Reduction of CO2 during serpentinization of olivine at 300 8C and 500 bar: Correction

Geology, v. 24, p. 351–354 (April 1996)

In our recent paper, we reported synthesis of an unusual morphologically distinct carbon-bearing phase to account for a depletion in dissolved CO2 concentrations during our study. Subsequently, however, Dr. Satish Srivastava notified us that this “phase” strongly resembled pine pollen, which was later confirmed by palynologists at the University of Minnesota. Apparently, the pollen contamination was introduced in the course of filtration and drying operations that were used to prepare run products for analysis. These procedures were performed at a time coinciding precisely with the local release of pollen from pines in our area.

This correction actually simplifies the interpretation of the results, because the origin of the unusual “phase” was problematic. It was not predicted to form from thermodynamic relations. This does not affect the more important conclusion in our paper of coupled H2 generation and slow conversion of CO2 to CH4 ,C2H6, and C3H8 during serpentinization. It is now likely, however, that the large loss in dissolved CO2 observed during the experiment was caused by precipitation of amorphous carbon or graphite—a phase that was predicted to precipitate during the experiment based on fluid-mineral equilibria calculations and that was observed in trace amounts.

We thank Dr. Satish Srivastava for bringing this to our attention.

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