西北欧海域及邻区构造单元与构造演化

    TECTONIC UNITS AND EVOLUTION IN THE NORTH-WEST EUROPE OFFSHORE AND NEIGHBOURING AREAS

    • 摘要: 西北欧海域及邻区可划分为4个一级构造单元,分别是劳伦提亚板块、阿维隆尼亚板块、波罗的板块和冈瓦纳板块。进一步可划分为7个二级构造单元,其中劳伦提亚板块划分了2个二级构造单元,分别为劳伦提亚地块和劳伦提亚加里东造山带;阿维隆尼亚板块划分了2个二级构造单元,分别为阿维隆尼亚加里东造山带和阿维隆尼亚海西造山带;波罗的板块划分了2个二级构造单元,分别是波罗的地块和波罗的加里东造山带;冈瓦纳板块划分1个二级构造单元,称为冈瓦纳海西造山带。西北欧海域及邻区古生代以来构造演化经历了古生代,包括晚奥陶世到志留纪的加里东期和中到晚石炭世海西期的大陆碰撞与大陆增生,中生代大陆裂谷作用和晚中生代到新生代大陆离散和海底扩展阶段。经过古生代的大陆碰撞与大陆增生,劳伦提亚板块、波罗的板块、阿维隆尼亚板块和冈瓦纳板块连成一体。中生代的大陆裂谷作用表现为穿过前寒武纪—古生代增生构造的重新活动或裂解和西北欧海域及邻区一系列裂谷盆地的形成。晚中生代到新生代大陆离散和海底扩张导致北美和伊比利亚,以及格陵兰和欧洲的分离和洋脊进积进入北极。

       

      Abstract: Four first order tectonic units, i.e the Laurentia plate, Avalonia plate, Baltica plate and Gongwana plate, are recognized in the North-West Europe offshore and neighbouring areas. There are seven second order units, incuding two units, the Laurentia block and Laurentia Caledonian orogenic belt in the Laurentia plate,two units, the Avalonia Caledonian orogenic belt and Avalonia Variscan orogenic belt in the Avalonia plate, two units, the Baltica block and Baltica Caledonian orogenic belt in the Baltica plate, and one unit, the Gongwana Variscan orogenic belt in the Gongwana palte.In the North-West Europe, Palaeozoic orogeny can be divided into two separate events, the Caledonian and the Variscan, The Caledonian collision involved three plates, the Laurentia plate, Avalonia plate and Baltica plate. Prior to the collision, the Tornquist Ocean separated the Baltica plate from Avalonia plate, and the Iaptus Ocean separated the Laurentia plate from the two opposite plates. The Caledonian collision resulted in the Caledonian orogeny. During the Mid to Late Carboniferous,the Variscan orogency closed the Iaptus Ocean among Laurentia plate, Avalonia plate and Baltica plate.The Mesozoic continental rifting tectonic movement represented a process to rework or break the preexisting Precambrian-Palaeozoic accretionary structures, and formed a series of rift basins in North-West Europe. During the Early Cretaceous, oceanic spreading broke through the Gibraltar Transform to initiate separation between North America and Iberia. During the Paleocene and Eocene, the North Atlantic was affected by a mantle plume that weakened the lithosphere and allowed the renewed spreading. Oceanic crust formed after only a slight amount of Eocene extension, leading to the separation of Greenland from Europe and ocean-ridge propagation into the Arctic.

       

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