The use of field dependence of AC susceptibility for the interpretation of magnetic mineralogy and magnetic fabrics in the HSDP-2 basalts, Hawaii

Vahle, C.; Kontny, Agnes

doi:10.1016/j.epsl.2005.07.010

Cited by 29 publications

(31 citation statements)

References 23 publications

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“…We found a logaritmic function between T C1 and k HD for samples from both regions (Fig. 7), which is in agreement with Vahle and Kontny (2005). Fig.…”

Section: Figsupporting

confidence: 89%

“…New K-Ar data, others from ** Lustrino and Wilson (2007) and * Pfeiffer at al. (1984); TiO 2 content taken from whole-rock analyses and magnetite grains using WDS; Curie temperature of original titanomagnetite (T C1 ), Curie temperature of magnetite after exsolution of ilmenite (T C2 ); field-dependence parameter k HD after Vahle and Kontny (2005). bearing rocks (high-Ti oliv proportion of ulvöspinel recrystallized dusty magn assemblages, if present, con Other factors that are (i) a higher proportion of titanomagnetite), (ii) large group mineral populations the most frequent minerals According to microscop 18, 19), the main silicates a and a matrix constituent nepheline as constituents o Olivine nephelinite (TiB-23) is an igneous rock with well preserved but broken olivine and zoned diopside phenocrysts as well as with serpentinized microxenoliths.…”

Section: Fig 2 the Tas Classification Diagram Aftermentioning

confidence: 99%

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Magnetic properties of high-Ti basaltic rocks from the Krušné hory/Erzgebirge MTS. (Bohemia/Saxony), and their relation to mineral chemistry

et al. 2010

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This study provides new thermomagnetic and petrographic data on specific basaltic rock association from the broader vicinity of the Loučná-Oberwiesenthal volcanic centre, western Bohemia/Saxony. Two types of volcanic rocks were recognized there: (i) high-Ti types (3.5−5.2 wt% TiO 2 ) represented by (mela)nephelinite s.s., and sporadically present (ii) medium-Ti types (2.5−3.5 wt% TiO 2 ) of olivine nephelinite, nepheline basanite and phonotephrite compositions. In order to examine the rock-magnetic behaviour, they were studied for their variations in the Curie temperature (T C ) and field-dependent susceptibility, spinel group minerals, chemistry and petrology.Magnetic susceptibility of ulvöspinel-rich titanomagnetite, as a dominant magnetic carrier, depends on the amplitude of measured magnetic field, whereas pure magnetite is field-independent. Field dependence parameter k HD of the studied basaltic rocks ranges from 0.8 to 18.7%, TiO 2 contents in titanomagnetite range from 12.7 to 20.1 wt.%. TiO 2 content in titanomagnetite does not correlate with whole-rock TiO 2 content (2.8 to 5.6 wt.%). The content of substituted titanium in the sublattice of magnetite is also sensitively reflected in the Curie temperature, ranging from 200 to 580°C. The spinel group minerals are designated as titanomagnetite with the dominance of ulvöspinel, magnetite and magnesioferrite components, or titanomagnetite with the magnetite, ulvöspinel and magnesioferrite components. Only two samples are characterized by a significant presence of Cr-spinel and magnesiochromite components forming cores of titanomagnetites.The titanomagnetite-bearing rocks in the studied area, likewise the low-to medium-Ti basaltic rocks from the České středohoří Mts., provide similar thermomagnetic curves.K e y w o r d s : high-Ti and medium-Ti basaltic rocks, magnetic carriers, thermomagnetic experiments, Curie temperature variation, field-dependent susceptibility, Krušné hory/Erzgebirge Mts., Ohře/Eger Rift P. Schnabl et al. 78Stud. Geophys. Geod., 54 (2010)

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“…We found a logaritmic function between T C1 and k HD for samples from both regions (Fig. 7), which is in agreement with Vahle and Kontny (2005). Fig.…”

Section: Figsupporting

confidence: 89%

Section: Fig 2 the Tas Classification Diagram Aftermentioning

confidence: 99%

Magnetic properties of high-Ti basaltic rocks from the Krušné hory/Erzgebirge MTS. (Bohemia/Saxony), and their relation to mineral chemistry

et al. 2010

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“…4) obtained from the SU-7 site can be explained by the presence of titanomagnetite and other spinelid-group minerals. A similar situation was detected for the volcanics from the Krušné hory Mts ) and corresponds with the findings of Vahle & Kontny (2005).…”

Section: Paleomagnetic and Basic Rock-magnetic Studiessupporting

confidence: 71%

Chronological implications of the paleomagnetic record of the Late Cenozoic volcanic activity along the Moravia-Silesia border (NE Bohemian Massif)

Cajz¹,

Schnabl²,

Pécskay

et al. 2012

Geologica Carpathica

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This paper presents the results of a paleomagnetic study carried out on Plio-Pleistocene Cenozoic basalts from the NE part of the Bohemian Massif. Paleomagnetic data were supplemented by 27 newly obtained K/Ar age determinations. Lavas and volcaniclastics from 6 volcanoes were sampled. The declination and inclination values of paleomagnetic vectors vary in the ranges of 130 to 174 and -85 to -68° for reversed polarity (Pleistocene); or 345 to 350° and around 62°f or normal polarity (Pliocene). Volcanological evaluation and compilation of older geophysical data from field survey served as the basis for the interpretation of these results. The Pleistocene volcanic stage consists of two volcanic phases, fairly closely spaced in time. Four volcanoes constitute the Bruntál Volcanic Field; two others are located 20 km to the E and 65 km to the NW, respectively. The volcanoes are defined as monogenetic ones, producing scoria cones and lavas. Exceptionally, the largest volcano shows a possibility of remobilization during the youngest volcanic phase, suggested by paleomagnetic properties. The oldest one (4.3-3.3 Ma), Břidličná Volcano, was simultaneously active with the Lutynia Volcano (Poland) which produced the Zálesí lava relic (normal polarity). Three other volcanoes of the volcanic field are younger and reversely polarized. The Velký Roudný Volcano was active during the Gelasian (2.6-2.1 Ma) and possibly could have been reactivated during the youngest (Calabrian, 1.8-1.1 Ma) phase which gave birth to the Venušina sopka and Uhlířský vrch volcanoes. The reliability of all available K-Ar data was evaluated using a multidisciplinary approach.

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“…Thirty and 300 A/m indicate the field, at which the magnetic susceptibility is measured. Detailed information on the fielddependence of magnetic susceptibility is also given in Vahle and Kontny (2005).…”

Section: Methodsmentioning

confidence: 99%

Petrography and shock‐related remagnetization of pyrrhotite in drill cores from the Bosumtwi Impact Crater Drilling Project, Ghana

Kontny

Elbra

Just

et al. 2007

Meteorit & Planetary Scien

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Abstract-Rock magnetic and magnetic mineralogy data are presented from the International Continental Scientific Drilling Program (ICDP) drill cores LB-07A and LB-08A of the Bosumtwi impact structure in order to understand the magnetic behavior of impact and target lithologies and their impact-related remagnetization mechanism. Basic data for the interpretation of the magnetic anomaly patterns and the magnetic borehole measurements as well as for new magnetic modeling are provided. Magnetic susceptibility (150-500 × 10 −6 SI) and natural remanent magnetization (10 −3 -10 −1 A/m) are generally weak, but locally higher values up to 10.6 × 10 −3 SI and 43 A/m occur. Sixty-three percent of the investigated rock specimens show Q values above 1 indicating that remanence clearly dominates over induced magnetization, which is a typical feature of impact structures. Ferrimagnetic pyrrhotite is the main magnetite phase, which occurs besides minor magnetite and a magnetic phase with a Curie temperature between 330 and 350 °C, interpreted as anomalous pyrrhotite. Coercive forces are between 20 and 40 mT. Brecciation and fracturing of pyrrhotite is a common feature confirming its pre-impact origin. Grain sizes of pyrrhotite show a large variation but the numerous stress-induced nanostructures observable by transmission electron microscopy (TEM) are assumed to behave as single-domain grains. We suggest that the drilled rocks lost their pre-shock remanence memory during the shock event and acquired a new, stable remanence during shock-induced grain size reduction. The observed brittle microstructures indicate temperatures not higher than 250 °C, which is below the Curie temperature of ferrimagnetic pyrrhotite (310 °C).

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The use of field dependence of AC susceptibility for the interpretation of magnetic mineralogy and magnetic fabrics in the HSDP-2 basalts, Hawaii

Cited by 29 publications

References 23 publications

Magnetic properties of high-Ti basaltic rocks from the Krušné hory/Erzgebirge MTS. (Bohemia/Saxony), and their relation to mineral chemistry

Magnetic properties of high-Ti basaltic rocks from the Krušné hory/Erzgebirge MTS. (Bohemia/Saxony), and their relation to mineral chemistry

Chronological implications of the paleomagnetic record of the Late Cenozoic volcanic activity along the Moravia-Silesia border (NE Bohemian Massif)

Petrography and shock‐related remagnetization of pyrrhotite in drill cores from the Bosumtwi Impact Crater Drilling Project, Ghana

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