Gaining from loss: Detrital zircon source-normalized α-dose discriminates first-versus multi-cycle grain histories

Detrital zircon U–Pb ages are widely employed as an archive of geological processes through time. Changes in detrital zircon age patterns within sediments reflect changes in source areas that are often related to tectonic and/or climatic processes. However, discrimination of first-cycle and multi-cy...

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Main Authors: Dröllner, Maximilian, Barham, Milo, Kirkland, Christopher
Format: Journal Article
Language:English
Published: ELSEVIER 2022
Subjects:
Online Access:http://purl.org/au-research/grants/arc/LE140100150
http://hdl.handle.net/20.500.11937/90951
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author Dröllner, Maximilian
Barham, Milo
Kirkland, Christopher
author_facet Dröllner, Maximilian
Barham, Milo
Kirkland, Christopher
author_sort Dröllner, Maximilian
building Curtin Institutional Repository
collection Online Access
description Detrital zircon U–Pb ages are widely employed as an archive of geological processes through time. Changes in detrital zircon age patterns within sediments reflect changes in source areas that are often related to tectonic and/or climatic processes. However, discrimination of first-cycle and multi-cycle detrital zircon with primary crystalline and secondary sedimentary sources, respectively, can be challenging using only crystallisation age constraints. Here, we present U–Pb geochronology of detrital zircon from modern fluvial and littoral environments on the Scott Coastal Plain in Western Australia to investigate the use of α-dose to identify sedimentary recycling. The majority of 1032 concordant U–Pb ages are interpreted to be ultimately sourced from the local basement. However, U–Pb ages do not reflect the areal extent of source rocks and indicate significant reworking of coastal plain sediments. A novel metric – source-normalized α-dose – demonstrates predominant detrital zircon routing via recycling through intermediate storage. This metric is defined as the ratio of the average α-dose (a measure of metamictization) of detrital zircon belonging to a characteristic age group and the average α-dose of zircon grains within the corresponding source crystalline basement. Average values of source-normalized α-dose of detrital zircon populations <1 are interpreted to reflect selective removal of more labile (metamict) grains via attrition and diagenesis, indicating greater grain transport and recycling, whereas values of c. 1 signify shorter transport and a first-cycle origin. Application of this approach to ancient clastic systems is supported by consistency of results with independent indicators of progressive sedimentary recycling and/or transport. Source-normalized α-dose is an internal measure using zircon grain chemistry (U and Th), and avoids bias associated with multi-mineral measures of sediment recycling that may be related to source fertility. Additionally, source-normalized α-dose uses measures typically captured during routine U–Pb geochronology. Source-normalized α-dose of detrital zircon provides an additional method to address sedimentary source-to-sink transport and recycling, and ultimately allows more robust interpretation of U–Pb zircon data.
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spelling curtin-20.500.11937-909512023-05-09T07:42:36Z Gaining from loss: Detrital zircon source-normalized α-dose discriminates first-versus multi-cycle grain histories Dröllner, Maximilian Barham, Milo Kirkland, Christopher Science & Technology Physical Sciences Geochemistry & Geophysics U-Pb geochronology sediment routing sedimentary recycling metamict zircon chemistry alpha dose U-PB AGES SEDIMENTARY SYSTEMS SIGNAL PROPAGATION WESTERN-AUSTRALIA PERTH BASIN HF-ISOTOPE PROVENANCE GEOCHRONOLOGY SANDSTONE FERTILITY Detrital zircon U–Pb ages are widely employed as an archive of geological processes through time. Changes in detrital zircon age patterns within sediments reflect changes in source areas that are often related to tectonic and/or climatic processes. However, discrimination of first-cycle and multi-cycle detrital zircon with primary crystalline and secondary sedimentary sources, respectively, can be challenging using only crystallisation age constraints. Here, we present U–Pb geochronology of detrital zircon from modern fluvial and littoral environments on the Scott Coastal Plain in Western Australia to investigate the use of α-dose to identify sedimentary recycling. The majority of 1032 concordant U–Pb ages are interpreted to be ultimately sourced from the local basement. However, U–Pb ages do not reflect the areal extent of source rocks and indicate significant reworking of coastal plain sediments. A novel metric – source-normalized α-dose – demonstrates predominant detrital zircon routing via recycling through intermediate storage. This metric is defined as the ratio of the average α-dose (a measure of metamictization) of detrital zircon belonging to a characteristic age group and the average α-dose of zircon grains within the corresponding source crystalline basement. Average values of source-normalized α-dose of detrital zircon populations <1 are interpreted to reflect selective removal of more labile (metamict) grains via attrition and diagenesis, indicating greater grain transport and recycling, whereas values of c. 1 signify shorter transport and a first-cycle origin. Application of this approach to ancient clastic systems is supported by consistency of results with independent indicators of progressive sedimentary recycling and/or transport. Source-normalized α-dose is an internal measure using zircon grain chemistry (U and Th), and avoids bias associated with multi-mineral measures of sediment recycling that may be related to source fertility. Additionally, source-normalized α-dose uses measures typically captured during routine U–Pb geochronology. Source-normalized α-dose of detrital zircon provides an additional method to address sedimentary source-to-sink transport and recycling, and ultimately allows more robust interpretation of U–Pb zircon data. 2022 Journal Article http://hdl.handle.net/20.500.11937/90951 10.1016/j.epsl.2021.117346 English http://purl.org/au-research/grants/arc/LE140100150 http://purl.org/au-research/grants/arc/LE190100176 http://creativecommons.org/licenses/by/4.0/ ELSEVIER fulltext
spellingShingle Science & Technology
Physical Sciences
Geochemistry & Geophysics
U-Pb geochronology
sediment routing
sedimentary recycling
metamict
zircon chemistry
alpha dose
U-PB AGES
SEDIMENTARY SYSTEMS
SIGNAL PROPAGATION
WESTERN-AUSTRALIA
PERTH BASIN
HF-ISOTOPE
PROVENANCE
GEOCHRONOLOGY
SANDSTONE
FERTILITY
Dröllner, Maximilian
Barham, Milo
Kirkland, Christopher
Gaining from loss: Detrital zircon source-normalized α-dose discriminates first-versus multi-cycle grain histories
title Gaining from loss: Detrital zircon source-normalized α-dose discriminates first-versus multi-cycle grain histories
title_full Gaining from loss: Detrital zircon source-normalized α-dose discriminates first-versus multi-cycle grain histories
title_fullStr Gaining from loss: Detrital zircon source-normalized α-dose discriminates first-versus multi-cycle grain histories
title_full_unstemmed Gaining from loss: Detrital zircon source-normalized α-dose discriminates first-versus multi-cycle grain histories
title_short Gaining from loss: Detrital zircon source-normalized α-dose discriminates first-versus multi-cycle grain histories
title_sort gaining from loss: detrital zircon source-normalized α-dose discriminates first-versus multi-cycle grain histories
topic Science & Technology
Physical Sciences
Geochemistry & Geophysics
U-Pb geochronology
sediment routing
sedimentary recycling
metamict
zircon chemistry
alpha dose
U-PB AGES
SEDIMENTARY SYSTEMS
SIGNAL PROPAGATION
WESTERN-AUSTRALIA
PERTH BASIN
HF-ISOTOPE
PROVENANCE
GEOCHRONOLOGY
SANDSTONE
FERTILITY
url http://purl.org/au-research/grants/arc/LE140100150
http://purl.org/au-research/grants/arc/LE140100150
http://hdl.handle.net/20.500.11937/90951