Lastarria

Lastarria
Name	Lastarria
Elevation m	5697
Location	Antofagasta Region, Chile / Catamarca Province, Argentina
Range	Andes
Type	Stratovolcano / lava dome complex
Last eruption	Holocene (unconfirmed)

Lastarria is a stratovolcanic complex located on the border between Chile and Argentina in the Andes. The edifice forms part of an extensive volcanic chain associated with the Nazca Plate subduction beneath the South American Plate and lies within the Altiplano–Puna volcanic region near other Quaternary centers. It is notable for persistent fumarolic activity, diverse eruptive products, and scientific interest from institutions across the region.

Geography and Location

The edifice sits in the high plateau of the Puna de Atacama close to the Salar de Antofalla and the Salar de Llullaillaco salt flats, straddling the administrative boundary between Antofagasta Region (Chile) and Catamarca Province (Argentina). Lastarria is positioned among regional volcanic peaks such as Ojos del Salado, Llullaillaco, Incahuasi, and Galán, and lies within the tectonically active western segment of the Altiplano. Access routes historically include approach from Antofagasta and San Antonio de los Cobres, while the nearest research bases and observatories include facilities in Calama and Salta.

Geological Characteristics

Lastarria is composed of an assemblage of lava domes, dacitic to rhyodacitic flows, pyroclastic deposits, and a complex summit crater sequence. The magmatic suite displays high silica content and accessory phenocrysts including plagioclase, amphibole, and biotite, consistent with fractional crystallization and crustal assimilation processes observed in other Andean centers like Licancabur and Llullaillaco. Geochronologic data from radiometric dating indicate Pleistocene to Holocene activity with compositional variations reflecting episodic magma recharge. The volcano overlies Paleozoic basement rocks and Tertiary ignimbrites related to the activity of the Altiplano–Puna Volcanic Complex and the Paleozoic Famatinian Belt influences the local crustal architecture.

Volcanic and Seismic Activity

Lastarria exhibits persistent hydrothermal and fumarolic manifestations, with gas emissions dominated by water vapor, carbon dioxide, and sulfur species similar to emissions documented at Lascar and Copahue. Seismicity in the area includes low-frequency volcanic tremor and tectonic earthquakes associated with regional strain release along the Andean orogeny. Instrumental records from regional networks operated by Servicio Nacional de Geología y Minería and Instituto de Geofísica document episodic swarms and long-period events, interpreted in the context of magmatic intrusion, hydrothermal fluid movement, and slab-related stress transfer similar to phenomena near Sairecabur and Llullaillaco. No confirmed historical explosive eruption has been recorded, but geomorphic and petrologic evidence supports Holocene eruptive episodes.

Glaciation and Climate

Situated at elevations approaching 5700 m, Lastarria lies within an arid, high-elevation Altiplano climate influenced by the South American summer monsoon and the Pacific Anticyclone. Precipitation is low and strongly seasonal; periglacial and sporadic glacier remnants have been identified on shaded flanks and in cirques, analogous to small rock glaciers reported on Ojos del Salado and Mercedario. Cryospheric interactions modulate slope stability and hydrothermal circulation, and paleoclimatic reconstructions using nearby lacustrine and glacial records from Salar de Atacama and Lake Titicaca provide regional context for Lastarria’s glacial history.

Biology and Ecology

Biotic communities around Lastarria are adapted to extreme high-altitude, hyperarid conditions characteristic of the Altiplano and include specialized vascular plants, lichens, and microbial mats observed at fumarolic outcrops. Faunal elements such as vicuña, llama, and highland bird species including Andean condor and rufous-bellied seedsnipe occupy surrounding puna habitats. Microbial ecosystems associated with sulfur-rich fumaroles parallel discoveries at El Tatio and support studies on chemosynthetic communities and extremophiles relevant to astrobiology and extremophile research.

Human History and Exploration

Human presence near Lastarria dates to pre-Columbian Andean pastoralists and ritual activity evident on neighboring summits like Llullaillaco and Ojos del Salado, while colonial and modern mining expeditions have traversed the region en route to deposits in Antofagasta and Salta Province. European and South American mountaineers and geologists from institutions such as Universidad de Chile, Universidad Nacional de Salta, and Servicio Nacional de Geología y Minería conducted early scientific reconnaissance. Contemporary field campaigns integrate volcanology, geochemistry, and high-altitude physiology research supported by national agencies and international collaborations.

Research and Monitoring Efforts

Ongoing research integrates geologic mapping, petrology, gas geochemistry, remote sensing, and seismology. Portable gas analyzers, satellite-based thermal anomalies from programs like MODIS and Sentinel products, and ground deformation measurements using InSAR have been applied to monitor fumarolic flux and surface changes. Collaborative projects involve Universidad de Chile, CONICET, Servicio Nacional de Geología y Minería, and international partners focusing on hazard assessment, magmatic processes, and hydrothermal systems comparable to studies at Lascar and Llaima. Continued multidisciplinary monitoring aims to resolve the timing of past eruptions and to quantify present-day unrest indicators.

Category:Volcanoes of the Andes Category:Stratovolcanoes of Chile Category:Volcanoes of Catamarca Province