Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2016 Polycyclic scoria cones of the Antofagasta de la Sierra basin, Southern Puna plateau, Argentina WALTER BA ´ EZ 1*, GERARDO CARRASCO NUN ˜ EZ 2, GUIDO GIORDANO 3,4 , JOSE´ G. VIRAMONTE 1 & AGOSTINA CHIODI 1 1Unidad de recursos geolo´gicos y geote´rmicos INENCO (UNSa – CONICET), Av. Bolivia 5150, A4400FVY Salta, Argentina 2Centro de Geociencias, UNAM Campus Juriquilla, Blvr. Juriquilla 3001 Quere´taro, Qro. 72300 Mexico 3Department of Sciences, University Roma Tre, 00146 Rome, Italy 4CNR-IDPA Institute for Dynamics of Environmental Processes, Via M. Bianco, 20131 Milan, Italy *Correspondence:
[email protected] Abstract: Despite a number of published papers focusing on the geodynamic implications of the recent Southern Puna mafic magmatism, there have been fewer studies of the volcanology and stratigraphy of this outstanding volcanism. This paper presents a detailed map of two well- preserved Quaternary scoria cones showing their complex stratigraphy. Complementary morpho- metric, morpho-structural, petrographic and geochemical data were used to reconstruct the evolu- tion of both volcanoes. The occurrence of more than one eruption at each volcano was inferred by the recognition of temporal hiatuses using morpho-stratigraphic criteria. The polycyclic nature of both scoria cones could be related to a combination of a high input magma in response to litho- spheric delamination, a favourable regional stress field and the interaction of rising magma with pre-existing faults. The youngest eruptions in both volcanoes were complex, with shifts in the erup- tive style from violent strombolian to hawaiian /strombolian phases, and probably lasted for a few years.