Role of kilometer-scale weak circular heterogeneities on upper crustal deformation patterns: Evidence from scaled analogue modeling and the Sudbury Basin, Canada
Role of kilometer-scale weak circular heterogeneities on upper crustal deformation patterns: Evidence from scaled analogue modeling and the Sudbury Basin, Canada
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千米级弱圆形不均匀性对上地壳变形模式的作用：来自比例模拟模型和加拿大萨德伯里盆地的证据
DOI：
10.1016/j.epsl.2010.07.009
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发表时间：
2010
影响因子：
5.3
通讯作者：
A. Cruden
中科院分区：
文献类型：
--
作者：
U. Riller;D. Boutelier;C. Schrank;A. Cruden
萨德伯里盆地是一个非圆柱形褶皱盆地，占据萨德伯里撞击构造的中心部分。碰撞构造对于探索含有长期软弱环形区的大陆地壳的构造演化具有很好的作用。在一系列按比例的模拟实验中，各种模型地壳结构以恒定速率水平缩短。在机械弱化的地壳中，形成了模拟萨德伯里盆地几个一级结构特征的模型盆地：（1）盆地的不对称、非圆柱形褶皱，（2）表明盆地横向终端周围同心缩短的结构，以及（3）模型盆地铰链区附近存在应变集中区。在几何学和运动学上，该区域对应于萨德伯里盆地的南山脉剪切带。根据我们的实验，这个剪切带是盆地形成的直接力学结果，而不是褶皱后逆冲作用的结果。总的来说，模型突出了结构异常的萨德伯里盆地内的古元古代东部Penokean造山带。特别是，我们的模型表明，盆地形成的纯剪切增厚的地壳，而在造山带的其他地方普遍存在的逆冲变形。模型盆地的变形增厚和非圆柱形的同形屈曲，而共轭transressive剪切带传播远离其侧端。这与强基体中弱圆形夹杂的纯剪切变形是一致的。这些模型表明，萨德伯里盆地的形成是由于陨石撞击造成的上地壳长期弱化的结果。
The Sudbury Basin is a non-cylindrical fold basin occupying the central portion of the Sudbury Impact Structure. The impact structure lends itself excellently to explore the structural evolution of continental crust containing a circular region of long-term weakness. In a series of scaled analogue experiments various model crustal configurations were shortened horizontally at a constant rate. In mechanically weakened crust, model basins formed that mimic several first-order structural characteristics of the Sudbury Basin: (1) asymmetric, non-cylindrical folding of the Basin, (2) structures indicating concentric shortening around lateral basin termini and (3) the presence of a zone of strain concentration near the hinge zones of model basins. Geometrically and kinematically this zone corresponds to the South Range Shear Zone of the Sudbury Basin. According to our experiments, this shear zone is a direct mechanical consequence of basin formation, rather than the result of thrusting following folding. Overall, the models highlight the structurally anomalous character of the Sudbury Basin within the Paleoproterozoic Eastern Penokean Orogen. In particular, our models suggest that the Basin formed by pure shear thickening of crust, whereas transpressive deformation prevailed elsewhere in the orogen. The model basin is deformed by thickening and non-cylindrical synformal buckling, while conjugate transpressive shear zones propagated away from its lateral tips. This is consistent with pure shear deformation of a weak circular inclusion in a strong matrix. The models suggest that the Sudbury Basin formed as a consequence of long-term weakening of the upper crust by meteorite impact.