古領家帯の構成要素と古領家-黒瀬川地帯の復元(古領家帯と黒瀬川帯の構成要素と改変過程)  [in Japanese] Constituents of the Paleo-Ryoke Belt and restoration of the Paleo-Ryoke and Kurosegawa Terranes(Geotectonic evolution of the Paleo-Ryoke and Kurosegawa Terranes)  [in Japanese]

本論は, 古領家帯構成要素の対比に関連するこの数年の研究成果をまとめる.その対比を明らかにするためには, さらなる年代学的検討を必要とするが, 竜峰山変成岩や水越層は南部北上帯の古生界に, また肥後変成岩や朝地変成岩および随伴する花崗岩類については, 大島変成岩, 寄居変成岩, 阿武隈帯の竹貫変成岩やそれらに随伴する花崗岩類に対比可能である.このことは, 九州の肥後帯そのものが古領家帯であることを示唆している.古領家-黒瀬川地帯を復元するために, 走向移動運動に分配されたプレートの斜め収束ベクトルのデータと, 脆性-延性剪断帯の幅と変位量の関係から, 中央構造線の総変位量の見積もりを実施した.MTLの白亜紀半ば以降の総変位量は, 100〜200kmと見なされる.この見積もりと, 柴田・高木(1989)および大槻・永広(1992)の地体構造形成モデルに基づき, 白亜紀半ばの古領家-黒瀬川地帯の復元モデルを提唱する.

This paper overviews the results of studies concerning on the correlation of constituents of Paleo-Ryoke Belt in these several years. Although further geochronological data will be needed to clarify the correlation, it is highly possible that the Ryuhozan metamorphics and Mizukoshi Formation are correlative to the Paleozoic formations in the South Kitakami Belt, and Higo and Asaji metamorphics and associated granitic rocks are correlative to those of the Oshima, Yorii and Takanuki metamorphics in the Abukuma Belt. This suggests that the Higo Belt in Kyshu itself is included in the Paleo-Ryoke Belt.For restoration of Paleo-Ryoke and Kurosegawa Terranes, the displacement of the Median Tectonic Line is estimated on the basis of strike-slip-partitioned vector of oblique plate convergence and of the relationship between thickness and displacement of brittle and ductile shear zones. The total sinistral displacement of the MTL from mid-Cretaceous may be 100-200km. Combined with this estimation and previous reconstructing model of the Japanese Islands after Shibata and Takagi (1989) and Otsuki and Ehiro (1992), we propose the geotectonic restoration model of the Paleo-Ryoke-Kurosegawa Terrane in mid-Cretaceous.