Magnetic properties of subaerial basalts at low temperatures

摘要: Magnetic properties have been measured as a function of temperature from 2 K to room for twenty-one samples subaerial basalts different origin and age, using an MPMS instrument. In all but four, titanomagnetite with titanium content less than 5 per cent has determined dominant magnetic mineral carrying NRM χ(T) measurements above Verwey transition observations. However, the new low-temperature experiments yielded evidence presence another in samples. This accounts up 70 saturation magnetization at acquires relatively strong thermally unstable SIRM this temperature. Comparison susceptibility vs. curves low high DC biasing fields reveals superparamagnetic behavior, peaks marking effective blocking temperatures being shifted <2 about 16 by 4.8 T field. At same time, high-field indicate that corresponding phase does not reach saturation, even highest field available us. A possible candidate account these is hemoilmenite 8–10 mole hematite, originating high-temperature deuteric oxidation. accordance prevailing occurrence exsolution lamellae within grains observed scanning electron microscopy (SEM) images.