A New Look at Maverick Basin Basement Tectonics
The current Eagle Ford play in South Texas has regenerated exploration interest in the Maverick Basin area. The greater Maverick Basin is shown to consist of several sub-basins, each having a unique tectonic character. Three broad Cretaceous basins overlie narrow Jurassic basins that are considered to be part of a left-stepping rift system associated with a regional southeast-northwest shear zone.
This new look at the Maverick area basement tectonics was not intended to provide direct leads to current Cretaceous plays but to provide new concepts regarding the evolution and relationships of the various sub-basins and regional faulting. More importantly, to stimulate new ideas about exploring for several potential new and deeper plays in the Jurassic and pre-Jurassic section.
Much of the current literature considers the greater Maverick Basin to be a classic Jurassic rift valley. Some papers describe the northern sub-basin as a deep Jurassic rift bounded to the southwest by northeast-directed folds or anticlines produced by Laramide compression from Mexico. Other papers describe the central sub-basin as a Cretaceous-Jurassic half-graben with the Chittim Anticline located over its steep northeast flank. This new integrated interpretation of seismic, subsurface, gravity and magnetic data tied the sub-basins together as a complex tectonic pattern of deep localized rifts in a left-stepping pattern along a southeast-northwest regional shear. The deep rift sub-basins are offset by local southwest-northeast left-lateral shears, with the character of each local Jurassic rift basin being influenced by adjacent deep basement features.
The deep tectonic patterns of the greater Maverick Basin have not been well documented in the literature due to the sparsity of pre-Upper Jurassic wells and published seismic data. However, the fact that several deep wells have been drilled and that some gas was encountered indicates that the deep Maverick could be a future exploration province under favorable economic circumstances. Deep structures and tectonic patterns must be better understood and mapped. All available geologic and geophysical data must be evaluated and integrated to provide results that are mutually compatible.