--> --> Orogenesis and Post-Orogenic Collapse: Rocky Mountain Analogs and New Permian Insights

AAPG Rocky Mountain Section Meeting

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Orogenesis and Post-Orogenic Collapse: Rocky Mountain Analogs and New Permian Insights

Abstract

The Permian Basin has been a very active place for drilling new oil and gas wells in the past decade, and yet most of the understanding of its structural history is based on work done in the late 1980’s and early 90’s and very little has been published during the last 20 years on the topic. The buried structure of the Permian is very complex owing to the presence of multiple deformational events including the Ouachita-Marathon, Ancestral Rockies, Laramide, and Rio Grande Rifting; all with limited surface expression across 61 Wyoming Geological Association – September 15-18, 2019 most of the basin. Nonetheless, there are limited outcrops from which to derive fracture data and plenty of seismic data from which to build models. Because of these difficulties, having good analogous structures is key to interpretation. Similarities are shown between Rocky Mountain structures, where Laramide, ENE-directed horizontal compression resulted in anastomosing arches and basins, and the Ancestral Rockies stress that emplaced the Central Basin Platform and the mini-basins thereon. New insights are given that indicate the Ancestral Rockies deformation continued much later than previously thought and an extent of deformation is proposed that reaches well into the Midland Basin. Distinguishing between Ancestral Rockies and Laramide deformation is much more difficult than originally thought. Observations, especially in the Southern Delaware Basin, are also shown that fit well with the onset of postorogenic collapse similar to what has been documented in the Rockies. In conclusion, a refined structural history is proposed for the Permian Basin that highlights the continuity between the Ancestral Rockies and the Laramide orogenies and the subsequent post-orogenic collapse that is seen in the modern stress field.