title: Origins of etioporphyrins in sediments:  evidence from stable carbon isotopes.
abstract: In samples of the Julia Creek and Condor oil shales (Australia, Albian, and early Tertiary, respectively) etioporphyrin III is significantly depleted in 13C (4%) relative to porphyrins derived from chlorophylls.  This isotopic difference suggests a large contribution from some independent source.  The haem group found in cytochromes derived from microbial sources is the most likely candidate.
authors.affiliation: Division of Continental Geology, BMR, Canberra, Australia.
authors.forename: C J
authors.initials: CJ
authors.lastname: Boreham
authors.forename: C J
authors.initials: CJ
authors.lastname: Fookes
authors.forename: B N
authors.initials: BN
authors.lastname: Popp
authors.forename: J M
authors.initials: JM
authors.lastname: Hayes
mesh_terms: D001315:Australia; D002247:Carbon Isotopes; D002734:Chlorophyll / Q000737:chemistry / Q000378:metabolism*; D003580:Cytochromes / Q000737:chemistry / Q000378:metabolism; D004783:Environmental Microbiology; D005044:Etioporphyrins / Q000032:analysis* / Q000737:chemistry; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry*; D006418:Heme / Q000737:chemistry / Q000378:metabolism*; D009532:Nickel / Q000737:chemistry; D010163:Paleontology; D011166:Porphyrins / Q000032:analysis / Q000737:chemistry*; D014638:Vanadates / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D003580:Cytochromes; D005044:Etioporphyrins; D011166:Porphyrins; D002734:Chlorophyll; D014638:Vanadates; D006418:Heme; D009532:Nickel