New age controls on the tephrochronology of the southernmost Andean Southern Volcanic Zone, Chile.

WELLER, DJ; DE PORRAS, M.E.; MALDONADO, A.J.; MÉNDEZ, C.; STERN, C.R.

QUATERNARY RESEARCH

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: Amsterdam; Año: 2018

0033-5894

The chronology of over 50 tephras preserved in a core from Laguna La Trapananda (LLT) in the southern portion of the Andean Southern Volcanic Zone (SSVZ), Chile, is constrained by seven new radiocarbon age determinations which span the period since glacial retreat to the late Holocene. These tephras, which are attributed to small to medium sized eruptions from the volcanoes of the SSVZ including Mentolat, Hudson, Macá, and potentially Cay or one of the many monogenetic eruptive centers (MEC) located along the Liquiñe-Ofqui Fault Zone (LOFZ) or surrounding the major volcanoes, are correlatable to tephras previously described from other lake cores from the region. The ages of the tephras in the LLT core and the other different lake cores are estimated through a Bayesian statistical method. In order to do that, seven new ages from LLT core and one from an outcrop of the widely dispersed H2 tephra, which was produced by a large mid-Holocene eruption of the Hudson volcano and occurs in all the lake cores from this region, were used. The results provide isochrones (surfaces of equal age) that can be used to constrain the frequency of eruptions of the different volcanic centers in the SSVZ, the complex depositional histories of these small lacustrine systems of southern Chile and the age of the corresponding tephras observed in other paleoclimatic, paleoecologic, and archeologic studies in the region.