Imaging the Nazca slab and surrounding mantle to 700 km depth beneath the central Andes (18°S to 28°S)

Alissa Scire, C. Berk Biryol, George Zandt, Susan Beck

Research output: Chapter in Book/Report/Conference proceedingChapter

15 Scopus citations

Abstract

The central Andes in South America is an ideal location to investigate the interaction between a subducting slab and the surrounding mantle to the base of the mantle transition zone. We used finite-frequency teleseismic P-wave tomography to image velocity anomalies in the mantle from 100 to 700 km depth between 18°S and 28°S in the central Andes by combining data from 11 separate networks deployed in the region between 1994 and 2009. Deformation of the subducting Nazca slab is observed in the mantle transition zone, with regions of both thinning and thickening of the slab that we suggest are related to a temporary stagnation of the slab in the mantle transition zone. Our study also images a strong low-velocity anomaly beneath the Nazca slab in the mantle transition zone, which is consistent with either a local thermal anomaly or a region of hydrated material. The shallow mantle (<165 km) under the Eastern Cordillera is generally fast, consistent with proposed underthrusting of the Brazilian cratonic lithosphere or a string of localized lithospheric foundering. Several discontinuous low-velocity anomalies are observed beneath parts of the Altiplano and Puna Plateau, including two strong low-velocity anomalies in the upper mantle under the Los Frailes volcanic field and the southern Puna Plateau, consistent with proposed asthenospheric influx following lithospheric delamination.

Original languageEnglish (US)
Title of host publicationGeodynamics of a Cordilleran Orogenic System
Subtitle of host publicationThe Central Andes of Argentina and Northern Chile
EditorsMihai N. Ducea, Mihai N. Ducea, Peter G. DeCelles, Paul A. Kapp, Barbara Carrapa
PublisherGeological Society of America
Pages23-41
Number of pages19
ISBN (Electronic)9780813712123
DOIs
StatePublished - Jan 1 2015

Publication series

NameMemoir of the Geological Society of America
Volume212
ISSN (Print)0072-1069

ASJC Scopus subject areas

  • Geology

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    Scire, A., Biryol, C. B., Zandt, G., & Beck, S. (2015). Imaging the Nazca slab and surrounding mantle to 700 km depth beneath the central Andes (18°S to 28°S). In M. N. Ducea, M. N. Ducea, P. G. DeCelles, P. A. Kapp, & B. Carrapa (Eds.), Geodynamics of a Cordilleran Orogenic System: The Central Andes of Argentina and Northern Chile (pp. 23-41). (Memoir of the Geological Society of America; Vol. 212). Geological Society of America. https://doi.org/10.1130/2015.1212(02)