255-9 One Billion Years of Sediment Recycling: Zircon Alpha Dose and Double Dates Reveal Multiple Sediment Transport Pathways for Cretaceous Foreland Strata in the Book Cliffs, USA

Session: Broad Applications of Thermochronology to Understanding Geologic Rates and Processes Through the Sedimentary Record

Presenting Author:

Authors:

Abstract:

Geochronologic methods for determining sediment provenance often provide information about the region where accessory minerals crystallized without constraining the pathway between crystallization and deposition. In some tectonic settings, this pathway may be direct, while in others, sediment may move through multiple deposition-exhumation cycles between crystallization and modern sedimentary sink. Understanding these intermediate “recycling” events is pertinent for constraining erosion and sediment transport rates which inform landscape evolution interpretations.

Detrital zircon (DZ) “double dating” that combines U-Pb and (U-Th)/He chronology (U-Pb and ZHe dates) illuminates recycling history in some, but not all cases. ZHe dates generally become less sensitive to different histories as length of history increases, which in part explains the difficulty in reconstructing recycling. To further resolve recycling histories, we propose the addition of radiation damage (alpha dose) data. Alpha dose retention is sensitive to different temperatures than the (U-Th)/He system and therefore provides complementary, potentially unique, information about sedimentary burial heating. We applied this approach to Grenville-age (1.10-1.25 Ga) DZ in the Cretaceous Sevier Orogeny foreland basin strata in the Book Cliffs area of Utah and Colorado, USA. The sediment provenance and post-depositional thermal history of these rocks are highly constrained, making this an ideal location to test the alpha dose approach. We designed forward thermal history models to predict alpha dose and ZHe for recycling history hypotheses that test the number, timing, and burial depth magnitude of recycling events pre-Book Cliffs deposition.

We used Raman spectroscopy to determine accumulated alpha dose for 430 DZ from 20 sandstone samples with existing double dates (n = 77). Inter-sample alpha dose variation supports existing U-Pb date hinterland provenance interpretations, validating the utility of alpha dose for provenance applications. Intra-sample alpha dose variation allows at least two different recycling histories. Both histories include only one recycling event but the timing of recycling differs. This suggests that sedimentary basins in western Laurentia were relatively stable and experienced little erosion until Sevier Orogeny exhumation. Alpha dose and ZHe data are most sensitive to the number and timing of recycling events and are generally consistent with each other, while ZHe dates alone are less discriminatory among different recycling histories, as predicted. Current work is further testing the limits of the combined dataset to constrain sedimentary burial magnitude.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9889

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