山形県大滝粗粒玄武岩岩床の岩石学的研究

抄録

The Otaki dolerite sills, Yamagata Prefecture intrude in the middle part of the Kusanagi formation (middle Miocene age). Contact effects of the intrusions on the sediments are very weak and are confined to the immediate contact zone. After the intrusion, the magma formed dolerite pegmatite and felsic patch (granophyre) by crystallization differentiation in situ. Trends of the differentiation of the Otaki dolerite magma accord with that of Palisade diabase, Tasmanian dolerites, Karroo dolerites, Dillsburg dolerite and Semi quartz dolerite sills.