1 Holocene volcanism at the Quetrupillán Volcanic Complex (39°30’ S, 71°43’ W), southern Chile 2 3 Isla C. Simmons1, Dave McGarvie2, Joaquín A. Cortés1,3, Eliza S. Calder1, Andrés Pavez4 4 1. School of GeoSciences, University of Edinburgh, Edinburgh, UK 5 2. Lancaster Environment Centre, Lancaster University, Lancaster, UK 6 3. Department of Geography, Edge Hill University, Ormskirk, UK 7 4. GEO-3, Chile 8 Email contact:
[email protected] 9 10 Abstract 11 This paper provides the first detailed description of Holocene volcanism at the Quetrupillán Volcanic 12 Complex. This little-known volcanic complex consists of a truncated stratocone plus numerous 13 satellite vents on its lower flanks. 14 The c.16 satellite vents are the products of c.10 eruptions, with seven erupting trachytes (a 15 composition unusual in Chile), two erupting trachyandesites, and one erupting a basaltic andesite. 16 Intense and atypical Holocene scouring of the stratocone by ice has removed evidence of its 17 Holocene eruptions, and thus Holocene volcanism at the stratocone remains largely unknown. 18 Geochemical analysis of tephra layers from three logged sections in nearby valleys provides evidence 19 of only three explosive eruptions from Quetrupillán. No evidence of PDC deposits were identified at 20 the logged sections. Our results suggest that the explosive volcanic hazards from Quetrupillán are 21 less than current hazard maps indicate. 22 23 Keywords 24 Holocene, Chile, trachyte, glacial scouring, volcanism 25 26 1. Introduction 27 The Quetrupillán Volcanic Complex (Complejo Volcánico Quetrupillán), henceforth shortened to 28 Quetrupillán, lies in the Southern Volcanic Zone of the Chilean Andes, with the stratocone summit 29 located at 39°30’ S, 71°43’ W (Figure 1).