Detrital Zircon U-Pb Data from the Permian Basin — Implications for Pangea Assembly, Southern Provenance and Sediment Routing
In order to resolve the late Paleozoic tectono-stratigraphic evolution of the Permian basin, Texas, we generated a large dataset of new detrital zircon (DZ) a U-Pb ages from Mississippian to Late Permian outcrop samples in the Glass Mountains, S Delaware basin (n=1720), and Wolfcampian to Leonardian subsurface samples from the Midland basin (n=3016). These data document the collisional assembly of Pangea and the resulting provenance and sediment-routing evolution of the Permian foreland basin. Long-standing hypotheses regarding the siliciclastic sediment input to the Permian basin have suggested dominant sourcing from the Ancestral Rocky Mountains (ARM) and/or axially through the Alleghenian-Ouachita foredeep. Our new DZ data paint a different and more nuanced picture of sediment sourcing and routing during the Mississippian to Pennsylvanian orogenic phase and the transition to Permian post-orogenic basin deposition. 1) DZ ages of Mississippian Tesnus strata record pre-collisional southern provenance and Pennsylvanian Haymond Fm. data reflect inversion and erosion of the distal Laurentian continental margin, incl. recycling of Rodinian rift volcanics; 2) up-section decrease in Grenville DZ ages (1300-920 Ma) and increase in Paleozoic DZ ages indicate a transition from orogenic highland sources during collision to Gondwanan hinterland sources during subsequent tectonic maturation and stabilization; and 3) invariant early-middle Permian DZ ages reflect relative tectonic quiescence and input of Cordilleran first-cycle volcanic zircons. Overall DZ age and core-rim signatures are dominated by Gondwanan, Rodinian, and Amazonian source areas, with sparse Laurentian ages and a conspicuous absence of Paleoproterozoic ARM ages. These data highlight the significance of sediment input from the Marathon orogenic belt and Gondwanan hinterland sources for the southern Delaware basin. In the Midland basin, the provenance signal appears to reflect more mixed Alleghenian-Ouachita and Gondwana sources, although true Appalachian sourcing is not supported. While isotopic provenance data reflect the original sediment sources, they might not reflect or capture the complexity and spatial patterns of sediment-routing pathway from the original sources to the ultimate basin sinks and additional work is required to constrain distributary pathways and fully integrate these data with decades of stratigraphic studies of the basin-margin sequences into an internally-consistent source-to-sink model. While this study demonstrates dramatic sediment input from the south, sediment delivery via late Paleozoic transcontinental drainages, axial transport within the Alleghenian-Ouachita foredeep, and input from the Ouachita hinterland across the E shelf need to be further studied.
AAPG Datapages/Search and Discovery Article #90350 © 2019 AAPG Annual Convention and Exhibition, San Antonio, Texas, May 19-22, 2019