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Lipid biomarkers record fundamental changes in the microbial community structure of tropical seas during the Late Ordovician Hirnantian glaciation

Rohrssen, Megan and Love, Gordon D. and Fischer, Woodward and Finnegan, Seth and Fike, David A. (2013) Lipid biomarkers record fundamental changes in the microbial community structure of tropical seas during the Late Ordovician Hirnantian glaciation. Geology, 41 (2). pp. 127-130. ISSN 0091-7613. https://resolver.caltech.edu/CaltechAUTHORS:20130301-112930002

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Abstract

The Late Ordovician mass extinction was linked to climate cooling and glaciation of Gondwana during the terminal Ordovician Hirnantian Age (444.7–443.4 Ma). Extinction patterns have been well described for many marine taxa, but much less is known about marine microbial communities through this interval. To elucidate the structure of microbial communities in tropical marine basins through the Late Ordovician, we analyzed lipid biomarkers in thermally well preserved strata from the Taconic foreland (Anticosti Island, Canada), the Cincinnati Arch (midwestern United States), and the western continental margin (Vinini Formation, Nevada, United States). Despite clear oceanographic differences, lipid biomarker profiles show similarities between these three localities. Major shifts in biomarker distributions of Anticosti Island and the Vinini Formation, mainly hopane/sterane ratios, record changes in the balance of bacterial versus algal primary production. Bacterial contributions to sedimentary organic matter were highest during warm intervals, both before and after Hirnantian cooling. In particular, 3β-methylhopanes, likely sourced from aerobic methanotrophic bacteria, occur in high relative abundance (many times the Phanerozoic average) across Laurentia throughout most of the interval studied. 3β-methylhopane abundances also reveal an overall positive relationship with paleotemperature proxies, implying increased methane cycling during warm intervals. These results suggest that enhanced methane cycling could have provided an important positive feedback on climate during extended intervals of early Paleozoic time.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1130/G33671.1DOIArticle
http://geology.geoscienceworld.org/content/41/2/127PublisherArticle
http://geology.gsapubs.org/content/41/2/127PublisherArticle
ORCID:
AuthorORCID
Love, Gordon D.0000-0002-6516-014X
Fischer, Woodward0000-0002-8836-3054
Fike, David A.0000-0003-2848-0328
Additional Information:© 2012 Geological Society of America. Manuscript received 25 May 2012. Revised manuscript received 23 July 2012. Manuscript accepted 27 July 2012. This work was supported by the Agouron Institute (Pasadena, California). We thank D. Boulet and the Société des établissements de plein air du Québec for assistance with work in Anticosti National Park, Stan Finney (California State University, Long Beach) for donation of the Vinini Formation samples, and David Jones (Amherst College) for providing carbon isotope data and help with fieldwork.
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Funding AgencyGrant Number
Agouron InstituteUNSPECIFIED
Issue or Number:2
Record Number:CaltechAUTHORS:20130301-112930002
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20130301-112930002
Official Citation: Megan Rohrssen, Gordon D. Love, Woodward Fischer, Seth Finnegan, and David A. Fike Lipid biomarkers record fundamental changes in the microbial community structure of tropical seas during the Late Ordovician Hirnantian glaciation Geology, February 2013, v. 41, p. 127-130, first published online 6 November 2012, doi:10.1130/G33671.1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37246
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:01 Mar 2013 19:44
Last Modified:13 Dec 2019 00:46

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