Stratification and Sequence in Prograding Shoreline Deposits
Published:January 01, 1975
1975. "Stratification and Sequence in Prograding Shoreline Deposits", Depositional Environments as Interpreted from Primary Sedimentary Structures and Stratification Sequences, J. C. Harms, J. B. Southard, D. R. Spearing, R. G. Walker
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Prograding shoreline deposits are used in this chapter to further illustrate the interpretation of primary structures and their sequence. Two main points are:
Structures in complex environments with waves, tides, and shifting currents can be interpreted in part from concepts presented in Chapters 2 and 3. But some of the primary structures are quite different and cannot be directly related to process on the basis of existing flume or wave tank experiments.
Stratigraphic position and facies sequence provide some general environmental constraints which can be used to infer the hydro-dynamic conditions that produce these poorly understood structures. For example, the vertical succession through a deposit formed by a prograding shoreline should be related to progressive depth and process change observed along modern shoreline profiles. Carefully used, these inferences about environmental and hydro-dynamic constraints can add to our understanding of primary sedimentary structures.
Shoreline and nearshore deposits are well represented in the geologic record. In keeping with the purpose and scope of this course, we shall discuss only a few examples that we believe to have common occurrence and broad application. The three types of prograding shoreline deposits we have chosen contrast mainly in dominant grain size. The first example is that of shoreline sediments composed of very fine or fine sand, drawn mainly from Upper Cretaceous deposits of the Western Interior of the USA. The second example is one of shoreface deposits containing significant quantities of
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Depositional Environments as Interpreted from Primary Sedimentary Structures and Stratification Sequences
The focus of these notes is on the use of primary sedimentary structures and stratification sequence as tools for interpretation of depositional environment of clastic sediments, emphasizing advances in understanding that the authors judge to be important. To accomplish the primary objective, several topics have been selected. Experimental flume studies are summarized with emphasis on work which extends the understanding of distribution of bed forms over increased ranges of grain size, flow depths, or velocity. Studies of modern and ancient sedimentary sequences are used to illustrate and interpret environments of deposition. Fluvial sediments are reviewed to show how experimentally derived generalizations are applied or qualified to interpret natural environments.