PROVENANCE AND SEDIMENT DISPERSAL TRENDS FROM EARLY PERMIAN STRATA OF THE ABO FORMATION: IMPLICATIONS FOR DRAINAGE NETWORKS AND BASIN FILL DURING THE FINAL PHASE OF THE ANCESTRAL ROCKY MOUNTAIN OROGENY IN NEW MEXICO

The Ancestral Rocky Mountain (ARM) orogeny was a Late Mississippian–Early Permian, thick-skinned deformational event that produced nearly a dozen basement-cored uplifts and adjacent depocenters in parts of Oklahoma, Texas, Arizona, Utah, Colorado, and New Mexico. While the timing and duration of ARM orogenesis are generally accepted, little is known about sediment dispersal trends and the extent of ARM basement blocks during the Early Permian phase of the ARM orogeny. Presented here are new U-Pb detrital zircon ages and sandstone modal composition trends from Early Permian (Wolfcampian) nonmarine, clastic strata of the Abo Formation in New Mexico.

Four samples (n=402) from northern New Mexico exhibit peak ages between 1376–1451, 1686–1694, and 1720–1725 Ma with rare Archean, Neoproterozoic, and Paleozoic ages. Sandstone modal composition trends show relatively high abundances of quartz and feldspar and minor lithic grains (Q=50% F=42% L=8%). Strata in northeastern New Mexico were likely locally derived from Yavapai (1.7-1.8 Ga), Mazatzal (1.6-1.7 Ga), and Granite/Rhyolite (1.3-1.5 Ga) provinces that were being exhumed along New Mexico ARM uplifts (Cimmaron Arch, Sierra Grande, southern Uncompahgre). Basin fill in northwestern New Mexico was farther traveled and derived from the Yavapai and Mesoproterozoic granitoids from the northern Uncompahgre uplift in Colorado and Utah.

Three samples (n=266) from southern New Mexico have peaks between 1232–1251, 1460–1470, and 1780–1790 Ma with scattered Archean, Neoproterozoic, and Paleozoic ages in some samples. Compositional trends show high relative abundances of feldspar, moderate quartz, and minor lithic grains (Q=36% F=56% L=8%­­­). Basin fill in south-central New Mexico was likely locally derived from Grenville-equivalent sources (De Baca Group) that were exhumed along the ARM Pedernal uplift. Abo strata in southwestern New Mexico were derived from local ARM uplifts in southern New Mexico (Pedernal) as well as northern ARM uplifts in Colorado, Utah, and New Mexico (Uncompahgre).

These data support a model where fluvial systems in eastern New Mexico were isolated from the western part of the basin by the Pedernal uplift. Conversely, the western basin consisted of a larger, more complex drainage network where fluvial systems were coalescing to the south.