郯庐断裂带中生代构造演化史:进展与新认识

    Mesozoic tectonic evolution history of the Tan-Lu fault zone: Advances and new understanding

    • 摘要: 总结出郯庐断裂带中生代运动学演化的过程与历史,概括为“两大运动时期、五个发展阶段”。第一运动时期对应于三叠纪—早侏罗世早期的“印支运动”,以扬子陆块与华北地块之间的拼合和碰撞造山为主导,郯庐断裂带经历了:①转换走滑阶段(240~220Ma),其走滑活动局限在大别和苏鲁超高压变质带之间。这个阶段的陆-陆深俯冲作用使苏鲁超高压变质带向西韧性挤出,导致徐淮弧形构造带的形成和发育。②左旋平移走滑阶段(220~190 Ma),徐淮弧形构造带向南错移了约145km,并被大别山以北地区的东西向逆冲系统所吸收。左旋走滑扩展使郯庐断裂带贯穿整个华北和东北地区。第二运动时期对应于中、晚侏罗世至古新世时期的“燕山运动”,郯庐断裂带的演化与东亚活动陆缘的演化紧密联系在一起,经历了③中、晚侏罗世至早白垩世早期挤压走滑活动,伴随着华北东部地区岩石圈、地壳增厚和郯庐左旋走滑断裂系的发育。④早白垩世以地壳伸展和陆内裂谷断陷作用为主,使早期增厚的华北克拉通岩石圈发生垮塌和减薄;⑤晚白垩世—古新世以右旋走滑为主,沿断裂带及其两侧发育一系列拉分盆地。系统地阐述了郯庐断裂带中生代发育过程与地质特征,及其在东亚大陆演化历史中独特的作用。

       

      Abstract: The authors put forward a new chronological evolution model of the Mesozoic kinematic history of the Tan-Lu fault zone, which is boiled down to “two movement periods and five development stages”. The first movement period corresponds to the Triassic to earliest Early Jurassic “Indosinian Movement”, characterized by amalgamation between the North China Craton and the Yangtze block and collisional orogeny. During this movement period, the Tan-Lu fault zone experienced two stages, i.e. the first and second stages. The first stage (240-220 Ma) was a transition strike-slip stage, when the strike-slip movement of the fault zone was restricted to a transform zone between two ultra-high pressure (UHP) metamorphic belts. The Xu-Huai orocline on the western side of the Tan-Lu fault zone was formed by westward ductile extrusion of the Sulu UHP metamorphic belt as a consequence of the deep subduction of the Yangtze block beneath the North China Craton. The second stage (220-190 Ma) was a left-lateral strike-slip stage. During this stage, the Xu-Huai orocline was displaced southward about 145 km and then was absorbed an E-W-striking thrust system in the hinterland area of the Dabie orogenic belt. Northward propagation of the left-slip motion made the Tan-Lu fault zone go through the whole of North China and Northeast China. The second movement period corresponded to the Middle-Late Jurassic to Paleocene “Yanshan Movement”, and the tectonic history of the Tan-Lu fault zone was closely associated with the evolution of the active continental margin of East Asia. The fault zone during this movement period underwent three stages, i.e. the third, fourth and fifth stages. The third stage (Middle-Late Jurassic to earliest Early Cretaceous) witnessed compressive strike-slip motion, accompanied by the lithospheric and crustal thickening of the eastern North China Block and formation and development of the Tan-Lu fault system. The fourth stage (Early Cretaceous) saw crustal extension and intracontinental rifting, resulting in collapse and thinning of the thickened lithosphere of North China. During the fifth stage (Late Cretaceous to Paleocene), dextral strike-slip motion predominated and a number of pull-apart basins formed along and at both sides of the Tan-Lu fault zone. The paper systematically describes the Mesozoic development history and geological features of the Tan-Lu fault zone and its specific role played in the tectonic evolution of the East Asian continent.

       

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