Abstract

The Delaware Basin is similar to other synorogenic basins in that sediment source areas and the sediment-routing history are important factors controlling oil and gas reservoir presence and quality. The Ouachita-Marathon orogeny was the Pennsylvanian-Permian mountain-building event as a result of the collision of Gondwana and Laurentia along the southern North American margin. The Glass Mountains of West Texas are situated just north of the Marathon thrust sheets. Outcrops of the Glass Mountains comprise mixed carbonate and siliciclastic deposits of Pennsylvanian (Haymond) to middle Permian (Guadalupian) age. Long-standing interpretations have concluded that a majority of the siliciclastic input to the Delaware Basin during middle Permian (Guadalupian) time was sourced from the Ancestral Rocky Mountains (ARM). Here we perform an integrated detrital zircon geochronologic and petrographic provenance analysis of the Pennsylvanian-Guadalupian strata found in the Glass Mountains to test the dominant source of Permian siliciclastic deposits in the Southern Delaware Basin. We isolated core and rim ages of detrital zircons within the siliciclastic deposits using Laser Ablation Inductively Coupled Mass Spectrometry at the University of Texas at Austin Geo-Thermochronometry Lab. A core age indicates initial crystallization age, whereas a rim age can be used to track recycling of the zircon and subsequent crystallization or metamorphism. We identified eight groups of core-rim ages, which correspond with Laurentian, Gondwanan, Rodinian, Pan-African and Amazonian sediment source areas. However, there is a conspicuous absence of Paleoproterozoic ARM core-rim ages. Therefore, we propose a more proximal, Marathon-Ouachita source area to the south of the Glass Mountains. This is to be expected as mountainous sediment source areas can provide large-magnitude sediment supply to neighboring depositional basins. We combine our data with published results from across the Delaware Basin to provide a more complete perspective of syn-orogenic Guadalupian basin fill.