title: Origin of petroporphyrins.  2.  Evidence from stable carbon isotopes.
abstract: Compared with the carbon-13 isotopic composition of the ubiquitous C32DPEP (DPEP, deoxophylloerythroetioporphyrin) the heavy but equivalent carbon-13 isotopic composition for the porphyrin structures 15(2)-methyl-15,17-ethano-17-nor-H-C30DPEP and 15,17-butano-, 13,15-ethano-13(2),17-propano-, and 13(1)-methyl-13,15-ethano-13(2),17-propanoporphyrin suggests a common precursor, presumably chlorophyll c, for these petroporphyrins isolated from the marine Julia Creek oil shale and the lacustrine Condor oil shale.  Similarly, the heavy but variable carbon-13 isotopic composition of 7-nor-H-C31DPEP compared with C32DPEP is consistent with an origin from both chlorophyll b and chlorophyll c3.  The equivalent carbon-13 isotopic composition for 13(2)-methyl-C33DPEP compared with C32DPEP suggests a common origin resulting from a weighted average of chlorophyll inputs.
authors.affiliation: Bureau of Mineral Resources, Geology and Geophysics, 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; D002244:Carbon / Q000032:analysis* / Q000737:chemistry; D002250:Carbon Radioisotopes; D002734:Chlorophyll / Q000032:analysis / Q000737:chemistry; D019015:Geologic Sediments / Q000737:chemistry*; D009792:Oceans and Seas; D010578:Petroleum / Q000032:analysis*; D011166:Porphyrins / Q000032:analysis* / Q000737:chemistry*
chemical_list: D002250:Carbon Radioisotopes; D010578:Petroleum; D011166:Porphyrins; D002734:Chlorophyll; C064041:chlorophyll c; D002244:Carbon