Abstract
AbstractInitiation 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 preexisting weak zones. Here, we investigate factors controlling the number and shape of retreating subducting slabs formed by plume‐lithosphere interaction. Using 3‐D thermomechanical models we show that the deformation regime, which defines formation of single‐slab or multi‐slab subduction, depends on several parameters such as age of oceanic lithosphere, thickness of the crust and large‐scale lithospheric extension rate. Our model results indicate that on present‐day Earth multi‐slab plume‐induced subduction is initiated only if the oceanic lithosphere is relatively young (<30–40 Myr, but >10 Myr), and the crust has a typical thickness of 8 km. In turn, development of single‐slab subduction is facilitated by older lithosphere and pre‐imposed extensional stresses. In early Earth, plume‐lithosphere interaction could have led to formation of either episodic short‐lived circular subduction when the oceanic lithosphere was young or to multi‐slab subduction when the lithosphere was old.
Highlights
The formation of new subduction zones is a key component of global plate tectonics (Bercovici, 2003; Gurnis et al, 2004; Stern & Gerya, 2018)
In our model suite we investigate the effect of thickness of the crust, mantle temperature, extension rate, and plume tail on the response of the lithosphere to plume‐lithosphere interaction
Using 3‐D thermo‐mechanical models we have shown 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, extension rate, and mantle temperature
Summary
The formation of new subduction zones is a key component of global plate tectonics (Bercovici, 2003; Gurnis et al, 2004; Stern & Gerya, 2018). In order to initiate subduction, the lithosphere has to be broken, which is most likely to occur in places of reduced strength that feature, for instance, a pre‐existing weakness zone in the lithosphere (McKenzie, 1977; Mueller & Phillips, 1991; Stern, 2004; Stern & Gerya, 2018). This kind of pre‐existing weakness might be created in a variety of tectonic settings such as transform/fracture zones, extinct mid‐ocean ridges or back‐arc regions of mature subduction zones. Subduction initiation in backarc of mature subduction zones occurs as a result of entering of buoyant continental crust or oceanic plateau to the subduction system (Cowley et al, 2004; Hathway, 1993; Kroenke, 1989; Phinney et al, 2004; Stern, 2004; Wells, 1989; Yan & Kroenke, 1993)
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