Uncovering the eruptive history using new tephra data from Argentine lacustrine cores linked to Chilean volcanoes in the southern segment of the Southern Volcanic Zone

Abstract

This study examines tephra layers from lacustrine sediment cores collected in Patagonian Andean Range, correlating them with volcanic sources from the southern segment of the Southern Volcanic Zone (SVZ). Ten distinct tephra layers, spanning approximately the last 2,000 years, were identified across four cores from lakes Rivadavia, La Zeta, Brychan, and Theobald, from ~42° to 44° S. Mainly geochemical and mineralogical analyses of tephra components (pumice, glass shards, scoria) reveal that Chaitén, Michinmahuida, and Huequi volcanoes are the main sources of tephra in the region. Identified eruptions include four from Chaitén (~2008 AD, ~12th, ~8th, and 4th to 5th centuries), two from Huequi (beginning of 19th and, possibly, 14th centuries), and four from Michinmahuida (~17th to 18th, 13th, 8th, and ~2nd centuries). Four of these tephra layers have also the potential as isochronous marker beds in the region, allowing a preliminary reconstruction of their regional dispersal patterns. Some tephras may represent previously undocumented or scarcely documented eruptions. These findings suggest that the eruptive frequency in the southern SVZ has been underestimated, emphasizing the need for further research to expand the eruptive history and more accurately assess the volcanic hazards associated with this region.