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

Mr Panayiotis Panaretos1,2, Dr Paul Albert3, Dr Zoë Thomas1,2, Dr Chris Turney1,2, Dr Charles Stern4, Dr Gwydion Jones3, Dr Alan Williams5,6, Dr Victoria  Smith7, Dr Alan Hogg8, Dr Christina Manning9

1Chronos 14Carbon-Cycle Facility, Mark Wainwright Analytical Centre, University of New South Wales, Sydney, NSW 2052, Australia, , , 2Earth and Sustainability Science Research Centre (ESSRC), School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia, , , 3Department of Geography, Faculty of Science and Engineering, Swansea University, Swansea, SA2 8PP, UK, , , 4Department of Geological Sciences, University of Colorado, Boulder, CO, 80309-0399, USA, , , 5EMM Consulting Pty Ltd, 20 Chandos Street, St Leonards, NSW 2065, Australia, , , 6ARC Centre of Excellence for Australian Biodiversity and Heritage, School of Biological, Earth and Environmental Sciences, University of New South Wales, NSW 2052, Australia, , , 7Research Laboratory for Archaeology and History of Art (RLAHA), University of Oxford, Oxford, OX1 3TG, UK, , , 8Carbon Dating Laboratory, School of Science, University of Waikato, Hamilton, New Zealand, , , 9Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, ,

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.

References
Panaretos, P et al., 2021. Distal ash fall from the mid-Holocene eruption of Mount Hudson (H2) discovered in the Falkland Islands: New possibilities for Southern Hemisphere archive synchronisation. Quaternary Science Reviews 266, 107074.


Biography:

Pana is a Policy Graduate at the NSW Department of Planning, Industry and Environment. He graduated from UNSW, Sydney in 2019 with a a Bachelor of Advanced Science (Honours Class I, Physical Geography). His thesis utilised radiocarbon dating to reconstruct the frequency of large magnitude flood events at Nitmiluk Gorge, in northern Australia. Pana has a keen interest in Quaternary Science, tephrochronology, and radiocarbon dating. His current research investigates the age and sources of microscopic volcanic ash preserved in peat bogs from the Falkland Islands in the South Atlantic Ocean.

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Date

Nov 08 - 19 2021