Paper No. 3
Presentation Time: 2:05 PM
PROVENANCE OF DISTAL CORDILLERAN FORELAND BASIN STRATA EXPOSED AT ACOMA PUEBLO, NEW MEXICO: LINKS BETWEEN FORELAND BASIN MIGRATION AND SEDIMENT SOURCES
New provenance and stratigraphic data from the distal Cordilleran foreland basin strata exposed at Acoma Pueblo, New Mexico record the interplay between foreland basin dynamics and sediment source areas. U-Pb detrital zircon geochronology and measured sections were used to examine both the late Jurassic through mid-Cretaceous distal foreland basin configuration and a major change from cratonic to magmatic sediment source areas during the deposition of the Entrada Sandstone, the Zuni Sandstone, the Morrison Formation, and the Dakota Sandstone. Overall, the most common peak ages include: 1416, 1168, 1035, and 1030 Ma. Potential source terranes for these peak ages include the Mid-Continent Granite-Rhyolite Province (1.55-1.35 Ga) and the Grenville Province (1.3-0.9 Ga), both located cratonward of the basin. An upsection increase in Mesozoic peak ages (216, 205, 193, and 98 Ma) in these formations is interpreted to record a transition in provenance from mainly cratonic sources to magmatic arc sources located west of the foreland basin. This increase in western sources of sediment is interpreted as a product of eastward thrust belt migration that resulted in a corresponding eastward migration of the foreland basin system. Upsection changes in depositional environments are consistent with the interpretation that the Jurassic aeolian and playa environments represent deposition within the back-bulge and forebulge depozones whereas the Cretaceous fluvial/shallow marine environments were deposited in the more distal foredeep depozone of the Cordilleran foreland basin system.