About This Item
Share This Item
A correlation model of adjacent coastal sedimentary lithosomes in a Holocene transgressive sequence and Pleistocene regressive sequence has been formed for use in the interpretation of ancient transgressive-regressive coastal sequences. During the present Holocene marine transgression in the mid-Atlantic coastal area, sedimentary lithosomes are forming in a series of coastal sedimentary environments in a typical transgressive vertical and horizontal sequence pattern. These transgressive coastal environments are directly adjacent to and over a mid-Wisconsin or Sangamon high sea regressive coastal environment sequence.
Diagnostic sedimentary structures and textures presently forming in the Holocene coastal sedimentary environments are used to identify adjacent Pleistocene coastal sediment lithosomes. These include beach, berm?, tidal delta, dune, and other barrier subenvironments, and fringing marsh, lagoonal and shallow marine-estuarine environments. Trends of Holocene and Pleistocene barriers diverge 25-35° with additional complexity in areas of major spit development.
In applying the concept "the present is a key to the past," studies of Holocene-Pleistocene transgressive-regressive coastal environmental relations suggest that great caution should be used in attempts to project coastal trends in ancient rocks. Transgressive-regressive vertical and horizontal sedimentary sequences formed during fluctuating sea-level conditions may occur adjacent to each other and appear to correlate. Accordingly, models of lateral and vertical facies relations in adjacent Holocene transgressive and Pleistocene regressive coastal sequences should be of use in facies correlation in similar but ancient geologic settings.
End_of_Article - Last_Page 634------------