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Field-dependence of AC susceptibility in titanomagnetites

Earth and Planetary Science Letters

By:
, , ,
DOI: 10.1016/S0012-821X(98)00032-6

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Abstract

AC susceptibility measurements as a function of field amplitude Hac and of frequency show a strong field dependence for a set of synthetic titanomagnetites (Fe3-xTixO4) and for certain basalts from the SOH-1 Hawaiian drill hole and from Iceland. In-phase susceptibility is constant below fields of about 10-100 A/m, and then increases by as much as a factor of two as Hsc is increased to 2000 A/m. Both the initial field-independent susceptibilities and field-dependence of susceptibility are systematically related to composition: initial susceptibility is 3 SI for a single-crystal sphere of TMO (x = 0) and decreases with increasing titanium content; field-dependence is nearly zero for TM0 and increases systematically to a maximum near TM60 (x = 0.6). This field dependence can in some cases be mistaken for frequency dependence, and leaf to incorrect interpretations of magnetic grain size and composition when titanomagnetite is present.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Field-dependence of AC susceptibility in titanomagnetites
Series title:
Earth and Planetary Science Letters
DOI:
10.1016/S0012-821X(98)00032-6
Volume
157
Issue:
3-4
Year Published:
1998
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Earth and Planetary Science Letters
First page:
129
Last page:
139
Number of Pages:
11