Subduction system and flat slab beneath the Eastern Cordillera of Colombia

Claudio Chiarabba, Pasquale De Gori, Claudio Faccenna, Fabio Speranza, Danilo Seccia, Viviana Dionicio, Germán A. Prieto

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Seismicity at the northern terminus of the Nazca subduction is diffused over a wide area containing the puzzling seismic feature known as the Bucaramanga nest. We relocate about 5000 earthquakes recorded by the Colombian national seismic network and produce the first 3-D velocity model of the area to define the geometry of the lithosphere subducting below the Colombian Andes. We found lateral velocity heterogeneities and an abrupt offset of the Wadati-Benioff zone at 5°N indicating that the Nazca plate is segmented by an E-W slab tear, that separates a steeper Nazca segment to the south from a flat subduction to the north. The flat Nazca slab extends eastward for about 400 km, before dip increases to 50° beneath the Eastern Cordillera, where it yields the Bucaramanga nest. We explain this puzzling locus of intermediate-depth seismicity located beneath the Eastern Cordillera of Colombia as due to a massive dehydration and eclogitization of a thickened oceanic crust. We relate the flat subducting geometry to the entrance at the trench at ca. 10 Ma of a thick - buoyant oceanic crust, likely a volcanic ridge, producing a high coupling with the overriding plate. Sub-horizontal plate subduction is consistent with the abrupt disappearance of volcanism in the Andes of South America at latitudes > 5°N.
Original languageEnglish (US)
Pages (from-to)16-27
Number of pages12
JournalGeochemistry, Geophysics, Geosystems
Volume17
Issue number1
DOIs
StatePublished - Jan 1 2016
Externally publishedYes

Fingerprint

Dive into the research topics of 'Subduction system and flat slab beneath the Eastern Cordillera of Colombia'. Together they form a unique fingerprint.

Cite this