Depositional Controls on the Distribution of Permian Phylloid Algal Bioherms in the Orogrande Basin, South Central New Mexico
Stautberg, Jonathon E.; Giles, Katherine; Mack, Greg
Late Paleozoic organic carbonate buildups are major petroleum reservoirs worldwide and by understanding controls on the nature and distribution of buildup reservoir facies, better exploration strategies can be implemented in these areas. Spatial and temporal distribution of these buildups is primarily controlled by glacial-eustasy, regional and local tectonics, and depositional profile style. In south central New Mexico, the Orogrande basin is the western extent of the Permian Basin, and contains Permian phylloid algal buildups. Previous work on the Orogrande basin has focused primarily on the eastern shelf margin where thick phylloid algal buildups are associated with restricted tidal flat and lagoonal facies, suggesting buildups formed a significant bank with topographic relief. In contrast, the western margin is interpreted as a distally steepened ramp, progressively deepening from west to east. New work in this region, focused on determining shelf geometry, will provide controls on buildup growth that can be applied to regional basin development.
Outcrop datasets of the lower Permian Hueco Limestone on the western margin of the Orogrande basin were analyzed in regard to depositional facies distribution and sequence stratigraphy. Six stratigraphic sections, ranging from 60 to 80 meters, were measured in the lower Hueco member to create a northwest to southeast (shoreline-basin) transect across the western shelf, and 130 samples were collected for detailed petrographic analysis. Five depositional facies are recognized: 1) tidal flat laminated dolomicrite with subordinated algal laminates, 2) restricted lagoonal ostracode-rich, cherty wackestones, 3) bank margin oolitic shoals, 4) bank margin phylloid algal bafflestones with crinoidal and calci-sponge packstones, and 5) upper slope open marine, intraclast packstones. Stratal stacking patterns indicate distinct shallowing upward sequences across the shelf, depicting shelf progradation into distal parts of the basin. Sequence stratigraphic analysis, augmented by fusulinid biostratigraphy, shows a flooding surface at the base of the Wolfcampian succession, overlain by a prograding phylloid algal bioherm complex with restricted facies shoreward. Based on the stratigraphic and geographic distribution of facies that are similar to the eastern margin but significantly thinner, the western margin appears to represent a platform style geometry that progrades basinward and shallows throughout the Wolfcampian.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013