The Holocene Pucón eruption of Volcán Villarrica, Chile: deposit architecture and eruption chronology

• Published in: Bulletin of volcanology Vol. 72; no. 6; pp. 677 - 692
• Main Authors: Silva Parejas, C., Druitt, T. H., Robin, C., Moreno, H., Naranjo, J.-A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-08-2010; Springer; Springer Nature B.V; Springer Verlag
• Subjects: Charcoal; Crystalline rocks; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Sciences; Exact sciences and technology; Geological time; Geology; Geophysics/Geodesy; Global Changes; Holocene; Igneous and metamorphic rocks petrology, volcanic processes, magmas; Lava; Magma; Mineralogy; Natural hazards: prediction, damages, etc; Research Article; River beds; Sciences of the Universe; Sedimentary structures; Sedimentology; Volcanic eruptions; Volcanoes; Volcanology; South America; Chile; Pucón eruption; Ignimbrite; Villarrica Volcano; Radiocarbon age; Pyroclastic flow; basement; pyroclastic flows; chronology; upper Quaternary; fragmentation; basaltic andesite; xenoliths; clasts; fallout; Cenozoic; flow; emplacement; eruptive cycles; andesites; shear; granitoids; ignimbrite; Quaternary; volcanic rocks; eruptions; volcanoes; igneous rocks; magmas; scoria; bedforms; pyroclastics; plutonic rocks; charcoal; cross-stratification; Phanerozoic; lahars; Holocene; Villarrica volcano
• ISSN: 0258-8900; 1432-0819
• DOI: 10.1007/s00445-010-0348-9

The Pucón eruption was the largest Holocene explosive outburst of Volcán Villarrica, Chile. It discharged >1.0 km
3
of basaltic-andesite magma and >0.8 km
3
of pre-existing rock, forming a thin scoria-fall deposit overlain by voluminous ignimbrite intercalated with pyroclastic surge beds. The deposits are up to 70 m thick and are preserved up to 21 km from the present-day summit, post-eruptive lahar deposits extending farther. Two ignimbrite units are distinguished: a lower one (P1) in which all accidental lithic clasts are of volcanic origin and an upper unit (P2) in which basement granitoids also occur, both as free clasts and as xenoliths in scoria. P2 accounts for ∼80% of the erupted products. Following the initial scoria fallout phase, P1 pyroclastic flows swept down the northern and western flanks of the volcano, magma fragmentation during this phase being confined to within the volcanic edifice. Following a pause of at least a couple of days sufficient for wood devolatilization, eruption recommenced, the fragmentation level dropped to within the granitoid basement, and the pyroclastic flows of P2 were erupted. The first P2 flow had a highly turbulent front, laid down ignimbrite with large-scale cross-stratification and regressive bedforms, and sheared the ground; flow then waned and became confined to the southeastern flank. Following emplacement of pyroclastic surge deposits all across the volcano, the eruption terminated with pyroclastic flows down the northern flank. Multiple lahars were generated prior to the onset of a new eruptive cycle. Charcoal samples yield a probable eruption age of 3,510 ± 60
14
C years BP.