Molecular fossils reveal fluid composition and flow intensity at a Cretaceous seep

Research Article| September 01, 2009 Molecular fossils reveal fluid composition and flow intensity at a Cretaceous seep Jörn Peckmann; Jörn Peckmann * 1MARUM–Zentrum für Marine Umweltwissenschaften, Universität Bremen, 28334 Bremen, Germany *E-mail: peckmann@uni-bremen.de. Search for other works by this author on: GSW Google Scholar Daniel Birgel; Daniel Birgel 1MARUM–Zentrum für Marine Umweltwissenschaften, Universität Bremen, 28334 Bremen, Germany Search for other works by this author on: GSW Google Scholar Steffen Kiel Steffen Kiel 2Institut für Geowissenschaften, Christian-Albrechts-Universität, 24118 Kiel, Germany3Department of Paleobiology, Smithsonian Museum of Natural History, Washington, D.C. 20013-7012, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Jörn Peckmann * 1MARUM–Zentrum für Marine Umweltwissenschaften, Universität Bremen, 28334 Bremen, Germany Daniel Birgel 1MARUM–Zentrum für Marine Umweltwissenschaften, Universität Bremen, 28334 Bremen, Germany Steffen Kiel 2Institut für Geowissenschaften, Christian-Albrechts-Universität, 24118 Kiel, Germany3Department of Paleobiology, Smithsonian Museum of Natural History, Washington, D.C. 20013-7012, USA *E-mail: peckmann@uni-bremen.de. Publisher: Geological Society of America Received: 10 Nov 2008 Revision Received: 20 Apr 2009 Accepted: 04 May 2009 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2009 Geological Society of America Geology (2009) 37 (9): 847–850. https://doi.org/10.1130/G25658A.1 Article history Received: 10 Nov 2008 Revision Received: 20 Apr 2009 Accepted: 04 May 2009 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Jörn Peckmann, Daniel Birgel, Steffen Kiel; Molecular fossils reveal fluid composition and flow intensity at a Cretaceous seep. Geology 2009;; 37 (9): 847–850. doi: https://doi.org/10.1130/G25658A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract An isolated Hauterivian marine limestone from the Crimean Peninsula containing masses of articulated specimens of the dimerelloid brachiopod Peregrinella has previously been interpreted to represent a hydrocarbon-seep deposit. In order to constrain the intensity of seepage and the composition of fluids, we investigated the lipid biomarker inventory of this seep limestone. The dominant biomarkers are 13C-depleted isoprenoids including tail-to-tail linked pentamethylicosane (δ13C value: −108‰), representing molecular fossils of methanotrophic archaea. This observation reveals that the seepage fluids contained methane. Because the seep carbonates have been found to be only moderately 13C-depleted (δ13C values as low as −14‰), a significant contribution from a less 13C-depleted carbon source than methane, probably marine carbonate, is apparent. Such a degree of admixture of marine carbonate is typical for seep limestones resulting from low flow rates. The observed biomarker pattern with the prominent occurrence of biphytanes, but lacking crocetane, reveals that the methanotrophic archaea at the Hauterivian seep site were similar to archaea of the ANME-1 cluster. Archaea of this cluster are known to be able to cope with lower methane concentrations than ANME-2 archaea; therefore ANME-1 archaea are better adapted to low seepage rates and diffusive flow. The Peregrinella limestone contains only a small amount of early diagenetic cement. Based on a comparison with biomarker patterns of other ancient seep deposits, it is apparent that diffusive seepage typically results in limestones with little cement, whereas advective, more intense seepage appears to favor cement precipitation. If applied with caution, this supposed relationship can be used as a first approximation of seepage intensity. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.