RECYCLING OF DETRITAL ZIRCONS FROM JURASSIC EOLIANITES OF THE COLORADO PLATEAU INTO QUARTZOSE CRETACEOUS SANDSTONE OF THE BISBEE BASIN IN SOUTHEASTERN ARIZONA

Sandstones in the Jurassic-Cretaceous Bisbee basin of the AZ–Sonora–NM border region include multiple petrofacies: (a) arkosic from internal basement tiltblocks within the Border rift belt, (b) lithic (volcaniclastic) from the Alisitos arc southwest of the basin, (c) subquartzose from sedimentary cover of the rift shoulder north of the basin, and (d) quartzose inferred to reflect reworking of Jurassic eolian sand from the Mogollon highlands of the rift shoulder along the southern rim of the Colorado Plateau (Dickinson and Lawton, 2001). Confirmation that sand was recycled into the Bisbee basin from plateau eolianites is provided by U-Pb ages of detrital zircons (n=100 with <10% age uncertainty and <20% discordance from LA-ICP-MS analysis using a beam diameter of 35 microns) in a sample (KBCR) of quartzose sandstone (Qm91-F6-Lt3) in the Lower Cretaceous (Albian) Cintura Formation of the Bisbee Group at Rucker Canyon in the Chiricahua Mountains (SE AZ). Analysis of plateau Jurassic eolianite provenance has shown that >295 Ma zircon grains were derived from deflation of floodplains lying north and northeast of the Colorado Plateau near the termini of transcontinental drainages heading in the Appalachian province, and include age populations unrepresented by bedrock in SW Laurentia. Comparative K-S statistics indicate that populations of >295 Ma zircon grains in KBCR (n=84 grains) and 10 plateau eolianites (n=887 grains) are statistically indistinguishable (P-value ~0.8), and further that populations of all >115 Ma grains in KBCR (n=98 grains) and four Middle to Upper Jurassic eolianites (n=365 grains) of the eastern Colorado Plateau north of the Mogollon highlands are also statistically indistinguishable (P-value ~0.9). The zircon grains >115 Ma but <295 Ma were derived ultimately from the Permian-Triassic East Mexico and Mesozoic Cordilleran magmatic arcs south of the Bisbee basin, but were apparently recycled into the basin from eastern plateau Jurassic eolianites exposed to the north. Zircon grains of distant ultimate provenance in Jurassic eolianites were recycled into Upper Jurassic and Cretaceous strata of the Colorado Plateau as well as into the Bisbee basin. Two post-Jurassic grains (111-108 Ma) in KBCR represent more juvenile arc contributions compatible with Albian (112-100 Ma) deposition.