THE STANSBURY UPLIFT: NORTH-SOUTH BOUNDARY OF DETRITAL ZIRCON PROVENANCE FOR THE LATE DEVONIAN CONTINENTAL MARGIN, WESTERN LAURENTIA

Detrital zircons record several different provenance signatures for Devonian-Mississippian sandstones along the western North American passive margin. In Utah and Nevada, pre-Antler sandstones interbedded with the carbonate platform display separate provenance north and south of the east-west trending Tooele Arch. During the Late Devonian, the arch is expressed by the Stansbury Uplift. Two hypotheses exist for the causation of the Stansbury Uplift: (1) an Antler related uplift and surrounding basin subsidence that preceded the classic Kinderhookian Antler foredeep migration, or (2) a non-Antler cratonal tectonic disturbance. Precise ages for the timing of the Stansbury Uplift are difficult to constrain, leading to complications in understanding the causal relations with the Antler Orogeny. Isopach maps and detrital zircon provenance data will identify the role played by the Stansbury Uplift along the changing western margin.

Preliminary isopach map constructions of the correlative Late Devonian Guilmette and Beirdneau Formations show a thicker package of sedimentary rocks west of the uplift than to the east. This is consistent with Antler orogenic loading and the first hypothesis for the formation of the Stansbury Uplift. Isopachs also show wedge-shaped stratal units thinning toward the Stansbury Uplift. Delineating the distribution and provenance of Late Devonian sands might constrain the extent to which the Stansbury Uplift relates to the Tooele Arch, as well as the structural reactivation of the arch by the Antler Orogeny.

A “northern” signature of central-southeastern Idaho consists of detrital zircon grains >1.8 Ga and subordinate populations of Archean grains. Detrital grains >1.8 Ga were proximally sourced from uplifted Ordovician Swan Peak Formation and Eureka Quartzite, and ultimately sourced from cratonic basement exposed by the Canadian Peace River Arch. The “southern” signature is identified by Grenville (1.3-1.0 Ga), and Yavapai-Mazatzal (1.8-1.6 Ga) zircon populations within the Guilmette sandstone of southern Nevada. “Mixed” signatures containing all mentioned zircon populations exist within northeastern Nevada and central Utah.