Rotation of a Ferromanganese Nodule in the Penrhyn Basin, South Pacific, Tracked by the Earth's Magnetic Field
Abstract Ferromanganese nodules are cm‐sized, authigenic, abyssal manganese‐iron‐hydroxide concretions. They grow very slowly at rates of a few mm per million years. Although their ages are older than millions of years, they are often found half buried on the modern sediment surface. The mechanisms...
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ftdoajarticles:oai:doaj.org/article:739f60e428b1428195d8b54f6dc00fb4 2023-12-03T10:13:49+01:00 Rotation of a Ferromanganese Nodule in the Penrhyn Basin, South Pacific, Tracked by the Earth's Magnetic Field Hirokuni Oda Wataru Katanoda Akira Usui Masafumi Murayama Yuhji Yamamoto 2023-03-01T00:00:00Z https://doi.org/10.1029/2022GC010789 https://doaj.org/article/739f60e428b1428195d8b54f6dc00fb4 EN eng Wiley https://doi.org/10.1029/2022GC010789 https://doaj.org/toc/1525-2027 1525-2027 doi:10.1029/2022GC010789 https://doaj.org/article/739f60e428b1428195d8b54f6dc00fb4 Geochemistry, Geophysics, Geosystems, Vol 24, Iss 3, Pp n/a-n/a (2023) ferromanganese nodule magnetite maghemite secondary magnetization paleomagnetic direction vernadite Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 article 2023 ftdoajarticles https://doi.org/10.1029/2022GC010789 2023-11-05T01:36:02Z Abstract Ferromanganese nodules are cm‐sized, authigenic, abyssal manganese‐iron‐hydroxide concretions. They grow very slowly at rates of a few mm per million years. Although their ages are older than millions of years, they are often found half buried on the modern sediment surface. The mechanisms for the nodules' persistence at the surface without complete burial could be linked to their occasional motion or agitation. Here, we report evidence for the rotation of a nodule from the Penrhyn Basin, South Pacific detected by paleomagnetism. The paleomagnetic inclinations of specimens from the nodules' surface are consistent with the recent geomagnetic fields. The paleomagnetic directions from the surface to the core show successive changes and form a great circle with a pole at (azimuth = 53.9°, dip = 32.1°). This suggests that the nodule rotated along its pole while successively recording magnetizations. As the nodule was found on a gentle slope at the foot of an abyssal hill, it may have moved downslope due to bottom current underwashing. Rock magnetic analyses of the nodule suggest the presence of magnetite in single domain and vortex states. Low temperature magnetometry revealed that magnetite grains were heavily oxidized to maghemite, especially close to the core of the nodule. The rotation may have exposed the rising part of the nodule to oxidative pore water. Oxygenated Antarctic Bottom Water might have caused remagnetization due to low temperature oxidation of magnetite. The rotation would also facilitate the omnidirectional growth of the nodules' mixed layer of diagenetic buserite and hydrogenetic vernadite. Article in Journal/Newspaper Antarc* Antarctic Directory of Open Access Journals: DOAJ Articles Antarctic Pacific Geochemistry, Geophysics, Geosystems 24 3 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
ferromanganese nodule magnetite maghemite secondary magnetization paleomagnetic direction vernadite Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 |
spellingShingle |
ferromanganese nodule magnetite maghemite secondary magnetization paleomagnetic direction vernadite Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 Hirokuni Oda Wataru Katanoda Akira Usui Masafumi Murayama Yuhji Yamamoto Rotation of a Ferromanganese Nodule in the Penrhyn Basin, South Pacific, Tracked by the Earth's Magnetic Field |
topic_facet |
ferromanganese nodule magnetite maghemite secondary magnetization paleomagnetic direction vernadite Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 |
description |
Abstract Ferromanganese nodules are cm‐sized, authigenic, abyssal manganese‐iron‐hydroxide concretions. They grow very slowly at rates of a few mm per million years. Although their ages are older than millions of years, they are often found half buried on the modern sediment surface. The mechanisms for the nodules' persistence at the surface without complete burial could be linked to their occasional motion or agitation. Here, we report evidence for the rotation of a nodule from the Penrhyn Basin, South Pacific detected by paleomagnetism. The paleomagnetic inclinations of specimens from the nodules' surface are consistent with the recent geomagnetic fields. The paleomagnetic directions from the surface to the core show successive changes and form a great circle with a pole at (azimuth = 53.9°, dip = 32.1°). This suggests that the nodule rotated along its pole while successively recording magnetizations. As the nodule was found on a gentle slope at the foot of an abyssal hill, it may have moved downslope due to bottom current underwashing. Rock magnetic analyses of the nodule suggest the presence of magnetite in single domain and vortex states. Low temperature magnetometry revealed that magnetite grains were heavily oxidized to maghemite, especially close to the core of the nodule. The rotation may have exposed the rising part of the nodule to oxidative pore water. Oxygenated Antarctic Bottom Water might have caused remagnetization due to low temperature oxidation of magnetite. The rotation would also facilitate the omnidirectional growth of the nodules' mixed layer of diagenetic buserite and hydrogenetic vernadite. |
format |
Article in Journal/Newspaper |
author |
Hirokuni Oda Wataru Katanoda Akira Usui Masafumi Murayama Yuhji Yamamoto |
author_facet |
Hirokuni Oda Wataru Katanoda Akira Usui Masafumi Murayama Yuhji Yamamoto |
author_sort |
Hirokuni Oda |
title |
Rotation of a Ferromanganese Nodule in the Penrhyn Basin, South Pacific, Tracked by the Earth's Magnetic Field |
title_short |
Rotation of a Ferromanganese Nodule in the Penrhyn Basin, South Pacific, Tracked by the Earth's Magnetic Field |
title_full |
Rotation of a Ferromanganese Nodule in the Penrhyn Basin, South Pacific, Tracked by the Earth's Magnetic Field |
title_fullStr |
Rotation of a Ferromanganese Nodule in the Penrhyn Basin, South Pacific, Tracked by the Earth's Magnetic Field |
title_full_unstemmed |
Rotation of a Ferromanganese Nodule in the Penrhyn Basin, South Pacific, Tracked by the Earth's Magnetic Field |
title_sort |
rotation of a ferromanganese nodule in the penrhyn basin, south pacific, tracked by the earth's magnetic field |
publisher |
Wiley |
publishDate |
2023 |
url |
https://doi.org/10.1029/2022GC010789 https://doaj.org/article/739f60e428b1428195d8b54f6dc00fb4 |
geographic |
Antarctic Pacific |
geographic_facet |
Antarctic Pacific |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
Geochemistry, Geophysics, Geosystems, Vol 24, Iss 3, Pp n/a-n/a (2023) |
op_relation |
https://doi.org/10.1029/2022GC010789 https://doaj.org/toc/1525-2027 1525-2027 doi:10.1029/2022GC010789 https://doaj.org/article/739f60e428b1428195d8b54f6dc00fb4 |
op_doi |
https://doi.org/10.1029/2022GC010789 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
24 |
container_issue |
3 |
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1784260760564662272 |