On low-latitude virtual geomagnetic poles in Icelandic basalt lava sequences

Kristjánsson, Leó

doi:10.1016/s0031-9201(99)00072-2

Cited by 13 publications

(17 citation statements)

References 14 publications

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“…In statistical models, the frequency of low-latitude virtual geomagnetic poles is greatest for high-latitude sites (29). And Ϸ10% of reliable virtual geomagnetic poles from Neogene Icelandic basalts show latitudes Ͻ40° (30,31). Interestingly, similar low-latitude VGPs are absent in our Arctic data (Fig.…”

Section: Paleosecular Variationmentioning

confidence: 59%

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The Cretaceous superchron geodynamo: Observations near the tangent cylinder

Tarduno

Cottrell²,

Смирнов³

2002

Proc. Natl. Acad. Sci. U.S.A.

130

106

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If relationships exist between the frequency of geomagnetic reversals and the morphology, secular variation, and intensity of Earth's magnetic field, they should be best expressed during superchrons, intervals tens of millions of years long lacking reversals. Here we report paleomagnetic and paleointensity data from lavas of the Cretaceous Normal Polarity Superchron that formed at high latitudes near the tangent cylinder that surrounds the solid inner core. The time-averaged field recorded by these lavas is remarkably strong and stable. When combined with global results available from lower latitudes, these data define a time-averaged field that is overwhelmingly dominated by the axial dipole (octupole components are insignificant). These observations suggest that the basic features of the geomagnetic field are intrinsically related. Superchrons may reflect times when the nature of coremantle boundary heat flux allows the geodynamo to operate at peak efficiency.

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Section: Paleosecular Variationmentioning

confidence: 59%

“…The Cretaceous Arctic region was at high latitudes near the tangent cylinder and should be especially sensitive to the extremes in secular variation (13,(29)(30)(31). The lack of large departures of poles from the mean in the Arctic dataset also suggests that fluctuations were not great enough to give rise to geomagnetic excursions.…”

Section: Discussionmentioning

confidence: 99%

The Cretaceous superchron geodynamo: Observations near the tangent cylinder

Tarduno

Cottrell²,

Смирнов³

2002

Proc. Natl. Acad. Sci. U.S.A.

130

106

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“…The cross-section runs southeast from GL and AF in the Öxnadalur valley through AS, SG, and KG, and then south through HO, VE and GR in the main Eyjafjördur valley (Eyjafjardardalur) of the volcanism, and the scarcity of radiometric dates, the usefulness of individual lava directions or groups of directions in stratigraphic work is limited. On the other hand, studies on overall statistical properties of these collections of remanence vectors have shed light on some characteristics of the field during the last 15 Ma (Kristjansson 1999(Kristjansson , 2002.…”

Section: Introductionmentioning

confidence: 99%

Stratigraphy and paleomagnetism of a 2.9-km composite lava section in Eyjafj�rdur, Northern Iceland: a reconnaissance study

Kristjánsson

Guðmundsson

Harðarson

2004

Int J Earth Sci (Geol Rundsch)

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Eight mountainside profiles in lava flows south of the fjord Eyjafjördur, Northern Iceland, were sampled for paleomagnetic studies. The sampling was concurrent with pilot stratigraphic mapping of the lava sequences in these and several supplementary profiles. The eight profiles are correlated with minor overlaps so that they form a composite section of 2.9 km thickness, estimated to cover the age range between about 9 and 5 million years ago (Hardarson et al. 1999). Paleomagnetic measurements made on 319 lavas generally yield primary remanence directions of high stability and within-unit consistency. Evidence for at least 17 reversals of the geomagnetic field is seen, as well as numerous field excursions. Frequent clustering of directions in successive lavas indicates that the volcanism was episodic.

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“…2.4 · 10 −3 cgs units). Both in these flows and in others of similar age from Eastern and Northern Iceland (Kristjánsson, 1984(Kristjánsson, , 1999, there is no overall correlation between remanence intensity and susceptibility.…”

Section: Magnetic Measurements and Quality Criteriamentioning

confidence: 67%

“…5(b), which also indicates some instances when lowor mid-latitude poles in successive lavas lie close to each other. Kristjánsson and Jóhannesson (1989) and Kristjánsson (1995Kristjánsson ( , 1999 included the data presented in this study, in their compilations. They discussed various aspects of the geomagnetic field dispersion such as the distribution of transitional geomagnetic poles in latitude and longitude.…”

Section: Mean Field Direction and Overall Scattermentioning

confidence: 99%

Secular variation and reversals in a composite 2.5 km thick lava section in central Western Iceland

Kristjánsson

Jóhannesson

2014

Earth Planet Sp

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The direction and intensity of primary remanence has been measured in oriented specimens from 367 lava flows of Late Miocene age in Western Iceland. The lavas which were sampled in 8 overlapping profiles, were generally good material for paleomagnetic measurements. In a 2500-m composite section, at least 15 reversals of polarity and several excursions are recorded. The mean remanence direction and other overall paleomagnetic parameters for the present collection of lavas are similar to those found elsewhere in Iceland. The average rate of buildup of this lava pile was rather low and possibly episodic. Hence, correlations to the geomagnetic polarity time scale and to polarity patterns in other composite sections mapped in Iceland are not straightforward.

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On low-latitude virtual geomagnetic poles in Icelandic basalt lava sequences

Cited by 13 publications

References 14 publications

The Cretaceous superchron geodynamo: Observations near the tangent cylinder

The Cretaceous superchron geodynamo: Observations near the tangent cylinder

Stratigraphy and paleomagnetism of a 2.9-km composite lava section in Eyjafj�rdur, Northern Iceland: a reconnaissance study

Secular variation and reversals in a composite 2.5 km thick lava section in central Western Iceland

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