Applying detrital zircon geochronology to identify variations in sedimentary

provenance of the Cretaceous Straight Cliffs Formation, Southern Utah

Tyler SzwarcAdvisor: Cari Johnson

COUT

NMAZ

Late Cretaceous (~85 Ma)http://www2.nau.edu/rcb7/ColoPlatCret_PictCliffs.jpg

Previous Research• Sedimentary provenance changes across

sequence boundaries

Lawton et al., 2003

Project Overview

• Infer sedimentary provenance of John Henry Member, Straight Cliffs Formation• Use detrital zircon ages from ~20

sandstone samples as “tracers”• Look for changes in provenance

through time and space

What is a Detrital Zircon?• Silicate mineral that forms in felsic igneous melts• Incorporates radioactive uranium into the crystal• U/Pb ratio provides crystallization age• “detrital” implies the zircon has been transported

from origin

COUT

NMAZ

Late Cretaceous (~80 Ma)http://www2.nau.edu/rcb7/ColoPlatCret_PictCliffs.jpg

Sevi

er F

old/

Thru

st B

elt

Mogollon

Highlands

UT CO

Dickinson and Gehrels, 2008

Importance

• Provenance studies help determine spatial extent of sandstones• Better understand the nature of

sequence boundaries in fluvial strata• Obtain a better understanding of

foreland basin evolution

References

• Blakey, Ron, 2011, Paleogeography of the Colorado Plateau and Vicinity, http://www2.nau.edu/rcb7/ColoPlatPalgeog.html

• Dickinson, W., and Gehrels, G., 2008. Sediment delivery to the Cordilleran Foreland Basin: Insights from U-Pb ages of detrital zircons in upper Jurassic and Cretaceous strata of the Colorado Plateau. American Journal of Science, vol. 308, December 2008, P. 1041 – 1082.

• Lawton, T., Polluck, S., and Robinson, R., 2003. Integrating sandstone petrology and nonmarine sequence stratigraphy: Application to the Late Cretaceous fluvial systems of southwestern Utah, U.S.A., Journal of Sedimentary Research, vol. 73, No. 3, May 2003, P. 389 – 406.