Sedimentary Features and Significance of Interdune Deposits
Thomas S. Ahlbrandt, Steven G. Fryberger, 1981. "Sedimentary Features and Significance of Interdune Deposits", Recent and Ancient Nonmarine Depositional Environments: Models for Exploration, Frank G. Ethridge, Romeo M. Flores
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Interdunes occur between dunes in most dune fields, but they have not been adequately studied. Our preliminary work indicates that interdunes among dunes formed in unimodal wind regimes are fundamentally different than interdunes among dunes formed in bimodal or complex wind regimes. The mechanism of alternate dune and interdune development producing lenticular, diachronous and relatively thin (<2 meters) interdune deposits among unimodal dunes (McKee and Moiola, 1975) is strongly supported in our experience. However, interdune deposits among dunes formed in bimodal or complex wind regimes, i.e. linear and star dunes respectively, seem to be thicker and more areally extensive than among unimodal dune regimes.
Interdunes broadly can be classed as deflationary or depositional; these in turn can each be informally subdivided, based upon water content, into dry, wet and evaporite interdunes. Sedimentary features of each type based on dune fields studied principally in the United States and Saudi Arabia, and eolianites in the western United States, are discussed and illustrated. Many interdune deposits are virtually structureless due to secondary processes.
Ancient interdune or sabkha deposits are important for several reasons: (1) they may form barriers to effective fluid migration in hydrocarbon reservoirs or isolate productive intervals; (2) they may be potential hydrocarbon sources; (3) they may be a source of minerals and trace elements; and (4) they may serve as faunal, floral or reference horizons within eolianites.
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This volume is a collection of papers that resulted from a symposium on Recent and Ancient Nonmarine Depositional Environments which was held in Casper, Wyoming on June 3 to 7, 1979. The nineteen papers may be divided into: (1) a review of recent and ancient nonmarine modes, (2) alluvial fan and fluvial deposits, (3) lacustrine deposits, (4) eolian deposits. Knowledge of the physical, biological and chemical characteristics and depostional environments on nonmarine sedimentary deposits has increased significantly over the last decade. Correspondingly, there has also been an increase in our ability to apply this knowledge to the exploration and exploitation of contained energy resources and minerals.