DETRITAL ZIRCON GEOCHRONOLOGY OF THE WARRENSBURG-MOBERLY CHANNEL SANDSTONE, CENTRAL MISSOURI: A PALEORIVER THAT CONNECTED THE APPALACHIAN OROGEN TO GRAND CANYON AND ADJACENT DEPOCENTERS?

Recent U-Pb detrital zircon geochronology reveals an increasing proportion of Grenville-age (ca. 1.2-1.0 Ga) and ca. 475-270 Ma grains in Mississippian to Permian strata of the Grand Canyon. These grain populations are interpreted to have been shed westward across the continent from the central Appalachian orogen. However, no late Paleozoic sediment dispersal systems have been documented between the Appalachian orogen and the Grand Canyon. This study asserts that the Warrensburg and Moberly channel sandstones of central Missouri represent a previously unrecognized Appalachian-Grand Canyon connection. These sandstones fill an ~2 to 8 km wide, ~30-50 m deep, valley-shaped erosional channel that runs ~250 km from NE to west-central Missouri. Both ends of the channel, plus a ~60 km long section separating eastern (Moberly) and western (Warrensburg) segments, have been removed by erosion. Sedimentary structures indicate that the direction of sediment transport was to the SW. Both Moberly and Warrensburg channel segments yield abundant ca. 1.2-1.0 Ga, ca. 460-300 Ma, and ca. 650-500 Ma detrital zircon grains, with diminishing proportions of Mazatzal Province-age (ca. 1.7-1.6 Ga), ca. 1.40-1.35 Ga, Yavapai Province-age (ca. 1.8-1.7 Ga), and ca. 2.7 Ga grains. Detrital zircon age spectra from Moberly and Warrensburg channel segments show significant overlap, bolstering previous sedimentological arguments that these portions originally formed a contiguous channel. Moreover, the Warrensburg-Moberly channel contains strikingly similar detrital zircon age distributions compared to Mississippian to Permian strata of both the Grand Canyon and the Appalachian foreland basin, strongly suggesting a source-to-sink connection between the three depositional environments. It is important to note that compared to Warrensburg-Moberly channel sandstones, Grand Canyon and Appalachian strata contain higher and lower proportions of Yavapai-Mazatzal age detrital zircon grains, respectively. Sediment transport from the Appalachian orogen, across Yavapai and Mazatzal provinces via the Warrensburg-Moberly and related paleorivers, and into the Grand Canyon depocenter provides an explanation for the westward increasing proportion of ca. 1.8-1.6 Ga grains in these areas.