PERSONAL DE APOYO
ARAMAYO Alejandro Jose
artículos
Título:
Spatial-temporal distribution of explosive volcanism in the 25?28°S segment of the Andean Central Volcanic Zone
Autor/es:
GUZMÁN SILVINA; PABLO GROSE; CAROLINA MONTERO LÓPEZ; FERNANDO HONGN; REX PILGER; IVÁN PETRINOVIC; RAÚL SEGGIARO; ALEJANDRO ARAMAYO
Revista:
TECTONOPHYSICS
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2014 vol. 636 p. 170 - 189
ISSN:
0040-1951
Resumen:
The present contribution describes and analyses the spatial?temporal distribution and main features of the volcanic rocks, with emphasis in pyroclastic deposits, located in the 25?28°S segment of the Central Andes. Webuilt a newdatabase, based on our own field studies and compilation fromthe literature,wherewe discriminate the different pyroclastic units. We find that the pyroclastic deposits cover an area of at least 7770 km2 and aredistributed mainly along N?S to NNE?SSW, NW?SE to WNW?ESE and NE?SW trends. The spatial distribution of these deposits has varied with time: those N14.5 Ma are concentrated west of 69°W; during 14.5?11.5 Ma explosive magmatism shifted east of 67°W; the deposits b11.5 Ma became more dispersed. The main explosiveactivity occurred during the 26?18 Ma, 14.5?11.5 Ma and ≤5.3 Ma intervals. For pyroclastic deposits, dacitic compositions dominate during theMiocene, whereas rhyodacitic and rhyolitic compositions are more abundant since the Pliocene. In the 25?28°S segment of the CVZ there is no clear migration pattern of the magmatism, except for the well-known eastward migration occurred at ca. 26 Ma.Moreover, we find that a) basement lithology or composition or mechanical features influenced distribution of volcanic activity; b) the NE?SW alignment of b2.5 Ma caldera complexes coincides with the maximum depth of the Moho discontinuity and may be a further indicator of delamination processes in the Puna?Eastern Cordillera/Pampean Ranges border; and c) intense explosive volcanism concentrated during the 14?11.5 Ma interval along the eastern Puna border, which coincides in time with a peak in deformation and in space withthe contact between basement units with different mechanical properties. No relationship between magmatic activity and azimuth or convergence rate between South American and Nazca plates are found, except for a peak in convergence rate at ~26 Ma.