A major perturbation of the carbon cycle before the Ghaub glaciation (Neoproterozoic) in Namibia: Prelude to snowball Earth?
Copyright © 2002 by the American Geophysical Union. <jats:p>A large (11–15‰) negative shift in δ<jats:sup>13</jats:sup>C is observed in shallow water carbonates directly beneath Neoproterozoic glacial deposits (or correlative disconformity) in northwest Namibia ascribed to a snowba...
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ftunivadelaidedl:oai:digital.library.adelaide.edu.au:2440/31817 2023-11-12T04:27:04+01:00 A major perturbation of the carbon cycle before the Ghaub glaciation (Neoproterozoic) in Namibia: Prelude to snowball Earth? Halverson, G. Hoffman, P. Schrag, D. Kaufman, A. 2002 http://hdl.handle.net/2440/31817 https://doi.org/10.1029/2001GC000244 en eng American Geophysical Union G3: Geochemistry, Geophysics, Geosystems: an electronic journal of the earth sciences, 2002; 3(6):1035- 1525-2027 http://hdl.handle.net/2440/31817 doi:10.1029/2001GC000244 http://www.agu.org/pubs/crossref/2002/2001GC000244.shtml Carbon cycle carbon isotopes methane snowball Earth Neoproterozoic Namibia Journal article 2002 ftunivadelaidedl https://doi.org/10.1029/2001GC000244 2023-10-23T22:15:45Z Copyright © 2002 by the American Geophysical Union. <jats:p>A large (11–15‰) negative shift in δ<jats:sup>13</jats:sup>C is observed in shallow water carbonates directly beneath Neoproterozoic glacial deposits (or correlative disconformity) in northwest Namibia ascribed to a snowball Earth. Reproducibility and stratigraphic concordance of this anomaly in 16 sections across the ancient continental shelf support a primary origin, and field relations show it predates the fall in sea level associated with the Ghaub glaciation. We crudely estimate the duration of the isotopic shift as ∼0.6 × 10<jats:sup>6</jats:sup> years from a simple thermal subsidence model. Similar or larger δ<jats:sup>13</jats:sup>C anomalies are found directly beneath Neoproterozoic glacial units in Australia, Canada, China, Scotland, and Svalbard. After considering conventional interpretations for negative δ<jats:sup>13</jats:sup>C anomalies, we conclude that a prolonged methane release to the atmosphere is most consistent with the timescale, magnitude, and geological context of the anomaly in Namibia. Counterintuitively, an anomalous methane flux that is sustained for 100s kyr may be consistent with a snowball glaciation.</jats:p> Article in Journal/Newspaper Svalbard The University of Adelaide: Digital Library Canada Svalbard Geochemistry, Geophysics, Geosystems 3 6 1 24 |
institution |
Open Polar |
collection |
The University of Adelaide: Digital Library |
op_collection_id |
ftunivadelaidedl |
language |
English |
topic |
Carbon cycle carbon isotopes methane snowball Earth Neoproterozoic Namibia |
spellingShingle |
Carbon cycle carbon isotopes methane snowball Earth Neoproterozoic Namibia Halverson, G. Hoffman, P. Schrag, D. Kaufman, A. A major perturbation of the carbon cycle before the Ghaub glaciation (Neoproterozoic) in Namibia: Prelude to snowball Earth? |
topic_facet |
Carbon cycle carbon isotopes methane snowball Earth Neoproterozoic Namibia |
description |
Copyright © 2002 by the American Geophysical Union. <jats:p>A large (11–15‰) negative shift in δ<jats:sup>13</jats:sup>C is observed in shallow water carbonates directly beneath Neoproterozoic glacial deposits (or correlative disconformity) in northwest Namibia ascribed to a snowball Earth. Reproducibility and stratigraphic concordance of this anomaly in 16 sections across the ancient continental shelf support a primary origin, and field relations show it predates the fall in sea level associated with the Ghaub glaciation. We crudely estimate the duration of the isotopic shift as ∼0.6 × 10<jats:sup>6</jats:sup> years from a simple thermal subsidence model. Similar or larger δ<jats:sup>13</jats:sup>C anomalies are found directly beneath Neoproterozoic glacial units in Australia, Canada, China, Scotland, and Svalbard. After considering conventional interpretations for negative δ<jats:sup>13</jats:sup>C anomalies, we conclude that a prolonged methane release to the atmosphere is most consistent with the timescale, magnitude, and geological context of the anomaly in Namibia. Counterintuitively, an anomalous methane flux that is sustained for 100s kyr may be consistent with a snowball glaciation.</jats:p> |
format |
Article in Journal/Newspaper |
author |
Halverson, G. Hoffman, P. Schrag, D. Kaufman, A. |
author_facet |
Halverson, G. Hoffman, P. Schrag, D. Kaufman, A. |
author_sort |
Halverson, G. |
title |
A major perturbation of the carbon cycle before the Ghaub glaciation (Neoproterozoic) in Namibia: Prelude to snowball Earth? |
title_short |
A major perturbation of the carbon cycle before the Ghaub glaciation (Neoproterozoic) in Namibia: Prelude to snowball Earth? |
title_full |
A major perturbation of the carbon cycle before the Ghaub glaciation (Neoproterozoic) in Namibia: Prelude to snowball Earth? |
title_fullStr |
A major perturbation of the carbon cycle before the Ghaub glaciation (Neoproterozoic) in Namibia: Prelude to snowball Earth? |
title_full_unstemmed |
A major perturbation of the carbon cycle before the Ghaub glaciation (Neoproterozoic) in Namibia: Prelude to snowball Earth? |
title_sort |
major perturbation of the carbon cycle before the ghaub glaciation (neoproterozoic) in namibia: prelude to snowball earth? |
publisher |
American Geophysical Union |
publishDate |
2002 |
url |
http://hdl.handle.net/2440/31817 https://doi.org/10.1029/2001GC000244 |
geographic |
Canada Svalbard |
geographic_facet |
Canada Svalbard |
genre |
Svalbard |
genre_facet |
Svalbard |
op_source |
http://www.agu.org/pubs/crossref/2002/2001GC000244.shtml |
op_relation |
G3: Geochemistry, Geophysics, Geosystems: an electronic journal of the earth sciences, 2002; 3(6):1035- 1525-2027 http://hdl.handle.net/2440/31817 doi:10.1029/2001GC000244 |
op_doi |
https://doi.org/10.1029/2001GC000244 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
3 |
container_issue |
6 |
container_start_page |
1 |
op_container_end_page |
24 |
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1782340808428486656 |