Multidomain behavior during Thellier paleointensity experiments: a phenomenological model

Leonhardt, Roman; Krása, David; Coe, Robert S.

doi:10.1016/j.pepi.2004.01.009

Cited by 58 publications

(81 citation statements)

References 24 publications

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“…MT2 experiments enable one to identify components of magnetization acquired during the field-on step which are not removed by thermal demagnetization to the same temperature, either due to alteration or multidomain (MD)-tails. All other paleointensity determinations were performed with the modified Thellier-technique MT4, which is a zero-field first method incorporating pTRM checks, additivity checks (Krá sa et al 2003) and pTRM-tail checks (Riisager and Riisager 2001) evaluated with respect to the directional difference between applied field and NRM according to Leonhardt et al (2004b). pTRM checks were conducted for all methods in-field after the demagnetization step.…”

Section: Methodsmentioning

confidence: 99%

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: Methodsmentioning

confidence: 99%

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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“…The standard means to detect pTRM tails is to vector subtract the measurement made after the demagnetisation treatment from that made after the pTRM tail check treatment. However, this must then be corrected for intensity and angular differences between the natural and laboratory field (Leonhardt et al, 2004) to become a meaningful parameter. In Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Consequently it is also not relevant to the present study. Leonhardt et al (2004) and Biggin (2006) modified Fabian's model so that pTRM tails as observed in this study were included. Both of their models predict that the pTRM tails occupy a portion of the blocking temperature spectrum in a manner similar to a conventional pTRM in SD grains.…”

Section: Discussionmentioning

confidence: 99%

The behaviour and detection of partial thermoremanent magnetisation (PTRM) tails in Thellier palaeointensity experiments

Biggin

Perrin

2007

Earth Planet Sp

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We analyse the results of Thellier palaeointensity experiments modified so that the measured magnetisation at any stage may be decomposed into components of natural remanent magnetisation (NRM) and laboratory thermal remanent magnetisation (TRM). We demonstrate that the very long high temperature tails of pTRM acquired by multidomain (MD) grains may be detected in Thellier experiments without recourse to explicit pTRM tail check measurements. This can save time in the experimental process and provides a more sensitive indication of how MD behaviour may affect that particular experiment than either pTRM tail checks or the observation of zigzagging in an IZZI experiment. We observe that the action of imparting a pTRM tail also involves some removal of NRM. However, the pTRM tails are not the analogues of classical overprints as may be intuitively expected but instead appear to favour remagnetisation over demagnetisation. This and other observed behaviour is not consistent with any phenomenological model of MD TRM but is consistent with predictions made by kinematic theory.

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“…The experiments followed the modified Thellier-technique MT4 by Leonhardt et al (2004b), which is a zero-field first method that incorporates pTRM checks (Coe, 1967), additivity checks (Krása et al, 2003), and pTRM tail checks (Riisager and Riisager, 2001). Directional differences between the applied field and the NRM of the pTRM-tail check are taken into account according to Leonhardt et al (2004a). All determinations were analyzed using the ThellierTool4.21 software (Leonhardt et al, 2004b).…”

Section: Thellier-type Experimentsmentioning

confidence: 99%

“…During the conduction of paleointensity experiments, one must be aware of potential problems such as alteration during geological time or even during the laboratory experiment itself (Valet et al, 1996), anisotropy of thermoremanence (Veitch et al, 1984), Correspondence to: A. Ferk (annika.ferk@geophysik.uni-muenchen.de) magnetic domain state bias (Leonhardt et al, 2004a), and different cooling histories in laboratory and nature (Fox and Aitken, 1980;Papusoi, 1972;Leonhardt et al, 2006). Especially during the last few years, several studies have tried to deal with these problems and to improve the quality of paleointensity determination either by introducing new methods (Dekkers and Böhnel, 2006;Fabian and Leonhardt, 2010;Muxworthy and Heslop, 2011) or by using samples that have remanence carriers in the SD range and for which corrections of some of the biasing effects are possible.…”

Section: Introductionmentioning

confidence: 99%

Paleointensities on 8 ka obsidian from Mayor Island, New Zealand

et al. 2011

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Abstract. The 8 ka BP (6050 BCE) pantelleritic obsidian flow on Mayor Island, Bay of Plenty, New Zealand, has been investigated using 30 samples from two sites. Due to a very high paramagnetic/ferromagnetic ratio, it was not possible to determine the remanence carriers. This is despite the fact that the samples were studied intensively at low, room, and high temperatures. We infer that a stable remanence within the samples is carried by single-or close to single-domain particles. Experiments to determine the anisotropy of thermoremanence tensor and the dependency on cooling rate were hampered due to alteration resulting from the repeated heating of the samples to temperatures just below the glass transition. Nonetheless, a well-defined mean paleointensity of 57.0 ± 1.0 µT, based on individual high quality paleointensity determinations, was obtained. This field value compares very well to a paleointensity of 58.1 ± 2.9 µT, which Tanaka et al. (2009) obtained for 5500 BCE at a site 100 km distant. Agreement with geomagnetic field models, however, is poor. Thus, gathering more high-quality paleointensity data for the Pacific region and for the southern hemisphere in general to better constrain global field models is very important.

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Multidomain behavior during Thellier paleointensity experiments: a phenomenological model

Cited by 58 publications

References 24 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

The behaviour and detection of partial thermoremanent magnetisation (PTRM) tails in Thellier palaeointensity experiments

Paleointensities on 8 ka obsidian from Mayor Island, New Zealand

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