紀伊大島で約1400万年前に形成された流紋岩や流紋岩質火砕岩からなる火山岩体です。流紋岩溶岩，貫入岩が流紋岩質火砕岩を覆い，流紋岩質火砕岩には一部に水中を流れた堆積構造が見られます。潮岬と紀伊大島に分布する中新世火成岩類は、熊野酸性火成岩類とはマグマの形成過程が異なり、苦鉄質火成岩類も含むことから、潮岬火成複合岩類として区別されています。

It is a volcanic rock body consisting of rhyolite and rhyolite pyroclastic rock formed about 14 million years ago on Kii Oshima. Rhyolite lava and intrusive rocks cover rhyolite pyroclastic rocks, and some of the rhyolite pyroclastic rocks have sedimentary structures that flow underwater. The Miocene igneous rocks distributed in Shionomisaki and Kii Oshima are distinguished as Shionomisaki igneous complex rocks because the magma formation process is different from that of Kumano acidic igneous rocks and they also include mafic igneous rocks.

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うえもり　う 2022/01/20(Thu) 17:54 No.155