Volcanic ash in bare ice south of Sør Rondane Mountains, Antarctica: geochemistry, rock magnetism and nondestructive magnetic detection with SQUID gradiometer
Abstract Nondestructive magnetic detection of tephra layers in ice cores will be an important method to identify and correlate stratigraphic horizons of ice bearing volcanic ash particles. Volcanic ash particles were extracted from tephra-bearing ice samples collected from Nansen Ice Field south of...
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ftbiomed:oai:biomedcentral.com:s40623-016-0415-3 2023-05-15T13:39:16+02:00 Volcanic ash in bare ice south of Sør Rondane Mountains, Antarctica: geochemistry, rock magnetism and nondestructive magnetic detection with SQUID gradiometer Oda, Hirokuni Miyagi, Isoji Kawai, Jun Suganuma, Yusuke Funaki, Minoru Imae, Naoya Mikouchi, Takashi Matsuzaki, Takuya Yamamoto, Yuhji 2016-03-09 http://www.earth-planets-space.com/content/68/1/39 en eng BioMed Central Ltd. http://www.earth-planets-space.com/content/68/1/39 Copyright 2016 Oda et al. Full paper 2016 ftbiomed 2016-03-13T01:00:34Z Abstract Nondestructive magnetic detection of tephra layers in ice cores will be an important method to identify and correlate stratigraphic horizons of ice bearing volcanic ash particles. Volcanic ash particles were extracted from tephra-bearing ice samples collected from Nansen Ice Field south of the Sør Rondane Mountains, Antarctica. Particles are fresh glassy volcanic ash with diameters of ~50 μm, and chemical composition of the matrix glass belongs to a low-K basaltic andesite group, ranging from SiO 2 60–62 wt% and K 2 O 0.40–0.50 wt%. Considering the grain size of ash particles and chemical composition of volcanic glass, the ash in tephra-bearing ice samples might be originated from the South Sandwich Islands located 2800 km northwest of the sampling sites. Correlations on major element concentrations with tephra layers associated with South Sandwich Islands in EPICA-Dome C, Vostok, and Dome Fuji ice cores show high similarity. Rock magnetic experiments show that the magnetic mineral is pseudo-single-domain titanomagnetite with ulvospinel content of 0.2–0.35 mixed with single-domain to superparamagnetic (titano)magnetite. Small blocks of the tephra-bering ice were measured with a SQUID gradiometer at 1-mm intervals with a spatial resolution of ~3 mm. With DC magnetic field of 25 mT, magnetic signal could be enhanced and detected for all the samples including the one with invisible amount of tephra particles. In order to simulate a thin ash layer in ice core, volcanic ash particles extracted from the tephra-bearing ice were used to fabricate a thin ash layer, which were subsequently magnetized, measured with the gradiometer. The noise level for Z axis gradiometer was about 0.6 pT. Detection limit for a half-cylinder with 29 mm radius and a thickness of 1 mm uniformly magnetized in X axis direction is ~9 × 10 −5 A/m, which could be improved down to ~2 × 10 −6 A/m by reducing the sensor-to-sample distance to 0.5 mm. Other/Unknown Material Antarc* Antarctica EPICA ice core South Sandwich Islands BioMed Central Dome Fuji ENVELOPE(39.700,39.700,-77.317,-77.317) Sandwich Islands South Sandwich Islands Sør Rondane Mountains ENVELOPE(25.000,25.000,-72.000,-72.000) Sør-Rondane ENVELOPE(25.000,25.000,-72.000,-72.000) |
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Open Polar |
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BioMed Central |
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ftbiomed |
language |
English |
description |
Abstract Nondestructive magnetic detection of tephra layers in ice cores will be an important method to identify and correlate stratigraphic horizons of ice bearing volcanic ash particles. Volcanic ash particles were extracted from tephra-bearing ice samples collected from Nansen Ice Field south of the Sør Rondane Mountains, Antarctica. Particles are fresh glassy volcanic ash with diameters of ~50 μm, and chemical composition of the matrix glass belongs to a low-K basaltic andesite group, ranging from SiO 2 60–62 wt% and K 2 O 0.40–0.50 wt%. Considering the grain size of ash particles and chemical composition of volcanic glass, the ash in tephra-bearing ice samples might be originated from the South Sandwich Islands located 2800 km northwest of the sampling sites. Correlations on major element concentrations with tephra layers associated with South Sandwich Islands in EPICA-Dome C, Vostok, and Dome Fuji ice cores show high similarity. Rock magnetic experiments show that the magnetic mineral is pseudo-single-domain titanomagnetite with ulvospinel content of 0.2–0.35 mixed with single-domain to superparamagnetic (titano)magnetite. Small blocks of the tephra-bering ice were measured with a SQUID gradiometer at 1-mm intervals with a spatial resolution of ~3 mm. With DC magnetic field of 25 mT, magnetic signal could be enhanced and detected for all the samples including the one with invisible amount of tephra particles. In order to simulate a thin ash layer in ice core, volcanic ash particles extracted from the tephra-bearing ice were used to fabricate a thin ash layer, which were subsequently magnetized, measured with the gradiometer. The noise level for Z axis gradiometer was about 0.6 pT. Detection limit for a half-cylinder with 29 mm radius and a thickness of 1 mm uniformly magnetized in X axis direction is ~9 × 10 −5 A/m, which could be improved down to ~2 × 10 −6 A/m by reducing the sensor-to-sample distance to 0.5 mm. |
format |
Other/Unknown Material |
author |
Oda, Hirokuni Miyagi, Isoji Kawai, Jun Suganuma, Yusuke Funaki, Minoru Imae, Naoya Mikouchi, Takashi Matsuzaki, Takuya Yamamoto, Yuhji |
spellingShingle |
Oda, Hirokuni Miyagi, Isoji Kawai, Jun Suganuma, Yusuke Funaki, Minoru Imae, Naoya Mikouchi, Takashi Matsuzaki, Takuya Yamamoto, Yuhji Volcanic ash in bare ice south of Sør Rondane Mountains, Antarctica: geochemistry, rock magnetism and nondestructive magnetic detection with SQUID gradiometer |
author_facet |
Oda, Hirokuni Miyagi, Isoji Kawai, Jun Suganuma, Yusuke Funaki, Minoru Imae, Naoya Mikouchi, Takashi Matsuzaki, Takuya Yamamoto, Yuhji |
author_sort |
Oda, Hirokuni |
title |
Volcanic ash in bare ice south of Sør Rondane Mountains, Antarctica: geochemistry, rock magnetism and nondestructive magnetic detection with SQUID gradiometer |
title_short |
Volcanic ash in bare ice south of Sør Rondane Mountains, Antarctica: geochemistry, rock magnetism and nondestructive magnetic detection with SQUID gradiometer |
title_full |
Volcanic ash in bare ice south of Sør Rondane Mountains, Antarctica: geochemistry, rock magnetism and nondestructive magnetic detection with SQUID gradiometer |
title_fullStr |
Volcanic ash in bare ice south of Sør Rondane Mountains, Antarctica: geochemistry, rock magnetism and nondestructive magnetic detection with SQUID gradiometer |
title_full_unstemmed |
Volcanic ash in bare ice south of Sør Rondane Mountains, Antarctica: geochemistry, rock magnetism and nondestructive magnetic detection with SQUID gradiometer |
title_sort |
volcanic ash in bare ice south of sør rondane mountains, antarctica: geochemistry, rock magnetism and nondestructive magnetic detection with squid gradiometer |
publisher |
BioMed Central Ltd. |
publishDate |
2016 |
url |
http://www.earth-planets-space.com/content/68/1/39 |
long_lat |
ENVELOPE(39.700,39.700,-77.317,-77.317) ENVELOPE(25.000,25.000,-72.000,-72.000) ENVELOPE(25.000,25.000,-72.000,-72.000) |
geographic |
Dome Fuji Sandwich Islands South Sandwich Islands Sør Rondane Mountains Sør-Rondane |
geographic_facet |
Dome Fuji Sandwich Islands South Sandwich Islands Sør Rondane Mountains Sør-Rondane |
genre |
Antarc* Antarctica EPICA ice core South Sandwich Islands |
genre_facet |
Antarc* Antarctica EPICA ice core South Sandwich Islands |
op_relation |
http://www.earth-planets-space.com/content/68/1/39 |
op_rights |
Copyright 2016 Oda et al. |
_version_ |
1766116600052711424 |