Remanent hysteresis study of dolerite dykes |
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| Authors: | G V S Poornachandra Rao S T Chacko M S Bhalla |
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| Institution: | (1) Palaeomagnetism Division, National Geophysical Research Institute, 500 007 Hyderabad, India |
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| Abstract: | Saturation remanent hysteresis studies were carried out on numerous dolerite dyke samples from the peninsular India. These studies result in four types of remanent hysteresis curves which indicate that the magnetic material is magnetite or titanomagnetite with variable grain-size having remanent coercive forces (H
cr
) of 8 to 30 mT, requiring saturating fields (H
s
) up to 250 mT. Two extreme types of samples with (1) low coercive forces requiring high saturating fields and (2) high coercive forces requiring low saturating fields are noticed along with the generally observed ones. The Granulometric and Lowrie-Fuller Tests on these samples indicated that the magnetic material i.e., magnetite or titanomagnetite in these rocks is in the form of Multi-Domain (MD), Cation Deficient (CD) and a mixture of these two forms (MD+CD) within. |
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| Keywords: | Coercive force grain size magnetics hysteresis granulometry domain wall relaxation time |
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