Effect of spatial distribution of Hormuz salt on deformation style in the Zagros fold and thrust belt: an analogue modelling approach
Effect of spatial distribution of Hormuz salt on deformation style in the Zagros fold and thrust belt: an analogue modelling approach
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DOI：
10.1144/0016-764902-135
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发表时间：
2003-09
影响因子：
2.7
通讯作者：
A. Bahroudi;H. Koyi
中科院分区：
文献类型：
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作者：
A. Bahroudi;H. Koyi
在相邻的粘性和摩擦性Dé岩系之上的薄皮肤同时缩短的比例模拟模型模拟了霍尔木兹盐对Zagros褶皱和冲断带上的缩短的影响。模型由沙层组成，沙层部分覆盖了粘性的硅胶层，并从一端缩短。粘性Dé岩块的空间分布沿走向和倾角变化，就像在扎格罗斯褶皱和逆冲带的部分地区所发生的那样。在该带中，显生宙沉积盖层部分缩短，位于前寒武纪结晶基底上的霍尔木兹盐之上，表现为底部粘性的dé胶结。模型结果显示了Dé拼接的性质如何影响造山带的演化。利用模型结果解释了偏转带的发育，并讨论了应变分配、不同地形楔体的形成以及沿扎格罗斯褶皱冲断带的差异沉积。模拟结果表明，在粘性的dé褶皱上方形成了一个平缓的锥体，在摩擦性dé褶皱上方形成了一个由向前和向后的推力组成的相对陡峭的锥体。然而，在我们的模型中，具有最高地形的最陡峭的楔形形成在粘性衬底的有限范围内，过渡边界(夹断)垂直于缩短方向。这一边界的缩短导致了与形变前锋后方地区的显著隆升相关的前缘斜坡的发展。
Scaled analogue models of thin-skinned simultaneous shortening above adjacent viscous and frictional décollements simulate the effect of Hormuz salt on the shortening in the Zagros fold and thrust belt. The models consisted of sand layers that partly overlay a viscous layer of silicone and were shortened from one end. Spatial distribution of the viscous décollement varied along strike and dip, as occurs in part of the Zagros fold and thrust belt. In this belt, Phanerozoic sedimentary cover was shortened partly above the Hormuz salt lying on the Precambrian crystalline basement, behaving as a basal viscous décollement. Model results display how the nature of the décollement affects the evolution of an orogenic belt. Using model results, we explain the development of deflection zones, and discuss strain partitioning, formation of different topographic wedges and differential sedimentation along the Zagros fold and thrust belt. Model results suggest the formation of a gentle taper, consisting of both foreward and backward thrusts above a viscous décollement and a relatively steeper taper consisting only of forward-vergent imbricates above a frictional décollement. However, in our models, the steepest wedge with the highest topography formed where the viscous substrate had a limited extent with a transitional boundary (pinch-out) perpendicular to the shortening direction. Shortening of this boundary led to development of frontal ramps associated with significant uplift of the area behind the deformation front.