Plate tectonics and the evolution of the British Isles
Plate tectonics and the evolution of the British Isles
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DOI：
10.1144/gsjgs.139.4.0371
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发表时间：
1982-07
影响因子：
2.7
通讯作者：
J. Dewey
中科院分区：
文献类型：
--
作者：
J. Dewey
本文以不列颠群岛的地质历史为例，论述了板块构造地质推论的合理性和困难。特别强调了大陆岩石圈在伸展过程中的力学机制，即盆地的形成和在会聚过程中，在伸展过程中变薄的大陆岩石圈被缩短并重新叠加形成造山带。上岩石圈应力集中弹性盖遭受非常复杂的不均匀变形以上的一个简单的，粘弹性的下岩石圈，其变形驱动应变和位移的弹性盖。板块构造作为多板块镶嵌体之间的相对运动的本质，为时空上的大规模地质复杂性提供了一个合理的半定量框架。不列颠群岛的加里东期和赫西期历史可以用板块边界演化来半定量地解释，但不可能定义明确的解。板块构造的合理性在更小、更直接的领域尺度上表现为蛇绿岩复合体的许多复杂性，如苏格兰的Ballantrae，这可以解释为脊/脊转换的演化效应，以及俯冲增生棱柱（如南部高地）中的历时变形和沉积作用。从三叠纪到现在，欧洲西北部的变形和沉积模式是由与贯穿大西洋的开口有关的伸展事件和与连续的阿尔卑斯山缩短阶段有关的压缩事件的复杂相互作用造成的。这些广泛分布的事件是典型的陆内板块边界系统，给希望从地质序列中破译相对板块运动的地质学家造成了巨大的困难，因为必须对比不列颠群岛大得多的巨大区域进行分析和综合，才能提取出许多意义。进一步的困难来自会聚边界的塑性和保存问题;造山缩短的伸缩和部分消减相带。大多数造山带都是由移位和旋转的地形元素拼凑而成，随后被压平、拉长和拉直，形成一种表面上看起来简单但具有欺骗性的简单结构。因此，虽然板块构造提供了一个合理的地质框架，例如，英国盆地的演化可以根据这个框架进行测试和解释，但我们还不能利用板块边界演化的地质效应来定量地重建板块的相对运动。
This paper is an essay on the rationalism and difficulties of the geological corollaries of plate tectonics, with illustrations particularly from the geological history of the British Isles. There is special emphasis on the mechanics of continental lithosphere in extension, when basins are formed and in convergence whereby continental lithosphere thinned in extension is shortened and restacked to form orogenic belts. An upper lithosphere stress-concentrating elastic lid suffers extremely complex inhomogeneous deformations above a simpler, viscoelastic lower lithosphere whose deformation drives strain and displacement in the elastic lid. The very nature of plate tectonics as relative motion among a multi-plate mosaic of plates provides a rational semi-quantitative framework for large-scale geological complexity in space and time. The Caledonian and Hercynian history of the British Isles may be explained semi-quantitatively in terms of plate boundary evolution but it is not possible to define unequivocal solutions. The rationalism of plate tectonics is exhibited on a smaller, more direct field-scale by many of the complexities of ophiolite complexes, such as Ballantrae (Scotland), that can be explained as the effects of the evolution of ridge/ridge transforms and by diachronous deformation and sedimentation in subduction accretion prisms such as the Southern Uplands. Deformational and sedimentary patterns in NW Europe from Triassic times to the present day resulted from a complex interaction of extensional events related to diachronous Atlantic opening and compressional events related to sequential Alpine shortening phases. Those widespread events are typical of intracontinental plate boundary systems and create great difficulties for the geologist wishing to decipher relative plate motion from geological sequences, because huge areas, much larger than the British Isles, must be analysed and synthesized before much sense can be extracted. Further difficulties arise from the palinspastic and preservation problems of convergent boundaries; orogenic shortening telescopes and partially subducts facies belts. Most orogenic belts were assembled as a collage of displaced and rotated terrain elements that were subsequently flattened, elongated and straightened to an apparent but deceiving simplicity. Therefore, while plate tectonics provides a rational geological framework against which, for example, British basin evolution can be tested and explained, we cannot yet use the geological effects of plate boundary evolution to reconstruct relative plate motion quantitatively.