Traction and strain-rate at the base of the lithosphere: an insight into cratonic survival
Traction and strain-rate at the base of the lithosphere: an insight into cratonic survival
复制标题
岩石圈底部的牵引力和应变率：洞察克拉通的生存
DOI：
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发表时间：
2019
影响因子：
2.8
通讯作者：
C. Conrad
中科院分区：
文献类型：
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作者：
J. Paul;A. Ghosh;C. Conrad
岩石圈是岩石圈中最古老的部分，其中一些自太古代以来一直存在。它们的长期存活有时归因于高粘度和低密度。在我们的研究中，我们使用一个数值模型来研究如何施加地幔对流的剪切力的工作变形对流剪切。我们发现，虽然在岩石圈底部的牵引力增加，随着岩石圈厚度的增加，相关的应变率降低。应力和应变率之间的这种反比关系是由于横向粘度变化以及施加在地球表面的模型自由滑动条件造成的，这使得应变能够沿着板块边界的弱带积累。此外，我们表明，通过对流剪切，我们表示为一个表观粘度的岩石圈变形的阻力，尺度与岩石圈厚度的平方。这表明，增加的厚度的岩石圈保护他们免受对流剪切，并允许他们生存的岩石圈变形最小的地区。事实上，我们表明，一个较小的软流圈的粘度下降和较大的粘性的组合，以及与周围的岩石圈相比，多余的厚度的软流圈，可以解释他们的生存，因为太古代的时间。
Cratons are the oldest parts of the lithosphere, some of them surviving since Archean. Their long-term survival has sometimes been attributed to high viscosity and low density. In our study, we use a numerical model to examine how shear tractions exerted by mantle convection work to deform cratons by convective shearing. We find that although tractions at the base of the lithosphere increase with increasing lithosphere thickness, the associated strain-rates decrease. This inverse relationship between stress and strain-rate results from lateral viscosity variations along with the model’s free-slip condition imposed at the Earth’s surface, which enables strain to accumulate along weak zones at plate boundaries. Additionally, we show that resistance to lithosphere deformation by means of convective shearing, which we express as an apparent viscosity, scales with the square of lithosphere thickness. This suggests that the enhanced thickness of the cratons protects them from convective shear and allows them to survive as the least deformed areas of the lithosphere. Indeed, we show that the combination of a smaller asthenospheric viscosity drop and a larger cratonic viscosity, together with the excess thickness of cratons compared to the surrounding lithosphere, can explain their survival since Archean time.
影响因子：
18.3
作者：
M. Kaban;W. Mooney;A. Petrunin
通讯作者：
M. Kaban;W. Mooney;A. Petrunin