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doi:10.2204/iodp.proc.318.203.2015 Data report: no alkenones detected by shore-based GC-MS analyses of Eocene samples from Site U13561James A.P. Bendle2 and Heiko Moossen2AbstractWe applied shore-based gas chromatography–mass spectrometry (GC-MS) to confirm shipboard analyses of samples from Integrated Ocean Drilling Program (IODP) Expedition 318. Initially, 25 samples from Site U1356, ranging in age from early Eocene to late Miocene, were extracted for lipids, separated into chemical fractions, and analyzed by GC-MS onboard the R/V JOIDES Resolution. Molecular biomarker classes identified include aliphatic hydrocarbons, hopanes, unresolved complex mixtures of branched alkanes, ketones, n-alkanols, sterols, diols, and n-alkanoic acid methyl esters. Relative to the Oligocene and Miocene, molecular concentrations generally increase by several orders of magnitude in the early Eocene sediments. Additional shore-based analyses confirmed the presence of a diverse range of terrestrial biomarkers that includes plant-waxes and hopanes. However, additional analysis of the ketone fraction from 50 Eocene samples from Site U1356 detected no alkenone compounds. This negative result supersedes the initial report of alkenones in the Eocene sediments from Site U1356 and indicates that shipboard assignation of alkenones was erroneous. |
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