Subduction zone forearc serpentinites as incubators for deep microbial life

Oliver Plümper, Helen E. King, Thorsten Geisler, Yang Liu, Sonja Pabst, Ivan P. Savov, Detlef Rost, Thomas Zack

Research output: Contribution to journalArticleResearchpeer-review

19 Citations (Scopus)

Abstract

Serpentinization-fueled systems in the cool, hydrated forearc mantle of subduction zones may provide an environment that supports deep chemolithoautotrophic life. Here, we examine serpentinite clasts expelled from mud volcanoes above the Izu-Bonin-Mariana subduction zone forearc (Pacific Ocean) that contain complex organic matter and nanosized Ni-Fe alloys. Using time-of-flight secondary ion mass spectrometry and Raman spectroscopy, we determined that the organic matter consists of a mixture of aliphatic and aromatic compounds and functional groups such as amides. Although an abiotic or subduction slab-derived fluid origin cannot be excluded, the similarities between the molecular signatures identified in the clasts and those of bacteria-derived biopolymers from other serpentinizing systems hint at the possibility of deepmicrobial life within the forearc. To test this hypothesis, we coupled the currently known temperature limit for life, 122 °C, with a heat conduction model that predicts a potential depth limit for life within the forearc at ∼10,000 m below the seafloor. This is deeper than the 122 °C isotherm in known oceanic serpentinizing regions and an order of magnitude deeper than the downhole temperature at the serpentinized Atlantis Massif oceanic core complex, Mid-Atlantic Ridge. We suggest that the organic-rich serpentinites may be indicators for microbial life deep within or below the mud volcano. Thus, the hydrated forearc mantle may represent one of Earth's largest hidden microbial ecosystems. These types of protected ecosystems may have allowed the deep biosphere to thrive, despite violent phases during Earth's history such as the late heavy bombardment and global mass extinctions.

Original languageEnglish
Pages (from-to)4324-4329
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume114
Issue number17
DOIs
Publication statusPublished - 25 Apr 2017
Externally publishedYes

Keywords

  • Deep biosphere
  • Forearc
  • Serpentinization
  • Subduction zone

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