Model for Estuarine Transgression Based on Facies Variants in Nearshore of Western Delaware Bay: ABSTRACT

Abstract

Delaware Bay is an example of a pre-Holocene river valley and tributary system gradually being inundated during the Holocene Epoch transgression. The stratigraphic record left as the coastal environments shift landward in response to the transgression provides keys to understanding a number of coastal processes and morphic variables which affect the completeness of the transgressive sedimentary record. These include: irregularity of the pre-Holocene surface being transgressed, variation in wave energy as determined by fetch and climate, availability of sediment source for littoral transport, and rates of compaction and subsidence. A number of specific coastal sites illustrate the high degree of variability in the subsurface stratigraphic record including the extremes of i cision of a pre-Holocene headland and migration of a thin barrier over 30 m of mud. Cross-sectional interpretations based on core data show the geometric variability of the resultant sedimentary units varying from sheetlike estuarine silts to irregular barrier remnant deposits to thick sequences of lagoonal/marsh muds. Using site specific examples and incorporating all the variables inherent in the preservation of the many sedimentary environmental units, a generalized model for an estuarine transgression has been developed. The Delaware coast is an excellent area from which to form this model since an extraordinarily high diversity of processes and stratigraphic factors have been introduced. Therefore, application of the model to other modern and ancient estuarine strandline and nearsho e areas becomes possible. Predictions concerning the nature and rate of coastal change of variable oceanic-estuarine systems have been made using the model. End_of_Article - Last_Page 953------------