Investigating the formation of the Cretaceous Western Interior Seaway using landscape evolution simulations
Investigating the formation of the Cretaceous Western Interior Seaway using landscape evolution simulations
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DOI：
10.1130/b35653.1
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发表时间：
2021-01-01
影响因子：
4.9
通讯作者：
Liu, Lijun
中科院分区：
文献类型：
--
作者：
Chang, Ching;Liu, Lijun
像广泛分布的晚白垩世西部内陆海道这样的瞬态板内沉积，传统上被认为是塞维尔造山运动的弯曲前陆盆地，现在普遍认为是由于地幔下降流的粘性力造成的动态地形的结果。然而，人们对弯曲沉降与动态沉降的相对贡献知之甚少。此外，详细的沉降历史和潜在的物理机制在很大程度上仍然不受约束。在这里，我们考虑了塞维尔造山载荷和对应于不同地球动力学配置的三种不同动态地形模型。我们使用正向景观演化模拟来研究这些构造情景在区域沉积历史上的表面表现。我们发现，仅靠地表过程无法解释纯造山荷载系统中的西部内陆海道沉积作用，并且随着动态沉降的额外存在，沉积作用容易在内陆增加。研究结果表明，动态沉降对于西部内陆海道的形成至关重要，并且对西部内陆海道沉积物分布的主导控制在90-84 Ma期间从弯曲沉降转变为动态沉降，这与拟议的共轭沙茨基海洋高原的侵位相一致。重要的是，沉积记录要求潜在的动态沉降是向陆地迁移的，这意味着潜在的机制是由向西移动的北美板块下方下沉的法拉伦平板引起的区域规模的地幔下涌。模拟的地貌演化还表明，美国西部显着的区域性拉拉米德隆升应该不早于白垩纪晚期。
Transient intraplate sedimentation like the widespread Late Cretaceous Western Interior Seaway, traditionally considered a flexural foreland basin of the Sevier orogeny, is now generally accepted to be a result of dynamic topography due to the viscous force from mantle downwelling. However, the relative contributions of flexural versus dynamic subsidence are poorly understood. Furthermore, both the detailed subsidence history and the underlying physical mechanisms remain largely unconstrained. Here, we considered both Sevier orogenic loading and three different dynamic topography models that correspond to different geodynamic configurations. We used forward landscape evolution simulations to investigate the surface manifestations of these tectonic scenarios on the regional sedimentation history. We found that surface processes alone are unable to explain Western Interior Seaway sedimentation in a purely orogenic loading system, and that sedimentation increases readily inland with the additional presence of dynamic subsidence. The findings suggest that dynamic subsidence was crucial to Western Interior Seaway formation and that the dominant control on sediment distribution in the Western Interior Seaway transitioned from flexural to dynamic subsidence during 90-84 Ma, coinciding with the proposed emplacement of the conjugate Shatsky oceanic plateau. Importantly, the sedimentation records require the underlying dynamic subsidence to have been landward migratory, which implies that the underlying mechanism was the regional-scale mantle downwelling induced by the sinking Farallon flat slab underneath the westwardmoving North American plate. The simulated landscape evolution also implies that prominent regional-scale Laramide uplift in the western United States should have occurred no earlier than the latest Cretaceous.