シコク チュウオウブ ササガタニ チイキ ニオケル チチブ ホクタイ ノ チシツ コウゾウ
Geological structures of the Northern Chichibu Terrain of the Sasagatani Area,Central Shikoku
山崎, 亮輔 日本道路株式会社
前川, 寛和 大阪府立大学大学院理学系研究科物理科学教室
Northern Chichibu Terrain
The Sasagatani fault in central Shikoku was considered to be a tectonic boundary between the Sanbagawa high-P/T metamorphic belt and the Chichibu non-high-P/T belt. Metamorphic minerals of the greenstones around the Sasagatani fault are examined. Alkali amphibole, alkali pyroxene, actinolite, stilpnomelane and pumpellyite are found not only on the north side of the fault, but also on the south side. Strata around the Sasagatani fault have undergone the pumpellyite-actinolite facies metamorphism. Thus, the Sasagatani fault is not an upper boundary fault of the Sanbagawa metamorphic rocks.
The Nanokawa thrust occurs in the Jurassic accretionary complexes of the Northern Chichibu Terrain in the Sasagatani Area. The greenstones of the hanging wall of the thrust have undergone the pumpellyite-actinolite facies metamorphism, whereas those of the footwall have undergone the prehnite-pumpellyite facies metamorphism. The Nanokawa thrust is a large overthrust, which has a different metamorphic grade between the hanging wall and footwall. The thrust is probably a southern boundary of the Jurassic accretionary deposits which have undergone the Sanbagawa metamorphism.
徳島大学総合科学部自然科学研究 = Natural Science Research, The University of Tokushima
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