High-resolution stalagmite stratigraphy supports the Late Holocene tephrochronology of southernmost Patagonia

Abstract

Volcanic ash layers are important markers for the chronostratigraphy of paleoclimate and paleoenvironmental archives at the southern tip of South America. However, this requires that tephras are well-dated. We report geochemical data from stalagmite MA1 formed in a non-karst cave near Mt. Burney volcano in southernmost Patagonia (~53°S). High-resolution LA-ICP-MS analyses, SEM imagery, EPMA data, and NanoSIMS enable to identify volcanogenic signals during the last 4.5 kyrs from sub-annual trace element variations and tephra particles in distinct laminae. Our new 230Th/U-chronology of MA1 provides precise dating of tephra from Mt. Burney (MB) and, probably, Aguilera (A) at 4,216 +93/−193 yrs BP (MB2), 2,291 ± 33 yrs BP (MB3), 853 +41/−60 yrs BP (MB4) and 2,978 +91/−104 yrs BP (A1). This unique high-resolution record holds potential to date further eruptions from Southern Andean volcanoes for the tephrochronology in this critical region, and potentially also large-volume explosive volcanism off South America.