Sulphur isotopes of alkaline magmas unlock long-term records of crustal recycling on Earth
Abstract
Earth’s surface and mantle sulphur reservoirs are connected via subduction, crustal recycling and volcanism. Although oceanic hotspot lavas currently provide the best constraints on the deep sulphur cycle, their restricted age range (<200 Ma) means they cannot reveal temporal variations in crustal recycling over Earth history. Sulphur-rich alkaline magmas offer the solution because they are associated with recycled sources (i.e. metasomatized lithospheric mantle and plumes) and, crucially, are found throughout the geological record. Here, we present a detailed study of sulphur isotope fractionation in a Mesoproterozoic alkaline province in Greenland and demonstrate that an enriched subduction-influenced source (δ34S of +1 to +5‰) can be reconstructed. A global δ34S compilation reveals secular variation in alkaline magma sources which support changes in the composition of the lithospheric mantle and/or Ga timescales for deep crustal recycling. Thus, alkaline magmas represent a powerful yet underutilized repository for interrogating crustal recycling through geological time.
Citation
Hutchison , W , Babiel , R , Finch , A A , Marks , M , Markl , G , Boyce , A J , Stüeken , E E , Friis , H , Borst , A M & Horsburgh , N J 2019 , ' Sulphur isotopes of alkaline magmas unlock long-term records of crustal recycling on Earth ' , Nature Communications , vol. 10 , 4208 . https://doi.org/10.1038/s41467-019-12218-1
Publication
Nature Communications
Status
Peer reviewed
ISSN
2041-1723Type
Journal article
Description
This project was supported by the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 689909. S isotope analysis at SUERC was supported by a NERC Stable Isotope Facility grant (IP-1713–0517). Analysis at Tübingen was supported by the Deutsche Forschungsgemeinschaft (grant MA 2563/9–1).Collections
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