Paleointensity of the geomagnetic field recovered on archaeomagnetic sites from France

Chauvin, Annick; Garcia, Yannick; Lanos, Philippe; Laubenheimer, Fanette

doi:10.1016/s0031-9201(00)00148-5

Cited by 219 publications

(258 citation statements)

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“…While it is generally agreed that AMS is a poor approximation for ATRM, the preference for AARM and ATRM remains controversial. Some authors prefer the ATRM correction because in theory AARM is different from ATRM (Chauvin et al, 2000). Others argue that AARM is preferable because the corrections are usually similar (Ben-Yosef et al, 2008a;Mitra et al, 2013), it is faster to determine the AARM tensor than the ATRM one, and there is no further laboratory alteration with the AARM tensor.…”

Section: Anisotropy Correctionmentioning

confidence: 99%

“…Others argue that AARM is preferable because the corrections are usually similar (Ben-Yosef et al, 2008a;Mitra et al, 2013), it is faster to determine the AARM tensor than the ATRM one, and there is no further laboratory alteration with the AARM tensor. Some studies use a partial TRM (pTRM) to determine the ATRM tensor in order to avoid bias introduced by alteration when heating to high temperatures (Chauvin et al, 2000;Genevey and Gallet, 2002;Hill et al, 2008), while total TRMs are used in other studies based on the assumption that total TRM correction avoids the complications of pTRM tails that may affect pTRMs. The use of pTRM checks insures that the ATRM tensor has not been affected by alteration (Shaar et al, 2010(Shaar et al, , 2011.…”

Section: Anisotropy Correctionmentioning

confidence: 99%

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Geomagnetic intensity variations for the past 8 kyr: New archaeointensity results from Eastern China

Cai

Tauxe

Deng

et al. 2014

Earth and Planetary Science Letters

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In this study, we have carried out paleointensity experiments on 918 specimens spanning the last ∼7 kyr, including pottery fragments, baked clay and slag, collected from Shandong, Liaoning, Zhejiang and Hebei Provinces in China. Approximately half of the specimens yielded results that passed strict data selection criteria and give high-fidelity paleointensities. The virtual axial dipole moments (VADMs) of our sites range from ∼2 × 10 22 to ∼13 × 10 22 Am 2 . At ∼2250 BCE our results suggest a paleointensity low of ∼2 × 10 22 Am 2 , which increases to a high of ∼13 × 10 22 Am 2 by ∼1300 BCE. This rapid (less than 1000 yrs) six-fold change in the paleointensity may have important implications for the dynamics of core flow at this time. Our data from the last ∼3 kyr are generally in good agreement with the ARCH3k.1 model, but deviate significantly at certain time periods from the CALS3k.4 and CALS10k.1b model, which is likely due to differences in the data used to constrain these models. At ages older than ∼3 ka, where only the CALS10k.1b model is available for comparison, our data deviate significantly from the model. Combining our new results with the published data from China and Japan, we provide greatly improved constraints for the regional model of Eastern Asia. When comparing the variations of geomagnetic field in three global representative areas of Eastern Asia, the Middle East and Southern Europe, a common general trend of sinusoidal variations since ∼8 ka is shown, likely dominated by the dipole component. However, significant disparities are revealed as well, which we attribute to non-dipolar components caused by movement of magnetic flux patches at the core-mantle boundary.

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Section: Anisotropy Correctionmentioning

confidence: 99%

Section: Anisotropy Correctionmentioning

confidence: 99%

Geomagnetic intensity variations for the past 8 kyr: New archaeointensity results from Eastern China

Cai

Tauxe

Deng

et al. 2014

Earth and Planetary Science Letters

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“…This should correlate to the same amount of bias in paleointensity estimates. This prediction was directly tested in control experiments by changing the cooling time between a few minutes to tens of hours, and the prediction was generally supported, but with a large sample-to-sample variation of a factor of 3-5 (Fox and Aitken, 1980;Chauvin et al, 2000;Genevey and Gallet, 2002;Leonhardt et al, 2006;Ferk et al, 2010;Yu, 2011). For plutonic rocks, the theory predicts that the paleointensity estimate will overestimate the true field by ∼30-60%, and it has become common to use these values as correction factors (e.g., Tarduno et al, 2007;Selkin et al, 2008;Donadini et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Paleointensity estimates from oceanic gabbros: Effects of hydrothermal alteration and cooling rate

Usui

2013

Earth Planet Sp

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Gabbros recovered by previous ocean drillings were investigated in paleointensity and rock magnetic experiments. The young ages of the samples (ca. 0.78-1.3 Ma) enable a direct comparison between the plutonic paleointensity and volcanic data. Microscopic observations revealed two kinds of magnetite: needle-shaped exsolution in plagioclase and aggregate associated with the hydrothermal alteration of olivine. In Shaw paleointensity experiments, some samples revealed reasonable estimates, while some others showed an anomalously low ratio of natural remanent magnetization (NRM) versus thermoremanent magnetization (TRM). First-order reversal curve (FORC) diagrams indicated that the reasonable NRM/TRM were from non-interacting single domain magnetite exsolved in plagioclase, while the anomalously low NRM/TRM were from secondary magnetite associated with olivine. From the paleointensity results, the mean virtual axial dipole moment (VADM) was calculated to be 8.2 ± 2.1 10 22 Am 2 . Volcanic records in the PINT database for 0.78-1.3 Ma revealed a mean virtual dipole moment (VDM) of 6.3 ± 0.73 10 22 Am 2 . The difference between them is consistent with the theoretical prediction of the cooling rate effect on paleointensity. These results indicate that oceanic gabbros are reliable paleointensity recorders.

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“…Reference curves (also called master curves), which reveal the variations in the intensity of the geomagnetic field are now available for several regions, including North America, Meso-America, Eastern Asia, Eastern and Western Europe (e.g., Kovacheva, 1997;Yu et al, 2000;Morales et al, 2001;Bowles et al, 2002;Genevey et al, 2003;Soler-Arechalde et al, 2006; see also the compilations of Valet, 2003;Perrin and Schnepp, 2004;. Archeointensity data for Western Europe are concentrated on archeological sites from France (e.g., Chauvin et al, 2000;Gallet et al, 2002;Genevey and Gallet, 2002;Gallet et al, 2005) while only few results are available for the Iberian Peninsula (Kovacheva et al, 1995;Gómez-Paccard et al, 2006). Although abundant archeological remains are available in Portugal and Brazil, archeomagnetic studies are almost nonexistent.…”

Section: Introductionmentioning

confidence: 99%

First archeointensity results from Portuguese potteries (1550-1750 AD)

et al. 2009

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Geomagnetic field variations at archeomagnetic timescales can be obtained from well-dated heated structures and archeological potsherds. Here, we present the first archeointensity results obtained on Portuguese ceramics (1550 to 1750 AD) collected at Brazilian archeological sites. The results are compared to those obtained from Western Europe and currently available geomagnetic field models. Continuous thermomagnetic and IRM acquisitions curves indicate that Ti-poor titanomagnetite is responsible for the remanence in these ceramic fragments. Five fragments (24 samples) out of twelve analyzed yielded reliable intensity estimates. The row archeointensity data were corrected for TRM anisotropy and cooling rate effect. The mean dipole moments are obtained for three different age intervals: 1550±30 AD, 1600±30 AD and 1750±50 AD. Mean intensities vary from 37.9±4.2 μT to 54.8±7.6 μT in agreement with the previously reported data for 1550 AD and 1750 AD. Relatively weaker, but still highly dispersed, values were obtained for 1600 AD ceramics.

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Paleointensity of the geomagnetic field recovered on archaeomagnetic sites from France

Cited by 219 publications

References 43 publications

Geomagnetic intensity variations for the past 8 kyr: New archaeointensity results from Eastern China

Geomagnetic intensity variations for the past 8 kyr: New archaeointensity results from Eastern China

Paleointensity estimates from oceanic gabbros: Effects of hydrothermal alteration and cooling rate

First archeointensity results from Portuguese potteries (1550-1750 AD)

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