超大陆裂解几何学研究新思路——截顶正二十面体模型的应用

A New Idea for Studying Geometry of Supercontinent Breakup: the Application of Truncated Icosahedra

截顶正二十面体是目前应用广泛的球体张拉整体结构模型之一。它具有60个顶点,12个五边形边,20个六边形面。球壳在均匀的伸展状态下,沿该模型的棱的方位最容易裂开。前人从全球规模的角度出发,用截顶正二十面体模型解释了劳仑大陆以及冈瓦纳超大陆裂解时期全球范围内的伸展构造组合的展布,包括裂谷系、非造山岩浆活动和岩墙群。本文在前人的基础上,用该模型解释了现代大洋中脊分布、东非—红海—亚丁湾裂谷系的平面几何形态以及华北克拉通1.80Ga裂谷系分布。根据该模型进行计算,得出半径为单位1的该模型的棱长为23.3°,带入地球平均半径则得全球最长直线裂谷的长度为2589.53km,同时得到五边形和六边形的顶角分别为111.4°和124.3o由此,超过该长度的裂谷将以120°左右的夹角拐弯。该模型能解释大范围伸展构造组合的分布规律。

Truncated icosahedra is one of the most widely used spherical tensility modules. Under uniform extension, spherical shell tends to break up along the edge of this module. Previous workers tried to use truncated icosahedra to explain the distribution of rifting system, anorogenic magmatism and dyke swarms of Laurentia and Gondwana in a global view. On such a basis, the authors have used this module to explain the distribution of the present mid-ocean ridge, the contour of the Great Rift Valley and the distribution of the rifting system of the North China Craton dated 1.80 Ga. According to this module, when its radius is unit 1, its edge should be 23.3°. If we use Earth＇s even radius, the length of the longest straight line rift is 2589.53 km, and the angle of pentagon and hexagon is 111.4° and 124.3° respectively. That is, a rift longer than 2589.53 km would turn at an angle of 120° or so.