Paleointensity determination from São Miguel (Azores Archipelago) over the last 3ka

Chiara, Anita Di; Tauxe, Lisa; Speranza, Fabio

doi:10.1016/j.pepi.2014.06.008

Cited by 27 publications

(21 citation statements)

References 103 publications

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“…In addition to these data from dominantly biogenic marine sediments (Figure 3a), data from mixed biogenicterrigenous marine sediments (Figure 3b) and from dominantly terrigenous marine sediments (Figure 3d) fall on a similar trend (Figure 9f). Hysteresis data from basalts (Di Chiara et al, 2014) fall on the same trend (Figure 9g). Intriguingly, this trend for sedimentary and volcanic data falls on a line calculated here for mixtures of MD magnetite and SD particles with cubic anisotropy (for parameters, see Table 1), or the multiaxial anisotropy proposed by Tauxe et al (2002), rather than on the lines of Dunlop (2002a).…”

Section: 1002/2017jb015247mentioning

confidence: 56%

“…(a) Biogenic‐dominated marine sediments from the Southern Ocean (summarized by Roberts et al, ), (b) mixed biogenic‐terrigenous marine sediments from the Mediterranean Sea (Dinarès‐Turell et al, ), (c) glaci‐marine sediment from Victoria Land Basin, Ross Sea, Antarctica (summarized by Roberts, Sagnotti, et al, ), (d) terrigenous marine sediments from the North Pacific Ocean (Roberts et al, ), and (e) various lake sediments from the Great Basin, western USA (summarized by Roberts et al, ). (f) Hysteresis results for igneous rocks, including submarine basaltic glass (Tauxe et al, ) and basalts from the Azores (Di Chiara et al, ) and from Mt St. Helens, USA, Mt Vesuvius, Italy, and Volcan Láscar, Chile (Paterson et al, ).…”

Section: Factors That Affect Data Distributions In a Day Diagrammentioning

confidence: 99%

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A Critical Appraisal of the “Day” Diagram

et al. 2018

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The “Day” diagram (Day et al., 1977, https://doi.org/10.1016/0031-9201(77)90108-X) is used widely to make inferences about the domain state of magnetic mineral assemblages. Based on theoretical and empirical arguments, the Day diagram is demarcated into stable “single domain” (SD), “pseudo single domain” (“PSD”), and “multidomain” (MD) zones. It is straightforward to make the necessary measurements for a sample and to plot results within the “domain state” framework based on the boundaries defined by Day et al. (1977, https://doi.org/10.1016/0031-9201(77)90108-X). We discuss 10 issues that limit Day diagram interpretation, including (1) magnetic mineralogy, (2) the associated magnetocrystalline anisotropy type, (3) mineral stoichiometry, (4) stress state, (5) surface oxidation, (6) magnetostatic interactions, (7) particle shape, (8) thermal relaxation, (9) magnetic particle mixtures, and (10) definitional/measurement issues. In most studies, these variables are unknowns and cannot be controlled for, so that hysteresis parameters for single bulk samples are nonunique and any data point in a Day diagram could result from infinite combinations of relevant variables. From this critical appraisal, we argue that the Day diagram is fundamentally ambiguous for domain state diagnosis. Widespread use of the Day diagram has also contributed significantly to prevalent but questionable views, including underrecognition of the importance of stable SD particles in the geological record and reinforcement of the unhelpful PSD concept and of its geological importance. Adoption of approaches that enable correct domain state diagnosis should be an urgent priority for component‐specific understanding of magnetic mineral assemblages and for quantitative rock magnetic interpretation.

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Section: 1002/2017jb015247mentioning

confidence: 56%

Section: Factors That Affect Data Distributions In a Day Diagrammentioning

confidence: 99%

A Critical Appraisal of the “Day” Diagram

et al. 2018

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“…Here we used the GEOMAGIA50.v3 database (Donadini et al 2006;Korhonen et al 2008;Brown et al 2015) to which we added recent archeo-and paleointensity results (Cai et al 2014(Cai et al , 2015Cromwell et al 2015;de Groot et al 2015;Di Chiara et al 2014;Gallet et al 2008Gallet et al , 2009Gallet & Al Maqdissi 2010;Hong et al 2013;Kapper et al 2015;Kissel et al 2015;Osete et al 2015;Shaar et al 2015;Stillinger et al 2015). Concerning the data compiled in this version of GEOMAGIA, the Mesopotamian data from Nachasova & Burakov (1995 were modified according to .…”

Section: Appendix A: Gmag9k Axial Dipole Evolutionmentioning

confidence: 99%

Solar activity during the Holocene: the Hallstatt cycle and its consequence for grand minima and maxima

Usoskin

Gallet

Lopes

et al. 2016

A&A

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Aims. Cosmogenic isotopes provide the only quantitative proxy for analyzing the long-term solar variability over a centennial timescale. While essential progress has been achieved in both measurements and modeling of the cosmogenic proxy, uncertainties still remain in the determination of the geomagnetic dipole moment evolution. Here we aim at improving the reconstruction of solar activity over the past nine millennia using a multi-proxy approach. Methods. We used records of the 14 C and 10 Be cosmogenic isotopes, current numerical models of the isotope production and transport in Earth's atmosphere, and available geomagnetic field reconstructions, including a new reconstruction relying on an updated archeo-and paleointensity database. The obtained series were analyzed using the singular spectrum analysis (SSA) method to study the millennial-scale trends. Results. A new reconstruction of the geomagnetic dipole field moment, referred to as GMAG.9k, is built for the last nine millennia. New reconstructions of solar activity covering the last nine millennia, quantified in terms of sunspot numbers, are presented and analyzed. A conservative list of grand minima and maxima is also provided. Conclusions. The primary components of the reconstructed solar activity, as determined using the SSA method, are different for the series that are based on 14 C and 10 Be. This shows that these primary components can only be ascribed to long-term changes in the terrestrial system and not to the Sun. These components have therefore been removed from the reconstructed series. In contrast, the secondary SSA components of the reconstructed solar activity are found to be dominated by a common ≈2400-year quasi-periodicity, the so-called Hallstatt cycle, in both the 14 C and 10 Be based series. This Hallstatt cycle thus appears to be related to solar activity. Finally, we show that the grand minima and maxima occurred intermittently over the studied period, with clustering near lows and highs of the Hallstatt cycle, respectively.

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“…A large number of paleomagnetic studies that employ a Day-Dunlop plot find often that the samples fall into the PSD size range [e.g., Cinku et al, 2013;Di Chiara et al, 2014;Guzm an et al, 2011;Hao et al, 2012;Kapper et al, 2014;Li et al, 2014;Stanton et al, 2011;Tianshui et al, 2012]. One possible reason could be that the samples consist of mixtures of grain sizes.…”

Section: Introductionmentioning

confidence: 99%

Experimental mixtures of superparamagnetic and single‐domain magnetite with respect to Day‐Dunlop plots

Kumari

Hirt

Uebe

et al. 2015

Geochem Geophys Geosyst

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Day-Dunlop plots are widely used in paleomagnetic and environmental studies as a tool to determine the magnetic domain state of magnetite, i.e., superparamagnetic (SP), stable single-domain (SD), pseudosingle-domain (PSD), multidomain (MD), and their mixtures. The few experimental studies that have examined hysteresis properties of SD-SP mixtures of magnetite found that the ratios of saturation remanent magnetization to saturation magnetization and the coercivity of remanence to coercivity are low, when compared to expected theoretical mixing trends based on Langevin theory. This study reexamines DayDunlop plots using experimentally controlled mixtures of SD and SP magnetite grains. End-members include magnetotactic bacteria (MSR-1) as the SD source, and a commercial ferrofluid or magnetotactic bacteria (DA12) as the SP source. Each SP-component was added incrementally to a SD sample. Experimental results from these mixing series show that the magnetization and coercivity ratios are lower than the theoretical prediction for bulk SP magnetic size. Although steric repulsion was present between the particles, we cannot rule out interaction in the ferrofluid for higher concentrations. The SP bacteria are noninteracting as the magnetite was enclosed by an organic bilipid membrane. Our results demonstrate that the magnetization and coercivity ratios of SD-SP mixtures can lie in the PSD range, and that an unambiguous interpretation of particle size can only be made with information about the magnetic properties of the end-members.

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Paleointensity determination from São Miguel (Azores Archipelago) over the last 3ka

Cited by 27 publications

References 103 publications

A Critical Appraisal of the “Day” Diagram

A Critical Appraisal of the “Day” Diagram

Solar activity during the Holocene: the Hallstatt cycle and its consequence for grand minima and maxima

Experimental mixtures of superparamagnetic and single‐domain magnetite with respect to Day‐Dunlop plots

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