すさみ町・マップ50:W8 戎島
紀伊半島の土台をなす牟婁付加体にマグマが貫入して形成された火砕岩岩脈です。マグマが地層の割れ目に網目状に入り込んだ様子や、周囲の地層がマグマに取り込まれた岩石(捕獲岩)を観察できます。すさみ町から白浜町にかけての温泉がこの岩脈にそって分布します。
It is a pyroclastic dike formed by invading magma into the Muro accretionary prism that forms the basis of the Kii Peninsula. You can observe how the magma has entered the cracks of the stratum in a mesh pattern, and the rocks (xenoliths) in which the surrounding strata have been incorporated into the magma. Hot springs from Susami Town to Shirahama Town are distributed along this dike.
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うえもり う 2022/01/20(Thu) 14:52 No.113