Alkaline Rocks and Carbonatites of the World

Setup during HiTech AlkCarb: an online database of alkaline rock and carbonatite occurrences

Sierra De Queupuniyeu


Occurrence number: 
Rio Negro
Longitude: -68.05, Latitude: -40.5

This volcanic province extending for 70 km north-south and 20 km east-west comprises flows and plugs of basanite and olivine basalt, with some pyroclastics, and plugs and necks of nephelinite, tephrite and phonolite. The basalts and basanites contain phenocrysts of olivine, augite and sometimes hornblende, in a matrix of olivine, pyroxene, plagioclase, magnetite, a little biotite and 5-20% nepheline plus analcime. Nephelinites are concentrated in the northern part of the province and form upstanding plugs; they comprise phenocrysts of olivine, augite, biotite and nepheline in a matrix predominantly of pyroxene and nepheline with accessory perovskite. There are rather fewer plugs of tephrite and phonolite, the former being characterized by about 10% analcime and some varieties containing aegirine-augite. The phonolites consist of alkali feldspar, 10-15% nepheline, 15% brown amphibole and 10% aegirine-augite.


CORBELLA, H. 1975. Hallazgo de un complejo alcalino vinculado a megatrazas de fracturas cortica les en la Sierra de Queupuniyeu, macizo norpatagonico provincia de Rio Negro, Argentina. II Congreso Ibero-Americano de Geologia Economica, 4‚ 45-68.

Fig. 1_188 Sierra de Queupuniyeu volcanic province (after Corbella, 1975, p. 47).
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith