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    华北克拉通北缘及邻区前燕山期主要地质事件

    Pre-Yanshanian geological events in the northern margin of the North China Craton and its adjacent areas

    • 摘要: 提要:近年来,华北克拉通北缘及邻区的研究进展集中在前燕山期的主要地质构造格架的廓清,以及晚中生代以来的构造岩浆事件和克拉通岩石圈减薄研究的深化。本文对前者的研究进展作评述和展望。华北克拉通自1.8~1.75 Ga形成后,时有岩浆扰动。1.35 Ga的基性岩床和岩墙群事件代表了华北克拉通与北美克拉通的裂解,说明华北克拉通曾经是哥伦比亚超大陆的组成部分。华北克拉通北缘大陆边缘的演化也应当从1.35 Ga以后开始。早古生代时期,在华北克拉通以北的兴蒙造山带南部发育了白乃庙岛弧岩带,但此时华北克拉通依然记录的是稳定沉积。该岛弧岩带在早古生代末期可能通过弧-陆碰撞形式增生到华北克拉通北部边缘。早中泥盆世期间,在华北克拉通北缘发育了年龄为410~380 Ma的碱性杂岩,可能与弧陆碰撞后的伸展有关。从晚石炭世(~320 Ma)开始,华北克拉通北缘发展为安第斯型活动大陆边缘,古亚洲洋向南俯冲在华北克拉通之下。在相邻的兴蒙造山带,古亚洲洋还存在向北的俯冲,形成了白音宝力道岛弧岩带。古亚洲洋沿索伦缝合带的最终闭合发生在二叠纪末—三叠纪初期。华北克拉通北缘大量~250 Ma以来的后碰撞岩浆活动记录了这一拼合过程。晚三叠世—早侏罗世华北克拉通北缘发生大规模逆冲推覆。早侏罗世时期,华北克拉通北缘已经出现基底结晶岩系的广泛剥露。在燕山期构造岩浆作用之前,华北克拉通北缘的东西向构造格架基本奠定。

       

      Abstract: Abstract:Recent researches on the northern margin of the North China Craton (NCC) and its adjacent areas have been mainly focused on the main pre-Yanshanian tectonic framework and the late Mesozoic tectonomagmatic evolution and lithosphere destruction. This paper gives a brief review on the previous research progress and future prospect in this aspect. The northern NCC has undergone multiple magmatic processes after its cratonization during ~1.8 Ga. Large volumes of 1.35-1.30 Ga mafic sill (dyke) swarms in northern NCC are related to the breakup of the NCC from the Columbia supercontinent and might indicate that the NCC was probably a member of Nena including the Laurentia (North America and Greenland), Siberia and Baltica cratons in the supercontinent. The evolution of the northern continental margin of the NCC was probably initiated at 1.35 Ga. During the Early Paleozoic, the Bainaimiao island arc belt was located to the south of the NCC. At the end of Early Paleozoic, the island arc was accreted to the NCC probably by arc-continental collision. Early-Middle alkaline complexes with emplacement ages ranging from 410-380 Ma in northern NCC are probably related to the extension after arc-continental collision between the NCC and the Bainaimiao arc terrane. From the Late Carboniferous (~320 Ma), the northern margin of the NCC became an Andean-style continental arc due to the southward subduction of the Paleo-Asian oceanic plate beneath the NCC. The southward subduction of the Paleo-Asian oceanic plate also occurred in the Xing-Meng orogenic belt during this period, which resulted in the formation of the Baolidao island arc. Final closure of the Paleo-Asian Ocean and collision between the Mongolian arc terrane and the NCC occurred during the latest Permian~earliest Triassic period with post-collison magmatism from ~250 Ma. During the Late Triassic~Early Jurassic period, the northern NCC is characterized by strong thrusting. In the early Jurassic, the Archean-Paleoproterozoic basement metamorphic rocks were widely exposed. The tectonic framework of the northern margin of the NCC and its adjacent areas was preliminarily established prior to the Yanshanian tectonism and magmatism.

       

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