A reversal of the Earth's magnetic field recorded in mid‐Miocene lava flows of Gran Canaria: Paleodirections

Leonhardt, Roman; Matzka, Jürgen; Hufenbecher, Felix; Soffel, H.; Heider, Franz

doi:10.1029/2001jb000322

Cited by 18 publications

(27 citation statements)

References 28 publications

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“…Mankinen et al 1985;Hoffman 1991;McElhinny et al 1996;Széréméta et al 1999). Recently, a similar field recurrence was reported from another volcanic record of a mid-Miocene geomagnetic reversal found in Gran Canaria (Leonhardt et al 2002). Directional groups can be interpreted either as multiple records of a single direction of a constantly changing geomagnetic field that are due to a brief outburst of volcanic activity (Mankinen et al 1985) or as reflecting a standstill of the geomagnetic field direction (Hoffman 1991).…”

Section: Discussion a N D C O N C L U S I O N Ssupporting

confidence: 63%

“…In the original study, not all the consecutive flows were sampled and only one (long) core was collected from each sampled flow. While there are several well-documented records of Upper Cenozoic reversals (Mankinen et al 1985;Prévot et al 1985a,b;Chauvin et al 1990;Kristjansson & Sigurgeirsson 1993;Goguitchaichvili et al 1999;Leonhardt et al 2002), the Lesotho reversal is to date the only detailed volcanic record of a geomagnetic transition that occurred during a long period of dipole low. According to Kosterov et al (1997) the average field intensity during the Early Jurassic was only half of the Late Cenozoic value.…”

Section: Introductionmentioning

confidence: 99%

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Revisiting the Jurassic geomagnetic reversal recorded in the Lesotho Basalt (Southern Africa)

Prévot¹,

Roberts²,

Thompson³

et al. 2003

Geophysical Journal International

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SUMMARY We carried out a detailed and continuous palaeomagnetic sampling of the reversed to normal geomagnetic transition recorded by some 60 consecutive flow units near the base of the Lesotho Basalt (183 ± 1 Ma). After alternating field or thermal cleaning the directions of remanence are generally well clustered within flow units. In contrast, the thermal instability of the samples did not allow us to obtain reliable palaeointensity determinations. The geomagnetic transition is incompletely recorded due to a gap in volcanic activity attested to both by eolian deposits and a large angular distance between the field directions of the flows underlying or overlying these deposits. The transition path is noticeably different from that reported in a pioneering work carried out in 1962. The most transitional virtual geomagnetic poles (VGPs) are observed after the volcanic hiatus. Once continents are replaced in their relative position 180 Myr, the post‐hiatus VGPs cluster over Russia. However, two successive rebounds from that cluster are found, with VGPs reaching repeatedly the Eastern Asia coast. Thus, the VGP path is not narrowly constrained in palaeolongitude. The decrease in intensity of magnetization as the field deviates from the normal or reversed direction suggests that the decrease in field magnitude during the reversal reached 80–90 per cent. We conclude that although the reversal is of a dipole of much weaker moment than that which existed on average during Cenozoic time, the characteristics of the reversing geodynamo seem to be basically similar.

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Section: Discussion a N D C O N C L U S I O N Ssupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Revisiting the Jurassic geomagnetic reversal recorded in the Lesotho Basalt (Southern Africa)

Prévot¹,

Roberts²,

Thompson³

et al. 2003

Geophysical Journal International

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“…Shcherbakova et al (Calvo Rathert et al 2009;Goguitchaichvili et al 2000Goguitchaichvili et al , 2002aGoguitchaichvili et al , 2003Juarez et al 1998;Lawrence et al 2009;Leonhardt et al 2000Leonhardt et al , 2002Leonhardt & Soffel 2006;Linder & Leonhardt 2009;Prévot et al 1985;Selkin & Tauxe 2000;Shcherbakova et al 2010;Shi et al 2002;Tauxe 2006;), (b) Cretaceous Normal Superchron, (c) the Cretaceous excluding CNS, (d) Middle-Upper Jurassic (Bol'shakov et al 1987;Sakai & Funaki 1988). Shcherbakova et al (Calvo Rathert et al 2009;Goguitchaichvili et al 2000Goguitchaichvili et al , 2002aGoguitchaichvili et al , 2003Juarez et al 1998;Lawrence et al 2009;Leonhardt et al 2000Leonhardt et al , 2002Leonhardt & Soffel 2006;Linder & Leonhardt 2009;Prévot et al 1985;Selkin & Tauxe 2000;Shcherbakova et al 2010;Shi et al 2002;Tauxe 2006;), (b) Cretaceous Normal Superchron, (c) the Cretaceous excluding CNS, (d) Middle-Upper Jurassic (Bol'shakov et al 1987;Sakai & Funaki 1988).…”

Section: Discussionmentioning

confidence: 99%

Palaeointensity and palaeomagnetic study of Cretaceous and Palaeocene rocks from Western Antarctica

Щербакова¹,

Бахмутов

Щербаков³

et al. 2012

Geophysical Journal International

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SUMMARY A combined palaeodirectional and palaeointensity study of a representative collection of plutonic rocks from the Antarctic Peninsula batholith from the western part of the Antarctic Peninsula, near the Ukrainian Antarctic base 'Academik Vernadsky' were carried out. Petrographically, the collection includes gabbros, diorites and quartz diorites, tonalities, granodiorites and granites. The ages of igneous complex emplacement vary from 50 to 117 Ma with most of the rocks belonging to the Cretaceous Normal Superchron. The characteristic remanent magnetizations were isolated by stepwise thermal demagnetization over the temperature interval 440–590°C and their intensities amount to 95 per cent of the NRM. The geographic positions of palaeopoles do not contradict the ‘key poles’ of the Antarctic Peninsula between 90 and 60 Ma. A significant part of the collection was subjected to Coe‐modified Thellier palaeointensity experiments with the pTRM checks, which yielded seven reliable palaeointensity determinations for seven different locations. The obtained VDMs are relatively low for all sites, being on average about half of the present day VDM. The analysis of available palaeointensity data for the Cretaceous, Miocene and Middle Jurassic indicates the existence of strong correlations between the mean VDM and VDM scatter versus the rate of reversals. However, due to the shortage of data, the correlations are not significant at the 5 per cent significance level.

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“…Specifically, lava flow sequences can be particularly helpful in revealing the behavior of the EMF during an extended time. This type of records can be found in sequences characterized by sequential image lava flow eruptions (e.g., Caccavari et al, ; Camps et al, ; Chauvin et al, ; Herrero‐Bervera & Valet, ; Jarboe et al, ; Kissel et al, ; Leonhardt et al, ; Mankinen et al, ; Moulin et al, ; Prévot et al, ).…”

Section: Introductionmentioning

confidence: 93%

Evidence of Unusual Geomagnetic Regimes Recorded in Plio‐Pleistocene Volcanic Sequences from the Lesser Caucasus (Southern Georgia)

Sánchez‐Moreno

Calvo‐Rathert

Goguitchaichvili

et al. 2018

Geochem Geophys Geosyst

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We report a detailed paleomagnetic study on two Plio‐Pleistocene lava flow sequences from the Djavakheti Highland, Lesser Caucasus. The Korkhi sequence is composed of two volcanic successions of distinct age (1.9 and 3.1 Ma), while the Apnia sequence was emplaced between 3.8 and 3.1 Ma according to available radiometric datings. Normal, reverse and intermediate polarities have been determined from both sequences. Mean directions of the normal and reverse polarity groups for each section do not match the expected field direction, but the possibility of tectonic rotations has been dismissed. A composite analysis of paleomagnetic directions, of virtual geomagnetic pole (VGP) scatter and available paleointensity results from a previous study, allow the interpretation of the observed paleomagnetic results. In the Apnia sequence, both a short recording time unable to average paleosecular variation (PSV) and an anomalous Earth magnetic field (EMF) record are responsible for the observed paleomagnetic directions. According to paleomagnetic results and radiometric ages, this sequence most probably records the reverse to normal polarity transition C2Ar to C2An‐3n. The upper Korkhi subsequence yields an anomalous EMF record, reflecting a transitional time interval. Paleomagnetic results and available absolute ages suggest that this subsequence either records transition C2r‐1r to Olduvai or Olduvai to C1r‐2r. The lower Korkhi subsequence registers a normal polarity interval within the Gauss chron, reflecting a stable stage of the EMF.

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A reversal of the Earth's magnetic field recorded in mid‐Miocene lava flows of Gran Canaria: Paleodirections

Cited by 18 publications

References 28 publications

Revisiting the Jurassic geomagnetic reversal recorded in the Lesotho Basalt (Southern Africa)

Revisiting the Jurassic geomagnetic reversal recorded in the Lesotho Basalt (Southern Africa)

Palaeointensity and palaeomagnetic study of Cretaceous and Palaeocene rocks from Western Antarctica

Evidence of Unusual Geomagnetic Regimes Recorded in Plio‐Pleistocene Volcanic Sequences from the Lesser Caucasus (Southern Georgia)

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