FIGURE 3.

C₂₆–C₃₀ sterane and C₂₇–C₃₅ hopane distributions from composite chromatograms (MRM-GC-MS transitions M⁺→217 + 191) of the free (extractable) organic matter highlight thermal maturity differences between the samples used in this study. Rocks from the Walcott Member of the Chuar Group are either (top) late oil window maturity, characteristic of the Nankoweap Butte section or (middle) of peak oil window maturity, characteristic of the Sixtymile Canyon locality. Conversely, rocks recovered from all sections in the Visingsö Group are less mature and of (bottom) intermediate early–middle oil window maturity, consistent with the compound distributions. See Table 2 footnote for peak identifications