Magnetic properties of dredged oceanic gabbros and the source of marine magnetic anomalies
Kent, D.V.; Honnorez, B.M.; Opdyke, N.D.; Fox, P.J. (1978). Magnetic properties of dredged oceanic gabbros and the source of marine magnetic anomalies. Geophy. J. R. astr. Soc. 55(3): 513-537
In: Geophysical Journal of the Royal Astronomical Society. Royal Astronomical Society (RAS): London. ISSN 0016-8009, more
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| Keywords |
Anomalies > Magnetic anomalies
Magnetism
Rocks > Igneous rocks > Gabbros
Seafloor spreading
Marine/Coastal |
| Authors | | Top |
- Kent, D.V.
- Honnorez, B.M.
- Opdyke, N.D.
- Fox, P.J.
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| Abstract |
Magnetic property studies (natural remanent magnetization, initial susceptibility, progressive alternating field demagnetization and magnetic mineralogy of selcted samples) were completed on 45 samples of gabbro and metagabbro recovered from 14 North Atlantic ocean-floor localities. The samples are medium to coarse-grained gabbro and metagabbro which exhibit subophitic intergranular to hypidiomorphic granular igneous textures. The igneous mineralogy is characterized by abundant plagioclase, varying amounts of clinopyroxene and hornblende, and lesser amounts of magnetite, ilmenite and sphene. Metamorphic minerals (actinolite, chlorite, epidote and fine-grained alteration products) occur in varying amounts as replacement products or vein material. The opaque mineralogy is dominated by magnetite and ilmenite. The magnetite typically exhibits a trellis of exsolution-oxidation ilmenite lamellae that appears to have formed during deuteric alteration. Model studies based on a magnetization distribution in the oceanic crust inferred from the magnetic property analysis of representative rock bodies within the oceanic crust, suggest that remanent magnetic contrasts in the gabbroic rocks of Layer 3 can be expected to contribute significantly to the generation of sea-floor spreading-type marine magnetic anomalies. |
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