关键词: 板块俯冲碰撞, 板块位移, 变形变质, 岩浆活动, 同位素年龄

Abstract:

Based on the isotopic ages collected in some collision zones of China and Europe continents, the process from subduction to collision between plates is discussed; in this process the following events occurred in sequence: the decrease in the moving velocity of plates, the disappearance of the oceanic crust on the surface, the beginning of the collision, the formation of the strong deformation and dynamic metamorphism, the occurrence of a series of magmatism and, at last, the uplifting of mountains. Above events have extremely different isotopic ages. The initial collision age is younger than that of the oceanic crust disappearing on the surface, and older than that of the formation of strong deformation and dynamic metamorphism. Obviously, it is very difficult to determine the initial age of subduction by using the isotopic age of only one geological event. The first decrease in moving velocity of subduction plate may have occurred because of the transformation from the subduction lithosphere plate with oceanic type to that with oceaniccontinental transition type. For the smaller plates with less strength, for example, the Chinese continental blocks, after the collision and amalgamation between two plates, the continental plate may subsequently rotate and migrate rather widely. The stitching pluton, intruded into main fault plane of collision zone, could be formed in syntectonic period and also in the period of subsequent collision, i.e. post collision.

Key words: plate subductioncollision, plate migration, rock deformation and metamorphism, magmatism, isotopic age