文档介绍：变质作用与大地构造环境
metamorphism and plate tectonics
stable cratons : cratons are stable and relatively cold, with 'normal' thermal gradients of ~20 K/km. In detail, this simplification is incorrect. Continental rocks usually begin life somewhat hotter than this as a result of crustal stacking and radiogenic heat generation, but then cool over time.
■离散板块边缘(大洋中脊、大陆裂谷)
■汇聚板块边缘(岛弧、俯冲带<大洋俯冲带、大陆俯冲带>)
-大洋中脊Mid-Ocean Ridges
Plate separation-induced passive upwelling pression melting for MORB.
During extension at mid-ocean ridges, convection carries heat to very shallow levels, where 7-km thick oceanic crust forms;
Hydrothermal circulation produces low P/T metamorphism, often called seafloor metamorphism
Ocean-floor metamorphism and representative lithologyies
●  Concept
●  Regional metamorphism
Horokanai Ophiolite
●   Hydrothermal metamorphism:
Serpentinization;Chlorization;Spilitization;Rodingitization;Epidotisation
2. 汇聚板块边界-岩浆弧Magmatic arcs
Magmatic arcs are sites where heat is advected to shallow levels, producing low P/T metamorphism.
The heat is chiefly provided by silicate melts derived from melting of the upper mantle.
Contact metamorphism mon in such settings. Good examples of this include the Sierra Nevada and Klamath Mountains.
岩浆弧(西太平洋型和科迪勒拉型)
岛弧岩浆作用:基性-酸性火山岩,花岗岩-花岗闪长岩
低压高温变质
深熔作用
Structure of an Island Arc
Figure 16-2. Schematic cross sect