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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| Format: | Article |
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Society for Sedimentary Geology
2019
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| Online Access: | http://hdl.handle.net/1721.1/120081 https://orcid.org/0000-0001-7332-4098 https://orcid.org/0000-0001-5179-5323 https://orcid.org/0000-0003-4664-308X |
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| author | Macdonald, Francis Du, Kimberly Lahr, Daniel J. G. Pruss, Sara B. Moore, Kelsey Reed Bosak, Tanja Newman, Sharon |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Macdonald, Francis Du, Kimberly Lahr, Daniel J. G. Pruss, Sara B. Moore, Kelsey Reed Bosak, Tanja Newman, Sharon |
| author_sort | Macdonald, Francis |
| collection | MIT |
| 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 |
| first_indexed | 2024-09-23T10:46:54Z |
| format | Article |
| id | mit-1721.1/120081 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T10:46:54Z |
| publishDate | 2019 |
| publisher | Society for Sedimentary Geology |
| record_format | dspace |
| spelling | mit-1721.1/1200812022-09-27T14:58:02Z 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 Bosak, Tanja Newman, Sharon 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) 2019-01-16T15:20:00Z 2019-01-16T15:20:00Z 2017-11 2017-08 Article http://purl.org/eprint/type/JournalArticle 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 https://orcid.org/0000-0001-7332-4098 https://orcid.org/0000-0001-5179-5323 https://orcid.org/0000-0003-4664-308X en_US https://doi.org/10.2110/palo.2017.063 PALAIOS Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf Society for Sedimentary Geology Prof. Bosak via Chris Sherratt |
| 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 |
| title | 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_short | PYRITIZED CRYOGENIAN CYANOBACTERIAL FOSSILS FROM ARCTIC ALASKA |
| title_sort | pyritized cryogenian cyanobacterial fossils from arctic alaska |
| url | http://hdl.handle.net/1721.1/120081 https://orcid.org/0000-0001-7332-4098 https://orcid.org/0000-0001-5179-5323 https://orcid.org/0000-0003-4664-308X |
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