Sulfide Dissolution and Awaruite Formation in Continental Serpentinization Environments and Its Implications to Supporting Life

Serpentinization environments are key locations that support microbial communities by the abiogenic formation of reduced species associated with peridotite alteration. Here we studied partially serpentinized peridotites from the Chimaera seeps (Turkey), an active continental serpentinization system...

Full description

Saved in:
Bibliographic Details
Published in:Journal of geophysical research. Solid earth 2021-05, Vol.126 (5), p.n/a
Main Authors: Schwarzenbach, E. M., Vrijmoed, J. C., Engelmann, J. M., Liesegang, M., Wiechert, U., Rohne, R., Plümper, O.
Format: Article
Language:English
Subjects:
awaruite
Chemical precipitation
Chimaera
Copper
Decomposition
Desulfurization
Dissolution
Dissolving
Electron microprobe
Electron microscopy
Electron probe microanalysis
Electron probes
Fluids
Geophysics
Hydrogen sulfide
Iron compounds
Isotopes
Metals
Methane
Microbial activity
Microorganisms
Microscopy
mineral dissolution
Mineral nutrients
Mineralogy
Minerals
nanoscale
Nickel base alloys
Nickel compounds
Nickel ores
Nutrients
Pentlandite
Peridotite
Platelets
Porosity
Precipitation
Rocks
Scanning electron microscopy
Seepages
Serpentine
Serpentinization
Single crystals
Sulfides
Sulfur
Sulfur isotopes
Sulphides
Sulphur
Transmission electron microscopy
Vents
water‐rock interaction
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Serpentinization environments are key locations that support microbial communities by the abiogenic formation of reduced species associated with peridotite alteration. Here we studied partially serpentinized peridotites from the Chimaera seeps (Turkey), an active continental serpentinization system that vents highly methane‐rich fluids, to investigate the impact of water‐rock interaction on the sulfide and metal mineralogy and its implications on supporting microbial communities. Using high‐resolution scanning electron microscopy, electron microprobe analysis, and transmission electron microscopy we found diverse pentlandite decomposition features with precipitation of secondary sulfides including millerite, heazlewoodite, as well as Cu‐bearing sulfides, native Cu, and awaruite (Ni3Fe). Awaruite forms dense veinlets to single crystal platelets tens of nanometers in size, which is formed by desulphurization of pentlandite. In addition, the nanometer‐sized awaruite platelets are intimately intergrown with serpentine suggesting its growth during peridotite alteration by a dissolution‐precipitation process, likely associated with the interaction of methane‐ and H2‐rich but highly sulfur‐undersaturated fluids. Based on sulfur isotope signatures we infer a mantle and mid‐ocean ridge origin of the sulfide minerals associated with the first stage of partial serpentinization and awaruite formation. Subsequent and ongoing continental fluid‐rock interaction causes significant sulfide decomposition resulting in the formation of porosity and the release of, amongst others, H2S and Fe. These species may likely provide a source of nutrients for active microbial communities in these comparatively nutrient‐starved, low‐temperature continental serpentinization environments. Key Points High disequilibrium conditions induce skeletal awaruite growth during continental serpentinization Pentlandite dissolution creates fluid pathways and nutrients for microbial life Sulfur isotope compositions document ocean floor and subsequent continental serpentinization processes
ISSN:2169-9313
2169-9356
DOI:10.1029/2021JB021758