A new paleomagnetic constraint on the duration of a twin caldera-forming eruption sequence: a potential solution to an enduring problem in decoding >VEI 7 eruption timescales
Abstract New paleomagnetic results from the twin caldera-forming Mamaku–Ohakuri eruption deposits in the Taupō Volcanic Zone of New Zealand show that the entire pyroclastic sequence accumulated within a geomagnetic excursion event. The deposits are predominately unconsolidated and include multiple a...
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SpringerOpen
2025-07-01
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| Series: | Earth, Planets and Space |
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| Online Access: | https://doi.org/10.1186/s40623-025-02179-9 |
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| author | Darren M. Gravley Takeshi Hasegawa Nobutatsu Mochizuki Chie Kusu Makoto Okada |
| author_facet | Darren M. Gravley Takeshi Hasegawa Nobutatsu Mochizuki Chie Kusu Makoto Okada |
| author_sort | Darren M. Gravley |
| collection | DOAJ |
| description | Abstract New paleomagnetic results from the twin caldera-forming Mamaku–Ohakuri eruption deposits in the Taupō Volcanic Zone of New Zealand show that the entire pyroclastic sequence accumulated within a geomagnetic excursion event. The deposits are predominately unconsolidated and include multiple airfall ash units and two caldera-forming ignimbrites. The older Mamaku ignimbrite is moderately welded and has been previously correlated with the ~240 ka Mamaku excursion. By utilizing a refined technique to extract samples from multiple units in the eruption sequence (including the Mamaku ignimbrite) and measuring mean characteristic remanent magnetization directions, we establish that the entire sequence may have occurred over decades to centuries, and that the geomagnetic directional changing rate probably fluctuated significantly during the excursion, up to several degrees per day. More research is required, but we argue that sequences of relatively rapidly deposited pyroclastic material have significant potential in not only refining the timescales of volcano explosivity index (VEI) 7 and larger VEI 8 eruptions, but also as an alternative recorder that could progress some well-documented and unanswered questions in paleomagnetic research, like the stop-and-go character of the geomagnetic field direction during excursions and reversals. Graphical Abstract |
| format | Article |
| id | doaj-art-47e66266572d48fbbf6a1d0c6a9ffaf6 |
| institution | DOAJ |
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| language | English |
| publishDate | 2025-07-01 |
| publisher | SpringerOpen |
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| series | Earth, Planets and Space |
| spelling | doaj-art-47e66266572d48fbbf6a1d0c6a9ffaf62025-08-20T03:03:38ZengSpringerOpenEarth, Planets and Space1880-59812025-07-0177111410.1186/s40623-025-02179-9A new paleomagnetic constraint on the duration of a twin caldera-forming eruption sequence: a potential solution to an enduring problem in decoding >VEI 7 eruption timescalesDarren M. Gravley0Takeshi Hasegawa1Nobutatsu Mochizuki2Chie Kusu3Makoto Okada4School of Earth and Environment, University of CanterburyDepartment of Earth Science, Ibaraki UniversityDepartment of Earth and Environmental Science, Faculty of Advanced Science and Technology, Kumamoto UniversityDepartment of Earth Science, Ibaraki UniversityDepartment of Earth Science, Ibaraki UniversityAbstract New paleomagnetic results from the twin caldera-forming Mamaku–Ohakuri eruption deposits in the Taupō Volcanic Zone of New Zealand show that the entire pyroclastic sequence accumulated within a geomagnetic excursion event. The deposits are predominately unconsolidated and include multiple airfall ash units and two caldera-forming ignimbrites. The older Mamaku ignimbrite is moderately welded and has been previously correlated with the ~240 ka Mamaku excursion. By utilizing a refined technique to extract samples from multiple units in the eruption sequence (including the Mamaku ignimbrite) and measuring mean characteristic remanent magnetization directions, we establish that the entire sequence may have occurred over decades to centuries, and that the geomagnetic directional changing rate probably fluctuated significantly during the excursion, up to several degrees per day. More research is required, but we argue that sequences of relatively rapidly deposited pyroclastic material have significant potential in not only refining the timescales of volcano explosivity index (VEI) 7 and larger VEI 8 eruptions, but also as an alternative recorder that could progress some well-documented and unanswered questions in paleomagnetic research, like the stop-and-go character of the geomagnetic field direction during excursions and reversals. Graphical Abstracthttps://doi.org/10.1186/s40623-025-02179-9Caldera-forming eruption durationGeomagnetic excursionPaleomagnetic mean directionMamaku–Ohakuri eruption sequence |
| spellingShingle | Darren M. Gravley Takeshi Hasegawa Nobutatsu Mochizuki Chie Kusu Makoto Okada A new paleomagnetic constraint on the duration of a twin caldera-forming eruption sequence: a potential solution to an enduring problem in decoding >VEI 7 eruption timescales Earth, Planets and Space Caldera-forming eruption duration Geomagnetic excursion Paleomagnetic mean direction Mamaku–Ohakuri eruption sequence |
| title | A new paleomagnetic constraint on the duration of a twin caldera-forming eruption sequence: a potential solution to an enduring problem in decoding >VEI 7 eruption timescales |
| title_full | A new paleomagnetic constraint on the duration of a twin caldera-forming eruption sequence: a potential solution to an enduring problem in decoding >VEI 7 eruption timescales |
| title_fullStr | A new paleomagnetic constraint on the duration of a twin caldera-forming eruption sequence: a potential solution to an enduring problem in decoding >VEI 7 eruption timescales |
| title_full_unstemmed | A new paleomagnetic constraint on the duration of a twin caldera-forming eruption sequence: a potential solution to an enduring problem in decoding >VEI 7 eruption timescales |
| title_short | A new paleomagnetic constraint on the duration of a twin caldera-forming eruption sequence: a potential solution to an enduring problem in decoding >VEI 7 eruption timescales |
| title_sort | new paleomagnetic constraint on the duration of a twin caldera forming eruption sequence a potential solution to an enduring problem in decoding vei 7 eruption timescales |
| topic | Caldera-forming eruption duration Geomagnetic excursion Paleomagnetic mean direction Mamaku–Ohakuri eruption sequence |
| url | https://doi.org/10.1186/s40623-025-02179-9 |
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