PYRITIZED CRYOGENIAN CYANOBACTERIAL FOSSILS FROM ARCTIC ALASKA
The Cryogenian was a time of climatic extremes, with two extended and severe global glaciations bracketing hothouse conditions. The effect of these extreme climate conditions on ocean chemistry and the marine biosphere remain poorly understood. Most of the previous studies of the fossil record from...
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ftmit:oai:dspace.mit.edu:1721.1/120081 2023-06-11T04:07:38+02:00 PYRITIZED CRYOGENIAN CYANOBACTERIAL FOSSILS FROM ARCTIC ALASKA Macdonald, Francis Du, Kimberly Lahr, Daniel J. G. Pruss, Sara B. Moore, Kelsey Reed Bosak, Tanja Newman, Sharon Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Bosak, Tanja Moore, Kelsey Reed Newman, Sharon 2017-08 application/pdf http://hdl.handle.net/1721.1/120081 en_US eng Society for Sedimentary Geology https://doi.org/10.2110/palo.2017.063 PALAIOS 0883-1351 http://hdl.handle.net/1721.1/120081 Moore, Kelsey R. et al. “PYRITIZED CRYOGENIAN CYANOBACTERIAL FOSSILS FROM ARCTIC ALASKA.” PALAIOS 32, 12 (December 2017): 769–778 © 2017 Society for Sedimentary Geology orcid:0000-0001-7332-4098 orcid:0000-0001-5179-5323 orcid:0000-0003-4664-308X Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ Prof. Bosak via Chris Sherratt Article http://purl.org/eprint/type/JournalArticle 2017 ftmit https://doi.org/10.2110/palo.2017.063 2023-05-29T08:21:42Z The Cryogenian was a time of climatic extremes, with two extended and severe global glaciations bracketing hothouse conditions. The effect of these extreme climate conditions on ocean chemistry and the marine biosphere remain poorly understood. Most of the previous studies of the fossil record from this interval focus on benthic organisms, with few examples of organisms with an inferred planktonic lifestyle and no firm evidence for photosynthetic organisms. Here, we present helically coiled, straight, and curved fossils composed of fine crystalline or framboidal pyrite in limestone samples from the Ikiakpuk formation of Arctic Alaska. These structures are morphologically identical to fossils of Obruchevella, a cyanobacterial form genus reported in pre-Sturtian and post-Marinoan strata, but not in deposits from the Cryogenian non-glacial interlude. We interpret fossils of the Ikiakpuk formation as planktonic cyanobacteria based on their morphology, which is identical to that of some modern planktonic cyanobacteria. Further evidence for a planktonic lifestyle comes from the preservation of these pyritized fossils in deep-water facies that lack evidence of microbial lamination. They provide the first direct evidence for bacterial primary productivity in the pelagic realm during the Cryogenian non-glacial interlude. Keywords: Alaska; metasomatism; paleoecology; United States; Cryogenian; Neoproterozoic; Proterozoic; upper Precambrian; Precambrian Simons Foundation (Grant 344707) Article in Journal/Newspaper Arctic Arctic Alaska DSpace@MIT (Massachusetts Institute of Technology) Arctic PALAIOS 32 12 769 778 |
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Open Polar |
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DSpace@MIT (Massachusetts Institute of Technology) |
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ftmit |
language |
English |
description |
The Cryogenian was a time of climatic extremes, with two extended and severe global glaciations bracketing hothouse conditions. The effect of these extreme climate conditions on ocean chemistry and the marine biosphere remain poorly understood. Most of the previous studies of the fossil record from this interval focus on benthic organisms, with few examples of organisms with an inferred planktonic lifestyle and no firm evidence for photosynthetic organisms. Here, we present helically coiled, straight, and curved fossils composed of fine crystalline or framboidal pyrite in limestone samples from the Ikiakpuk formation of Arctic Alaska. These structures are morphologically identical to fossils of Obruchevella, a cyanobacterial form genus reported in pre-Sturtian and post-Marinoan strata, but not in deposits from the Cryogenian non-glacial interlude. We interpret fossils of the Ikiakpuk formation as planktonic cyanobacteria based on their morphology, which is identical to that of some modern planktonic cyanobacteria. Further evidence for a planktonic lifestyle comes from the preservation of these pyritized fossils in deep-water facies that lack evidence of microbial lamination. They provide the first direct evidence for bacterial primary productivity in the pelagic realm during the Cryogenian non-glacial interlude. Keywords: Alaska; metasomatism; paleoecology; United States; Cryogenian; Neoproterozoic; Proterozoic; upper Precambrian; Precambrian Simons Foundation (Grant 344707) |
author2 |
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Bosak, Tanja Moore, Kelsey Reed Newman, Sharon |
format |
Article in Journal/Newspaper |
author |
Macdonald, Francis Du, Kimberly Lahr, Daniel J. G. Pruss, Sara B. Moore, Kelsey Reed Bosak, Tanja Newman, Sharon |
spellingShingle |
Macdonald, Francis Du, Kimberly Lahr, Daniel J. G. Pruss, Sara B. Moore, Kelsey Reed Bosak, Tanja Newman, Sharon PYRITIZED CRYOGENIAN CYANOBACTERIAL FOSSILS FROM ARCTIC ALASKA |
author_facet |
Macdonald, Francis Du, Kimberly Lahr, Daniel J. G. Pruss, Sara B. Moore, Kelsey Reed Bosak, Tanja Newman, Sharon |
author_sort |
Macdonald, Francis |
title |
PYRITIZED CRYOGENIAN CYANOBACTERIAL FOSSILS FROM ARCTIC ALASKA |
title_short |
PYRITIZED CRYOGENIAN CYANOBACTERIAL FOSSILS FROM ARCTIC ALASKA |
title_full |
PYRITIZED CRYOGENIAN CYANOBACTERIAL FOSSILS FROM ARCTIC ALASKA |
title_fullStr |
PYRITIZED CRYOGENIAN CYANOBACTERIAL FOSSILS FROM ARCTIC ALASKA |
title_full_unstemmed |
PYRITIZED CRYOGENIAN CYANOBACTERIAL FOSSILS FROM ARCTIC ALASKA |
title_sort |
pyritized cryogenian cyanobacterial fossils from arctic alaska |
publisher |
Society for Sedimentary Geology |
publishDate |
2017 |
url |
http://hdl.handle.net/1721.1/120081 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Arctic Alaska |
genre_facet |
Arctic Arctic Alaska |
op_source |
Prof. Bosak via Chris Sherratt |
op_relation |
https://doi.org/10.2110/palo.2017.063 PALAIOS 0883-1351 http://hdl.handle.net/1721.1/120081 Moore, Kelsey R. et al. “PYRITIZED CRYOGENIAN CYANOBACTERIAL FOSSILS FROM ARCTIC ALASKA.” PALAIOS 32, 12 (December 2017): 769–778 © 2017 Society for Sedimentary Geology orcid:0000-0001-7332-4098 orcid:0000-0001-5179-5323 orcid:0000-0003-4664-308X |
op_rights |
Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ |
op_doi |
https://doi.org/10.2110/palo.2017.063 |
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32 |
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