阿尔卑斯旋回中喜马拉雅山链和阿尔卑斯山链的主要变形特征

<正> 特提斯—阿尔卑斯山系是当今世界两大造山带之一,它自加勒比海开始,横贯欧亚大陆南部,直达印度尼亚西。这一山系的形成经历新特提斯洋打开至闭合的整个过程。特提斯洋是在华力西造山运动之后(T—J)联合大陆由西太平洋开始剪切张开而形成的;晚侏罗世至老第三纪时期,由于大西洋由南往北张开造成特提斯洋闭合。与此同时大洋内及洋壳和陆壳间发生俯冲或仰冲,以至大洋消亡,南北大陆板块碰撞(有些地段无碰撞)。

MAJOR DEFORMATION FEATURES OF THE ALPINE CHAIN AND THE HIMALAYAN CHAIN IN THE ALPINE CYCLE

The Alpine Chain and the Himalayan Chain, both formed during the Alpine Cycle, bear a resemblance to each other in their deformation regularity. Large-scale nappe structures are present in the form of a series of ductile nappe-shear zones of "crust-mantle" type and "inner crust" type. Intense plasic flowages, such as recumbent folds, horizontal cleavages and extended lineations, and shear strain are observed in a thickness of several kilometres. Highly strained mylonite zones and high-pressure metamorphic zones are distributed along the major interface of the shear zone. Diachronism is shown in deformation and metamorphism. Migration is characteristic of deformation and the major deformation mechanism seems to be simple shearing superimposed by contraction deformation. It is believed consequently that both the mountain chains underwent a structural evolution in a sequence of oceanic shearing-obduction-collision-intracontinental deformation-su-bduction inside continental crust.