Figure 6

Histograms quantifying the elemental composition in the vicinity of the cracks for a 5 px (25 µm) or 25 px (125 µm) neighborhood. Schematic in legend demonstrates how the histograms are calculated for a 2 px neighborhood. Also shown is the background elemental composition over the same length scale. As indicated by the highlighted arrows in the central panel the delamination cracks in most of these rocks tend to seek out trajectories that are enriched in organic carbon, offset by a similar reduction in silica content. The subtle compositional shift extends at least 25 µm but less than 125 µm from the crack. Symbols in the upper right corner of each panel correspond to the sample shown in Fig. 5C.