Evidence for Orbitally-Driven Sedimentary Cycles in the Devonian Catskill Delta Complex
Jay Van Tassell, 1994. "Evidence for Orbitally-Driven Sedimentary Cycles in the Devonian Catskill Delta Complex", Tectonic and Eustatic Controls on Sedimentary Cycles, John M. Dennison, Frank R. Ettensohn
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Recent computer climate modeling has revealed possible mechanisms which allow Milankovitch orbital parameters to influence climate and sedimentation in tropical areas with monsoonal climates such as the setting of the Devonian Catskill Delta complex of the Appalachians. There is evidence that the shoreline, shelf, slope, and basin sediments of the Catskill Delta complex contain sedimentary cycles with depositional periods of approximately 1-3 ka, 20-40 ka, 100 ka, 400 ka, and, possibly, 1.3, 2.0 and 3.5 Ma, which may be related to orbital precession, obliquity and eccentricity cycles, plus harmonics of these forcing periods. Preliminary correlations suggest that at least some of these rhythms may be traceable throughout the Appalachian basin and some may be of global extent. Until more complete age-dating and improved stratigraphic correlation becomes available, the synchronism of these events will remain unproven.
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Tectonic and Eustatic Controls on Sedimentary Cycles
The collected volume begins with a brief perspective by one of the conveners, followed by articles in order of increasing stratigraphic age. Eustatic sea-level changes and tectonic warpings of basins are competing mechanisms for explaining many stratigraphic patterns. The model for sea-level changes should be developed first for a basin, since it is allocyclic and leads to a series of time bands in the strata. The residual effects should then be modeled for tectonic patterns affecting the depositional processes. Doing the reverse limits time constraints on the tectonic warping models and will blur the resolution of detailed time surfaces in the strata. Case histories of situations with both tectonic warping and time surfaces marked by sea-level events will lead to improved interpretations of earth history.