Composition and thickness of the southern Altiplano crust, Bolivia

G. Zandt, A. A. Velasco, S. L. Beck

Research output: Contribution to journalArticle

98 Scopus citations

Abstract

Slant stacking of broadband seismograms recorded in the western US for two 1993 intermediate-depth earthquakes that occurred near the Bolivia-Argentina-Chile borders reveals small but clear precursors to both the wave and S wave depth phases. These precursors represent underside reflections from the thickened Andean Altiplano crust. The best-fit model has an average crustal velocity of 5.9-6.0 km/s, a crustal V p /V s of 1.6, a crustal thickness of 75-80 km, and a high-velocity, high-V p /V s mantle wedge. The finding of a thick felsic crust overlying a high-velocity mantle supports models of Altiplano uplift due predominantly to crustal shortening as opposed to mafic magmatic addition and is inconsistent with recent mantle delamination. -from Authors

Original languageEnglish (US)
Pages (from-to)1003-1006
Number of pages4
JournalGeology
Volume22
Issue number11
DOIs
StatePublished - Jan 1 1994

ASJC Scopus subject areas

  • Geology

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