Granitic layer - Granitic layer

…The P-wave velocity of the main part of the oceanic crust is about 7 km/s, which corresponds to the lower part of the continental crust, and there is no layer that corresponds to the upper part of the continental crust. Comparing with the seismic wave velocity that propagates through rocks, the upper part of the continental crust is thought to be composed of granite-like acidic rocks, and is called the granite layer. On the other hand, the lower part of the continental crust and the oceanic crust are thought to be composed of gabbro-like basic rocks (basaltic plutonic rocks), and are called the basaltic layer. …

*Some of the terminology that refers to the "granite layer" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…海洋地殻の主要部のP波速度は約7km/sで，大陸地殻の下部に相当し，大陸地殻の上部に対応する層は存在しない。岩石中を伝わる地震波速度との比較から，大陸地殻上部は，花コウ岩的な酸性岩よりなると考えられ，花コウ岩質層と呼ばれる。一方，大陸地殻下部や海洋地殻は，斑レイ岩(玄武岩質の深成岩)的な塩基性岩よりなると考えられ，玄武岩質層と呼ばれる。…

※「花コウ岩質層」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