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- Title
The Role of Lower Crustal Rheology on Surface Deformation During Oblique Extension: Insights From Sandbox Modeling.
- Authors
Mao, Yuqiong; Li, Yiquan; Jia, Dong; Wang, Xianyan; Chen, Yingying; Li, Qin; Li, Rui
- Abstract
Extensive researches have been conducted on the relationship between surface deformation and the properties of upper crust. However, the link between surface deformation and lower crustal rheology, especially in a three‐dimensional context, remains unclear. In this study, we utilize sandbox modeling to investigate the impact of lower crustal rheology on surface deformation during oblique extension. Under the same conditions, six models with different lower crustal viscosities, both with and without syn‐kinematic deposits, are conducted. The results indicate that a decrease in lower crustal viscosity may contribute to an increase in: (a) graben width, (b) graben length, (c) graben spacing, (d) the number of isolated rifts and (e) topographic relief of oblique extensional systems, while also leading to a reduction in the total number of grabens. Notably, there exists a negative linear correlation between graben spacing and lower crustal viscosity. In map view, the angle between fault strike and the direction of pre‐existing discontinuities increases as the viscosity of the lower crust decreases. Furthermore, the frequency of large rakes (>50°) decreases with decreasing lower crustal viscosity. These findings align with natural examples such as the East African Rift System, Weihe Graben and the South Tibetan Rift in terms of geomorphology, tectonics, and crustal rheology. Through a comprehensive comparison of the graben width, spacing, and the angle between fault strike and the direction of pre‐existing discontinuities, our study provides valuable insights into the rheology of the lower crust in natural settings. Key Points: Lower crustal viscosity affects width, spacing, relief, and fault strike of oblique rifts, forming regular changes in rift geomorphologyFaults show increasing strike‐slip components with decreasing lower crustal viscosityOur models can provide new insights on understanding the lower crustal viscosity from surface deformation in nature
- Subjects
RHEOLOGY; DEFORMATIONS (Mechanics); CRUST of the earth; KINEMATICS; VISCOSITY
- Publication
Tectonics, 2024, Vol 43, Issue 8, p1
- ISSN
0278-7407
- Publication type
Article
- DOI
10.1029/2024TC008365