CLOSING OF EASTERN QINLING PALAEOOCEAN AND COLLAGING BETWEEN THE NORTH CHINA AND YANGTZE BLOCKS
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摘要: 东秦岭古海洋是一个从晚元古代开始发育,晚志留开始关闭的古海洋。其关闭的后期,华北板块与扬子板块开始拼贴,340Ma基本拼贴结束。古秦岭海洋的北部(华北板块南部)从晚奥陶世起,由原来的被动边缘转化为一具沟、弧、盆体系的活动大陆边缘,而其南部(扬子板块北部)边缘仍为被动大陆边缘。泥盆纪到石炭纪,上述两类大陆边缘拼贴。根据东秦岭造山带内的大型推覆体构造组合及其配置关系、推覆岩片的变质相倒置、推覆岩片内应变标志物特征及其应变参数测量(发育在420—340Ma期间的推覆体)以及前陆盆地(泥盆—石炭纪)的研究,认为华北板块与扬子板块是以仰冲兼右行剪切方式碰撞拼贴。Abstract: Eastern Qinling Palaeoocean is one developed in late Proterozoic and closed during Silurian-Devonian(420-400Ma). At the late stage of closing, collage between the north China and Yangtze plates took place, which did not end until Carboniferous (340Ma).The northern part of Qinling Palaeoocean (the southern margin of the north China plate) was turned into an active continental margin with a system of trench-island arc-back arc basin formed from late Ordovician, but its southern part (northern margin of Yangtze plate) remained a passive continental margin. The two kinds of continental margins mentioned above had been collaged from Devonian until Carboniferous. With the basis of the following informations: the tectonic assemblage and its collacative relations of major nappes; the inversion of metamorphic facies and the characteristics of strain markers within the nappe sheet and the measurements on strain parameters (the nappes developed during 420-340Ma); and the studies of foreland basin, the tectonism of the north China and Yangtze blocks is a collisional collage accompanied by obduction and a dextral shearing.
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