Terrane

In geology, a terrane is a fragment of crust that formed on one tectonic plate and was later accreted, or sutured, onto crust belonging to a different plate. Because it originated elsewhere, a terrane preserves its own distinctive geologic history, one that differs from the rock surrounding it, which is why it is sometimes called an exotic terrane. The suture where a terrane joins the adjoining crust is usually identifiable as a fault, and later geological activity can obscure that boundary: a sedimentary deposit that buries the contact is called an overlap formation, while an igneous intrusion that obscures it is called a stitching pluton.