出羽丘陵産粗粒玄武岩の岩石型の地域的変遷

概要

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Dolerites of several rock-types have been found in the Dewa Hills and its adjacent district. They belong to the tholeiitic rock series. Of these, olivine dolerite occurs in the central part of the Dewa Hills where the thickness of the hard shale of the Onnagawan stage is generally over 300 meters. On the other hand, pyroxene dolerite is dominant in the eastern margin of the broad intrusion district of olivine dolerite. Topographically, it is located in the western side of the Back-bone Range, paralleling the 300 m Isopach line of hard shale. Such rocks are characterized by occurring near the boundary between the remarkable sinking area in the Onnagawan stage and the weak sinking area where the sediments of the Onnagawan stage became rich in sandstone and the thickness of the hard shale decreases. Finally, the writer considers the pyroxene dolerite magma to have its origin in the shallow depth of the earth crust, contrary to the olivine dolerite magma which is deep-seated.
東北大学の論文
1960-05-05