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In geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...
, the slab is a significant constituent of subduction zones .
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 (geology), crust and the portion of the upper mantle (geology), mantle that behaves elastically on time sca ...
to which they attach in a process known as slab pull
Slab pull is a geophysical mechanism whereby the cooling and subsequent densifying of a subducting tectonic plate produces a downward force along the rest of the plate. In 1975 Forsyth and Uyeda used the inverse theory method to show that, of the ...
and by inducing currents in the mantle via slab suction
Slab suction is one of the four main forces that drive plate tectonics. It creates a force that pulls down plates as they are subducting and speeds up their movement, creating larger amounts of displacement.
It is because of these forces, slab pul ...
. The slab affects the convection
Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convec ...
and evolution of the Earth's mantle due to the insertion of the hydrous oceanic 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 portion of the upper mantle that behaves elastically on time scales of up to thousands of years or ...
. 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 lo ...
s, generating volcanism
Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called ...
. Recycling the subducted slab presents volcanism by flux melting from the mantle wedge
A mantle wedge is a triangular shaped piece of mantle that lies above a subducting tectonic plate and below the overriding plate. This piece of mantle can be identified using seismic velocity imaging as well as earthquake maps. Subducting oceanic ...
. 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
Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...
imaging. Subduction slabs are dynamic; slab characteristics such as slab temperature evolution, flat-slab, deep-slab, and slab detachment
In plate tectonics, slab detachment or slab break-off may occur during continent-continent or arc-continent collisions. When the continental margin of the subducting plate reaches the oceanic trench of the subduction zone, the more buoyant contin ...
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
The Mariana Trench is an oceanic trench located in the western Pacific Ocean, about east of the Mariana Islands; it is the deepest oceanic trench on Earth. It is crescent-shaped and measures about in length and in width. The maximum known ...
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