磨拉石与造山旋回

Molasse and the Orogenic Cycle

磨拉石不是一个沉积相术语，而是大地构造学中的一个构造相，是碰撞造山带的重要组成部分，主要指造山带前陆和山间盆地中的沉积，可以是陆相，也可以是海相或海陆交互相。磨拉石发育在造山旋回晚期陆—陆碰撞造山阶段，其底部不整合标志着陆—陆碰撞时代的上限，其内部的不整合记录着陆—陆碰撞造山阶段同沉积构造作用，其顶部与代表另一个造山旋回开始的海侵初期形成的陆缘移地滨岸相沉积之间的不整合则代表着整个造山旋回的结束。

Molasse is a tectofacies,but not a term of sedimentary faoies。It is one of the important parts of an orogenic belt,mainly referred to the deposits in the foreland and intrmontane basins,and composed of marine,nonmarine or paralic deposits, Molasse is formed during the continent-continent collision stage。The unconformity at its bottom is the upper limit of the continent-continent collision time。Those inside the molasse represent the synsedimentary tectonization of the continent-continent collision stage in the late of the orogenic cycle。And the end of the orogenic cycle is represented by the unoonformity between the molasse and the trans-gressive deposlts which marks the beglnning of a new orogenic cycle.