北部九州, 脊振山地雷山周辺の低圧高温型変成岩類とその帰属(古領家帯と黒瀬川帯の構成要素と改変過程)  [in Japanese] Low P/T metamorphic rocks from Sefuri Mountains and its correlation with low P/T type metamorphic rocks in Kyushu, southwest Japan(Geotectonic evolution of the Paleo-Ryoke and Kurosegawa Terranes)  [in Japanese]

北部九州西部, 脊振山地雷山周辺には, 花崗岩類と変成岩類が分布する.変成岩類は主に角閃岩と黒雲母片麻岩からなり, 少量の結晶質石灰岩, 蛇紋岩および花崗岩質片麻岩を伴う.これらの変成岩類は白亜紀糸島花崗閃緑岩の貫入以前に変形・変成作用を被っていた.黒雲母片麻岩はしばしばザクロ石, キンセイ石およびカリ長石を含む.また, 黒雲母や石英はザクロ石に含まれる場合もある.これらの鉱物組み合わせから, 変成岩類は低圧高温型の変成作用を被ったと推定される.黒雲母, ザクロ石, キンセイ石そしてカリ長石を含む岩石は, 最高750℃, 6.5kbarの変成温度・圧力条件を示す.これらの変成条件は肥後変成帯のD帯に産するものと類似する.黒雲母片麻岩の同位体比組成から, 本地域の変成岩類は肥後変成岩類と類似の起源で, 同じ様な同位体の進化をたどったと考えられる.以上から, 本地域の変成岩類は肥後変成岩類に対比される可能性がある.

Mt. Raizan area, Sefuri Mountains in north Kyushu is underlain by Cretaceous granitic rocks accompanied by various kind of metamorphic rocks. The metamorphic rocks consist mainly of amphibolite and biotite gneiss with small amounts of crystalline limstone and serpentinite occurring as a lens or a block. These metamorphic rocks have been undergone by deformation and regional metamorphism before intrusion of the granitic rocks. The biotite gneiss locally contains garnet and cordierite coexisting with K-feldspar. In some case, biotite and quartz are included in garnet. These mineral assemblages indicate that the metamorphic rocks around Mt. Raizan area have been suffered by low pressure and high temperature type metamorphism. Metamorphic P-T condition of the garnet-cordierite-biotite gneiss shows up to 6.5 kbar and 750℃. These values are similar to those of the metamorphic rocks in Zone D from the Higo metamorphic terrane, west-central Kyushu. Origin and evolution of the metamorphic rock from Mt. Raizan area is identical with those of the Higo metamorhic rocks in terms of isotopic compositions. Therefore, the metamorphic rocks around Mt. Raizan area can be correlated with the Higo metamorphic rocks.