Mélange dehydration and melting beneath South Sandwich Islands arc

Shu, Yunchao; Nielsen, Sune G.; Le Roux, Veronique; Santiago Ramos, Danielle; Blusztajn, Jerzy; Auro, Maureen; Leat, Philip T.; Horner, Tristan J.. 2025 Mélange dehydration and melting beneath South Sandwich Islands arc. Nature Communications, 16, 1440. 13, pp. 10.1038/s41467-025-56554-x

Before downloading, please read NORA policies.

Preview

Text (Open Access) Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/. s41467-025-56554-x.pdf - Published Version Available under License Creative Commons Attribution 4.0. Download (1MB) | Preview

Abstract/Summary

Mechanisms regulating material transfer from subducted slabs to arc magmas remain debated, centered on metasomatized mantle wedge interactions versus mélange mobilization at the slab-mantle interface. The South Sandiwch Islands arc offers a unique setting to distinguish between these models due to the significant barium isotope contrast between altered oceanic crust and sediments, the latter displaying unusually light barium isotope compositions compared to the global sediment range. Here we show substantial barium isotope variations coupled with invariant strontium isotope ratios in arc lavas, consistent with mélange mobilization beneath the arc. Northern arc lavas display a broader range of barium isotope values than expected from slab inputs, suggesting barium isotope fractionation during slab material transport, potentially driven by phengite-related barium retention within the mélange. Notably, sediments, rather than altered oceanic crust, emerge as the dominant source of barium in arc lavas. While a comparison of barium isotope data from four additional arcs indicates mantle wedge metasomatism remains visible in several cases, mélange mobilization is consistent with available data across all of these subduction zones.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1038/s41467-025-56554-x
ISSN:	20411723
Additional Keywords:	subduction zones; altered oceanic crust; sediments; trace elements; barium
Date made live:	10 Feb 2025 09:55 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/537714

Actions (login required)

View Item

Document Downloads

More statistics for this item...