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In geology
Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth ...
, the slab (variously called subducting, downgoing or oceanic lithosphere slab) is a significant constituent of subduction zones. It is the part of the subducting plate which bends downward and descends into the mantle in a convergent tectonic plate boundary.
Although during subduction it is the oceanic lithosphere that subducts, creating an oceanic lithosphere slab, towards the end of this process and just before continental collision
In geology, continental collision is a phenomenon of plate tectonics that occurs at Convergent boundary, convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroy ...
, continental lithosphere attached to the subducting oceanic crust slab can also subduct. Consequently, there can also be continental lithosphere slabs.
Subduction slabs drive plate tectonics by pulling along the lithosphere
A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the lithospheric mantle, the topmost portion of the upper mantle that behaves elastically on time ...
to which they attach in a process known as slab pull and by inducing currents in the mantle via slab suction. The slab affects the convection
Convection is single or Multiphase flow, multiphase fluid flow that occurs Spontaneous process, spontaneously through the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoy ...
and evolution of the Earth's mantle due to the insertion of the hydrous oceanic lithosphere. Dense oceanic lithosphere retreats into the Earth's mantle, while lightweight continental lithospheric material produces active continental margins and volcanic arc
A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc ...
s, generating volcanism. Recycling the subducted slab presents volcanism by flux melting from the mantle wedge. The slab motion can cause dynamic uplift and subsidence of the Earth's surface, forming shallow seaways and potentially rearranging drainage patterns.
Geologic features of the subsurface can infer subducted slabs by seismic imaging. Subduction slabs are dynamic; slab characteristics such as slab temperature evolution, flat-slab, deep-slab, and slab detachment can be expressed globally near subduction zones. Temperature gradients of subducted slabs depend on the oceanic plate's time and thermal structures. Slabs experiencing low angle (less than 30 degrees) subduction is considered flat-slab, primarily in southern China and the western United States. Marianas Trench is an example of a deep slab, thereby creating the deepest trench in the world established by a steep slab angle. Slab breakoff occurs during a collision between oceanic and continental lithosphere, allowing for a slab tear; an example of slab breakoff occurs within the Himalayan subduction zone.
See also
*References
Subduction {{tectonics-stub