The portion of a tectonic plate that is being subducted
For rock layers containing fossils, seeCounter slab.
The figure is a schematic diagram depicting a subduction zone. The subduction slab on the right enters the mantle with a varying temperature gradient while importing water in a downward motion.A model of the subductingFarallon slab underNorth America
Ingeology, theslab (variously called subducting, downgoing or oceanic lithosphere slab) is a significant constituent ofsubduction zones.[1] It is the part of the subducting plate which bends downward and descends into themantle in a convergent tectonic plate boundary.
Although during subduction it is the oceanic lithosphere that subducts, creating anoceanic lithosphere slab, towards the end of this process and just beforecontinental collision,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 thelithosphere to which they attach in a process known asslab pull and by inducing currents in the mantle viaslab suction.[2] The slab affects theconvection and evolution of the Earth'smantle due to the insertion of the hydrousoceanic lithosphere.[3] Dense oceanic lithosphere retreats into the Earth's mantle, while lightweight continental lithospheric material produces active continental margins andvolcanic arcs, generatingvolcanism.[4] Recycling the subducted slab presents volcanism by flux melting from themantle wedge.[5] The slab motion can causedynamic uplift and subsidence of the Earth's surface, forming shallow seaways[2] and potentially rearranging drainage patterns.[6]
Geologic features of the subsurface can infer subducted slabs byseismic imaging.[7][8] Subduction slabs are dynamic; slab characteristics such as slab temperature evolution,flat-slab, deep-slab, andslab detachment can be expressed globally near subduction zones.[9] Temperature gradients of subducted slabs depend on the oceanic plate's time and thermal structures.[10] Slabs experiencing low angle (less than 30 degrees) subduction is consideredflat-slab, primarily in southern China and the western United States.[11][12]Marianas Trench is an example of a deep slab, thereby creating the deepest trench in the world established by a steep slab angle.[13]Slab breakoff occurs during a collision between oceanic and continental lithosphere,[14] allowing for a slab tear; an example of slab breakoff occurs within the Himalayan subduction zone.[4]
