Receiver function images from the Moho and the slab beneath the Altiplano and Puna plateaus in the Central Andes

I WÖLBERN; HEIT, B; YUAN, X; ASCH,G; KIND, R; VIRAMONTE JOSÉ G.; TAWACKOLI, S; WILKE H.

GEOPHYSICAL JOURNAL INTERNATIONAL

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2009 p. 296 - 308

0956-540X

Teleseismic data recorded during one and a half years are investigated with the receiver functiontechnique to determine the crustal and upper mantle structures underneath the highly elevatedAltiplano and Puna plateaus in the central Andes. A series of converting interfaces are determinedalong two profiles at 21°S and 25.5°S, respectively, with a station spacing of approx. 10 km. Thedata provides the highest resolution gained from a passive project in this area, so far. The oceanicNazca plate is detected down to 120 km beneath the Altiplano while beneath the Puna, the slab canunexpectedly be traced down to 200 km depth at longer periods. A shallow crustal low velocityzone is determined beneath both plateaus exhibiting segmentation. In the case of the Altiplano, thesegments present vertical offsets and are separated by inclined interfaces which coincide with majorfault systems at the surface. An average depth to Moho of about 70 km is determined for theAltiplano plateau. A strong negative velocity anomaly located directly below the Moho along withlocal crustal thinning is interpreted beneath the volcanic arc of the Altiplano plateau between 67°Wand 68.5°W. A deep section of the Puna profile reveals thinning of the mantle transition zone.Although poorly resolved, the detected anomaly may suggest the presence of a mantle plume,which may constitute the origin of the anomalous temperatures at the depth of the upper mantlediscontinuities.