Contrasting Guadalupian Infill Histories of the Midland and Delaware Basins
The Permian Basin includes a more orogen-proximal southwestern Delaware sub-basin (DB) and an eastern Midland sub-basin (MB). Evolution of the sub-basins shifted from a parallel stratigraphic record in the Wolfcampian-Leonardian to a different set of infill records during the Guadalupian, with the MB filling by the middle Guadalupian (mid-Wordian, 265 ma) some 5-7 ma earlier than the early Wuchiapingian (258 ma?) filling of the DB. The accelerated hydrocarbon development of DB and MB for both unconventional resources and linked salt water disposal has driven the need for a better understanding of these contrasting basin-fill records. Here we combine outcrop data, 2D and 3D seismic, extensive wireline logs, and core information to highlight the divergence in basin fill and consider drivers.
Early and Middle Permian (Wolfcampian and Leonardian) successions in the Delaware and Midland basins differ in terms of total thickness and reservoir quality but in general follow similar patterns of deep-water deposition and basin fill coincident with deposition of Hueco and Victorio Peak/Clear Fork platforms. A grossly similar infill history is noted in DB and MB for the lower San Andres composite sequence and its widespread Cutoff/Bone Spring Lime basinal equivalents. At the Wordian-Capitainian basin-fill history diverges, with 400 m of Brushy Canyon sandstones fed into the Delaware Basin while only 100 m of approximately equivalent basinal sand enters the Midland Basin. A basin-wide (eustatic?) sea level fall at in mid-Wordian time marks the key period of divergence. Karstification of San Andres platform top carbonates is documented from Guadalupe Mt outcrops to the SE corner of the Central Basin Platform, with solution dolines up to 30 m deep, and a downward shift in coastal onlap of 50-70 m is seen in Brokeoff Mt/Cutoff Mt outcrops. Contemporaneous with the end-San Andres fall, a set of forced regressive alternating oolitic and siliciclastic-bearing clinoforms fills the Midland Basin in north-to-south (150 km) and east to west (50-70 km) directions. We propose that a combination of tidal focusing in the restricted Midland Basin amplified by basin water carbonate supersaturation drove the accumulation of the greatest accumulation of oolitic sediments seen in the Permian Basin. This unique infill history illustrates that both extrabasinal clastic sources and autogenically driven sediment sourcing must be considered to understand fully the basin fill history.
AAPG Datapages/Search and Discovery Article #90350 © 2019 AAPG Annual Convention and Exhibition, San Antonio, Texas, May 19-22, 2019