PROVENANCE OF THE CASTLE VALLEY EOLIANITE, PARADOX BASIN, UTAH: A MIX OF NEARBY AND DISTANT DETRITAL SOURCES

Eolian strata exposed in the Castle Valley NE of Moab, Utah, long correlated with the Early Permian (Leonardian) White Rim Sandstone, were deposited on the SW flank of the NE-trending Castle Valley salt wall. The strata, as much as 183 m thick in outcrop, consist of two dune intervals separated by a thin sheet-flood deposit that contains pebbles derived from both the salt wall and upturned conglomeratic strata adjacent to the wall. Eolian and fluvial deposits alike thin and onlap eastward onto the now-collapsed salt wall. Large-scale foresets in the lower dune unit indicate consistent NE paleowind (present coordinates), directly away for the Uncompahgre uplift, whereas foresets in the upper unit indicate more variable NE to E and rare westerly paleowinds. The eolian strata thus accumulated on the lee side of the salt wall. These wind directions contrast with NW winds documented for the greater White Rim erg to the west, but are broadly similar to regional Leonardian wind directions.

The eolian sandstone is compositional subarkose with potassium feldspar, plagioclase and biotite derived from local Uncompahgre sources. These minerals are absent from quartzarenite of the greater White Rim erg, and comparison of detrital zircon populations in the Castle Valley eolianite and locally-derived redbeds of the underlying Cutler Group indicate that only a subordinate fraction of the zircons were locally derived, with the majority of zircon ages similar to those of the greater White Rim erg. Grain ages include late Paleoproterozoic and early Mesoproterozoic grains (~1.80-1.49 Ga) and important populations of Grenville, Neoproterozoic and Paleozoic grains, the latter three groups absent from the subjacent redbeds and therefore not attributable to the Uncompahgre uplift. Grenville and younger grains are generally interpreted as having an eastern Laurentian (Appalachian) source, and the older grains as having a more local source in southwestern Laurentia, although the winds generally blew toward SW Laurentia. We posit that many of the Paleoproterozoic and Mesoproterozoic grains in the eolian sandstone were derived from the Sveconorwegian province of western Baltica by trans-Pangean fluvial systems analogous to those that delivered the eastern Laurentian grains to the western edge of the continent.