|
Magnetic Property
|
Pillow basalts
|
Massive basalts
|
Metadiabase
|
|---|---|---|---|
| Alteration or metamorphism | Slightly or pervasively altered, low-temperature oxidation | Nearly unaltered | Highly altered, greenschist facies metamorphism |
| Wasp-waisted hysteresis loops | Yes | No | No |
| Grain size (magnetic domain) | SSD to PSD | Larger PSD | Larger PSD |
| Curie temperature | 250°-400°C | 170°-230°C | ~370° and 580°C |
| Thermomagnetic curve | Irreversible | Almost reversible (in vacuum) | Irreversible |
| Thermal demagnetization of low-T IRM | — | Transition at ~55 K | Transition at ~120 K (Verwey transition) |
| Magnetic minerals | Titanomaghemite | Titanomagnetite | Magnetite + maghemite(?) |
Note: PSD = pseudosingle domain, SSD = stable single domain.