ORCID Profile
0000-0003-4703-8674
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Publisher: American Geophysical Union (AGU)
Date: 02-2020
DOI: 10.1029/2019GC008663
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-8187
Abstract: & & The impingement of a hot buoyant mantle plume onto the lithosphere can result in either breaking of the lithosphere, which might results in subduction initiation or in under-plating of the plume beneath the lithosphere. Key natural ex les of the former and latter are formation of subduction along the southern margin of Caribbean and northwestern South America in the late Cretaceous as well as the hotspot chains of Hawaii, respectively. In previous studies the interaction of a buoyant mantle plume with lithosphere was investigated either for the case of stationary lithosphere or for moving lithosphere but ignoring the effect of magmatic weakening of the lithosphere above the plume head. In this study we aim to investigate the response of a moving lithosphere to the arrival of a stationary mantle plume including the effect of magmatic lithospheric weakening. To do so we use 3d thermo-mechanical models employing the finite difference code I3ELVIS. Our setup consists of an oceanic lithosphere, mantle plume and asthenosphere till depth of 400 km. The moving plate is simulated by imposing a kinematic boundary condition on the lithospheric part of the side boundaries. The mantle plume in our models has a mushroom shape. The experiments differ in the age of the lithosphere, rate of the plate motion and size of the mantle plume. For different combinations of these parameters model results show either (1) breaking of the lithosphere and initiation of subduction above the plume head or (2) asymmetric spreading of the plume material below the lithosphere without large deformation of the lithosphere. We find that the critical radius of the plume that breaks the lithosphere and initiates subduction depends on plume buoyancy and the lithospheric age, but not on the plate speed. In general, the modeling results for the moving plate are similar to the results for a stationary plate, but the shapes of the region of the deformed lithosphere differ.& &
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-7783
Abstract: & & The formation of new subduction zones is a key component of global plate tectonics. Initiation of subduction following the impingement of a hot buoyant mantle plume is one of the few scenarios that allow breaking the lithosphere and recycling a stagnant lid without requiring any pre-existing weak zones. According to this scenario, upon arrival of a hot and buoyant mantle plume beneath the lithosphere, the lithosphere breaks apart and the hot mantle plume materials flow atop of the broken parts of the lithosphere. This leads to bending of the lithosphere and eventually initiation of subduction. Plume-lithosphere interaction can lead to subduction initiation provided that the plume causes a critical local weakening of the lithospheric material above it, which depends on the plume volume, its buoyancy, and the thickness of the lithosphere. Previous modeling studies showed that plume-lithosphere interaction can result in initiation of multi- or single-slab subduction zones around the newly formed plateau. However, they did not explore the parameters playing key roles in discriminating between the single- and multi-slab subduction scenarios. Here, we investigate factors controlling the number and shape of retreating subducting slabs formed by plume-lithosphere interaction. Using 3d thermo-mechanical models we show that the response of the lithosphere to arrival of a mantle plume beneath it depends on several parameters such as age of oceanic lithosphere, thickness of the crust, large-scale lithospheric extension rate, relative location of plume head and plateau edge and mantle temperature. The numerical experiments reveal that plume-lithosphere interaction in present day Earth can result in three different deformation regimes: (a) multi-slab subduction initiation, (b) single-slab subduction initiation and (c) plateau formation without subduction initiation. On early Earth (in Archean times) plume-lithosphere interaction could result in formation of either multi-slab subduction zones, very efficient in production of new crust, or episodic short-lived circular subduction. Extension eases subduction initiation caused by plume-lithosphere interaction. Plume-induced subduction initiation of old oceanic lithosphere with a plateau with thick crust is only possible if the lithosphere is subjected to extension.& &
Publisher: American Geophysical Union (AGU)
Date: 08-2020
DOI: 10.1029/2020GC009119
Location: Germany
Location: Germany
Location: No location found
No related grants have been discovered for Marzieh Baes.