丹沢石英閃緑岩体北縁で観察された変成岩類と非変成岩類の関係

概要

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It has often been said that the metamorphic rocks and so-called non-metamorphic greenrocks of the Tanzawa mountainland were separated each other by some tectonic events. The present auther carried out some field and microscopic observations on the problem in the northern district of the Mountainland. The metamorphic rocks consist mainly of hornfels and partly of schistose rocks which is thermally metamorphosed. The original rocks of the meta-morphics are composed of fine-grained intermediate pyroclastics with some argilaceous rocks. On the contrary, so-called non-metamorphic greenrocks mainly consist of coarse-grained basic pyroclastics. The two systems discord each other and the boundary gently dips to the north. Along the boundary, sheared zones or dolerite dikes are necessarily distributed. As to the effect of the thermal metamorphism, it was found that in so-called non-metamorphic greenrocks, some metamorphic minerals such as green biotite which are thought to be caused by contact effect occur. Shistose rocks, on the other hand, were clearly separated from the so-called non-metamorphic greenrocks. Furthermore, the intrusive boundary of the plutonic rock cuts across the schistosity plane with high angles. The present auther suggests the possibility that the schistose rocks had been formed before the deposition of so-called non-metamorphic green rocks.
地学団体研究会の論文
1969-03-25