Numerical modeling of crenulation cleavage development: A polymineralic approach
Numerical modeling of crenulation cleavage development: A polymineralic approach
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DOI：
10.1016/j.jsg.2010.01.004
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发表时间：
2010-03-01
影响因子：
3.1
通讯作者：
Koons, Peter O.
中科院分区：
文献类型：
--
作者：
Naus-Thijssen, Felice M. J.;Johnson, Scott E.;Koons, Peter O.
用有限元方法研究了石英和白云母矿物弹性相互作用对褶皱解理发育不同阶段的颗粒尺度应力和应变分布的影响。多矿物结构由单个颗粒组成，每个颗粒都被分配了自己的3D硬度张量和取向。在褶皱发育的最早阶段，石英颗粒内的平均应力和体积应变的梯度在微褶皱的四肢和铰链之间发展，在微褶皱的四肢中有较高的值。这些梯度随着褶皱解理的发展而减小，因为微褶皱的四肢变成了富层硅酸盐(P)域，铰链变成了富石英和富长石域(QF)。石英颗粒的结晶取向对平均应力和体积应变分布的影响相对较小。我们的发现与压溶和应变驱动的解理发展模型大体一致。然而，由于褶皱解理的发展通常涉及变质反应，我们倾向于这样的模型，即溶解由这些反应驱动，导致矿物分离组构发展的质量传递由跟随体积应变梯度的孔隙流体压力梯度驱动。矿物界面上的局部应力和应变集中可以识别出反应增强的位置。(C)2010爱思唯尔有限公司。保留所有权利。
The finite element method was used to investigate how the elastic interactions of quartz and muscovite minerals affect grain-scale stress and strain distributions at different stages of crenulation cleavage development. The polymineralic structure comprises individual grains that were each assigned their own 3D stiffness tensor and orientation. Gradients in mean stress and volumetric strain within quartz grains develop between the limbs and hinges of microfolds at the earliest stages of crenulation development, with higher values in the microfold limbs. These gradients decrease with development of the crenulation cleavage, as the microfold limbs become phyllosilicate-rich (P) domains and the hinges become quartz- and feldspar-rich (QF) domains. Crystallographic orientations of the quartz grains have a relatively minor effect on the mean stress and volumetric strain distributions.Our findings are broadly consistent with both pressure solution and strain-driven dissolution models for crenulation cleavage development. However, because crenulation cleavage development typically involves metamorphic reactions, we favor a model in which dissolution is driven by those reactions, and mass transfer leading to development of the mineralogically segregated fabric is driven by pore fluid pressure gradients that follow gradients in volumetric strain. Local concentrations of stress and strain across mineral interfaces may identify sites of enhanced reaction. (C) 2010 Elsevier Ltd. All rights reserved.