Tracing olivine carbonation and serpentinization in CO2-rich fluids via magnesium exchange and isotopic fractionation

Diffusion-driven magnesium and iron isotope fractionation in Hawaiian olivine

H2-rich fluids from serpentinization: geochemical and biotic implications.

Metamorphic hydration and oxidation of ultramafic rocks produces serpentinites, composed of serpentine group minerals and varying amounts of brucite, magnetite, and/or FeNi alloys. These minerals buffer metamorphic fluids to extremely reducing conditions that are capable of producing hydrogen gas. Awaruite, FeNi3, forms early in this process when the serpentinite minerals are Fe-rich. Olivine w...

Control of the Products of Serpentinization by the FeMg 1 Exchange Potential of Olivine and Orthopyroxene

It is argued that the high-Mg content (mg-number1⁄4 95 3) of the serpentine minerals in serpentinized peridotite is a consequence of the environmental FeMg 1 exchange potential imposed on the system by the abundance of olivine and orthopyroxene. Mass balance in the serpentinization reaction then requires the precipitation of an ironrich mineral that in most cases is magnetite.This causes hydrog...

Methane generation during experimental serpentinization of olivine.

Oze et al. (1) observed generation of methane (CH4) during experimental serpentinization of olivine, and use the results to make inferences about sources of methane in natural serpentinites. Their data interpretation, however, is directly contradicted by results of prior studies, critically undermining the credibility of their conclusions. Several prior studies conducted using experimental meth...

Magnesium isotopic compositions of olivine, spinel, and hibonite from the Murchison carbonaceous chondrite

The Mg isotopic compositions of olivine, spinel, and hihonite from the Murchison carbonaceous chondrite have been determined by secondary ion mass spectrometry. The olivines exhibit only marginal effects. They have no detectable intrinsic mass fractionation; however, after correcting for mass fractionation, the mean residual 26Mg/24Mg for the five grams is slightly in excess of the terrestrial ...