Hafnium isotope evidence on the provenance of ~ 1.1 Ga detrital zircons from western North America.

摘要

Detrital zircon U-Pb age determinations are increasingly used to define the provenance of siliciclastic sediments, but can have spatial limitations when basement rocks of the same age are widely located spatially. One approach to improving this resolution is through the use of combined U-Pb age and Hf isotope determinations from the same detrital zircon grain using LA-MC-ICPMS analyses. This study tested the ability of this technique to better resolve the source of Mesoproterozoic detrital zircon deposited in western North America. The Hf isotopic compositions of igneous zircon in potential ∼1.1 Ga source rocks were first determined, then compared to ∼1.1 Ga detrital zircon from Neoproterozoic to Cambrian sedimentary rocks from western North America. These sediments are traditionally thought to be eroded from the Appalachians, but the results of this study suggest that some of these sediments may have been more proximally derived from Grenville-aged plutons in western North America.