Campanian Shannon Sandstone: An Example of a Falling Stage Systems Tract Deposit
Katherine M. Bergman, Roger G. Walker, 1999. "Campanian Shannon Sandstone: An Example of a Falling Stage Systems Tract Deposit", Isolated Shallow Marine Sand Bodies: Sequence Stratigraphic Analysis and Sedimentologic Interpretation, Katherine M. Bergman, John W. Snedden
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Recent interpretations of the lower Campanian Shannon Sandstone in the Powder River Basin, Wyoming have suggested that it was deposited in incised shorefaces of the falling stage and lowstand systems tracts rather than in offshore stacked shelf ridge complexes. A complete high resolution stratigraphic analysis of the Shannon requires that outcrops in the Bighorn and Powder River Basin be correlated with subsurface fields basinward. In the Hartzog Draw area where there is good core control, a consistent pattern of facies and erosion surfaces can be defined. From this pattern a template was constructed that could be used to interpret depositional patterns in uncored areas. The template consists of a regressive surface of erosion (RSE) that forms the base of an incised shoreface sandbody and a transgressive surface of erosion (TSE) that truncates the top of the sandbody and the RSE. Applying the template to the cross section suggests that six progradational successions and six transgressions can be defined within the Shannon. Positions of the RSEs and TSEs allow estimates of the magnitude of relative sea level fluctuations that controlled Shannon deposition (a few meters to 60 m). The correlations are consistent with the interpretation of the Shannon as incised shoreface sandbodies of falling stage and lowstand systems tracts, separated by mudstone deposits of the following transgressive systems tract.
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Isolated Shallow Marine Sand Bodies: Sequence Stratigraphic Analysis and Sedimentologic Interpretation
Isolated Shallow Marine Sand Bodies: Sequence Stratigraphic Analysis and Sedimentologic Interpretation - Isolated shallow marine sand bodies are significant hydrocarbon reservoirs and understanding sand body genesis and geometry is critical to successful exploration and exploitation of these deposits. Recent advances in sequence stratigraphy have rekindled and refocused the discussions surrounding these important reservoirs. This volume stems from a 1995 SEPM sponsored targeted research conference that brought together the proponents of the differing interpretations to discuss facts and principles as they relate to isolated shallow marine sand bodies, using the controversial Lower Campian Shannon Sandstone as the focus for discussion.