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Stratigraphy, age and correlation of Lepué Tephra: a widespread c . 11 000 cal a BP marker horizon sourced from the Chaitén Sector of southern Chile
Author(s) -
Alloway Brent V.,
Moreno Patricio I.,
Pearce Nick J. G.,
De PolHolz Ricardo,
Henríquez William I.,
Pesce Oscar H.,
Sagredo Esteban,
Villarosa Gustavo,
Outes Valeria
Publication year - 2017
Publication title -
journal of quaternary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.142
H-Index - 94
eISSN - 1099-1417
pISSN - 0267-8179
DOI - 10.1002/jqs.2976
Subject(s) - tephra , geology , phreatomagmatic eruption , pyroclastic rock , holocene , deglaciation , rhyolite , diachronous , stratigraphy , tephrochronology , paleontology , geochemistry , volcano , physical geography , geomorphology , volcanic rock , geography , tectonics
We describe the stratigraphy, age and correlation of a prominent tephra marker, named Lepué Tephra, extensively distributed in north‐western Patagonia. Lepué Tephra is well dated at c . 11 000 cal a BP from numerous lake and soil cover‐bed sequences and its recognition is useful for assessing the rate and timing of deglaciation as well as associated environmental changes in this region during the last glacial termination and early Holocene. Lepué Tephra has attributes typical of a complex and compositionally zoned phreatomagmatic eruptive. While the initial rhyolitic phase can be readily distinguished from multiple eruptive products sourced from the adjacent Volcán Chaitén, the main erupted end member is of basaltic–andesitic bulk composition − similar to younger tephras sourced from Holocene monogenetic cones adjacent to the Volcán Michimahuida massif (tMim). Lepué Tephra can be correlated to an equivalent‐aged pyroclastic flow deposit (Amarillo Ignimbrite) prominently distributed in the south‐eastern sector of tMim. The source vent for these co‐eruptive events is obscured by an extensive ice field and is currently unknown. The widespread radially symmetrical distribution of Lepué Tephra centred on tMim cannot be attributed solely to volcanological considerations. Reduced Southern Hemisphere westerly wind influence interpreted from climate proxies at the time of eruption are also implicated. Copyright © 2017 John Wiley & Sons, Ltd.