Plate Boundaries

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Obduction
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Not to be confused with Abduction (disambiguation).
This article is about the geological process. For the video game, see Obduction (video game). For the medical procedure, see autopsy.

Obduction was originally defined by Coleman [1] to mean the overthrusting of oceanic lithosphere onto continental lithosphere at a convergent plate boundary where continental lithosphere is being subducted beneath oceanic lithosphere.

Subsequently, this definition has been broadened to mean the emplacement of continental lithosphere by oceanic lithosphere at a convergent plate boundary, such as closing of an ocean or a mountain building episode. This process is uncommon because the denser oceanic lithosphere usually subducts underneath the less dense continental plate.[citation needed] Obduction occurs where a fragment of continental crust is caught in a subduction zone with resulting overthrusting of oceanic mafic and ultramafic rocks from the mantle onto the continental crust. Obduction may occur where a small tectonic plate is caught between two larger plates, with the lithosphere (both island arc and oceanic) welding onto an adjacent continent as a new terrane. When two continental plates collide, obduction of the oceanic lithosphere between them is often a part of the resulting orogeny.[citation needed]

Most obductions appear to have initiated at back-arc basins above the subduction zones during the closing of an ocean or an orogeny.[citation needed]

Contents

1 Characteristic rocks
2 Types of obductions
2.1 Upwedging in subduction zones
2.2 Compressional telescoping onto Atlantic-type continental margins
2.3 Gravity sliding onto Atlantic-type continental margins
2.4 Transformation of a spreading ridge to a subduction zone
2.5 Interference of a spreading ridge and a subduction zone
2.6 Obduction from rear-arc basin
2.7 Obduction during continental collision
3 Examples
4 See also
5 References