(U-Th)/He and U-Pb Double Dating Constraints on the Interplay between thrust Deformation and Basin Development, Sevier Foreland Basin, Utah

Edgardo Pujols
University of Texas at Austin, Jackson School of Geosciences
Austin, Texas, United States
[email protected]

In thrust belts and foreland basins the temporal aspects between progressive exhumation, clastic progradation and the resulting basin architecture remain partially obscured by the many intricate feedback and allogeneic processes involved. Additionally, there is insufficient analytical data directly linking hinterland chronological denudation to stratal packages in foreland basins. This information becomes crucial when trying to accurately identify the leading forces controlling thrust and basin architecture. This study aims to constrain the spatial and temporal aspects of the Sevier foreland sedimentary successions, in a detailed stratigraphic context, as a function of thrust unroofing. This will be accomplished by developing an unprecedented systematic U-Pb and (U-Th)/He detrital zircon double dating provenance record. Current detrital zircon U-Pb signatures obtained from the Canyon Range hinterland are dominated by Grenville ages (~1-1.15Ga), granites intruded in the Yavapai-Mazatzal craton (~1.4-1.6Ga) and Trans-Hudson ages (~1.8-1.9Ga). (U-Th)/He ages in Canyon Range so far show a zircon He partial retention zone exposed in Caddy Canyon formation with ages as young as Santonian. The Late Cretaceous Canyon Range Conglomerate recorded (U-Th)/He ages equivalent to their biostratigraphic ages. In the Sevier foredeep, (U-Th)/(He-Pb) data show that the Ferron and Bluegate sandstones were dominated by volcanic ages whereas younger units like the Blackhawk and Castlegate show a stronger unroofing age component. The wedgetop ages suggest very short depositional lag-times and fast hinterland exhumation whereas the foredeep unroofing-derived sediments did not become dominant far into the basin until the Coniacian. This research will ultimately help develop comprehensive models on hinterland and foreland basin feedbacks.

AAPG Search and Discovery Article #90183©2013 AAPG Foundation 2013 Grants-in-Aid Projects