Magnetic study of serpentinized harzburgites from the Islas Orcadas Fracture Zone

摘要: Magnetic properties and bulk densities of 27 serpentinized harzburgite samples from the Islas Orcadas Fracture Zone, located in vicinity Bouvet Triple Junction, have been measured analyzed. Polished sections were examined using reflected light scanning electron microscopy to characterize size geometric arrangement opaque minerals. The relationship between saturation magnetization (IS) remanent coercive force (HR) is considered terms amount ferrimagnetic material maghemitization. A suite continental serpentinites Canada offered as contrast, consider role weathering Magnetite variably maghemitized, whereas do not appear contain maghemitized oxides. We verify this with optical microscopy, thermomagnetic analyses cryogenic temperature cycling remanence. Maghemitization serves reduce initial magnetic susceptibility, introduce error use IS evaluate mode magnetite. presence maghemite existence a three dimensional vein network for magnetite geometry would suggest that hysteresis parameters can reliably indicate grain size. ratios fall restricted range regardless coercivity. apparent configured plus maghemitization might be responsible observation. does affect thermal stability enhances geophysical importance remanence serpentinites. Paleomagnetic data important information about geologic circumstances oceanic rock serpentinization embodied paleomagnetic records. This observation may very generation long wavelength aeromagnetic possibly even satellite anomalies.