Nappe Boundary Migration during the Subcretion: Exhumation Processes of the Sambagawa Schists

The Sambagawa schists consist of some successively subcreted units as nappes, Saruta unit as Saruta nappe II and Saruta nappe I, Fuyunose unit (Fuyunose nappe) and Sogauchu unit (ST subunit, KAT subunit and NOM subunit) etc. in descending order of structural level. The coupling of the Saruta nappe II and the Saruta nappe I occurred accompanying the underplating of the Fuyunose unit schists. When the underplating of the Sogauchi unit occurred accompanying the exhumation of the previously subcreted units, the latter was highly deformed, accompanying the formation of large—scale recumbent folds such as Shirataki II fold and Suryo fold and the nappe boundary migration from the Saruta I —II boundary and Saruta I — Fuyunose boundary to the Kuwanokawa thrust.