LATE TRIASSIC SEDIMENT ROUTING TO THE DEEPWATER AULD LANG SYNE BACKARC BASIN BASED ON DETRITAL ZIRCON U-PB ANALYSIS, CENTRAL NEVADA, U.S.A

Siliciclastic turbidites of the Middle Jurassic to Upper Triassic Jungo Terrane in the Auld Lang Syne marine basin in present-day western Nevada represent a known deepwater sediment sink for this time period. Sediment sources for the Jungo Terrane have been debated over time, with several alternative models proposed in the peer-reviewed literature. These studies argue that Jungo Terrane sediment was (a) locally sourced from a regionally uplifted area, (b) shed from the incipient Mesozoic Cordilleran magmatic arc that bounded the basin to the west, or (c) distally derived via fluvial transport from somewhere to the south or east. This work uses detrital zircon (DZ) U-Pb and sandstone petrographic data to examine source terrains and sediment routing for Jungo Terrane turbidites.

DZ U-Pb age distributions are interpreted to indicate that Jungo Terrane sediments were derived from the Appalachian-Ouachita Cordillera to the southeast, as well as the midcontinent region to the east. Samples display prominent ca. 500-400 Ma, 1250-950 Ma, 1550-1300 Ma, and 1800-1600 Ma grains, consistent with ultimate derivation from the Appalachian, Grenville, Midcontinent, and Yavapai-Mazatzal provinces, respectively. Sample sandstones are compositionally mature and contain sparse feldspar or lithic grains, confirming that Jungo Terrane sediments were derived from cratonic interior sources. Due to similar DZ U-Pb signatures and sand compositions between Jungo Terrane turbidites and coeval Chinle Formation fluvial sandstones, we interpret that the Auld Lang Syne marine basin represents the terminal sink of the Chinle sediment-dispersal system.