title: Distributions of C22-C30 even-carbon-number n-alkanes in Ocean Anoxic Event 1 samples from the Basque-Cantabrian Basin.
abstract: The Ocean Anoxic Event 1 (OAE-1) in central sites of the Basque-Cantabrian Basin exhibits very reducing depositional conditions of sedimentation. These sedimentation events have left a distinct mixture of hydrocarbons that are represented by C22-C30 n-alkanes with a predominance of the even-carbon-number homologues, high relative proportions of squalane and C16-C24 n-alkylcyclopentanes predominated by n-undecyl-, n-tridecyl- and n-pentadecylcyclopentane. Other minor compounds encompass a series of C18-C21 n-alkylcyclohexanes and C18-C24 dimethyl n-alkylcyclohexanes maximized by the even-carbon-number homologues as well as iso- and anteiso-alkanes. This unusual distribution of n-alkanes in this environment provides a new case for comparison with previously reported hypersaline and phosphorite sedimentary deposits where the occurrence of similar n-alkane distributions was reported. In the present case, these major n-alkanes and squalane are indicative of transformation under strong reducing conditions. In contrast, the occurrence of the alkylcyclopentanes, irrespective of the presence of even-carbon-number n-alkanes or squalane, suggests that reductive cyclization of fatty acids is less dependent on strong reducing conditions.
authors.affiliation: Institute of Chemical and Environmental Research (CSIC), Jordi Girona 18, 08034, Barcelona, Catalonia, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Chaler
authors.forename: C
authors.initials: C
authors.lastname: Dorronsoro
authors.forename: J O
authors.initials: JO
authors.lastname: Grimalt
authors.forename: L M
authors.initials: LM
authors.lastname: Agirrezabala
authors.forename: P A
authors.initials: PA
authors.lastname: Fernández-Mendiola
authors.forename: J
authors.initials: J
authors.lastname: García-Mondejar
authors.forename: I
authors.initials: I
authors.lastname: Gómez-Pérez
authors.forename: M
authors.initials: M
authors.lastname: López-Horgue