Structural heterogeneities in the deep lithosphere have been identified as an important factor in crustal tectonics, particularly where inherited deep zones of weakness may initiate orogenesis in continent interiors. Aside from structural heterogeneity, the rheological strength of the lithosphere may also have a primary role affecting the kinematics of deformation in the lithosphere. To investigate the interplay of rheology and preexisting structures, we designed a set of physical scaled analog experiments for a convergent setting that tests (a) the presence and absence of a preexisting weak zone in the lithospheric mantle and (b) the effects of the rheological strength of the lithospheric mantle. Tectonic evolution of the model is recorded to acquire a time series data set of the velocity field and subsequently strain in the model. Results show that a weak zone in the lithospheric mantle allows deformation to be accommodated by displacement along this zone and into the overlying lower and upper crust, regardless of lithosphere strength. In contrast, a model absent of a weak zone accommodates deformation by folding and thickening of the viscous layers. The viscous lithosphere in models with a strong lithospheric mantle tends to buckle creating a sequence of brittle faulting in the upper crust. Specifically, the rheology of the lithosphere dictates the distribution of strain. Our results are considered in the context of the formation of the Eurekan fold and thrust belts in an intraplate setting on Ellesmere Island, where deformation may be related to the influence of deep lithosphere structure(s) and deep lithosphere strength.

中文翻译：

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岩石圈地幔疤痕和流变学对板内变形和造山作用的影响：构造模拟模型的启示

深层岩石圈的结构异质性已被认为是地壳构造的重要因素，尤其是在继承的深层薄弱带可能启动大陆内部造山作用的地方。除了结构上的非均质性，岩石圈的流变强度还可能对岩石圈变形的运动学起主要作用。为了研究流变学和预先存在的结构之间的相互作用，我们设计了一套物理规模的模拟实验用于汇聚环境，以测试（a）岩石圈地幔中是否存在预先存在的薄弱区域，以及（b）流变学的影响岩石圈地幔的强度。记录模型的构造演化，以获取速度场的时间序列数据集，然后获取模型中的应变。结果表明，岩石圈地幔中的薄弱区域允许变形沿该区域向上，下地壳和上地壳移动，以适应变形，而与岩石圈的强度无关。相反，缺乏薄弱区域的模型通过折叠和增厚粘性层来适应变形。在岩石圈地幔强的模型中，粘性岩石圈趋于弯曲，在上地壳中形成一系列脆性断层。具体而言，岩石圈的流变性决定了应变的分布。我们的研究结果是在Ellesmere岛上的板内设置Eurekan褶皱和逆冲带的背景下考虑的，那里的变形可能与深层岩石圈结构和深层岩石圈强度的影响有关。