Table 1 Organic carbon abundance estimates for EGA signals above 500°C.

See table S1 for abundances of individual molecules and abundances in other mudstones. Errors are propagated from integration uncertainty (30%, ±1σ SD, n ≥ 3 analyses), smoothing error (5%, ±1σ SD, n ≥ 3 analyses), and ionization cross-section uncertainties (reported in the literature). The total for thiophenic compounds is the sum of thiophene and methyl thiophene abundances. The total for other aromatic compounds is the sum of abundances of benzene, toluene, and benzoic acid (a proxy for benzoate ion or alkylbenzene contributions). The total for aliphatic compounds is the sum of C1 to C3 alkanes and C2 to C5 alkenes determined from modeling. The total for C1 and C2 sulfur compounds is the sum of methanethiol, dimethylsulfide, carbonyl sulfide, and carbon disulfide abundances (11).

SampleOrganic carbon abundance (nmol of C) in compound class(es)Total organic carbon
(nmol of C)
ThiophenicAromaticAliphaticThiophenic,
aromatic,
and aliphatic
C1 and C2
sulfur
Mojave2.20 ± 0.936.99 ± 1.9938.4 ± 5.6347.61 ± 6.0443.8 ± 11.691.4 ± 13.1
Confidence Hills2.02 ± 0.848.03 ± 2.1120.8 ± 2.7930.8 ± 3.6029.3 ± 7.6160.2 ± 8.42
Confidence Hills blank0.49 ± 0.183.04 ± 0.865.35 ± 0.838.88 ± 1.211.49 ± 0.4210.4 ± 1.28