Plate tectonics is the primary method for cycling of material between the mantle, crust, and surface reservoirs of our planet. Oxygen isotopes (18O/16O, δ18O) in zircon have been shown to track source components through subduction, primarily by detecting the presence of isotopically heavy supracrustal material. Isotopically light signatures are relatively rare, suggesting recycling of high-temperature hydrothermal sources is negligible. Here, we report light δ18O data from magmatic-arc rocks of the 511−500 Ma Stavely Belt in western Victoria, Australia. These rocks demonstrate a two-stage mixing history: (1) constant, highly radiogenic εHf with decreasing δ18O, indicating sub-mantle δ18O initial compositions, interpreted to represent a sub-arc mantle contaminated with low-δ18O slab melts and/or fluids; and (2) decreasing εHf with increasing δ18O, implying crustal contamination with country-rock turbidites. These new data suggest that high-temperature hydrothermal sources can be recycled through subduction zones and alter the composition of the sub-arc mantle. We demonstrate how slab tearing could have driven this process, its connection to the architecture of the Delamerian Orogen, and implications for circum-supercontinent margins.
Research Article|
January 16, 2025
Early Publication
A slab origin for low-δ18O arc magmas
David R. Mole;
David R. Mole
1
Geoscience Australia, Canberra ACT 2609, Australia2
School of Earth Sciences, University of Western Australia, Perth WA 6009, Australia
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Christopher J. Lewis;
Christopher J. Lewis
1
Geoscience Australia, Canberra ACT 2609, Australia
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Simon Bodorkos;
Simon Bodorkos
1
Geoscience Australia, Canberra ACT 2609, Australia
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James L. Crowley;
James L. Crowley
3
Isotope Geology Laboratory, Boise State University, Boise, Idaho 83706, USA
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Anthony Schofield;
Anthony Schofield
1
Geoscience Australia, Canberra ACT 2609, Australia
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Stacey O. Curtis;
Stacey O. Curtis
4
STEM, University of South Australia, Mawson Lakes SA 5095, Australia5
MinEx CRC, Perth WA 6151, Australia
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Noreen J. Evans
Noreen J. Evans
6
John de Laeter Centre, Curtin University, Perth WA 6102, Australia
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David R. Mole
1
Geoscience Australia, Canberra ACT 2609, Australia2
School of Earth Sciences, University of Western Australia, Perth WA 6009, Australia
Christopher J. Lewis
1
Geoscience Australia, Canberra ACT 2609, Australia
Simon Bodorkos
1
Geoscience Australia, Canberra ACT 2609, Australia
James L. Crowley
3
Isotope Geology Laboratory, Boise State University, Boise, Idaho 83706, USA
Anthony Schofield
1
Geoscience Australia, Canberra ACT 2609, Australia
Stacey O. Curtis
4
STEM, University of South Australia, Mawson Lakes SA 5095, Australia5
MinEx CRC, Perth WA 6151, Australia
Noreen J. Evans
6
John de Laeter Centre, Curtin University, Perth WA 6102, Australia
Publisher: Geological Society of America
Received:
23 Sep 2024
Revision Received:
24 Nov 2024
Accepted:
06 Dec 2024
First Online:
16 Jan 2025
Online ISSN: 1943-2682
Print ISSN: 0091-7613
© 2025 The Authors
Geology (2025)
Article history
Received:
23 Sep 2024
Revision Received:
24 Nov 2024
Accepted:
06 Dec 2024
First Online:
16 Jan 2025
Citation
David R. Mole, Christopher J. Lewis, Simon Bodorkos, James L. Crowley, Anthony Schofield, Stacey O. Curtis, Noreen J. Evans; A slab origin for low-δ18O arc magmas. Geology 2025; doi: https://doi.org/10.1130/G52782.1
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