Archeomagnetism of Ontario potsherds from the last 2000 years

Yu, Yongjae; Dunlop, David J.; Pavlish, L. A.; Cooper, Martin

doi:10.1029/2000jb900177

Cited by 21 publications

(15 citation statements)

References 29 publications

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“…The same procedures were followed for the second set of 60 specimens, Atm. is the heating atmosphere: A, air, H, helium; N is the number of points used in paleointensity determination; vT is the interval of temperature used in slope calculation; f and g are NRM fraction and gap factor, respectively [45]; SP is the quality factor de¢ned by Yu et al [46]; H þ c are the estimated paleointensity and its standard error after AARM correction. b The uncertainty in the mean is the standard deviation rather than the commonly used standard error [45].…”

Section: Paleointensity Experiments and Resultsmentioning

confidence: 99%

Multivectorial paleointensity determination from the Cordova Gabbro, southern Ontario

Dunlop

2002

Earth and Planetary Science Letters

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We report geomagnetic field intensities for the A (V1000 Ma) and B (V850 Ma) natural remanent magnetizations of the Cordova Gabbro of southern Ontario. We interpret A and B to be secondary thermal overprints produced during regional uplift and cooling following the Grenvillian Orogeny. Multivectorial A+B paleointensity data were analyzed using pairs of Arai diagrams for the separated A and B vectors. From 18 reliable A results and 15 reliable B results, we find paleofield values of 18.1 þ 2.1 WT and 7.1 þ 1.5 WT, respectively. The corresponding virtual axial dipole moments (VADMs) are (3.12 þ 0.36) and (1.82 þ 0.38)U10 22 A m 2 , about 70% and 40% of the average Phanerozoic dipole moment based on data from 0.3^300 Ma. The Cordova data and other Precambrian paleointensities are generally within a range of approximately 0.5^1.5 times the Phanerozoic mean VADM. Three sets of paleofield values as a function of paleolatitude, including the Cordova data, support a dipole configuration for the Earth's field in 251 50 Ma time windows around 2700 Ma, 1100 Ma, and 850 Ma. ß

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Section: Paleointensity Experiments and Resultsmentioning

confidence: 99%

Multivectorial paleointensity determination from the Cordova Gabbro, southern Ontario

Dunlop

2002

Earth and Planetary Science Letters

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“…In a palaeointensity study on older potsherds from Ontario, Yu and Dunlop (2000) concluded that there is no correlation between the degree of remanence anisotropy and the estimated palaeointensity value. However, in our study, we were able to show that the values of the correcting factor of palaeointensity determinations, even if is low, depend on the degree of remanent anisotropy and also on the angle between the NRM direction and the laboratory field direction.…”

Section: Discussionmentioning

confidence: 99%

Remanence anisotropy effect on the palaeointensity results obtained from various archaeological materials, excluding pottery

et al. 2009

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The effect of magnetic anisotropy on the palaeointensity results has been evaluated in different materials, including samples from archaeological structures of various ages, such as baked clay from prehistoric domestic ovens or pottery kilns, burnt soil from ancient fires, and bricks and bricks or tiles used in the kiln's construction. The remanence anisotropy was estimated by the thermoremanent (TRM) anisotropy tensor and isothermal remanence (IRM) tensor methods. The small anisotropy effect (less than 5%) observed in the palaeointensity results of baked clay from the relatively thin prehistoric oven's floors estimated previously through IRM anisotropy was confirmed by TRM anisotropy of this material. The new results demonstrate the possibility of using IRM anisotropy evaluation to correct baked clay palaeointensity data instead of the more difficult to determine TRM anisotropy ellipsoid. This is not always the case for the palaeointensity results from bricks and tiles. The anisotropy correction to palaeointensity results seems negligible for materials other than pottery. It would therefore appear that the palaeointensity determination is more sensitive to the degree of remanence anisotropy P and the angle between the natural remanent magnetization (NRM) vector and the laboratory field direction, than to the angle between the NRM and the maximum axis of the remanence anisotropy ellipsoid (K max ).

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“…Directional and intensity data obtained from these materials have been used to produce reference curves for the past few millennia. 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).…”

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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Archeomagnetism of Ontario potsherds from the last 2000 years

Abstract: Abstract. An archeomagnetic study was carried out on potsherds samples from sites in

Cited by 21 publications

References 29 publications

Multivectorial paleointensity determination from the Cordova Gabbro, southern Ontario

Multivectorial paleointensity determination from the Cordova Gabbro, southern Ontario

Remanence anisotropy effect on the palaeointensity results obtained from various archaeological materials, excluding pottery

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

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