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中国东部的苏鲁造山带印支期先后经历了大洋消减俯冲、大陆碰撞、陆壳深俯冲、陆内造山等复杂过程。综合苏鲁造山带的构造地质学、岩石学、岩相古地理学、年代学进展,发现以下事实用传统的华南向华北俯冲难以解释:(1)徐淮地区形成了明显的朝北西拓展的逆冲构造变形,此外,苏鲁造山带中还存在大量的北西向逆冲推覆构造;(2)苏鲁造山带中出露的白垩纪花岗岩中来自古元古代的继承锆石,以及Sr、Nd、Pb同位素示踪结果都显示与华北地块南缘地质体更为相似;(3)苏鲁造山带北侧的胶莱盆地以及胶北隆起缺乏晚古生代到中生代的弧后火山岩证据;(4)华北南缘三叠纪时期的古地理环境更接近被动大陆边缘。基于这些事实,本文认为,晚古生代-早三叠世早期苏鲁段的商丹洋可能向南东俯冲,不同于秦岭-大别段的商丹洋向北俯冲,消减到秦岭-大别微陆块苏鲁段之下,发生华北地块与该微陆块的拼合,华北地块整体向南东楔入秦岭-大别微陆块,导致大别-苏鲁超高压岩石垂向折返剥露;中三叠世-晚三叠世,勉略洋自东向西的剪刀式闭合,华南地块向北秦岭-大别微陆块俯冲拼合,并逐渐将华南地块与华北地块之间的秦岭-大别微陆块向西、向北侧向挤出,到了中生代华北地块持续向南东俯冲并楔入华南地块,将苏鲁-大别造山带沿郯庐断裂错断并最终形成该区总体构造格局。
The Indosinian belt of the Sulu orogenic belt in the eastern part of China experienced complex processes such as oceanic descending and subduction, continental collision, deep continental crust subduction and intracontinental orogeny. Based on the tectonic geology, petrology, lithofacies palaeogeography and chronology of the Sulu orogenic belt, it is difficult to explain the following fact with the traditional South China subduction to the North China: (1) Xuhuai area has developed obvious northwestward expansion In addition, there are still a large number of NW-trending thrust nappe structures in the Sulu orogenic belt. (2) The inherited zircons from the Paleoproterozoic of Cretaceous granites that are exposed in the Sulu orogen and Sr , Nd and Pb isotopic tracing results show that they are more similar to the geologic bodies in the southern margin of North China block. (3) Late Paleozoic to Mesozoic arc-arc volcanic evidence is lacking in the Jiaolai Basin and the Jiaobei uplift on the north side of the Sulu orogen; (4) Paleogeography in the southern margin of North China is closer to the passive continental margin. Based on these facts, this paper argues that the Late Paleozoic-Shanglongyang Early Jurassic Upper Triassic may dive to the east and south, different from the Qinling-Dabie Member’s Shangdan Ocean subducting northward and down to Qinling-Dabie Micro Under the belt of the Lulu block, the combination of the North China block and the micro-continental block occurred. The whole of the North China block wedged the Qinling-Dabie micro-block to the south, leading to the vertical reentry of the Dabie-Sulu UHP rock. During the Middle Triassic-Late Triassic and Mianliao Ocean scalings from east to west, the South China block subducted and merged the North Qinling-Dabie micro-block, and gradually separated the South China block from the North China block The Qinling-Dabie micromass block is extruded to the west and to the north, and the Mesozoic North China block continued its subduction to the south and east and wedged into the South China block, dislocating the Sulu-Dabie orogenic belt along the Tan-Lu fault and finally The formation of the overall structure of the pattern.