Experimental procedure to detect multidomain remanence during Thellier–Thellier experiments

Krása, David; Heunemann, C.; Leonhardt, Roman; Petersen, N.

doi:10.1016/s1474-7065(03)00122-0

Cited by 81 publications

(110 citation statements)

References 16 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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“…A major drawback of these methods is the repeated heating and cooling cycles at high temperatures, which favor the formation of new magnetic phases and often lead to a failure of the experiment. A variety of checks to detect non-ideal behavior is normally used: pTRM checks (Coe 1967b) are used to detect the formation of new magnetic phases; pTRM-tail checks (Shcherbakova and Shcherbakov 2000;Riisager and Riisager 2001) to define the presence of multidomain grains; additivity checks (Krása et al 2003) can ensure that the Thellier law of additivity is respected. An alternative to this method was suggested by Shaw (1974), who proposed using only one heating above the Curie temperature of the material, but imparting Anhysteretic Remanent Magnetization (ARM) twice to check for any possible alteration.…”

Section: Methods Used To Identify Paleodirections and Paleofield Strementioning

confidence: 99%

Millennial Variations of the Geomagnetic Field: from Data Recovery to Field Reconstruction

Donadini

Korte²,

Constable

2010

Space Sci Rev

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Variations of the geomagnetic field over past millennia can be determined from archeomagnetic data and paleomagnetic sediment records. The resolution and validity of any field reconstruction depends on the reliability of such indirect measurements of past field values. Considerable effort is invested to ensure that the magnetic minerals carrying the ancient magnetization are good, if not ideal, recorders of the magnetic field. This is achieved by performing a wide array of rock magnetic and microscopy investigations, many of which are outlined here. In addition to data quality, the spatial and temporal distributions of archeomagnetic and sediment records play a significant role in the accuracy of past field reconstruction. Global field reconstructions enable studies of dynamic processes in Earth's core. They rely on data compilations which ideally include information about the quality of a measurement and provide a useful archive for selecting data with the best characteristics. There is, however, a trade off between the total number of reliable data and the geographic or temporal coverage. In this review we describe the various types of paleomagnetic recorders, and the kind of measurements that are performed to gather reliable geomagnetic field information. We show which modeling strategies are most suitable, and the main features of the field that can be derived from the resulting models. Finally, we discuss prospects for progress in this kind of research.

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“…For infield steps, laboratory fields of 30 ± 0.1µT were applied during heating and cooling. 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).…”

Section: Thellier-type Experimentsmentioning

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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Experimental procedure to detect multidomain remanence during Thellier–Thellier experiments

Cited by 81 publications

References 16 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

Millennial Variations of the Geomagnetic Field: from Data Recovery to Field Reconstruction

Paleointensities on 8 ka obsidian from Mayor Island, New Zealand

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