Styles of rifting and fault spacing in numerical models of crustal extension
Styles of rifting and fault spacing in numerical models of crustal extension
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地壳伸展数值模型中的裂谷类型和断层间距
DOI：
10.1002/2014jb011813
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
J. Revote
中科院分区：
文献类型：
--
作者：
W. Sharples;Louis Moresi;M. Jadamec;J. Revote
地壳的延伸会导致不同类型的裂谷，例如地垒地堑、半地堑、变质核复合体和分布式地壳减薄区域。故障模式的范围可以从分布式到高度局部化。观测表明，控制伸展变形、对称性和断层间距的因素包括流变方面（如屈服机制和应变软化）和物理方面（如初始非均质性和下地壳与上地壳相比的强度）。提出了与时间相关的伸展数值模型，研究了屈服机制、下地壳强度、应变弱化和地壳初始非均质性对（a）裂谷类型、（b）断层间距和（c）上地壳综合强度的影响。与具有各向同性屈服机制的模型相比，具有各向异性屈服机制的模型会产生更真实的岩石圈强度剖面、滑移面角度分布和断层相互作用。异质性类型和屈服机制对变形的对称性影响最大，而应变弱化量对不对称性影响最大。变质核复合模式发生的可能性主要受下地壳强度控制。少量的应变减弱和坚固的下地壳都促进了地壳变薄。下地壳粘度主要控制所产生的变形是分布的还是局部的。应变弱化程度对上地壳平均强度和上地壳强度剖面斜率影响最大。
Extension of the Earth's crust can result in differing styles of rifting, such as horst‐and‐graben, half‐graben, metamorphic core complexes and areas of distributed crustal thinning. Faulting patterns can range from either being distributed to highly localized. Observations indicate that the factors controlling the extensional deformation, symmetry, and fault spacing include rheological aspects such as the yielding mechanism and strain softening, and physical aspects such as initial heterogeneities and the strength of the lower crust compared to the upper crust. Time‐dependent numerical models of extension are presented, which investigate the influence of the yielding mechanism, lower crust strength, strain weakening, and initial heterogeneity in the crust have on (a) the style of rifting, (b) fault spacing, and (c) integrated strength in the upper crust. Models with an anisotropic yielding mechanism result in more realistic lithospheric strength profiles, slip plane angle distributions, and fault interaction than models with an isotropic yielding mechanism. Heterogeneity type and yielding mechanisms have the largest effect on the resulting symmetry of deformation, whereas the amount of strain weakening has the greatest influence on asymmetry. The likelihood of the metamorphic core complex mode occurring is primarily controlled by lower crust strength. Crustal thinning is encouraged by both low amounts of strain weakening and a strong lower crust. Lower crust viscosity exerts the primary control on whether the resulting deformation is distributed or localized. The degree of strain weakening has the largest influence on the average strength of the upper crust and the slope of the strength profile in the upper crust.