Abstract

This study examines the trace element chemistry of fumarolic deposits and fumarolic plumes at Lastarria volcano, located in northern Chile. Fumarolic deposits were manually collected, while fumarolic plumes were sampled using the filter pack technique; after sample preparation, both sample types were analyzed by ICP-MS. The research focuses on chalcophile elements (As, Cd, Sb, Te, Cu, Zn, Tl, Pb, and Bi) and B, with the findings revealing significant enrichment of As and Pb in fumarolic deposit samples, especially in medium- and high-temperature fumarolic vents, respectively. On the other hand, filter pack measurements in the fumarolic plume indicate a notable enrichment in Te, B, As, and Tl, with Sc-normalized enrichment factors within the range of 104–106. From these elements, B, Tl, and Te appear to be less scavenged at the vent, presenting more significant enrichments in fumarolic plumes than in fumarolic deposits. By comparing our results with subduction-related volcanoes such as Etna, Stromboli, Lascar, Masaya, or La Soufrière de Guadeloupe, Lastarria fumarolic plume can be regarded as the one with the highest concentrations of B and As ever recorded. Moreover, Lastarria has chalcophile enrichments comparable to those volcanoes with shallower magma chambers and high-temperature magmatic emissions such as Stromboli. The higher abundance of chalcophiles suggests a significant magmatic influence feeding Lastarria fumaroles and the presence of ligands, such as Cl, which can transport significant amounts of chalcophiles at shallower levels of the crust during late-stage magma crystallization. Large amounts of chalcophiles released by Lastarria and Lascar volcanoes could be responsible for the naturally elevated concentrations of these elements in the Altiplano-Puna area. Future studies should focus on the lifetime of chalcophiles in the Central Andean atmosphere, where these elements could reside for a longer time given the dominant hyperarid environment.