Geology and hydrocarbon resource potential of Cretceous strata in the Jornada del Muerto, Sierra and Socorro counties, New Mexico
Thomas E. Ewing
The Jornada del Muerto is a sparsely drilled intermontane valley in south-central New Mexico with real but limited hydrocarbon potential in Cretaceous rocks. Cretaceous strata were deposited on a southwest-downcutting unconformity related to the Mogollon rift shoulder. Thin (15-30m) “Dakota” sandstones are overlain by a thicker (90-115m) marine succession; the lower part includes black organic shale, limestone and heterolithic sandstone that are Greenhorn (Eagle Ford) equivalents. The overlying Tres Hermanos Formation is consistent in thickness (75-90 m) and character across the area, possibly indicating a forced regression, and contains thin coaly layers. The Gallup sandstone consists of multiple shorefaces that slowly and episodically prograded northeastward over a thickening D-Cross Shale tongue. The immediately overlying Crevasse Canyon Formation contains thin coals. Correlation of outcrop data to subsurface well data enhances our understanding of facies relationships. All the above strata were buried by latest Cretaceous McRae and early Paleogene Love Ranch formations. Coeval Laramide folding and faulting occurred along the Rio Grande axis on the east flank of the Sierra uplift. Fold and fault patterns indicate a right-lateral transpression related to northeast-directed compressive stresses, which raised the Rio Grande uplift to the south. Strata were also buried by middle Eocene to Oligocene volcanic and volcaniclastic rocks (Datil Group and equivalents), which are now mostly removed. Burial has matured source rocks well into the gas window and past oil stability. All conventional hydrocarbon accumulations were disturbed or destroyed by Neogene extensional faulting related to the Rio Grande rift. The San Andres Mountains to the east and the Caballos and Fra Cristobal Mountains to the west rose as Neogene rift-flank highs, creating the Jornada del Muerto syncline between them. Unconventional accumulations may have a better chance of survival. The gas-prone nature of the preserved source rocks and the lack of infrastructure for producing and transporting natural gas are serious impediments to further exploration in the area.
- Ewing, Thomas E., 2012, Geology and hydrocarbon resource potential of Cretceous strata in the Jornada del Muerto, Sierra and Socorro counties, New Mexico, in: Geology of the Warm Springs region, Lucas, Spencer G.; McLemore, Virginia T.; Lueth, Virgil W.; Spielmann, Justin A.; Krainer, Karl, New Mexico Geological Society, Guidebook, 63rd Field Conference, pp. 569-580.