Conifers are a major source of sedimentary leaf wax n-alkanes when dominant on the landscape: Case studies from the Paleogene

Paleobotanical site information, terpenoid, n-alkane, and other and biomarker quantification and carbon isotope data from sediment samples collected from North America Paleogene fossil leaf sites that extend from Colorado to the High Arctic. Sediment samples were collected laterally along fossil leaf-bearing zones. To disentangle the vegetation source of sediment n-alkanes, we measured the carbon isotope (δ13C) values of nonsteroidal triterpenoids (angiosperm biomarkers) and tricyclic diterpenoids (conifer biomarkers) to determine angiosperm and conifer end member δ13C values. Compounds were isolated using column chromatography and identified and quantified with an Agilent 7890A gas chromatograph (GC) interfaced to an Agilent 5975C quadrupole mass selective detector (MSD) and flame ionization detector (FID). Compound-specific carbon isotope analyses were performed, where possible, on n-C27 through n-C35 alkanes, diterpenoids, and triterpenoids by gas chromatograph-combustion-isotope ratio mass spectrometry (GC-C-IRMS).