During the Lascar volcano eruption in Chile, the ground was covered by ash and debris. The ash and debris were transported to the Salar de Atacama, which is a lake in northern Chile. The ash and debris were also released in the form of gaseous pollutants such as nitrogen and argon. The resulting vapours were then blown off the ash and debris and transported to the air. The resulting fumes were then carried to Mexico, where they were released into the atmosphere. Click here
Xenoliths
Xenoliths have been identified from the Lascar volcano eruption in northern Chile. The volcano is composed of two overlapping cones and is situated 17 km from Talabre and 34 km from Toconao. Various volcanic eruptions have occurred at Lascar over the past century. The eruptions range from effusive to explosive events and eject gas high into the atmosphere.
Calcsilicate xenoliths are present in the eruptive products of some active volcanoes. Their presence provides an opportunity to study the interactions between high-temperature magma and carbonate minerals. They fall into specific groups, which are defined by their composition. These include:
Type A calcites are nearly unmodified calcite compositions. They are characterized by anhedral rims and an abundance of sulphur-enriched and fluorine-enriched phases. Their d13C values are low, ranging from -3 to +3%. They are derived from pyroxene. They are also characterized by a low viscosity, which may allow them to be released into Merapi magma. The inclusions in wollastonite are similar to Type B calcites but have an assemblage of different minerals.
Type E calcites are millimetre-sized crystals with anhedral rims and a distinct mineral assemblage. They are located within the aureole alteration zone, which is a region of contrasting processes. These contrasting processes are rare in contact with metamorphic aureoles. However, they are preserved in the xenoliths.
Unlike type A and B calcites, type E calcites do not contain a silicate glass phase. They can be modelled by fluid mixing and decarbonisation from local limestone. The decarbonisation process is probably less pronounced in country rock.
The presence of a fluid phase in the skarn zone is likely to facilitate oxygen isotope exchange, thereby facilitating calcite melting. This interaction is likely to have a stronger influence on the eruptive dynamics than thermal metamorphic influence.
Magma chamber
During a study of the volcanic activity at Lascar volcano in northern Chile, several measurements were made with a Landsat Thematic Mapper to detect thermal features. These measurements have shown that the volcano has an extensive thermal anomaly. The thermal anomaly resembles a similar thermal anomaly at Erta’ale in Ethiopia.
The thermobarometric data indicate that magma chambers at Lascar are relatively shallow. The depth of the chamber is estimated to be around 6km. The plagioclase and pyroxenes chemistry of the April 1993 eruption products shows that the magma chamber is fairly oxidised. The halogen content of the inclusions indicates that a major transfer of volatile components occurred. This indicates the importance of sulphur in the April 1993 eruption.
The pyroclastic flows produced by the Lascar volcano are mainly 2-pyroxene andesites. They are ejecting ash high into the atmosphere. There are also smaller steam-driven explosions that are rarely monitored.
The Lascar volcanic system is believed to have developed during the last glacial maximum. This period marked the transition from the Kos-Kefalos and Nisyros-type magmas. During this transition, the silicic production zone was recharged from the mid to lower crust. The mafic magma ejected from the lower crust and then evolved in the upper crust.
The Suncor ignimbrite formed during the Lascar volcanic complex. This ignimbrite contains orthopyroxene, pumice, hornblende, and minor minerals. It is considered to be at least 26.5 ka in age. It contains banded pumices and a mixture of orthopyroxene and clinopyroxene oxides.
The Piedras Grandes hornblende andesite unit represents the pre-Soncor dome complex. The hornblende andesite is a heterogeneous phenocryst assemblage of plagioclase-amphibole-orthopyroxene-oxide. It is thought to have been sourced from the Altiplano-Puna Magma Body (APMB). The compositions of the plagioclase are thought to be influenced by the APMB.
Minerals found
During a volcano eruption, the magma is heated to extremely high temperatures. This allows the molten rock to spread over the surface, filling valleys and forming large lava flows. A variety of minerals are formed in the process. These include basalt, pegmatite, andesite, and rhyolite. Some of these minerals are used as gemstones.
The Lascar volcano is located in the central volcanic zone of northern Chile. It has had 36 Holocene eruptions. Most of the products from the eruptions have been two-pyroxene andesites. The eruptions also contain other ejecta such as phenocrysts, volcanic glass, and broken volcanic glass.
The Lascar volcano is part of the Altiplano-Puna Magma Body. The magma body is an NW-trending structural lineament in the main Miocene-Pleistocene volcanic arc.
The magma chamber is located at least six kilometres deep. Drill core data have shown that pyroxenes and plagioclase have a high degree of magmatic signatures at depth. The majority of the Lascar Volcano eruptions are two-pyroxene andesites. This is because a higher percentage of dissolved gases are found in the lava near the point of cooling. The fluids in the magma allow for larger crystals to form.
During a volcanic eruption, lighter felsic material rises toward the surface, while the heavier, lower-temperature materials remain buried in the mantle. The lighter, lower-temperature minerals begin to melt and dissolve as the rock sinks. As a result, the xenoliths stand out from the surrounding magma.
These minerals include rhyolite, olivine, pyroxene, and basalt. Some rare-earth elements and strategic metal-bearing minerals may also be found in the pegmatites.
Pegmatites typically form as masses in igneous dikes and veins. They sometimes contain rare-earth elements and precious gem minerals.
Argon and nitrogen released
During Lascar volcano eruptions, sulfur dioxide, argon and nitrogen gas are released. The gases react with oxygen and moisture and are blown by the wind. The gas then transforms to fine particles that can harm livestock operations and agricultural crops. These particles also scatter sunlight and can be dangerous for people to breathe.
The most prominent non-hydrous component is sulfur dioxide. This gas has a low boiling point, which means that it does not evaporate easily. However, it reacts with other gases to form fine particles, which can damage agricultural crops. The gas is measured by the USGS using a Differential Optical Absorption Spectrometer. In addition, SO2 is monitored via satellites.
In 2005, Lascar was the third largest source of sulfur dioxide in South America. It produces a sulfur dioxide output of 200-2300 tonnes per day. This output was comparable to the output of Kilauea. The output at Lascar is higher than most other central Andes volcanoes.
There are six or five craters at Lascar. Two of them are located on the summit, and the other four are on the western and eastern flanks. These craters have formed two distinct chamber systems. They appear to be separated by a depth of between 10 and 17 kilometres.
Lascar volcanic activity relates to the subduction of the Nazca Plate beneath the South America Plate. There are a number of lava flows on the northern and western flanks of Lascar, but they are buried under pyroclastic material. These flows were erupted in the early stages of the Lascar volcano’s activity.
The oldest eruption at Lascar was in 26,500 years ago, but the current eruption is less than one million years old. Lascar has produced large V-shaped plumes, which blow eastwards. The eruptive column is made up of volcanic ash and hot gases. It is about 40 kilometres long and originates from a point about 100 kilometres southeast of the volcano.
Decay flows towards Salar de Atacama
Located in the Central Andes in northern Chile, Lascar Volcano is an active volcanic edifice. This edifice is one of the more active in the Andes. Since the mid-19th century, small to moderate explosive eruptions have occurred on a regular basis. These eruptions have produced ashfall hundreds of kilometres away from the volcano.
The largest known eruptive event in the Nevados de Chillan volcanic complex was the pyroclastic flows of 1993. This event, which occurred in the middle of a large, well-known lava flow, caused a localized ashfall that affected areas as far as Buenos Aires and San Pedro de Atacama. The aforementioned teetering edifice may be just the first in a series of eruptions that will continue into the distant future.
The latest eruption has a measured rate of 0.6 km3 per thousand years. This eruptive rate is a lot lower than the estimated average of 1 km3 per century. This rate is probably driven by the fact that the edifice is surrounded by fertile land. The plateau beneath the MLV has been downward by 0.5 km. This could lead to some seriously bad stuff if the eruption comes to pass.
The Landsat Thematic Mapper has shown a thermal anomaly in the area of Lascar Volcano. This particular anomaly resembles the similar ones found at Erta’ale in Ethiopia. The TM is not a perfect fit for every volcano in the region, but it is an excellent monitoring tool for active volcanoes. It can identify thermal anomalies that exceed 150 degrees C. In addition, the TM has been able to detect changes in the crater area. This is a big help in determining if the crater is about to be breached or not.
