推覆构造在太平洋东西两岸的表现及其成因机制的探讨

Demonstration and Genesis of the Nappe Structure Both in Eastern and Weastern Coasts of the Pacific Oeasen

推覆构造的概念一开始便与造山作用联系在一起。经过一个世纪的研究,认识到推覆构造的本质是在地壳挤压的条件下,造成岩石物质的水平运动而使地壳表面积相对缩小的一种构造形态。中国东部和美国西部在晚侏罗世同时形成了具有相似性的推覆构造。以后的构造发展、演化也具有相似性,如此次构造运动之后引起了大规模的花岗岩及花岗闪长岩的侵入活动,在新生代形成一系列构造盆地,在以后的发展中发育了高角度正断层及伸展构造。这些盆地又都是陆相含油盆地。中国东部和美国西部在中新生代的构造发展上之所以如此相似是因为它们同处于全球走滑带同纬度的对称位置上。由于地球自转速度变更引起地球质量向两极及赤道的移动,这种移动是沿着全球走滑带发生的,同时造成巨型断裂的走滑作用。其结果造成了中国东部及美国西部构造应力场的左右旋扭及缩、伸构造的形成。

The conception of nappe structure,at its first,is related to the orogeny,Af- ter the extensive studies in past Century,it is considered that the nappe structure actually is formed by the horizontal movement of the crust and the contraction of the Earth sur- face under the crust compression. During late Jurissic,similar nappe structures simultaneously formed in Eastern China and Western United States.Subsequently,tectonic evolution within the two area still have some similarities.For instance,the tectonic movement is followed by large scale of granitic to granodioritic plutonic magmatism.A series of tectonic basins developed during the Cenozoic.Afterward,is the developing of steep clined normal faults and extended structures.All these basins are oil—and gas—bearing structures. The tectonic evolutions between Eastern China and Western United States are very similar because they are located at the globle strike—slip belts,in same latitude.The al- ternative changes of the Earth rotation cause the Earth mass moving to the poles or the eguator.The mass movement is along the globle strike—slip belts,which led to the strike ——ship movement of gigantic faults.This could be a good explanation for the formation of clockwise or counterclockwise rotation and compression or extension in Eastern China and Western United States.