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DOI | 10.1073/pnas.2017342118 |
Intensity of the Earth's magnetic field: Evidence for a Mid-Paleozoic dipole low | |
Louise M. A. Hawkins; J. Michael Grappone; Courtney J. Sprain; Patipan Saengduean; Edward J. Sage; Sheikerra Thomas-Cunningham; Banusha Kugabalan; Andrew J. Biggin | |
2021-08-24 | |
发表期刊 | Proceedings of the National Academy of Science
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出版年 | 2021 |
英文摘要 | The Mesozoic Dipole Low (MDL) is a period, covering at least ∼80 My, of low dipole moment that ended at the start of the Cretaceous Normal Superchron. Recent studies of Devonian age Siberian localities identified similarly low field values a few tens of million years prior to the Permo-Carboniferous Reverse Superchron (PCRS). To constrain the length and timing of this potential dipole low, this study presents paleointensity estimates from Strathmore (∼411 to 416 Ma) and Kinghorn (∼332 Ma) lava flows, United Kingdom. Both localities have been studied for paleomagnetic poles (Q values of 6 to 7), and the sites were assessed for their suitability for paleointensity from paleodirections, rock magnetic analysis, and microscopy. Thermal and microwave experiments were used to determine site mean paleointensity estimates of ∼3 to 51 μT (6 to 98 ZAm2) and 4 to 11 μT (9 to 27 ZAm2) from the Strathmore and Kinghorn localities, respectively. These, and all the sites from 200 to 500 Ma from the (updated) Paleointensity database (PINT15), were assessed using the Qualitative Paleointensity criteria (QPI). The procurement of reliable (QPI ≥ 5) weak paleointensity estimates from this and other studies indicates a period of low dipole moment (median field strength of 17 ZAm2) from 332 to 416 Ma. This “Mid-Paleozoic Dipole Low (MPDL)” bears a number of similarities to the MDL, including the substantial increase in field strength near the onset of the PCRS. The MPDL also adds support to the inverse relationship between reversal frequency and field strength and a possible ∼200-My cycle in paleomagnetic behavior relating to mantle convection. |
领域 | 地球科学 |
URL | 查看原文 |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/335981 |
专题 | 地球科学 |
推荐引用方式 GB/T 7714 | Louise M. A. Hawkins,J. Michael Grappone,Courtney J. Sprain,et al. Intensity of the Earth's magnetic field: Evidence for a Mid-Paleozoic dipole low[J]. Proceedings of the National Academy of Science,2021. |
APA | Louise M. A. Hawkins.,J. Michael Grappone.,Courtney J. Sprain.,Patipan Saengduean.,Edward J. Sage.,...&Andrew J. Biggin.(2021).Intensity of the Earth's magnetic field: Evidence for a Mid-Paleozoic dipole low.Proceedings of the National Academy of Science. |
MLA | Louise M. A. Hawkins,et al."Intensity of the Earth's magnetic field: Evidence for a Mid-Paleozoic dipole low".Proceedings of the National Academy of Science (2021). |
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