Coastal Plain Sequences

sequence Coastal plain sediments are arranged in packages known as sequences (Posamentier et al., 1998). Deposition of sequences on the coastal plain is controlled by global sea level changes. The packages contain repetitive transgressive-regressive facies changes within sequences (Owens and Sohl, 1969;Sugarman et al., 1993, 1995) that consist of: 1) a basal, generally thin, transgressive quartz sand equivalent to the transgressive systems tract (TST) of Posamentier et al. (1988); and 2) a coarsening-upward succession of medial regressive silt and upper quartz sand equivalent to the highstand systems tract (HST) of Posamentier et al. (1988).  Lowstand systems tracts (LSTs) are generally absent in the up dip sections in the mid-Atlantic coastal plain (Browning et al., 2008).
Sequence boundaries are recognized in cores on the basis of physical stratigraphy.  Significant features include: irregular contacts, reworking, rip-up clasts, bioturbation, major facies changes, gamma ray peaks (often indicating lag deposits), and age breaks.