| Autor: |
Rodríguez Corcho, Andrés Felipe, Polanco, Sara, Farrington, Rebecca, Beucher, Romain, Montes, Camilo, Moresi, Louis |
| Předmět: |
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| Zdroj: |
Geochemistry, Geophysics, Geosystems: G3; Nov2022, Vol. 23 Issue 11, p1-22, 22p |
| Abstrakt: |
We investigate how the mechanical properties of intra‐oceanic arcs affect the collision style and associated stress‐strain evolution with buoyancy‐driven models of subduction that accurately reproduce the dynamic interaction of the lithosphere and mantle. We performed a series of simulations only varying the effective arc thickness as it controls the buoyancy of intra‐oceanic arcs. Our simulations spontaneously evolve into two contrasting styles of collision that are controlled by a 3% density contrast between the arc and the continental plate. In simulations with less buoyant arcs (15–31 km; effective thickness), we observe arc‐transference to the overriding plate and slab‐anchoring and folding at the 660 km transition zone that result in fluctuations in the slab dip, strain‐stress regime, surface kinematics, and viscous dissipation. After slab‐folding occurs, the gravitational potential energy is dissipated in the form of lithospheric flow causing lithospheric extension in the overriding plate. Conversely, simulations with more buoyant arcs (32–35 km; effective thickness) do not lead to arc‐transference and result in slab break‐off, which causes an asymptotic trend in surface kinematics, viscous dissipation and strain‐stress regime, and lithospheric extension in the overriding plate. The results of our numerical modeling highlight the importance of slab‐anchoring and folding in the 660 km transition zone on increasing the mechanical coupling of the subduction system. Plain Language Summary: Continents grow by the successive accretion of material to their margins, mostly collision and accretion of intra‐oceanic magmatic arcs. We investigate the effect of arc buoyancy and viscosity on the mode of collision, and the effects on the margin using a computer modeling approach. Our simulations show that upon collision, it is a small differential in density (3%) between the colliding arc and the continental margin that dictates whether subduction continues or stops after collision. In addition, our models show that arc buoyancy and viscosity drive lithospheric extension in the continental plate. Also, as the subducting slab reaches a mantle discontinuity at 660 km depth, it folds and causes strain and stress fluctuations on the margin. Key Points: Arc‐continent collision can result in two contrasting styles of collision depending on the buoyancy of the weak intra‐oceanic arcThe mechanical properties of intra‐oceanic arcs decrease the mechanical coupling of the subduction system and drive extension in the overriding plateLithospheric‐deep mantle interactions increase the mechanical coupling of the subduction system and drive punctuated events of increased compression [ABSTRACT FROM AUTHOR] |
| Databáze: |
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