PROVENANCE AND DEPOSITIONAL INTERPRETATION OF THE LOWER PERMIAN GARBER SANDSTONE: IMPLICATIONS FOR PALEOGEOGRAPHY AND SEDIMENT DISPERSAL IN CENTRAL OKLAHOMA

The Lower Permian (Cisuralian) Garber Sandstone records a time of profound climatic and tectonic transition in central Pangea with the collapse of an icehouse climate, inception of Pangean monsoonal circulation, and the termination of the Wichita, Ouachita, and Arbuckle regional uplifts. The depositional environment and provenance of the Garber Sandstone in central Oklahoma remains poorly understood, although recent studies suggest transcontinental fluvial systems crossed the region. Previous interpretations of this unit range from deltaic to fluvial to shallow/marginal marine owing to a lack of consensus on the paleogeographic extent of shallow seas covering Oklahoma in the Early Permian. This study utilizes U-Pb detrital zircon geochronology supported by sandstone petrography, grain size analysis, and outcrop and core-based facies analyses to assess trends in sediment provenance and depositional environments along strike of an approximately 435 km outcrop belt.

New U-Pb ages of detrital zircons (n=1858) from seven medium to fine-grained sandstones sampled across the outcrop belt reveal strong similarities in source modes across all samples. The primary age peak for all samples is 0.9-1.3 Ga, indicating a predominantly Grenville source located to the east/southeast of the outcrop belt. The second dominant mode for all samples is between 300-485 Ma indicating sources likely derived from terranes exposed in the Appalachian and Ouachita orogens. There are notably few grains sourced from Cambrian igneous rocks exposed in the proximal Wichita Uplift. Initial facies interpretations of outcrops suggest the presence of a large fluvial system as evidenced by amalgamated channels and abundant cross laminations, ripple marks, and sandstones that become more thinly bedded on the western edge of the outcrop belt.

These data support a fluvial-dominated model of deposition across the Garber Sandstone outcrop belt. U-Pb data also better constrains major detrital sediment sources to be from Grenville and Appalachian and Ouachita uplifts. Understanding the depositional environment of the Garber Sandstone will assist in constructing more accurate paleogeographic reconstructions and sediment dispersal pathways during the Early Permian in Oklahoma.