Journal cover Journal topic
Solid Earth An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 4.165 IF 4.165
  • IF 5-year value: 4.075 IF 5-year
    4.075
  • CiteScore value: 4.28 CiteScore
    4.28
  • SNIP value: 1.501 SNIP 1.501
  • SJR value: 1.060 SJR 1.060
  • IPP value: 4.21 IPP 4.21
  • h5-index value: 29 h5-index 29
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 27 Scimago H
    index 27
Discussion papers
https://doi.org/10.5194/se-2019-51
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/se-2019-51
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 22 Mar 2019

Research article | 22 Mar 2019

Review status
This discussion paper is a preprint. A revision of the manuscript was accepted for the journal Solid Earth (SE).

Fluid–rock interactions in the shallow Mariana forearc: carbon cycling and redox conditions

Elmar Albers1, Wolfgang Bach1, Frieder Klein2, Catriona D. Menzies3,a, Friedrich Lucassen1, and Damon A. H. Teagle3 Elmar Albers et al.
  • 1Department of Geosciences and MARUM–Centerfor Marine Environmental Sciences, University of Bremen, Bremen, 28359, Germany
  • 2Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole (MA), 02543, USA
  • 3Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, SO16 7PP, UK
  • anow at: Department of Geology and Petroleum Geology, University of Aberdeen, Aberdeen, AB24 3FX, UK

Abstract. Few data exist that provide insight into processes affecting the long-term carbon cycle at shallow forearc depths. To better understand the mobilization of carbon in sediments and crust of the subducting slab, we investigated carbonate materials that originate from the subduction channel at the Mariana forearc (< 20 km) and were recovered during International Ocean Discovery Program Expedition 366. The calcium carbonates exist as vein precipitates within metavolcanic and metasedimentary clasts. The clasts represent portions of the subducting lithosphere, including ocean island basalt, that were altered at lower blueschist facies conditions and were subsequently transported to the forearc seafloor by serpentinite mud volcanism. Euhedral aragonite and calcite and the lack of deformation within the veins suggest carbonate formation in a strain-free environment, that is after peak metamorphism affected their hosts. Intergrowth with barite and marked negative Ce anomalies in carbonate attest the precipitation within a generally oxic environment that was not controlled by serpentinization. Strontium and O isotopic compositions in carbonate (87Sr/86Sr = 0.7052 to 0.7054, δ18OVSMOW = 20 to 24 ‰) imply precipitation from slab-derived fluids at temperatures between ~ 130 and 300 °C. These temperature estimates are consistent with the presence of blueschist facies phases, such as lawsonite coexisting with the carbonates in some veins. Incorporated carbon is inorganic (δ13CVPDB = −1 to +4 ‰) and likely derived from the decarbonation of carbonaceous sediment and/or oceanic crust. These findings provide evidence for the mobilization of carbon in the downgoing slab at depths of < 20 km. Our study for the first time shows in detail that a portion of this carbon forms carbonate precipitates in the subduction channel of an active convergent margin. This process may be an important asset in understanding the deep carbon cycle since it highlights that C is lost from the subducting lithosphere before reaching greater depths.

Elmar Albers et al.
Interactive discussion
Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Login for Authors/Topical Editors] [Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement
Elmar Albers et al.
Elmar Albers et al.
Viewed  
Total article views: 328 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
255 72 1 328 12 1 1
  • HTML: 255
  • PDF: 72
  • XML: 1
  • Total: 328
  • Supplement: 12
  • BibTeX: 1
  • EndNote: 1
Views and downloads (calculated since 22 Mar 2019)
Cumulative views and downloads (calculated since 22 Mar 2019)
Viewed (geographical distribution)  
Total article views: 210 (including HTML, PDF, and XML) Thereof 210 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Cited  
Saved  
No saved metrics found.
Discussed  
Latest update: 24 May 2019
Publications Copernicus
Download
Short summary
To understand the fate of carbon in subducted oceanic sediments and crust, we studied carbonate phases in rocks from the Mariana subduction zone. These show that carbon is liberated from the downgoing plate at depths less than 20 km. Some of the carbon is subsequently trapped in minerals and likely subducts to greater depths, whereas fluids carry the other part back into the ocean. Our findings imply that shallow subduction zone processes may play an important role in the deep carbon cycle.
To understand the fate of carbon in subducted oceanic sediments and crust, we studied carbonate...
Citation