The Tian Shan region is a typical example of crustal deformation within an intracontinental environment, where the lithospheric rheological properties are marked by significant spatial heterogeneity. However, the role of lithospheric rheology in crustal strain partitioning within the interior of the Tian Shan orogenic belt remains nebulous. Here, we utilized a two-dimensional viscoplastic model with contact elements constrained by GPS velocities and fault slip rates to investigate the influence of the block's strength on crustal deformation in the southwestern Tian Shan region. Our founding suggests that a weaker lower crust beneath the northern Tian Shan region offers a potential mechanism for the contemporary deformation patterns. Contemporary crustal deformation at Tian Shan is mainly concentrated along the piedmont thrust-and-fold belts and diffuses in the orogen's interior. This pattern of crustal strain partitioning is closely linked to the interplay between fault slips and lithospheric deformation. This finding emphasizes the significant role that the lithospheric rheology and pre-existing faults played in the deformation partitioning in the interior of the Tian Shan orogeny.

中文翻译：

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天山造山带西南部当代地壳变形分区的数值研究


天山地区是大陆内环境中地壳变形的典型例子，其中岩石圈流变特性以显著的空间异质性为标志。然而，岩石圈流变学在天山造山带内部地壳应变分区中的作用仍然模糊不清。在这里，我们利用了一个二维粘塑性模型，其中接触元件受 GPS 速度和断层滑移速率的约束，研究了块体强度对天山西南部地区地壳变形的影响。我们的建立表明，天山北部地区下方较弱的下地壳为当代变形模式提供了潜在的机制。天山的当代地壳变形主要集中在山麓逆冲和褶皱带上，并在造山带内部扩散。这种地壳应变分区模式与断层滑移和岩石圈变形之间的相互作用密切相关。这一发现强调了岩石圈流变学和预先存在的断层在天山造山运动内部变形分区中发挥的重要作用。