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Serpentinization, Fluids and Life: Comparing Carbon and Sulflur Cycles in Modern and Ancient Environments

English title Serpentinization, Fluids and Life: Comparing Carbon and Sulflur Cycles in Modern and Ancient Environments
Applicant Bernasconi-Green Gretchen
Number 116226
Funding scheme Project funding (Div. I-III)
Research institution Institut für Mineralogie und Petrographie ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Other disciplines of Earth Sciences
Start/End 01.05.2007 - 30.04.2009
Approved amount 140'374.00
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Keywords (14)

marine hydrothermal systems; multidisciplinary studies; serpentinization; ophicalcites; volatiles; microbial activity; Lost City; Mid-Atlantic Ridge; carbonate precipitation; organic geochemistry; stable isotopes; carbon; sulfur; CO2 sequestration

Lay Summary (English)

Lay summary
The alteration of mantle rocks during serpentinization is a fundamental process that has significant geophysical, geochemical and biological importance for the global marine system and for subduction zone processes. This project is a comparative bio-geochemical and isotopic study of the Lost City hydrothermal system (North Atlantic) with modern and ancient serpentinite-carbonate systems. The Lost City hydrothermal system is distinctly different than all other known marine hydrothermal systems and represents an important analogue for ancient ophicalcite deposits. It is an off-axis, peridotite-hosted system and consists of active and inactive carbonate-brucite structures that are deposited from warm, high pH fluids emanating from fault zones that tap a region of active serpentinization in underlying peridotites. Diffuse fluids support dense microbial communities and variable mixing with seawater creates distinct domains of methane- and/or sulfur-cycling thermophiles. This study builds on an immense data set produced through multidisciplinary collaboration between the ETH Zurich, University of Washington, Syracuse University, and WHOI/MIT over the past six years. Our project focuses on understanding the links between inorganic reactions that produce hydrogen and hydrocarbons, biogeochemical cycling of carbon and sulfur, and microbial activity in high pH systems associated with serpentinization. In addition to conducting follow-up geochemical analyses on samples from Lost City, we will investigate high alkaline Ca-OH springs associated with present-day serpentinization and carbonate deposition in Liguria and Oman and compare these with studies of Jurassic ophicalcites. The overall goal of our project is to quantify carbon and sulfur pools in active serpentinite-carbonate systems and to model their changes over time. Furthermore, our investigations of the Lost City system and the comparative studies of similar systems on land has the potential to provide important information about the mass of CO2 locked into serpentinite-dominated environments and the viability of variably serpentinized rocks to sequester anthropogenic CO2.
Direct link to Lay Summary Last update: 21.02.2013

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Associated projects

Number Title Start Funding scheme
121840 Life in Extreme Environments: Carbon and Sulfur Organic Geochemistry of High Alkaline Systems 01.11.2008 Project funding (Div. I-III)
134947 Fluid-Rock Interaction and Fluid Fluxes in Mafic and Ultramafic Seafloor: Peridotite-hosted Hydrothermal Systems Past and Present 01.04.2011 Project funding (Div. I-III)
124669 Serpentinization, Fluids and Life II: Comparing Carbon and Sulflur Cycles in Modern and Ancient Environments 01.05.2009 Project funding (Div. I-III)
107620 Understanding peridotite-hosted hydrothermal systems on the seafloor: Insights from Lost City 01.04.2005 Project funding (Div. I-III)