Tectonics of some forearc fold belts in and around the arc-arc crossing area in central Japan

Abstract

Summary The zonal structure of the old Honshu arc in central Japan is deflected and cut by the colliding younger Izu-Bonin arc causing peculiar types of accretionary fold belts. The Shimanto Fold Belt (s.s.), made up of Cretaceous flysch and pre-flysch sediments, shows a collisional fold pattern: arcward vergence in the inner side and oceanward vergence on the outer side. The minor structures are also different, with shear folds on the inner side of the belt and lens folds on the outer side. Structures in the inner side grew by flattening and those in the outer side by simple shearing. The divergent development of structural characteristics is explained by the differences in geothermal gradient and stress fields across the belt. The Izu-Bonin arc has a forearc fold belt situated between the Honshu and Izu-Bonin arcs. The stratigraphical, palaeogeographical and structural history of the area shows that it developed in a strike-slip regime associated with the transform fault between the Eurasian and Philippine Sea plates.

Problemy ophiolitów Zagros i ciał bazaltowych, przykłady z Regionu Kurdystanu, północny Irak

“…The fourth is photos of claimed pillow basalts of the previous studies of the Bulfat, Mawat Penjween ophiolites Complexes. A rechecking of the locations of these photos unproved the presence of pillow basalts since their form and shape and boundary condition indicated their development by shearing and subsquent weathering as indicated by Ogawa (1982) [52] (Fig. 17d).…”