--> ABSTRACT: Relationships Between Parasequence Stacking Patterns and Depositional Sequence Geometries: Upper Guadalupian (Permian) Strata of Slaughter Canyon, New Mexico, by D. J. Lehrmann, E. C. Rankey, and R. K. Goldhammer; #91021 (2010)

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Relationships Between Parasequence Stacking Patterns and Depositional Sequence Geometries: Upper Guadalupian (Permian) Strata of Slaughter Canyon, New Mexico

LEHRMANN, D. J., E. C. RANKEY, and R. K. GOLDHAMMER

Analysis of vertical facies and parasequence stacking patterns has been widely used to identify and correlate depositional sequences in carbonate-platform strata. Currently there is debate, however, about the level of randomness in stacking patterns and the degree of accuracy of the technique for chronostratigraphic correlation. We have used a variety of statistical and graphical analysis techniques to determine how well vertical thickness and facies stacking of parasequences in individual sections can be used to identify depositional sequences identified independently on the basis of stratal geometries.

Although statistical analysis indicates considerable levels of randomness in vertical facies and parasequence thickness succession longer-term deterministic patterns permit identification and correlation of the larger (3rd or 4th order sequences from stacking patterns of individual sections. Slaughter Canyon contains four 3 to 4 order sequences: SB-1 and 2 exhibit shingled, toplapping geometries reflecting rapid progradation, SB-2 and 3 have onlapping geometries reflecting greater aggradation. The change from progradation to aggradation is reflected in stacking patterns as a shift from nested sandstone-bounded parasequences (sands preserved due to greater accommodation in shingled sequences) to carbonate dominated parasequences (deflation of sands from the flat-topped aggradational sequences).

Detailed analysis of facies distribution and stratal geometries indicates that the amplitude of sea-level fluctuations progressively declined from 20 to 8 m. during the evolution of the earlier sequences. Comparison of Slaughter Canyon stacking patterns with those of other systems suggests that declining amplitudes of sea-level change from ice-house to green-house conditions resulted in the superposition of low-amplitude, high-frequency fluctuations on higher-amplitude fluctuations of lower frequency which allowed for further recording of the sequence stratigraphic hierarchy and therefore accurate identification of depositional sequences from parasequence stacking patterns.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.