A revised age estimate for the mid-Holocene eruption of Mount Hudson (H2) using a high-resolution radiocarbon chronology

Full text: Cryptotephra deposits (microscopic volcanic ash) are important geochronological tools that can be used to synchronize records of past environmental change. Here we report a distal cryptotephra from a Holocene peat sequence (Canopus Hill) in the Falkland Islands, in the South Atlantic. Using a high-resolution radiocarbon chronology and geochemical analysis (major- and trace-element) of individual volcanic glass shards, we provide a robust correlation between this cryptotephra and the large mid-Holocene explosive eruption of Mt. Hudson in Patagonia, Chile (H2; ~3.9 ka cal BP). While the commonly cited age for the H2 eruption is 3600 BP; ~3.9 ka cal yr BP, this is derived from ¹⁴C ages of bulk organic soil, sediment and peat deposits bracketing the tephra in South America. To better constrain the age of the H2 eruption, we derive a chronology from the peat sequence using a Bayesian deposition model from radiocarbon analysis of terrestrial plant macrofossils. Our age model dates the H2 tephra to 4265 ± 65 cal yr BP, suggesting that the eruption occurred slightly earlier than previously reported. The refined age and new geochemical reference dataset will facilitate the identification of the H2 tephra in other distal locations. We recommend future studies search for its presence across the sub-Antarctic islands and Antarctic Peninsula as a potentially useful chronological marker. Finally, this study improves our knowledge of the dispersion of volcanic ash from Mt. Hudson, allowing us to better understand the eruptive frequency and risks associated with the Hudson volcano.