T115 Magmatism and Accreted Terranes from the North American Cordillera to the Norwegian Caledonides: a Session in Honor of the Scientific Contributions of Calvin G. Barnes (Posters)

Monday, 23 September 2024
8:00 AM - 5:30 PM
Hall D

FINGERPRINTING SEDIMENT SOURCES OF THE UPPER JURASSIC GALICE AND MARIPOSA FORMATIONS, OREGON AND CALIFORNIA: AGE AND ƐHF OF TRIASSIC-NEOPROTEROZOIC DETRITAL ZIRCON

Paper number: T115-5
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

The detailed provenance record of the Upper Jurassic Galice and Mariposa Formations, Oregon and California, may improve our understanding of the North American continental margin during the Late Jurassic Nevadan orogeny. Detrital zircon age and ƐHf data require that these strata were deposited along the continental margin from ca. 159-148 Ma, and received sediment from an active Jurassic arc(s) as well as the continental arc framework and retroarc region. Here, we expand our existing ƐHf dataset of Mesozoic arc-derived zircon (n=1360) to include Paleozoic-Neoproterozoic detrital zircon from the Galice and Mariposa Formations. We present new ƐHf data from selected 215-850 Ma detrital zircon (n ~ 600) from 12 metasandstone samples that span the ~275 km strike-length of the Galice Formation in the Western Klamath terrane of the Klamath Mountains Province, and the ~140 km strike-length of the Mariposa Formation in the western Sierra Nevada foothills. 215-850 Ma detrital zircon comprise 9-31% of the detrital zircon age spectra from each of 12 regional compilations in the Galice and Mariposa Formations; Galice samples tend to have more zircon within this age range (average 22%) than Mariposa samples (average 16%). Compiled age data from each formation reveal three common age modes of 225-270 Ma, 390-450 Ma, and 550-630 Ma, suggesting similar sediment sources. In addition, Mariposa samples include a distinct 330-375 Ma age mode that is not present in Galice samples. New ƐHf data from grains that comprise these four Triassic-Neoproterozoic age modes in the Galice and Mariposa Formation detrital zircon age spectra may identify unique source regions and thereby better delimit source-to-sink connections along the Late Jurassic continental margin.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-404474

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