Open AccessReceiver function images from the Moho and the slab beneath the Altiplano and Puna plateaus in the Central Andes
Author(s) -
Wölbern I.,
Heit B.,
Yuan X.,
Asch G.,
Kind R.,
Viramonte J.,
Tawackoli S.,
Wilke H.
Publication year - 2009
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2008.04075.x
Subject(s) - geology , receiver function , transition zone , slab , mantle (geology) , seismology , volcano , plume , classification of discontinuities , plateau (mathematics) , crust , geophysics , tectonics , lithosphere , mathematical analysis , physics , mathematics , thermodynamics
SUMMARY Teleseismic data recorded during one and a half years are investigated with the receiver function technique to determine the crustal and upper‐mantle structures underneath the highly elevated Altiplano and Puna plateaus in the central Andes. A series of converting interfaces are determined along two profiles at 21°S and 25.5°S, respectively, with a station spacing of approximately 10 km. The data provide the highest resolution gained from a passive project in this area, so far. The oceanic Nazca plate is detected down to 120 km beneath the Altiplano whereas beneath the Puna, the slab can unexpectedly be traced down to 200 km depth at longer periods. A shallow crustal low‐velocity zone is determined beneath both plateaus exhibiting segmentation. In the case of the Altiplano, the segments present vertical offsets and are separated by inclined interfaces, which coincide with major fault systems at the surface. An average depth to Moho of about 70 km is determined for the Altiplano plateau. A strong negative velocity anomaly located directly below the Moho along with local crustal thinning is interpreted beneath the volcanic arc of the Altiplano plateau between 67°W and 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‐mantle discontinuities.