3D finite amplitude folding: Implications for stress evolution during crustal and lithospheric deformation
3D finite amplitude folding: Implications for stress evolution during crustal and lithospheric deformation
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3D 有限振幅折叠：地壳和岩石圈变形过程中应力演化的影响
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
S. Schmalholz
中科院分区：
文献类型：
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作者：
B. Kaus;S. Schmalholz
岩石圈、沉积序列或石英脉的挤压可能导致褶皱不稳定。我们对粘性单层折叠进行了数值模拟，以研究这种3D不稳定性。结果表明，线性理论正确地描述了小振幅的不稳定性。然而，在更大的振幅下，理论就失效了。对于这些阶段，我们提出了一个新的非线性放大方程。初始水平层的折叠，随机噪声扰动的数值模拟表明，在大多数情况下，折叠轴形成垂直于主缩短方向。褶皱的纵横比是有限的，并且图案对所施加的背景缩短方向相对不敏感。此外，3D折叠不稳定性降低了折叠（“强”）层内的平均差应力，与2D结果一致。这意味着，如果在变形过程中发生褶皱，那么表示地壳和岩石圈强度的圣诞树方法可能无效。
Compression of the lithosphere, sedimentary sequences or quartz veins may result in a folding instability. We perform numerical simulations of viscous single‐layer folding to study this instability in 3D. It is demonstrated that linear theories correctly describe the instability for small amplitudes. At larger amplitudes, however, the theory breaks down. For these stages we present a new nonlinear amplification equation. Numerical simulations of folding of an initially horizontal layer, perturbed with random noise, demonstrate that in most cases fold axes form perpendicular to the main shortening direction. Aspect ratios of folds are finite and the patterns are relatively insensitive to the applied background shortening directions. Furthermore, the 3D folding instability reduces the averaged differential stress within the folded (“strong”) layer, in agreement with 2D results. This implies that the Christmas‐tree approach to represent the strength of the crust and lithosphere may be invalid if folding occurs during the deformation.