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The AAPG/Datapages Combined Publications Database

CSPG Special Publications


Sequences, Stratigraphy, Sedimentology: Surface and Subsurface — Memoir 15, 1988
Pages 584-585

Role of Stratigraphic Discontinuities in Development of Reservoir Quality, Muddy and Skull Creek Sandstones, Denver Basin: Abstract

R. K. Suchecki1, G. R. Baum2, S. Phillips3, J. S. Hewlett4


Sandstone composition and related reservoir quality, and isotopic compositions of diagenetic minerals in sandstones and mudstones produced during the stratigraphic evolution of the Cretaceous Skull Creek, Muddy, and Mowry sediments vary in patterns that correspond to the following: (1) Skull Creek sandstones, consisting of transgressive highstand deposits, are litharenites that contain abundant kaolinite cement and local concentrations of quartz cement at a subaerial unconformity that separates the Skull Creek from the overlying Muddy Sandstone. The subaerial exposure in outcrops of Skull Creek deposits between Fort Collins and Turkey Creek, Colorado, is characterized by 18O-enriched quartz overgrowths in a 10 to 15 m thick interval, indicating that the quartz cement in the Skull Creek sandstones formed during early meteoric water diagenesis beneath a subaerially exposed surface; (2) Overlying Muddy sandstones, consisting of incised valley-fill deposits, are porous quartzarenites and sublitharenites that contain abundant quartz cement formed from evolved, warmer subsurface fluids; and (3) Mowry shales with relatively high total organic content and siderite were deposited in a condensed interval during maximum flooding. The isotopic composition of diagenetic carbonate in both the Skull Creek and Muddy/Mowry stratigraphic sequences has variations in the δ13O compositions that correspond to variations in total organic content. Co-varying patterns of regional stratal “geometry” and diagnetic modifications illustrate the strong impact of genetic stratigraphy on reservoir quality.


Acknowledgments and Associated Footnotes

1 Department of Geological Sciences, Southern Methodist University, Dallas, Texas 75275

2 Arco Research and Technology Services, Plano, Texas 75075

3 Arco Research and Technology Services, Plano, Texas 75075

4 Arco Research and Technology Services, Plano, Texas 75075

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