论文部分内容阅读
丹凤—信阳蛇绿混杂带作为秦岭—大别碰撞造山带主缝合带，其南部属于扬子板块北部大陆边缘。研究区域位于东秦岭南翼，是扬子板块北部大陆边缘的一部分。①晚元古—中震旦世，扬子板块北缘（东秦岭段）为活动型大陆边缘，发育有陡岭岛弧和武当弧后盆地；②晚震旦—早古生代，扬子板块北缘转为被动型大陆边缘，陡岭古岛弧构成边缘地块，武当古弧后盆地演化为边缘盆地；③早古生代晚期，华北板块南缘的秦岭岛弧首先与扬子板块北缘的陡岭边缘地块（古岛弧）碰撞，造成武当边缘（古弧后）盆地的闭合，并形成刘岭前渊和二峪沟前陆盆地；④由于岛弧—边缘地块碰撞加之弧后和边缘盆地的存在，因此在早古生代末期，秦岭—大别山并未大规模隆起，造山带只具雏形。直至中生代早期，华北与扬子两个板块间进一步的陆内俯冲作用才使秦岭—大别山大规模隆起。陡岭古岛弧和武当古弧后盆地的确认合理地解释了秦岭—大别碰撞造山带“加里东碰撞不造山，印支造山不碰撞”的“矛盾”现象。
Danfeng - Xinyang ophiolite mixed belt as Qinling - Dabie collision orogenic belt suture zone, the southern belonged to the northern margin of the Yangtze plate edge. The study area is located in the southern wing of the East Qinling Mountains and is part of the northern margin of the Yangtze Plate. ① late Neoproterozoic - Middle Sinian, the northern margin of the Yangtze Plate (East Qinling section) is a movable continental margin, developed with a steep ridge island arc and Wudang back-arc basin; ② late Sinian - Early Paleozoic, the northern margin of the Yangtze plate turn For the passive continental margin, the steep Ridge ancient island arc constitutes the marginal landform, and the Wudang ancient backarc basin evolved into the marginal basin. In the late Early Paleozoic, the Qinling Island arc on the southern margin of the North China Plate was first closed to the marginal edge of the steep ridge on the northern margin of the Yangtze Plate (Ancient island arc) collisions, resulting in the closure of the Wudang margin (Paleo-arc) basin and the formation of the Liuling Qianyuan and Ergyugou foreland basins. ④ Due to the collision between the island arc-margin block and the back arc and marginal basin Therefore, at the end of the Early Paleozoic, the Qinling-Dabie Mountains did not scale up and the orogenic belt only had the embryonic form. Up to the early Mesozoic, further intracontinental subduction between the North China and Yangtze plates caused a large uplift of the Qinling-Dabie Mountains. The confirmation of the steep ridge ancient island arc and the Wudang ancient backarc basin reasonably explained the phenomenon of “contradiction” in the Qinling-Dabie collision orogen, that “the Caledonian collision is not orogenic and the Indosinian orogenic belt does not collide.”