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GEOREF RECORD

Magnetic susceptibility of bedded iron-formation

Charles E. Jahren
Magnetic susceptibility of bedded iron-formation
Geophysics (October 1963) 28 (5): 756-766

Abstract

The susceptibility of natural and artificial Fe-formation samples in the form of cylinders with length-to-diameter ratio less than 1.2 and susceptibility up to 1 cgs unit was measured in fields of the order of 1 gauss. Demagnetization factors calculated for the centers of the cylinders explain observed changes of apparent susceptibility with length and direction of magnetization. Layered samples made by stacking disks of magnetic and nonmagnetic material alternately show susceptibility as much as 3 times greater parallel to the layers than across them, with layer susceptibility as high as 0.5 cgs. This anisotropy increases with increasing layer susceptibility and is largely independent of the details of layering when less than half the volume of the sample is magnetic material. Natural layered samples show the same range of susceptibility anisotropy. The relationship between susceptibility, k, and volume % magnetite, V, can be approximated by k=0.00116 V (super l.39) cgs, 10<V<40, corresponding to susceptibility 0.7 for pure magnetite The along-the-layer susceptibility of a bedded sample containing 20 volume % total magnetite is twice that a homogeneous sample of the same over-all magnetite content. For 1% total magnetite, it is 3 times as great.


ISSN: 0016-8033
EISSN: 1942-2156
Coden: GPYSA7
Serial Title: Geophysics
Serial Volume: 28
Serial Issue: 5
Title: Magnetic susceptibility of bedded iron-formation
Author(s): Jahren, Charles E.
Pages: 756-766
Published: 196310
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
Accession Number: 1963-008482
Categories: General geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus., tables
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
Update Code: 1963
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