Thin-section detrital zircon geochronology mitigates bias in provenance investigations

Detrital zircon U–Pb geochronology has enabled advances in the understanding of sediment provenance, transportation pathways, and the depositional age of sedimentary packages. However, sample selection and processing can result in biasing of detrital zircon age spectra. This paper presents a novel a...

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Bibliographic Details
Published in:Journal of the Geological Society
Main Authors: Zutterkirch, Isabel C., Kirkland, Christopher, Barham, Milo, Elders, Chris
Format: Article in Journal/Newspaper
Language:English
Published: GEOLOGICAL SOC PUBL HOUSE 2022
Subjects:
Science & Technology
Physical Sciences
Geosciences
Multidisciplinary
Geology
NORTHERN CARNARVON BASIN
U-PB GEOCHRONOLOGY
HF-ISOTOPE
CRUSTAL EVOLUTION
DEPOSITIONAL AGES
EAST ANTARCTICA
PERTH BASIN
WEST SHELF
RIFT BASIN
AUSTRALIA
East Antarctica
Antarc*
Antarctica
Online Access:https://hdl.handle.net/20.500.11937/90918
https://doi.org/10.1144/jgs2021-070
Description
Summary:Detrital zircon U–Pb geochronology has enabled advances in the understanding of sediment provenance, transportation pathways, and the depositional age of sedimentary packages. However, sample selection and processing can result in biasing of detrital zircon age spectra. This paper presents a novel approach using in situ detrital zircon U–Pb measurements on thin-sections to provide greater confidence in maximum depositional ages and provenance interpretations. New U–Pb age data of 310 detrital zircon grains from 16 thin-sections of the Triassic Mungaroo Formation from two wells in the Northern Carnarvon Basin, Australia, are presented. Whilst detrital zircon age modes are consistent with previous work, there are some differences in the relative proportions of age modes, which are partly attributed to a lack of small grains in handpicked grain mounts. The relative sample bias is quantified via grain size comparison of dated zircon (in thin-sections or handpicked mounts) relative to all zircons identified in bulk-mounts and thin-sections. The youngest age mode (c. 320–195 Ma) is consistent with an active margin to the north. The dated zircons reveal a single grain defined maximum depositional age of 197 Ma for the upper part of the Mungaroo Formation, suggesting deposition may have continued into the Early Jurassic.

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