Presenter
Tim Lawton, Ph.D.
Research Scientist, Quantitative Clastics Laboratory
Bureau of Economic Geology
Jackson School of Geosciences
The University of Texas at Austin
Description
Despite decades of geologic study and petroleum exploration, the Permian, or West Texas, basin remains something of an enigma as to its tectonic origins and the processes that delivered sediment to it during the Carboniferous and Permian. The basin both occupied the foreland of a developing collisional orogenic wedge and formed the southern limit of an assemblage of rapidly evolving intracontinental uplifts and basins. Ongoing debate centers on the relative importance of collisional orogenesis as opposed to poorly understood mechanisms of far-field deformation that took place in the continental interior. Between Pennsylvanian and Middle Permian time, the West Texas basin received sediment from almost every identified basement province of Laurentia, as well as from Gondwanan sources on the far side of the evolving continental suture. Recent and ongoing studies of detrital zircon geochronology combined with limited sandstone petrography provide insight into the locations and evolution of these source areas. General conclusions from these studies are that sediment source regions and sediment-delivery mechanisms alike changed dramatically in early Permian time. These conclusions in turn provide insight into the influence of source area tectonics and continental climate on composition and nature of the basin fill as well as potential linkages between shelf and basinal depositional systems.
