A new constraint on the antiquity of anaerobic oxidation of methane: Late Pennsylvanian seep limestones from southern Namibia

Abstract

Research Article| July 01, 2008 A new constraint on the antiquity of anaerobic oxidation of methane: Late Pennsylvanian seep limestones from southern Namibia Daniel Birgel; Daniel Birgel 1MARUM–Center for Marine Environmental Sciences, Universität Bremen, 28334 Bremen, Germany Search for other works by this author on: GSW Google Scholar Tobias Himmler; Tobias Himmler 2Geozentrum Nordbayern, FG Paläoumwelt, Universität Erlangen, 91054 Erlangen, Germany Search for other works by this author on: GSW Google Scholar André Freiwald; André Freiwald 2Geozentrum Nordbayern, FG Paläoumwelt, Universität Erlangen, 91054 Erlangen, Germany Search for other works by this author on: GSW Google Scholar Jörn Peckmann Jörn Peckmann * 3MARUM–Center for Marine Environmental Sciences, Universität Bremen, 28334 Bremen, Germany * E-mail: [e-mail]. Search for other works by this author on: GSW Google Scholar Geology (2008) 36 (7): 543–546. https://doi.org/10.1130/G24690A.1 Article history received: 08 Dec 2007 rev-recd: 04 Mar 2008 accepted: 06 Mar 2008 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 Daniel Birgel, Tobias Himmler, André Freiwald, Jörn Peckmann; A new constraint on the antiquity of anaerobic oxidation of methane: Late Pennsylvanian seep limestones from southern Namibia. Geology 2008;; 36 (7): 543–546. doi: https://doi.org/10.1130/G24690A.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 Late Pennsylvanian seep limestones (ca. 300 Ma) enclosed in the Ganigobis shales in southern Namibia formed by microbial activity. The process that induced carbonate precipitation was the anaerobic oxidation of methane. The presence of 13C-depleted pentamethylicosane (PMI) (−113‰) and a mixture of crocetane and phytane (−112‰) in concert with similarly 13C-depleted pseudohomologous series of regular isoprenoids reveals that methanotrophic archaea oxidized methane anaerobically at the ancient seep site. Biphytane and a C39 pseudohomologue are other archaeal molecular fossils with δ13C values of −99‰ and −97‰, respectively. The former presence of sulfate-reducing bacteria as the syntrophic partners of methanotrophic archaea in the anaerobic oxidation of methane is indicated by isotopically depleted iso- and anteiso-alkanes. These compounds most probably derive from non-isoprenoidal monoethers and diethers, synthates of sulfate-reducing bacteria. These findings show that anaerobic oxidation of methane is at least 300 m.y. old, extending the record of this process for ~140 m.y. As the molecular fossils of archaea and bacteria are preserved in a product of their own metabolic activity (i.e., methane-derived carbonates with δ13C values as low as −51‰), the syngenicity of molecular fossils and enclosing deposits is unambiguous. This reveals that microbially formed rocks can represent excellent archives for studying past biogeochemical processes. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.