ABSTRACT: Self-Similarity of High-Frequency Sequences--Implications for Correlation and Reservoir Characterization, Gallup Sandstone (Turonian), Northwestern New Mexico

VALASEK, DAVID W., Colorado School of Mines, Golden, CO

The Gallup Sandstone (Turonian) shoreface complex in the San Juan basin, New Mexico, consists of multiple orders of sequences that have been placed in a hierarchy based upon the length of progradation in the dip direction. The Gallup Sandstone and associated Tocito Sandstone display four orders of sequences (third- to sixth-order Exxon terminology).

Stratal architecture and facies distributions appear to be similar at various scale. Facies variability is highly organized with respect to time and bounding surfaces at different scales, and hence to changes in accommodation potential. Tidally influenced shelf and shoreface sandstones occur at the top and seaward portions of sequences. Wave-influenced shoreface, storm deposits, and coastal plain deposits occur within the landward portion of the sequence. Fluvial systems incise into the shoreface in the landward portion of the sequence, suggesting base level fall and/or sediment bypass. The most landward upper shoreface deposits may be removed by the fluvial systems. Transgressive deposits are thin and discontinuous and may be correlated to tidally influenced coastal plain deposits.

This similarity of the stratal deposits is termed self-similar; that simply implies symmetry across scales. The obvious impact of this concept is that information obtained from small-scale (e.g., reservoir scale) may be applied directly in a predictable and quantitative manner to large-scale features. Information obtained from large-scale (e.g., seismic) observations may apply directly in a predictive and quantitative way to small-scale features. Determination of self-similar characteristics of depositional sequences indicates fractal analysis may be applied to stratigraphy and sedimentology.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)