301-12 Detrital Zircon Age and Geochemical Constraints on Provenance of Cambrian Sandstones from Western Newfoundland

Session: Geochronology (Posters)

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Abstract:

This study presents a new record of sediment provenance in Cambrian (Dyeran to Steptoean) strata in western Newfoundland using detrital zircons (DZs) from the Hawke Bay, March Point, and Petit Jardin Formations. U-Pb dates and trace and rare earth element (TREE) ratios were measured using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry. These data, together with sedimentological and stratigraphic information, are used to test the hypothesis that the provenance of sediment here changed over this interval, and to compare provenance across the Laurentian passive margins. Analysis of TREE concentrations and ratios, including Nb, Ta, Th, U, Yb, P, Gd, and Y will be used investigate potential differences in sources between grains of the same age population.

Our data show no evidence for a temporal shift in sediment provenance in western Newfoundland based on U-Pb dates alone. Samples are dominated by Archean, Paleoproterozoic, and Grenville-aged sources, and age populations are highly consistent between samples from the Hawke Bay, March Point, and Petit Jardin formations. Previous studies along the eastern Laurentian margin support these findings, and further characterize the development of this passive margin and the opening of the Iapetus Ocean and the Humber seaway.

These data contrast with DZ spectra from middle to late Cambrian sediment deposited on the western and northern margins of Laurentia. Samples from these margins often show two distinct provenance profiles: the first being dominated by Archean and Paleoproterozoic-aged sources and the second type comprised of significant Grenville-aged input. Spatial and temporal variations between these two signatures are interpreted as reflecting different sediment sources, isolation of some basins from Grenville-aged input by uplift of the Transcontinental Arch, and/or changes in the inundation of Laurentia during the Sauk sequences of the Cambrian Period. We integrate and compare these diverse records to gain a better understanding of Laurentian sediment sources and barriers to sediment dispersal during the Cambrian Period.

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

doi: 10.1130/abs/2025AM-9020

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