Paleozoic volcanic events in the Central Andes

Paleogeography of the upper Paleozoic basins of southern South America: An overview

“…Moreover, the westernmost basins of southern South America exhibit a very complex tectonic history associated with widespread magmatic activity encompassing a large extensional episode along the active margin of Gondwana during the Permian and Early Triassic (Nasi et al, 1985;Breitkreuz et al, 1989;Kontak et al, 1990;Bahlburg and Breitkreuz, 1991;Llambías, 1999). Subsidence rates were high, leading to the accumulation of several thousands of meters of Late Paleozoic rocks.…”

“…)-Late Carboniferous marine sediments crop out, forming intensively deformed turbiditic and deep marine facies of the Chañ aral mélange (Bell, 1987). This sequence, largely composed of interbedded sandstones and mudstones, shows some intercalations of basic lavas and siliceous tuffs (Bell, 1987;Breitkreuz et al, 1989;Fig. 4).…”

“…Thus, sedimentological studies reconstruct not only the timing of different glacial episodes but also the transition to semiarid and arid climatic conditions toward the Permian (Bigarella et al, 1967;Rocha-Campos, 1967;Limarino and Spalletti, 1985;Ló pez Gamundí, 1986, 1997Ló pez Gamundi et al, 1992;Isaacson et al, 1999). The extensive magmatic activity registered in the western margin of southern South American basins during the Late Paleozoic (Breitkreuz et al, 1989;Kontak et al, 1990;Bahlburg and Breitkreuz, 1991;Llambías, 1999) is among the most important recorded in the Gondwana supercontinent. The rich paleontological record many of these basins have yielded makes them even more significant.…”

The Sierra de Macon, Plutonic expression of the Ordovician magmatic arc, Salta Province Argentina

“…Related to these sediments are known contemporary volcanic sequences, including lavas and pyroclastic flows of acidic (rhyolitic -dacitic) to mesosilicic (andesitic) composition. Certain Ordovician sequences have been well described, including the Aguada de la Perdiz (Breitkreuz et al, 1989), Huaitiquina (Coira and Barber, 1989;Bahlburg, 1990), Salina de Jama (Coira and Nullo, 1989), and Guayaos (Coira et al, 1987;Koukharsky, 1988b;Koukharsky et al, 1996). Volcanic activity was coeval with sedimentation, as shown by the frequent interfingering.…”

Inferred Palaeoproterozoic arc rifting along a consuming plate margin: insights from the stratigraphy, volcanology and geochemistry of the Kangerluluk sequence, southeast Greenland

“…In addition to primitive N-MORB tholeiitic and LREEenriched basaltic rocks (Thurston 1994;Leybourne et al 1997), mafic, intermediate and felsic calc-alkaline volcanic rocks (Breitkreuz et al 1989;Hochstaedter et al 1994), or distinct shoshonitic rock suites (Lin et al 1989), characterize arc settings. The geochemical diversity of arc systems indicates changing geodynamic crustal and mantle conditions which are often difficult to decipher in ancient arc systems.…”