Paleomagnetic study of basaltic rocks from Baengnyeong Island, Korea: efficiency of the Tsunakawa–Shaw paleointensity determination on non-SD-bearing materials and implication for the early Pliocene geomagnetic field intensity
Abstract Finding the statistical intensity signatures of the Earth’s magnetic field over geologic time has helped understanding of the evolution of the Earth’s interior and its interactions with other integral parts of Earth systems. However, this has been often hampered by a paucity of absolute pal...
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ftdoajarticles:oai:doaj.org/article:7771efbc4a11484ebe19c95343d5d941 2023-05-15T16:19:42+02:00 Paleomagnetic study of basaltic rocks from Baengnyeong Island, Korea: efficiency of the Tsunakawa–Shaw paleointensity determination on non-SD-bearing materials and implication for the early Pliocene geomagnetic field intensity Hyeon-Seon Ahn Yuhji Yamamoto 2019-11-01T00:00:00Z https://doi.org/10.1186/s40623-019-1107-6 https://doaj.org/article/7771efbc4a11484ebe19c95343d5d941 EN eng SpringerOpen http://link.springer.com/article/10.1186/s40623-019-1107-6 https://doaj.org/toc/1880-5981 doi:10.1186/s40623-019-1107-6 1880-5981 https://doaj.org/article/7771efbc4a11484ebe19c95343d5d941 Earth, Planets and Space, Vol 71, Iss 1, Pp 1-20 (2019) Baengnyeong island Early pliocene Paleomagnetism Non-SD-bearing material Tsunakawa–Shaw paleointensity Thellier-type paleointensity Geography. Anthropology. Recreation G Geodesy QB275-343 Geology QE1-996.5 article 2019 ftdoajarticles https://doi.org/10.1186/s40623-019-1107-6 2022-12-31T10:35:55Z Abstract Finding the statistical intensity signatures of the Earth’s magnetic field over geologic time has helped understanding of the evolution of the Earth’s interior and its interactions with other integral parts of Earth systems. However, this has been often hampered by a paucity of absolute paleointensity (API) data, which are difficult to obtain primarily because of non-ideal magnetic behaviors of natural materials. Here, we present new API determination data with paleodirectional and rock magnetic analyses from basaltic rocks probably aged ~ 4‒5 Ma in Baengnyeong Island, Korea. Paleodirectional analysis obtained an overall mean direction of D = 347.3° and I = 38.3° (α 95 = 4.9°, k = 113.4) corresponding to a virtual geomagnetic pole at 342.1° E and 70.2° N. Comprehensive rock magnetic analyses identified Ti-poor titanomagnetite with, in part, multi-domain (MD) particles as a main carrier of remanent magnetization. The Tsunakawa–Shaw (TS) method yielded 12 qualified API estimates with a high success rate, efficiently removing possible MD influences, and resulted in a mean value of 13.1 μT with good precision (1.7 μT, standard deviation). The Thellier method of the IZZI protocol with pTRM checks, coupled with the use of a bootstrap approach instead of the “conventional best-fitting” in API determination, gave 6.6‒19.7 μT as a 95% confidence interval of its mean API estimate, which supports the reliability of our TS-derived API mean estimate; but it is not considered in the final mean value because of the relatively large uncertainty. The virtual dipole moment corresponding to the TS-derived API mean, 2.9 (± 0.4) × 1022 Am2, is somewhat lower than the expectations of the past few Myr averages. Combined with a global API database, our new data implies a larger dispersion in the dipole moment during the early Pliocene than previously inferred. This also suggests that the issue of whether the early Pliocene average dipole strength was moderately high (> 5 × 1022 Am2) or consistent (4‒5 × 1022 Am2) should be ... Article in Journal/Newspaper Geomagnetic Pole Directory of Open Access Journals: DOAJ Articles Earth, Planets and Space 71 1 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Baengnyeong island Early pliocene Paleomagnetism Non-SD-bearing material Tsunakawa–Shaw paleointensity Thellier-type paleointensity Geography. Anthropology. Recreation G Geodesy QB275-343 Geology QE1-996.5 |
spellingShingle |
Baengnyeong island Early pliocene Paleomagnetism Non-SD-bearing material Tsunakawa–Shaw paleointensity Thellier-type paleointensity Geography. Anthropology. Recreation G Geodesy QB275-343 Geology QE1-996.5 Hyeon-Seon Ahn Yuhji Yamamoto Paleomagnetic study of basaltic rocks from Baengnyeong Island, Korea: efficiency of the Tsunakawa–Shaw paleointensity determination on non-SD-bearing materials and implication for the early Pliocene geomagnetic field intensity |
topic_facet |
Baengnyeong island Early pliocene Paleomagnetism Non-SD-bearing material Tsunakawa–Shaw paleointensity Thellier-type paleointensity Geography. Anthropology. Recreation G Geodesy QB275-343 Geology QE1-996.5 |
description |
Abstract Finding the statistical intensity signatures of the Earth’s magnetic field over geologic time has helped understanding of the evolution of the Earth’s interior and its interactions with other integral parts of Earth systems. However, this has been often hampered by a paucity of absolute paleointensity (API) data, which are difficult to obtain primarily because of non-ideal magnetic behaviors of natural materials. Here, we present new API determination data with paleodirectional and rock magnetic analyses from basaltic rocks probably aged ~ 4‒5 Ma in Baengnyeong Island, Korea. Paleodirectional analysis obtained an overall mean direction of D = 347.3° and I = 38.3° (α 95 = 4.9°, k = 113.4) corresponding to a virtual geomagnetic pole at 342.1° E and 70.2° N. Comprehensive rock magnetic analyses identified Ti-poor titanomagnetite with, in part, multi-domain (MD) particles as a main carrier of remanent magnetization. The Tsunakawa–Shaw (TS) method yielded 12 qualified API estimates with a high success rate, efficiently removing possible MD influences, and resulted in a mean value of 13.1 μT with good precision (1.7 μT, standard deviation). The Thellier method of the IZZI protocol with pTRM checks, coupled with the use of a bootstrap approach instead of the “conventional best-fitting” in API determination, gave 6.6‒19.7 μT as a 95% confidence interval of its mean API estimate, which supports the reliability of our TS-derived API mean estimate; but it is not considered in the final mean value because of the relatively large uncertainty. The virtual dipole moment corresponding to the TS-derived API mean, 2.9 (± 0.4) × 1022 Am2, is somewhat lower than the expectations of the past few Myr averages. Combined with a global API database, our new data implies a larger dispersion in the dipole moment during the early Pliocene than previously inferred. This also suggests that the issue of whether the early Pliocene average dipole strength was moderately high (> 5 × 1022 Am2) or consistent (4‒5 × 1022 Am2) should be ... |
format |
Article in Journal/Newspaper |
author |
Hyeon-Seon Ahn Yuhji Yamamoto |
author_facet |
Hyeon-Seon Ahn Yuhji Yamamoto |
author_sort |
Hyeon-Seon Ahn |
title |
Paleomagnetic study of basaltic rocks from Baengnyeong Island, Korea: efficiency of the Tsunakawa–Shaw paleointensity determination on non-SD-bearing materials and implication for the early Pliocene geomagnetic field intensity |
title_short |
Paleomagnetic study of basaltic rocks from Baengnyeong Island, Korea: efficiency of the Tsunakawa–Shaw paleointensity determination on non-SD-bearing materials and implication for the early Pliocene geomagnetic field intensity |
title_full |
Paleomagnetic study of basaltic rocks from Baengnyeong Island, Korea: efficiency of the Tsunakawa–Shaw paleointensity determination on non-SD-bearing materials and implication for the early Pliocene geomagnetic field intensity |
title_fullStr |
Paleomagnetic study of basaltic rocks from Baengnyeong Island, Korea: efficiency of the Tsunakawa–Shaw paleointensity determination on non-SD-bearing materials and implication for the early Pliocene geomagnetic field intensity |
title_full_unstemmed |
Paleomagnetic study of basaltic rocks from Baengnyeong Island, Korea: efficiency of the Tsunakawa–Shaw paleointensity determination on non-SD-bearing materials and implication for the early Pliocene geomagnetic field intensity |
title_sort |
paleomagnetic study of basaltic rocks from baengnyeong island, korea: efficiency of the tsunakawa–shaw paleointensity determination on non-sd-bearing materials and implication for the early pliocene geomagnetic field intensity |
publisher |
SpringerOpen |
publishDate |
2019 |
url |
https://doi.org/10.1186/s40623-019-1107-6 https://doaj.org/article/7771efbc4a11484ebe19c95343d5d941 |
genre |
Geomagnetic Pole |
genre_facet |
Geomagnetic Pole |
op_source |
Earth, Planets and Space, Vol 71, Iss 1, Pp 1-20 (2019) |
op_relation |
http://link.springer.com/article/10.1186/s40623-019-1107-6 https://doaj.org/toc/1880-5981 doi:10.1186/s40623-019-1107-6 1880-5981 https://doaj.org/article/7771efbc4a11484ebe19c95343d5d941 |
op_doi |
https://doi.org/10.1186/s40623-019-1107-6 |
container_title |
Earth, Planets and Space |
container_volume |
71 |
container_issue |
1 |
_version_ |
1766006108503146496 |