Late Paleozoic synorogenic stratigraphy, tectonic evolution, and flexural modeling of the Permian Basin, West Texas and New Mexico

Abstract

The Permian Basin of west Texas and southern New Mexico is located in the foreland of the Marathon-Ouachita orogenic belt. This complex foreland area consists of several sub-basins that are separated by intraforeland uplifts. This study focused on the kinematic history of the Central Basin Platform (CBP), subsidence and stratigraphy of the sub-basins; and the effect of tectonic load from the intraforeland uplifts on the subsidence in the sub-basins. Uplift of the CBP is best explained by clockwise rotation of these blocks. The rotation model explains: (1) the steeply dipping thrust faults at the SW and NE corners and local normal faults at NW corners of individual crustal blocks that comprise the CBP; (2) the large structural relief observed at the SW and NE corners of individual blocks; and (3) decreasing amounts of basement shortening away from thrust-faulted corners. The variable platform-to-basin relief that was produced during uplift of the CBP resulted in very different patterns of stratigraphic onlap during late Pennsylvanian to early Permian time. Patterns of intraforeland deformation could have dramatically affected basin stratigraphy during both syn- and post-orogenic stages of basin development. In this study, the CBP was treated as a topographic load that produced lithospheric flexure of the adjacent basinal areas. Results from flexural analyses compare well with reconstructed synorogenic geometries of the adjacent basins, indicating that subsidence of these basins most likely was produced by the combined topographic loads of the Marathon orogenic belt, the CBP, and probably structures associated with the uplifts surrounding the Permian Basin. Values for the flexural rigidity of lithosphere in the Permian Basin region are lowest near a prominent salient in the Marathon orogenic belt and the SW corner of the CBP, where the amount of basement shortening is greatest along the boundaries of the CBP. These low calculated rigidities reflect locally weaker lithosphere that might be related to inherent lateral strength variations in the Marathon foreland. Alternatively, high bending stresses produced in front of the prominent salient of the Marathon orogenic belt may also have weakened the lithosphere in this area.