Investigating the Effect of Mantle Flow and Viscosity Structure on Surface Velocities in Alaska Using 3‐D Geodynamic Models
Investigating the Effect of Mantle Flow and Viscosity Structure on Surface Velocities in Alaska Using 3‐D Geodynamic Models
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DOI：
10.1029/2022jb024704
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发表时间：
2016-12
期刊：
影响因子：
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通讯作者：
Joseph McConeghy;L. Flesch;J. Elliott
中科院分区：
文献类型：
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作者：
Joseph McConeghy;L. Flesch;J. Elliott
我们利用三维有限元地球动力学模型，结合上板块运动的长期运动学估计，以更好地了解粘性结构和地幔牵引力在阿拉斯加产生板块运动和大陆内部变形中的作用。阿拉斯加和加拿大西北部的太平洋-北美板块边界区的地表变形受到平板俯冲、重力塌陷和地幔牵引之间复杂相互作用的强烈影响。从最近的全球定位系统（GPS）数据集得出的长期构造块体运动预测揭示了其他大陆会聚板块边界带的非典型地表运动。具体来说，在阿拉斯加的北方和西北部，观测到向东南方向的运动是直接朝向板块边界的。地球动力学模型，包括一个东南方向的长波地幔牵引2.5-3.8 MPa最好复制阿拉斯加的表面速度。这些地幔牵引力，与雅库塔特微板块的碰撞相结合，似乎驱动了麦肯齐山脉的隆起和变形。此外，在阿拉斯加州南部和中部的向北运动的程度是由雅库特平板的前缘的位置控制。
We utilize 3‐D finite element geodynamic models, incorporating long‐term kinematic estimates of upper plate motion, to better understand the roles that viscosity structure and mantle tractions play in generating plate motions and continental interior deformation in Alaska. Surface deformation in the Pacific‐North American plate boundary zone in Alaska and northwest Canada is strongly influenced by the complex interactions between flat‐slab subduction, gravitational collapse and mantle tractions. Predictions of long‐term tectonic block motion derived from recent Global Positioning System datasets (GPS) reveal surface motions atypical of other continental convergent plate boundary zones. Specifically, in northern and northwestern Alaska, southeastward motion is observed directed back toward the plate boundary. Geodynamic models that incorporate a southeastward directed long‐wavelength mantle traction of ∼2.5–3.8 MPa best replicate surface velocities in Alaska. These mantle tractions, in conjunction with the collision of the Yakutat microplate, appear to drive the uplift and deformation in the Mackenzie Mountains. Furthermore, the extent of the northward motion in southern and central Alaska is controlled by the location of the leading edge of the Yakutat flat slab.