Fig. 2.

(A) MSA before and after removal of OM by six bleach treatments (method discussed in SI Text). This relation that does not show a loss of MSA indicates that the EGME is not dissolving or interacting with kerogen within these samples. The slight gain in MSA may be attributed to the opening of pore space by OM removal. (B) TOC cross-plotted with MSA shows three distinct groupings of data coinciding with bioturbated, mixed bioturbated, and laminated and laminated intervals. Identified loading rate for each grouping is calculated using a regression within the group population (gray lines) with an overall relationship of r² = 0.76, R² = 0.43 (oxic facies), R² = 0.58 (mixed facies), and R² = 0.66 (reducing facies). The monolayer equivalent line was identified by measuring weight addition of ethylene glycol by a series of standards exposed to EGME (see text); it is included to show a reference line only and does not imply that OM in natural samples occurs in a monolayer coating. Pierre Shale samples from ref. 18 and modern clay size fraction separated from sea floor sediments from ref. 13.