抄録
There are various types of linear structures in the Palaeozoic and Mesozoic Systems in the central zone of the Kitakami massif., Among them, the most prominent and extensively developed lineation is that shown by the axis of gentle undulation of the bedding-plane., It is noteworthy that the Palaeozoic and Mesozoic formations can be divided into several homo-axial structural groups with respect to the directions and plunges of lineations., These structural divisions almost correspond to the stratigraphical clarssification., (Table 1)., Table 1 Era Homo-axial group of sedimentary formation Plunge of the lineation Main unconformities Paleo-Cretaceous Ofunato series N Jurassic Shishiori series Karakuwa series NNW in the upper part, S in the lower Triassic Inai series Toyoma series Kanokura series S Permian Sakamotozawa series Nagaiwa series Onimaru series Yukisawa basin NNE (absent) N or S (doubly-plunge) Hikoroichi basin NNW Carboniferous Odaira series Arisu series Hikoroichi series S Devonian-Gotlandian Takainari series SW The intrusion-axes of the three granitic masses (Higami granite, Takekoma granodiorite and Hirota quartz-monzonite) already described in the previous paper are in harmony respectively with the Iineations and the fold-axes of such homo-axial structural groups that may have been folded synchronously with or prior to the intrusions of these granitic masses., (Table 2)., Table 2 Granitic mass Principal Lineation Intrusion axis or Fold-axis Sedimentary formation Higami granite NNW-NW The lower Permian (Sakamotozawa series) and the middle Carboniferous (Nagaiwa series) Takekoma granodiorite S The middle and upper Permian (Kanokura and Toyoma series respectively) and the Triassic (Inai series) Hirota quartz-monzonite N The paleo-Cretaceous (Ofunato series)
