The large eruption 4.2 ka cal BP in Cerro Blanco, Southern Central Volcanic Zone, Andes: could its ash have reached Antarctica?

Abstract

We have studied the 4410¿4150 a cal BP eruption of the Cerro Blanco Volcanic Complex (CBVC). The CBVC is located in the southern region of the Central Volcanic Zone of the Andes. in the southern Puna in NW Argentina. Stratigraphy, geomorphology, physical volcanology, radiocarbon dating, petrography, and geochemistry allow us to fingerprint its deposits and model the extents of the Plinian phase of the eruption during the paroxysmal syn¿caldera phase of the eruption. Results provide evidence for a major rhyolitic explosive eruption that spread volcanic deposits over an area of >500,000 km2, accumulating >170 km3 of bulk volume tephra. We have found ash fallout deposits mantled the region at distances > 400 km from the source and thick pyroclastic flow deposits filled the neighbouring valleys up to 35 km away. This eruption is the largest documented during the past five millennia in the Central Volcanic Zone of the Andes, and is probably one of the largest Holocene explosive eruptions in the world. The identification and characterisation of this significant volcanic event provide new insights into regional Holocene geological and archaeological records, and offer an excellent, extensive regional chronostratigraphic marker for reconstructing Holocene geological history over a wide geographical area of South America. The implications of the findings of the present work reach far beyond having some chronostratigraphic markers. The high, steady, and sustained eruption plume considered here may impact wide areas through pyroclastic fallout and perturb normal climatic cycles in the Southern Hemisphere. One of the main questions that remains is the extent of the record of this large eruption of CBVC beyond the Atlantic continental limit of South America. Further multidisciplinary research should be performed in order to draw general conclusions on its impact in Antarctica. This is invaluable not just for understanding how the system may have been affected over time, but also for evaluating potential future volcanic hazards related to large explosive eruptions in the Central Andes.