Plate generation and two-phase damage theory in a model of mantle convection
Plate generation and two-phase damage theory in a model of mantle convection
复制标题
地幔对流模型中的板块生成和两相损伤理论
DOI：
10.1111/j.1365-246x.2008.03844.x
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发表时间：
2008
影响因子：
2.8
通讯作者：
Y. Ricard
中科院分区：
文献类型：
--
作者：
W. Landuyt;D. Bercovici;Y. Ricard
狭窄的、快速变形的板块边界的形成将强大的板块内部分隔开来，这是板块构造由地幔对流形成的重要组成部分。窄板边界的发展需要非线性流变和对流的相互作用。其中一种非线性流变学是两相损伤理论，它利用界面表面能、压力和粘性变形之间的非平衡关系，形成了一种孔隙生成的理论模型。两相损伤理论最近被扩展到允许变形工作来增加基体相的细度（减小晶粒尺寸）。我们展示了在二维对流驱动系统中测试两相损伤理论的结果，其中我们允许(1)纯粹的空洞产生损伤，(2)纯粹的细度产生损伤和(3)空洞和细度结合产生损伤。发现单纯的产生空洞的损伤不能产生片状特征。在某些情况下，细度生成损伤成功地诱导了类似板的行为，包括增加粘度对细度的敏感性，以及某些损伤输入和愈合率的制度。由于产生细度的变形功输入明显增加，孔隙和细度同时产生损伤的情况比端元产生更明显的局部化。两相损伤理论中微裂纹与晶粒尺寸减小的相互作用为板块构造边界形成所必需的剪切局部化提供了一种流变模型。
SUMMARY The formation of narrow, rapidly deforming plate boundaries separating strong plate interiors are integral components of the generation of plate tectonics from mantle convection. The development of narrow plate boundaries requires the interaction of a non-linear rheology and convection. One such non-linear rheology is two-phase damage theory which employs a nonequilibrium relation between interfacial surface energy, pressure and viscous deformation, thereby forming a theoretical model for void generation. Two-phase damage theory was recently extended to allow for deformational work to increase the fineness (reduce the grain size) of the matrix phase. We present results testing two-phase damage theory in a 2-D convectively driven system where we allow for (1) pure void-generating damage, (2) pure fineness-generating damage and (3) combined void- and fineness-generating damage. Pure void-generating damage is found to be unsuccessful at producing plate-like features. Finenessgenerating damage is successful at inducing plate-like behaviour in certain circumstances, including increasing viscosity sensitivity to fineness and certain regimes of damage input and healing rate. Cases with combined void- and fineness-generating damage produce significantly more localization than the end-members due to the apparent increase of deformational work input into fineness generation. The interaction of microcracks and grain size reduction in two-phase damage theory suggests a rheological model for shear localization necessary for the formation of plate tectonic boundaries.