Editing Subduction (section)

===Subduction of continental lithosphere===
Continents are pulled into subduction zones by the sinking oceanic plate they are attached to. Where continents are attached to oceanic plates with no subduction, there is a deep basin that accumulates thick suites of sedimentary and volcanic rocks known as a passive margin. Some passive margins have up to 10&nbsp;km of sedimentary and volcanic rocks covering the continental crust. As a passive margin is pulled into a subduction zone by the attached and negatively buoyant oceanic lithosphere, the sedimentary and volcanic cover is mostly scraped off to form an orogenic wedge. An orogenic wedge is larger than most accretionary wedges due to the volume of material there is to accrete. The continental basement rocks beneath the weak cover suites are strong and mostly cold, and can be underlain by a >200&nbsp;km thick layer of dense mantle. After shedding the low density cover units, the continental plate, especially if it is old, goes down the subduction zone. As this happens, metamorphic reactions increase the density of the continental crustal rocks, which leads to less buoyancy.

One study of the active Banda arc-continent collision claims that by unstacking the layers of rock that once covered the continental basement, but are now thrust over one another in the orogenic wedge, and measuring how long they are, can provide a minimum estimate of how far the continent has subducted.<ref>{{cite journal
| title=Australia going down under: Quantifying continental subduction during arc-continent accretion in Timor-Leste
|author=Garrett W. Tate|author2=Nadine McQuarrie |author3=Douwe J.J. van Hinsbergen |author4=Richard R. Bakker| author5=Ron Harris|author6=Haishui Jiang
| journal=Geosphere
| volume=11
| issue=6
| pages=1860–1883
| doi=10.1130/GES01144.1
| year=2015| bibcode=2015Geosp..11.1860T
| doi-access=free
}}</ref> The results show at least a minimum of 229 kilometers of subduction of the northern Australian continental plate. Another example may be the continued northward motion of India, which is subducting beneath Asia. The collision between the two continents initiated around 50 my ago, but is still active.