Glacial erosion on a snowball Earth: testing for bias in flux balance, geographic setting, and tectonic regime
On the southwest cape of the Congo craton, a subtropical carbonate bank the size of Greenland was heavily glaciated during two Cryogenian panglacial episodes spaced 10–20 Myr apart. In NW Namibia, the bank underwent crustal stretching with resultant Aegean Sea-type topography during the older and lo...
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crcansciencepubl:10.1139/cjes-2022-0004 2024-03-03T08:45:03+00:00 Glacial erosion on a snowball Earth: testing for bias in flux balance, geographic setting, and tectonic regime Hoffman, Paul F. 2023 http://dx.doi.org/10.1139/cjes-2022-0004 https://cdnsciencepub.com/doi/full-xml/10.1139/cjes-2022-0004 https://cdnsciencepub.com/doi/pdf/10.1139/cjes-2022-0004 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 60, issue 7, page 765-777 ISSN 0008-4077 1480-3313 General Earth and Planetary Sciences journal-article 2023 crcansciencepubl https://doi.org/10.1139/cjes-2022-0004 2024-02-07T10:53:37Z On the southwest cape of the Congo craton, a subtropical carbonate bank the size of Greenland was heavily glaciated during two Cryogenian panglacial episodes spaced 10–20 Myr apart. In NW Namibia, the bank underwent crustal stretching with resultant Aegean Sea-type topography during the older and longer Sturtian glaciation (717–661 Ma). This is indicated by angular discordance between glacial and preglacial strata and diamictites sourced from all older units, including crystalline basement. In contrast, the bank was flat-topped and underwent broad thermal subsidence during Marinoan glaciation (646 ± 5–635 Ma), attested by stratal parallellism and diamictites sourced from ≤100 m stratigraphic depth. However, ≥2.0 km of relief existed on the Marinoan continental slope, where most glacial erosion and accumulation occurred. The average rates of Marinoan erosion (2.55–6.80 m/Myr, n = 190) and accumulation (2.65–7.07 m/Myr, n = 211) are indistinguishable, implying that the location in a continental promontory did not bias erosion over accumulation. The average accumulation rates for the Sturtian and Marinoan, scaled for different averaging times, including Marinoan uncertainty, are 3.95–4.93 m/Myr ( n = 183) and 2.65–7.07 m/Myr ( n = 190), respectively, suggesting that a Marinoan glacioeustatic coastal escarpment substituted for rift-related Sturtian basin-and-range topography. These slow rates, comparable to long-term pre-Quaternary accumulation rates on existing abyssal plains, reconcile glacial sedimentology with the feeble hydrologic cycle of snowball Earth. Article in Journal/Newspaper Greenland Canadian Science Publishing Greenland Canadian Journal of Earth Sciences |
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Canadian Science Publishing |
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crcansciencepubl |
language |
English |
topic |
General Earth and Planetary Sciences |
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General Earth and Planetary Sciences Hoffman, Paul F. Glacial erosion on a snowball Earth: testing for bias in flux balance, geographic setting, and tectonic regime |
topic_facet |
General Earth and Planetary Sciences |
description |
On the southwest cape of the Congo craton, a subtropical carbonate bank the size of Greenland was heavily glaciated during two Cryogenian panglacial episodes spaced 10–20 Myr apart. In NW Namibia, the bank underwent crustal stretching with resultant Aegean Sea-type topography during the older and longer Sturtian glaciation (717–661 Ma). This is indicated by angular discordance between glacial and preglacial strata and diamictites sourced from all older units, including crystalline basement. In contrast, the bank was flat-topped and underwent broad thermal subsidence during Marinoan glaciation (646 ± 5–635 Ma), attested by stratal parallellism and diamictites sourced from ≤100 m stratigraphic depth. However, ≥2.0 km of relief existed on the Marinoan continental slope, where most glacial erosion and accumulation occurred. The average rates of Marinoan erosion (2.55–6.80 m/Myr, n = 190) and accumulation (2.65–7.07 m/Myr, n = 211) are indistinguishable, implying that the location in a continental promontory did not bias erosion over accumulation. The average accumulation rates for the Sturtian and Marinoan, scaled for different averaging times, including Marinoan uncertainty, are 3.95–4.93 m/Myr ( n = 183) and 2.65–7.07 m/Myr ( n = 190), respectively, suggesting that a Marinoan glacioeustatic coastal escarpment substituted for rift-related Sturtian basin-and-range topography. These slow rates, comparable to long-term pre-Quaternary accumulation rates on existing abyssal plains, reconcile glacial sedimentology with the feeble hydrologic cycle of snowball Earth. |
format |
Article in Journal/Newspaper |
author |
Hoffman, Paul F. |
author_facet |
Hoffman, Paul F. |
author_sort |
Hoffman, Paul F. |
title |
Glacial erosion on a snowball Earth: testing for bias in flux balance, geographic setting, and tectonic regime |
title_short |
Glacial erosion on a snowball Earth: testing for bias in flux balance, geographic setting, and tectonic regime |
title_full |
Glacial erosion on a snowball Earth: testing for bias in flux balance, geographic setting, and tectonic regime |
title_fullStr |
Glacial erosion on a snowball Earth: testing for bias in flux balance, geographic setting, and tectonic regime |
title_full_unstemmed |
Glacial erosion on a snowball Earth: testing for bias in flux balance, geographic setting, and tectonic regime |
title_sort |
glacial erosion on a snowball earth: testing for bias in flux balance, geographic setting, and tectonic regime |
publisher |
Canadian Science Publishing |
publishDate |
2023 |
url |
http://dx.doi.org/10.1139/cjes-2022-0004 https://cdnsciencepub.com/doi/full-xml/10.1139/cjes-2022-0004 https://cdnsciencepub.com/doi/pdf/10.1139/cjes-2022-0004 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Canadian Journal of Earth Sciences volume 60, issue 7, page 765-777 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/cjes-2022-0004 |
container_title |
Canadian Journal of Earth Sciences |
_version_ |
1792500560819126272 |