FIG. 9.

Carbon distribution in oligotrophic, clastic sediments, Josefsdal Chert. (a) Outcrop view showing parallel deposits of tephra ash fall separated by thin black horizons. (b, c) Optical micrographs of these sediments showing thin concentrations of mainly microscale pyrite but also some carbon coating the tops of the sediment bedding planes. The large, euhedral black particle is a hydrothermal pyrite. The red boxes denote details shown in the Raman maps (d, e). (d) Distribution of carbon (green) associated with coarse-grained volcanic particles. The volcanic grains have been altered to anatase (blue) or muscovite (pink). The whole sediment was permeated with silica (yellow-orange) during diagenesis. (e) Detail showing the concentration of carbon (green) associated with the black tops of the bedding planes; pyrite (pale blue), anatase (dark blue), quartz (yellow).