi of the basin edge and commonly is found at depths greater than 1,000 ft. Excellent reservoir conditions occur throughout the onshore stratigraphic section.
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