Map showing the location of Nazca Ridge off the west coast of Peru
The Nazca Ridge is a submarine ridge, located on the Nazca plate off the west coast of South America. This plate and ridge are currently subducting under the South American plate at a convergent boundary known as the Peru-Chile Trench at approximately 7.7 cm (3.0 in) per year.[1] The Nazca Ridge began subducting obliquely to the collision margin at 11°S, approximately 11.2 Ma, and the current subduction location is 15°S.[2] The ridge is composed of abnormally thick basaltic ocean crust, averaging 18 ±3 km thick.[3] This crust is buoyant, resulting in flat slab subduction under Peru.[4] This flat slab subduction has been associated with the uplift of Pisco Basin[5] and the cessation of Andes volcanism and the uplift of the Fitzcarrald Arch on the South American continent approximately 4 Ma.[6]
^Hampel, Andrea (2002). "The migration history of the Nazca Ridge along the Peruvian active margin: a re-evaluation". Earth and Planetary Science Letters. 203 (2): 665–679. Bibcode:2002E&PSL.203..665H. doi:10.1016/S0012-821X(02)00859-2.