Characterizing the Geomagnetic Field at High Southern Latitudes: Evidence From the Antarctic Peninsula

Biasi, Joseph; Kirschvink, Joseph L.; Fu, R. R.

doi:10.1029/2021jb023273

Cited by 4 publications

(3 citation statements)

References 89 publications

(185 reference statements)

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“…Therefore, we focused on studies for which the measurement level data were available, and applied the same selection criteria. Seven studies met these requirements (Asefaw et al., 2021; Biasi et al., 2021; Cai et al., 2017; Cromwell, Tauxe, & Halldorsson, 2015; Leonhardt et al., 2003; Tauxe & Love, 2003; Wang et al., 2015). The data were either in the MagIC database (http://earthref.org/MagIC) already, or the authors agreed to share their measurement level data.…”

Section: Discussionmentioning

confidence: 99%

“…Biasi et al. (2021) sampled 31 sites from the James Ross Island in the Antarctic Peninsula and subjected them to the IZZI protocol (Yu et al., 2004), Tsunakawa‐Shaw (Yamamoto & Yamaoka, 2018) and the pseudo‐Thellier method (Tauxe et al., 1995) “calibrated” using the approach of de Groot et al. (2013).…”

Section: Discussionmentioning

confidence: 99%

“…The two successful sites from the Galapagos are insufficient for a meaningful average. Biasi et al (2021) sampled 31 sites from the James Ross Island in the Antarctic Peninsula and subjected them to the IZZI protocol (Yu et al, 2004), Tsunakawa-Shaw (Yamamoto & Yamaoka, 2018) and the pseudo-Thellier method (Tauxe et al, 1995) "calibrated" using the approach of de Groot et al (2013). None of these data passed the CCRIT or BiCEP criteria used here, so we proceed with the data from Iceland, Hawaii and Antarctica (see Figure 7 for locations).…”

Section: Comparison Of Intensities With Similar Studies From Elsewherementioning

confidence: 99%

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Paleointensity Estimates From the Pleistocene of Northern Israel: Implications for Hemispheric Asymmetry in the Time‐Averaged Field

Tauxe

Asefaw

Behar

et al. 2022

Geochem Geophys Geosyst

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Twenty‐two sites, subjected to an IZZI‐modified Thellier‐Thellier experiment and strict selection criteria, recover a paleomagnetic axial dipole moment (PADM) of 62.2 ± 30.6 ZAm2 in Northern Israel over the Pleistocene (0.012–2.58 Ma). Pleistocene data from comparable studies from Antarctica, Iceland, and Hawaii, re‐analyzed using the same criteria and age range, show that the Northern Israeli data are on average slightly higher than those from Iceland (PADM = 53.8 ± 23 ZAm2, n = 51 sites) and even higher than the Antarctica average (PADM = 40.3 ± 17.3 ZAm2, n = 42 sites). Also, the data from the Hawaiian drill core, HSDP2, spanning the last half million years (PADM = 76.7 ± 21.3 ZAm2, n = 59 sites) are higher than those from Northern Israel. These results, when compared to Pleistocene results filtered from the PINT database (http://www.pintdb.org) suggest that data from the Northern hemisphere mid‐latitudes are on average higher than those from the southern hemisphere and than those from latitudes higher than 60°N. The weaker intensities found at high (northern and southern) latitudes therefore, cannot be attributed to inadequate spatiotemporal sampling of a time‐varying dipole moment or low quality data. The high fields in mid‐latitude northern hemisphere could result from long‐lived non‐axial dipole terms in the geomagnetic field with episodes of high field intensities occurring at different times in different longitudes. This hypothesis is supported by an asymmetry predicted from the Holocene, 100 kyr, and 5 million year time‐averaged geomagnetic field models.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Comparison Of Intensities With Similar Studies From Elsewherementioning

confidence: 99%

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Paleointensity Estimates From the Pleistocene of Northern Israel: Implications for Hemispheric Asymmetry in the Time‐Averaged Field

Tauxe

Asefaw

Behar

et al. 2022

Geochem Geophys Geosyst

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MCADAM: A Continuous Paleomagnetic Dipole Moment Model for at Least 3.7 Billion Years

Bono

Paterson

Biggin

2022

Geophysical Research Letters

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The evolution of Earth's deep interior since core formation (Nimmo, 2015) >4 billion years ago (Ga) remains a topic of considerable study. Obtaining information of the deep interior is generally restricted to present-day observations. Alternatively, insights on processes occurring before the modern era require sampling geologic materials that formed at, or were transported to, Earth's surface. However, the geomagnetic field is generated in the liquid fraction of Earth's core through the geodynamo, and changes in the morphology, strength and variability in the geodynamo may reflect the evolution of core processes and the pattern of heat flux across the core-mantle boundary. The geomagnetic field is also a critical component for Earth's habitability (Rodríguez-Mozos & Moya, 2017) due to the protective envelope provided by the magnetosphere against atmospheric erosion by charged solar particles. It is speculated that changes in the paleomagnetosphere may have contributed to substantial changes in the evolution of life (e.g., Meert et al., 2016).Paleomagnetic studies offer the potential to help close this gap: when rocks bearing magnetic carriers form, the geomagnetic field imparts a remanent magnetization that under ideal circumstances can be robustly preserved for billions of years. The strength of the geodynamo can be described by the magnitude of the dipole moment, the first-degree spherical harmonic component of the field, which should reflect ∼90% of the surface field signal. A fundamental question regarding Earth's dynamo is how the dipole moment has changed over long timescales (≫millions of years). Paleointensities measured from the same geologic time (e.g., from the same cooling-unit, referred to as a "site") can be related to paleointensities from other locations by transforming the paleointensity (B) into a virtual (axial) dipole moment (V(A)DM) using the following equation (Smith, 1967):

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Thermal rock magnetic cycling (TRMC): a method to track thermal alteration details for palaeointensity interpretations

Miao,

Wang

2024

Geophysical Journal International

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Summary Accurate absolute palaeointensity is essential for understanding dynamo processes on the Earth and other planetary bodies. Although great efforts have been made to propose techniques to obtain magnetic field strength from rock samples, such as Thellier-series methods, the amount of high-fidelity palaeointensities remains limited. One primary reason for this is the thermal alteration of samples that pervasively occurred during palaeointensity experiments. In this study, we developed a comprehensive rock magnetic experiment, termed thermal rock magnetic cycling (TRMC), that can utilize measurements of critical rock magnetic properties at elevated temperatures during multiple heating-cooling cycles to track thermal changes in bulk samples and individual magnetic components with different Curie temperatures in samples for palaeointensity interpretations. We demonstrate this method on a Galapagos lava sample, GA 84.6. The results for this specimen revealed that GA 84.6v underwent thermophysical alteration throughout the TRMC experiment, resulting in changes in its remanence carrying capacity. These findings were then used to interpret the palaeointensity results of specimen GA 84.6c, which revealed that the two-slope Arai plot yielded two linear segments with distinct palaeointensity values that were both biased by thermophysical alteration. To further test the TRMC method, we selected another historical lava sample (HS 2) from Mt. Lassen, detecting slight thermal-physical changes after heating the specimen HS 2–8C to a target temperature of 400° C. We also isolated a stable magnetic component with a Curie temperature below 400° C using the TRMC method, which may provide a more reliable palaeointensity estimate of 51 μT. By providing a method for tracking thermal alteration independent of palaeointensity experiments, the TRMC method can explore subtle, unrecognizable thermal alteration processes in less detailed palaeointensity measurements, which can help to assess the thermal stability of the measured samples and interpret the changes in the TRM unblocking spectrum and palaeointensity estimates, facilitating the acquisition of more reliable records for constrain the formation of the inner core and the evolution of Earth's magnetic field.

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Characterizing the Geomagnetic Field at High Southern Latitudes: Evidence From the Antarctic Peninsula

Cited by 4 publications

References 89 publications

Paleointensity Estimates From the Pleistocene of Northern Israel: Implications for Hemispheric Asymmetry in the Time‐Averaged Field

Paleointensity Estimates From the Pleistocene of Northern Israel: Implications for Hemispheric Asymmetry in the Time‐Averaged Field

MCADAM: A Continuous Paleomagnetic Dipole Moment Model for at Least 3.7 Billion Years

Thermal rock magnetic cycling (TRMC): a method to track thermal alteration details for palaeointensity interpretations

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