Intraplate lithosphere deformation and the strength of the lithosphere
Intraplate lithosphere deformation and the strength of the lithosphere
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DOI：
10.1111/j.1365-246x.1984.tb02238.x
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发表时间：
1984-11
影响因子：
2.8
通讯作者：
N. Kusznir;R. Park
中科院分区：
文献类型：
--
作者：
N. Kusznir;R. Park
摘要本文用一个综合考虑岩石圈材料弹性、韧性和脆性响应的数学模型研究了大陆岩石圈板内变形对应力的响应。韧性变形在地壳中由石英中的位错蠕变控制，在地幔中由橄榄石中的位错蠕变和塑性控制。用修正的Griffith理论预测了脆性破坏。该模型的一个基本特征是岩石圈内的应力重新分布后，应力释放的韧性和脆性变形。这种再分布在中地壳或下地壳的弹性-韧性或脆-韧性转变之上产生高水平的应力，岩石圈变形被证明是严重依赖于温度结构，其中表面热流是一个方便的指标。当地温梯度较高时，岩石圈下部的应力释放更迅速、更完全，导致岩石圈上部的应力水平更大。当外加应力足够大或地温梯度很陡时，中地壳和上地壳的应力水平将导致岩石圈上部的完全破裂。整个岩石圈破裂（WLF）的结果，通过持续的脆性和韧性变形，造成地质上显着的应变。已计算出的临界值所需的施加应力，使WLF的拉伸和压缩变形作为表面热流的函数。然后将预测的岩石圈体强度与由板块边界力和均衡补偿载荷引起的板内应力的预期水平进行比较，这些应力被认为在大陆岩石圈中产生+0.25至-0.25 kB的净应力水平。使用这些预期的最大应力水平，该模型预测了在q > c的中等热流区域的显著的拉伸变形。60 mWm-'（如中欧）以及高热流地区，如盆地山脉省。在q > c的高热流区预测有显著的压缩变形。75 mWm-2，但仅适用于应力组合的限制条件。这些结果与
Summary. The intraplate deformation of continental lithosphere in response to applied stress has been investigated using a mathematical model which incorporates the elastic, ductile and brittle response of lithosphere material. Ductile deformation is assumed to be controlled in the crust by dislocation creep in quartz, and in the mantle by dislocation creep and plasticity in olivine. Brittle failure is predicted using modified Griffith theory. A fundamental feature of the model is the redistribution of stress within the lithosphere following stress release by both ductile and brittle deformation. This redistribution produces high levels of stress in the middle or lower crust immediately above the elastic-ductile or brittle-ductile transition, Lithosphere deformation is shown to be critically dependent on the temperature structure of which surface heat flow is a convenient indicator. For higher geothermal gradients, the release of stress in the lower lithosphere by ductile deformation is more rapid and complete and results in large stress levels in the upper lithosphere. For sufficiently large applied stresses or steep geothermal gradients, the stress levels in the upper and middle crust will cause complete fracture of the upper lithosphere. Whole lithosphere failure (WLF) then results, by continued brittle and ductile deformation, causing geologically significant strains. The critical value of applied stress required to give WLF has been calculated for both tensional and compressional deformation as a function of surface heat flow. The predicted lithosphere bulk strength is then compared with expected levels of intraplate stress arising from plate boundary forces and isostatically compensated loads, which are thought to give net stress levels in the continental lithosphere in the range +0.25 to -0.25 kB. Using these expected maximum stress levels, the model predicts significant extensional deformation in regions of moderate heat flow with q > c. 60mWm-’ (e.g. Central Europe) as well as for areas of high heat flow like the Basinand-Range Province. Significant compressional deformation is predicted for areas of high heat flow with q > c. 75 mWm-2 but only for restricted conditions of stress combination. These results are in good agreement with