1984/01/01 by P. W. Francis, W. F. McDonough, M. Hammill +2 · 5 citations
Earth and Planetary Sciences · #Geological and Geochemical Analysis #Geology and Paleoclimatology Research #Paleontology and Stratigraphy of Fossils #Mafic #Geology #Geochemistry #Radiometric dating #Andesite #Rhyolite #Lava #Volcanic rock #Xenolith #Silicic #Basalt #Petrology #Volcano
paper · doi:10.1007/978-1-4684-7335-3_8
openalex publication_date 1984/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
Cerro Purico is a 1.3 Ma old ignimbrite shield volcano. The first erupted unit was the rhyolitic Toconao ignimbrite ( 87 Sr/ 86 Sr = 0.7100), followed after an erosional interval by the dacitic Purico ignimbrite with the same radiometric age ( 87 Sr/ 86 Sr = 0.7085). Andesitic to dacitic lavas and extrusive domes were later emplaced in the summit region. The upper part of the Purico ignimbrite contains banded and mafic (andesitic) pumices isotopically indistinguishable from the host. The youngest dome (Chascon) contains basaltic xenoliths characterized by Sr isotope ratios (0.7059) lower than the host dacite (0.7073). While the major and trace element chemistry of the suite is unexceptional, a complex magmatic history is required to explain the origin of mafic pumice clasts and isotopically contrasted mafic xenoliths. Simple crustal anatexis cannot account for the range of compositions observed. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.