The Sambagawa metamorphic terrane in the Kanto Mountains is divided into four zones northward; zone I (prehnite-pumpellyite facies), zones IIa and IIb (glaucophane schist fades), and zone III (greenschist fades). The chemical and mechanical processes of the Sambagawa metamorphism are elucidated. In the chemical process, the equilibrium crystallization of metamorphic minerals ad vances progressively with rising temperature. The mechanical process brings about local concentration of some minerals in rock. Albite spot, compositional banding and related local concentration of some minerals are formed by the me chanical accretion and annealing of albite, quartz and calcite being induced by stress. The mechanical process introduces the chemical gradient in rock, and it advances the chemical reaction. Analytical data of minerals suggest such a mechanical process.

The fold-type is controlled by the mechanical process accompanied by chemical reaction process. Grain displacement induces flow-folding in rock, and block movement results in lens-type folding. The lens type fold occurs in zones I and IIa, while flow fold occurs in zones IIb and III.

The thermal conditions in the Sambagawa metamorphism can be estimated by the chemical process. Analytical data of coexisting actinolite and alkali amphibole indicate the wide range of formative temperature. Based on the simple mixture model of an actinolite-alkali amphibole solid solution, having a critical temper ature of 600°K, the temperature range of zones IIa and IIb are 30°C and 120°C, respectively. The pressure difference between these zones is geologically estimated to be about 0.7 Kb. The estimated ΔT/ΔP ratio in the Sambagawa metamorphic terrane of the Kanto Mountains is 100°C/Kb.