12 Unresolved Issues in Integrating Pennsylvanian Stratigraphy, Depositional Systems, and Tectonics in the Eastern Shelf of the Permian Basin

Monday, 9 March 2020
1:30 PM - 5:30 PM
Meeting Room 202AB

THE RELATIONSHIP OF COASTAL-SHELFAL TIDAL CLASTIC SYSTEMS TO RAMP CARBONATES IN THE UPPER STRAWN REVEALED FROM CORE AND WIRELINE LOGS IN STONEWALL AND KING COUNTIES, PERMIAN BASIN, TEXAS

Paper number: 12-8
Program: Theme Sessions
Time: 3:30 PM – 3:50 PM

Authors

Abstract

Upper Strawn (Desmoinesian) cyclicity is well-documented. However, complex coastlines/shelves and the distribution of deposystems vary regionally. Active tectonics, fluctuating accommodation and sediment supply, and a low-latitude setting controlled shifting depocenters and carbonate reefs. Cyclicity varies depending on basinal location. We focus on uppermost Strawn cycles in Stonewall/King Counties, Eastern Shelf, Permian Basin to understand: 1) complex deposystems and underlying controls on stratal characteristics, and 2) the spatio-temporal relationship of clastic systems to carbonate factories.

We examined ~20 whole cores and 100+ wireline logs in Stonewall-King Counties. Clastic-rich, proximal-marine deposits in Katz Field, Stonewall County, contain interbedded quartz-rich and carbonate-clast-rich sandstone, and bioturbated, wavy-to lenticular bedded siltstone. Quartz-rich sandbodies are trough, current-ripple, and herringbone cross-stratified, or are heavily bioturbated (ii=6) with a diverse-abundant marine trace-fossil assemblage. Calcareous sandstones are trough-to ripple cross-stratified and contain mud drapes, mud inclusions, and fragments of crinoids, bivalves, carbonate, and ooids. Stratal characteristics and log character indicate tidally modified deposystems including flood-tidal deltas, bayhead deltas, tidal flats, backbarrier, and near-barrier shoreface. Increasing-upward gamma ray logs overlain by a blocky log record transgression of backbarrier deltaics by a shoreface in the uppermost Strawn cycle.

Contrastingly, Anne Tandy Field, King County and adjacent fields are carbonate dominated with cycles of interbedded mudstone and quartz-rich sandstone containing mud-drapes and mud inclusions. Carbonates record tidally modified to sediment-starved carbonate ramp, slope to ramp margin debris flows or grain flows, muddy outer ramp-slope, and ooid shoals. Clastics record interfingering tidal flats, deltas and/or estuaries, tidal/wave modified shelf, and muddy offshore-slope.

Overall, uppermost Strawn complex tidally modified deltaic transgressive shorelines to the east give way to interfingering clastic carbonate shelf-ramp-slope systems to the west.

Geological Society of America Abstracts with Programs. Vol. 52, No. 1

doi: 10.1130/abs/2020SC-343532

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