Helvetic zone

...Low-pressure secondary Alpine metamorphism progressed in the depths, and metamorphic rocks of the greenschist and breccia facies facies were formed (38 million years ago), followed by the intrusion of the Alpine granites (29 to 33 million years ago). (3) Around the Miocene of the Neogene Period The formation of a large overthrust structure in the Helvetic Zone of the Western Alps was the main cause of the deformation during this period (Third Alpine Metamorphism). Folds and thrust faults were formed from the end of the Oligocene to the early Miocene, and the basement rocks were laterally shortened by about 50% due to plastic deformation. ...

*Some of the terminology that mentions "Helvetic zone" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…深部では低圧型の第2期アルプス変成がすすみ，緑色片岩相，角セン岩相の変成岩が形成された(3800万年前)のち，アルプス花コウ岩類が貫入した(2900万～3300万年前)。(3)新第三紀中新世ごろ　西アルプスのヘルベット帯Helvetic zoneの大きな押しかぶせ構造の形成がこの時期の変動の主体である(第3期アルプス変成)。漸新世末～中新世前半に褶曲･衝上断層が形成され，塑性変形によって基盤岩石は約50％側方短縮した。…

※「Helvetic zone」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報