Petrologic Study of Peridotite Carbonation in Oman: Temperature, Timing and Fluid Composition

Lead PI: Prof. Peter B. Kelemen

Unit Affiliation: Geochemistry, Lamont-Doherty Earth Observatory (LDEO)

March 2011 - February 2015
Asia ; Middle East
Project Type: Research

DESCRIPTION: The study aims to constrain the temperatures, timing, and fluid composition of both active low-T systems and fossil high-T systems through chemical and isotopic analyses. This will show which factors control efficient carbonation of peridotite, expand thermodynamic models of phase equilibriums incorporating solid solution models, and provide cross-calibration of isotope thermometers.

OUTCOMES: Low-T mineral carbonation forms from 1) surficial weathering of peridotite to form Mg-HCO3; 2) such fluids migrate deeper and precipitate serpentine+magnetite+Mg-rich carbonate minerals while creating Ca(OH)2 rich waters; 3) these waters emerge in springs and combine with atmospheric CO2 to form calcite travertine deposits. Carbonate veins are formed at low-T and Listvenites are formed at high-T. Calibrating the clumped isotope thermometry method for magnesite. Discovered a new reservoir for carbon in the leading edge of mantle wedges above Subduction zones. Advanced understanding of reaction driven cracking. 25 journal publications.