东秦岭古洋盆与加里东运动

THE ANCIENT OCEAN AND CALEDONIAN OROGENY IN THE EAST QINLING

秦岭造构带曾经存在分隔华北和扬子板块的古洋盆的认识已为众多地层事实所证实。同位素定年结果和古生物资料共同表明古洋盆主要发育于早古生代期间。洋壳滴减遂导致华北和扬子板块边缘的对接。但是,沿缝合带,中、上泥盆系和早石炭系的发育、以及不存在造山磨拉石的事实说明,板块对接并未发生地形学意义上的造山作用,沿缝合带尚残留陆表海。秦岭在地形学意义上的造山作用主要发生于印支期。而秦岭的印支运动当属于陆内性质的造山作用,并非大洋板块消亡之后的碰撞造山。

The result of researohes on the ophiolite complex which occurs discontinuously along the East Qinling belt suggests there might exist an ancient ocean between the Yangtze plate and the North China plate. Evidences of paleontology and isotopic age determination reveal that the ancient ocean developed during the early palaeozoic. The possible subsequent subduotion of the ocean floor led to convergency of the Yangtze and the North China plates, accompanied by magmatism and metamorphism. However, the convergency of the two plates did not result in the final continent-continent collision mountain-building. The Qinling Mountains formed during the Indosinian movement. The absence of Mesozoic ophiolite suggests that the Indosinian movement is an intra-continental orogeny.