We investigated nitrogen (N) sources and incorporation in the shallow forearc of an active subduction zone by studying samples from two serpentinite seamounts (South Chamorro and Conical; Ocean Drilling Program Legs 195 and 125) along the Mariana convergent margin. We report N concentrations and δ15N values for serpentinized peridotites, serpentinite muds, and metabasaltic clasts. All are enriched in N relative to likely ultramafic and mafic protoliths. A modest positive correlation between N and δ15N for the serpentinized peridotites could reflect extents of N infiltration by N-bearing fluids. Mixing calculations identify the source of the fluids as dehydrating metasediments and/or altered oceanic crust from the subducting Pacific slab. Such addition is consistent with that of other fluid mobile elements (B, Li, As, and Cs), but their concentrations show little correlation with N. The general lack of correlation in concentrations of N and major and trace elements complicates the identification of mineral hosts and N residency (e.g., loose adsorption on serpentine minerals). The enrichment of N in these samples indicates that serpentinized mantle wedges could be a globally significant N reservoir. If subducted, this reservoir could provide significant amounts of isotopically heavy N to sub-arc depths and beyond.
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Research Article|
November 04, 2024
Early Publication
Nitrogen (N) and its isotopes in serpentinized forearc wedges and implications for N cycling across subduction zones
Juan Felipe Bustos-Moreno;
Juan Felipe Bustos-Moreno
1
Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA
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Gray E. Bebout;
Gray E. Bebout
1
Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA
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Ivan P. Savov
Ivan P. Savov
2
Institute of Geophysics and Tectonics, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
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Juan Felipe Bustos-Moreno
1
Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA
Gray E. Bebout
1
Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA
Ivan P. Savov
2
Institute of Geophysics and Tectonics, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
Publisher: Geological Society of America
Received:
19 Jun 2024
Revision Received:
02 Oct 2024
Accepted:
23 Oct 2024
First Online:
04 Nov 2024
Online ISSN: 1943-2682
Print ISSN: 0091-7613
© 2024 The Authors
Geology (2024)
Article history
Received:
19 Jun 2024
Revision Received:
02 Oct 2024
Accepted:
23 Oct 2024
First Online:
04 Nov 2024
Citation
Juan Felipe Bustos-Moreno, Gray E. Bebout, Ivan P. Savov; Nitrogen (N) and its isotopes in serpentinized forearc wedges and implications for N cycling across subduction zones. Geology 2024; doi: https://doi.org/10.1130/G52492.1
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Index Terms/Descriptors
- basins
- Conical Seamount
- crust
- fore-arc basins
- igneous rocks
- isotope ratios
- isotopes
- Leg 125
- Leg 195
- Mariana Trough
- metabasalt
- metaigneous rocks
- metamorphic rocks
- metasedimentary rocks
- metasomatic rocks
- N-15/N-14
- nitrogen
- North Pacific
- Northwest Pacific
- Ocean Drilling Program
- ocean floors
- oceanic crust
- Pacific Ocean
- peridotites
- plate boundaries
- plate convergence
- plate tectonics
- plutonic rocks
- seamounts
- serpentinite
- stable isotopes
- ultramafics
- West Pacific
- South Chamorro Seamount
Latitude & Longitude
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