| Abstract |
In most geological samples, signals of iron ions (Fe3 +) are found in the measurements by Elec~ron Spin Resonance (ESDI. The signals tells us not only the existence of Fe3+ ions in the sample. but also the information on the sites occupied by Fe ions. In this work, we have a preliminary result that the cooling rates of §~Icanic materials (basalts, lavas, etc.1 can be estimated by signals of Fe ions in those samples. We have measured a scoria (SC) and two volcanic lavas (LV1,LV21, got at Mt. Mihara in Izuoshima Is., and a pillow basalt (PB), The former three samples were offered by Hot Springs Research Institute of Kanagawaken Prefecture and the latter one is by Geophysics Institute of Tokyo Universi ty. We crushed these samples of 200-300 mg and got signals at room temperature by an ESR spectrometer eJEOL, RElX), We also investigated the changes of signals frum the samples heated in air at3~00-900C. Fig.l (aI, (bl, and (cl show the signals by Fe ions in busal ts and lavas. The upper ones are signals before heatine and the lower after tlealing. The numbers indicates the gains of ESR spectrometer and the number just aftel' the sumple name of lower figures are the temperatures of heating In centigrade degree. The s3~rla shows one large peak at g=2 (about 336 mIl. This signal is by free Fe i6ns in amorphous glass formed at the time of rapid quenching. The lavas and the basalt show not only an peak at g=2 but also other peaks at g=·t and at g=9 (70 mIl. These signals are due to a fine structure of Fe at high spin state in some crystalline field. The cooling rate of la§,!!s are more moderate than that of scoria, the some crystals including Fe are formed In lavas and a basalt. |