北极地区地质构造及主要构造事件

北极地区范围很广,北极圈面积达2 100×104 km2,区域地质复杂。通过对北极地区区域地质编图,笔者认为前寒武纪主要由波罗的、劳伦和西伯利亚三大克拉通,以及其间的微板块或地块组成。主要造山带包括新元古代—早寒武世的贝加尔造山带、晚志留世—早石炭世的加里东造山带、晚古生代—早中生代的海西造山带、晚中生代的上扬斯克造山带、新西伯利亚造山带与楚科奇—布鲁克斯造山带。根据北极地区区域地质构造特征,显生宙以来经历的构造事件大致包括:新元古代—早寒武世的贝加尔运动,致使波罗的古陆与斯瓦尔巴—喀拉地块碰撞造山;晚泥盆世—早石炭世的加里东运动,在劳伦古陆周边形成规模巨大的加里东造山带;晚古生代的海西运动,波罗的古陆与西伯利亚古陆的碰撞造山形成海西造山带;北极阿拉斯加—楚科奇微板块裂离加拿大边缘,侏罗纪加拿大海盆开始张开;早白垩世,阿拉斯加—楚科奇微板块继续与西伯利亚碰撞,阿纽伊洋(Anyui Ocean)消亡,形成上扬斯克—布鲁克斯造山带。受北极调查程度影响,许多问题有待进一步研究。

Tectonic Features and Main Tectonic Events in the Arctic Area

It is quite big area, with about 21 × 10 6 km2 , in the north of Arctic Circle, and complicated in tectonics.A basal structural map of Arctic area was compiled,based on the published data.It can be suggested that Precambrian base is composed of 3 cratons,such as Laurentia,Siberian and Baltica,and some terrains between them.The main orogenic belts include Baikalides,Caledonides, Hercynides,Verkhoyansk,and New Siberian-Chukotka-Brooks orogenic belts.Based on the tectonic features,the Arctic area should undergo the following main tectonic events in Phanerozoic Eon:1 ) Baikalidian movement in Late Neoproterozoic-Early Cambrian,which resulted in the collision of Baltica continent with Svalbard-Kara massif and formation of Baikalides;2 )Caledonian movement in Late Silurian-Early Carbonferous,which resulted in the formation of Caledonides around the Laurentia continent;3 )Hercynidian movement in Late Palaeozoic-Early Mesozoic,which led to the collision between Baltica continent and Siberian continent;4)Microplate of Alaska-Chukotka split from the north margin of Canada;and the Canadian Ocean started opening as the breakup of Pangea in Jurassic;5 ) Alaska-Chukotka microplate shifted forward to the Siberia and collided to the northern Siberia in Early Cretaceous,which resulted in the formation of Verkhoyansk and New Siberian-Chukotka-Brooks orogenic system.In consideration with the limited geological and geophysical survey,further research is needed to discover much more tectonic features in Arctic region.