Paleointensity variations across the last geomagnetic reversal at La Palma, Canary Islands, Spain

Valet, Jean‐Pierre; Brassart, Jacques; Quidelleur, Xavier; Soler, Vicente; Gillot, Pierre‐Yves; Hongre, Lionel

doi:10.1029/1998jb900099

Cited by 53 publications

(35 citation statements)

References 38 publications

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“…Local investigations of paleomagnetic field strength indicate low values for mid-Miocene rocks from the Canaries, approximately half of the present day field intensity (Leonhardt et al 2000;Leonhardt and Soffel 2002) and values in the range of the present day field around the last polarity reversal, the 0.78 Ma Matuyama/Brunhes transition (Valet et al 1999). Such a geomagnetic field intensity difference between the Miocene and the Pleistocene is found globally (Juá rez et al 1998;Selkin and Tauxe 2000;Shcherbakov et al 2002;Heller et al 2002).…”

Section: Introductionmentioning

confidence: 84%

The growth, collapse and quiescence of Teno volcano, Tenerife: new constraints from paleomagnetic data

Leonhardt

Soffel

2006

Int J Earth Sci (Geol Rundsch)

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Tenerife basically consists of three Miocene shield volcanoes, the Anaga, the Teno and Central shield, as well as the Pliocene Cañ adas volcano. The temporal evolution and structural significance of each volcano with respect to the history of Tenerife is still a matter of debate. We present paleomagnetic results in order to enhance the view of the volcanic history of the Teno volcano by means of magnetostratigraphy. It is found that the initial subaerial phase shows reverse magnetizations throughout. After two major sector collapses, dominantly normally magnetized lavas extruded. Comparisons of observed magnetic polarities with the geomagnetic polarity timescale show that these volcanic activities occurred within 0.4 Myr between 6.3 and 5.9 Ma. Significantly younger flows, 5.3 Myr old according to their radiometric age, revealed again normal polarity throughout. The absence of inversely magnetized lavas in-between the two normal periods indicates a volcanic hiatus or erosional phase. The evolutionary sequence and the estimated high production rates for the initial building phase are similar as would be expected for a hotspot volcano. The average geomagnetic field for 6.0 -0.2 Ma is close to an axial dipole field showing a slight far-sided/right-handed effect. The field strength, determined by Thellier-type intensity determinations, corresponds to a virtual axial dipole moment of 4.9 · 10 22 A m 2 . This value is approximately half of the present day field strength, but similar to values obtained for the mid-Miocene. It also corresponds to the proposed tertiary low-field level of the geomagnetic dipole moment.

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Section: Introductionmentioning

confidence: 84%

The growth, collapse and quiescence of Teno volcano, Tenerife: new constraints from paleomagnetic data

Leonhardt

Soffel

2006

Int J Earth Sci (Geol Rundsch)

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“…There is now a general agreement among the paleomagnetic community that intensity drops significantly compared to the stable field during the large departures of the geomagnetic field from the axial dipole position (Laj and Channell, 2007). It has also been observed that polarity transitions is first expressed in the intensity record than in the directional one (Valet et al, 1999;Prévot et al, 1985a, b;Riisager et al, 2000). No systematic intensity drops are related, however, to the pre and post transitional regimes.…”

Section: Introductionmentioning

confidence: 78%

Absolute paleointensity determinations by using of conventional double-heating and multispecimen approaches on a Pliocene lava flow sequence from the Lesser Caucasus

Goguitchaichvili

Caccavari

Calvo‐Rathert

et al. 2016

Physics of the Earth and Planetary Interiors

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“…The non-dipole field is given by the harmonic contributions from 2 to 6. reversal, where the north magnetic pole moved toward the Southern geographic pole reaching the present normal polarity. This feature has been deeply studied becoming the best documented past geomagnetic event in the basis of the huge density of paleomagnetic data recording this polarity transition (see Valet et al, 1999 for a review). During the last decade, these paleomagnetic data have been used to model the behavior of the geomagnetic field during this transition (Leonhardt and Fabian, 2007) or to constrain the geodynamo numerical simulations (e.g., Aubert et al, 2008) pointing out different scenarios for the precedent phase of a geomagnetic reversal.…”

Section: Discussionmentioning

confidence: 99%

“…On the other hand, according to other studies (Hartmann and Pacca, 2009;De Santis et al, 2013), the behavior of the SAA during the last centuries is related to the higher harmonic degrees n = 2 and 3, i.e., the quadrupole and octupole fields. This is an important issue because these non-dipolar contributions play an important role during the geomagnetic reversals that are characterized by high ratios between the non-dipolar over dipolar contribution (e.g., Valet et al, 1999). In this paper we have analyzed in more details how these both contributions, i.e., the dipolar (n = 1) and non-dipolar (n > 1), affect to the evolution of the SAA during the last two centuries.…”

Section: The Origin Of the Saa: A Case Study For The Last 200 Yearsmentioning

confidence: 99%

The South Atlantic Anomaly: The Key for a Possible Geomagnetic Reversal

Pavón‐Carrasco

Santis

2016

Front. Earth Sci.

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The South Atlantic Anomaly is nowadays one of the most important features of the Earth's magnetic field. Its extent area at the Earth's surface is continuously growing since the intensity instrumental measurements are available covering part of the Southern Hemisphere and centered in South America. Several studies associate this anomaly as an indicator of an upcoming geomagnetic transition, such an excursion or reversal. In this paper we carry out a detailed study about this issue using the most recent models that also include data from the last ESA mission Swarm. Our results reveal that one of the reversed polarity patch located at the CMB under the South Atlantic Ocean is growing with a pronounced rate of −2.54·10 5 nT per century and with western drift. In addition, we demonstrate that the quadrupole field mainly controls this reversal patch along with the rapid decay of the dipolar field. The presence of the reversal patches at the CMB seems to be characteristic during the preparation phase of a geomagnetic transition. However, the current value of the dipolar moment (7.7 10 22 A 2 ·m ) is not so low when compared with recent paleomagnetic data for the Holocene (last 12 ka) and for the entire Brunhes geomagnetic normal polarity (last ∼0.8 Ma), although the rate of decay is similar to that given by previous documented geomagnetic reversals or excursions.

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Paleointensity variations across the last geomagnetic reversal at La Palma, Canary Islands, Spain

Cited by 53 publications

References 38 publications

The growth, collapse and quiescence of Teno volcano, Tenerife: new constraints from paleomagnetic data

The growth, collapse and quiescence of Teno volcano, Tenerife: new constraints from paleomagnetic data

Absolute paleointensity determinations by using of conventional double-heating and multispecimen approaches on a Pliocene lava flow sequence from the Lesser Caucasus

The South Atlantic Anomaly: The Key for a Possible Geomagnetic Reversal

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