Carbon isotopic analyses of ca. 3.0 Ga microstructures imply planktonic autotrophs inhabited Earth’s early oceans

Research Article| June 01, 2013 Carbon isotopic analyses of ca. 3.0 Ga microstructures imply planktonic autotrophs inhabited Earth's early oceans C.H. House; C.H. House * 1Department of Geosciences and Penn State University Astrobiology Research Center, The Pennsylvania State University, 220 Deike Building, University Park, Pennsylvania 16802, USA †These authors are co–first authors and their names are listed alphabetically. *E-mails: chrishouse@psu.edu; dorothy.z.oehler@nasa.gov. Search for other works by this author on: GSW Google Scholar D.Z. Oehler; D.Z. Oehler * 2Astromaterials Research and Exploration Science Directorate, NASA–Johnson Space Center, 2101 NASA Parkway, Houston, Texas 77058, USA †These authors are co–first authors and their names are listed alphabetically. *E-mails: chrishouse@psu.edu; dorothy.z.oehler@nasa.gov. Search for other works by this author on: GSW Google Scholar K. Sugitani; K. Sugitani 3Department of Environmental Engineering and Architecture, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, Japan Search for other works by this author on: GSW Google Scholar K. Mimura K. Mimura 4Department of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, Japan Search for other works by this author on: GSW Google Scholar Geology (2013) 41 (6): 651–654. https://doi.org/10.1130/G34055.1 Article history received: 21 Sep 2012 rev-recd: 07 Jan 2013 accepted: 10 Jan 2013 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation C.H. House, D.Z. Oehler, K. Sugitani, K. Mimura; Carbon isotopic analyses of ca. 3.0 Ga microstructures imply planktonic autotrophs inhabited Earth's early oceans. Geology 2013;; 41 (6): 651–654. doi: https://doi.org/10.1130/G34055.1 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 The ca. 3 Ga Farrel Quartzite (FQ, Western Australia) contains possible organic microfossils of unusual spindle-like morphology that are surprisingly large and complex, preserved along with spheroids. The unusual nature of the possible fossils, coupled with their antiquity, makes their interpretation as biogenic difficult and debatable. Here, we report 32 in situ carbon isotopic analyses of 15 individual FQ specimens. The spheroids and the spindle-like forms have a weighted mean δ13C value of –37‰, an isotopic composition that is quite consistent with a biogenic origin. Both the spheroids and the spindle-like structures are isotopically distinct from the background organic matter in the same thin section (weighted mean δ13C value of –33‰), which shows that the preserved microstructures are not pseudofossils formed from physical reprocessing of the bulk sedimentary organic material. When considered along with published morphological and chemical studies, these results indicate that the FQ microstructures are bona fide microfossils, and support the interpretation that the spindles were planktonic. Our results also provide metabolic constraints that imply most of these preserved microorganisms were autotrophic. The existence of similar spindles in the ca. 3.4 Ga Strelley Pool Formation of Australia and the ca. 3.4 Ga Onverwacht Group of South Africa suggests that the spindle-containing microbiota may be one of the oldest, morphologically preserved examples of life. If this is the case, then the FQ structures represent the remains of a cosmopolitan biological experiment that appears to have lasted for several hundred million years, starting in the Paleoarchean. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.