Tata Sabaya is a high
volcano
A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most oft ...
in
Bolivia
Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...
. It is part of the
Central Volcanic Zone, one of several
volcanic belts in the Andes which are separated by gaps without volcanic activity. This section of the Andes was volcanically active since the
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...
, with an episode of strong
ignimbritic volcanism occurring during the
Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
. Tata Sabaya lies in a thinly populated region north of the
Salar de Coipasa salt pan.
Volcanic activity at Tata Sabaya and elsewhere in the Central Volcanic Zone is the consequence of the
subduction
Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second p ...
of the
Nazca Plate
The Nazca plate or Nasca plate, named after the Nazca region of southern Peru, is an oceanic list of tectonic plates, tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction, along the Peru– ...
beneath the
South America Plate. The volcano has developed along a
lineament that separates older
crust north of the lineament from younger crust in the south, and the edifice has been formed by
andesitic
Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...
rocks.
The southern flank of Tata Sabaya
failed during the latest
Pleistocene
The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
about 12,000–12,360 years before present. Debris from the collapse entered a lake that covered the Salar de Coipasa at that time and formed a deposit with a volume of . Subsequently, the collapse scar was partly filled in with more recent
lava flows
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or unde ...
and
lava dome
In volcanology, a lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions ...
s; one eruption occurred about 6,000 years
before present
Before Present (BP) or "years before present (YBP)" is a time scale used mainly in archaeology, geology, and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Because ...
.
Geography and geomorphology
Tata Sabaya lies just north of the
Salar de Coipasa in
Bolivia
Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...
. The small village of
Pagador lies west-southwest of the volcano, but the whole region is overall thinly inhabited.
The name means "Father Sabaya"; the term "Sabaya" may be the
Aymara corruption of the
Quechua term for "devil", "demon".
The volcano, which features a summit sanctuary, is a topic in local myths, where it is sometimes personified,
and subject of a ritual involving it and neighbouring volcanoes.
Tata Sabaya is part of the
Central Volcanic Zone of the Andes, which consists of a
volcanic arc
A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc ...
that mainly follows the
Western Cordillera. There are about 44
Holocene
The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...
volcanoes, however the remoteness of the region and dry climate has restricted scientific research of these volcanoes; among the better known are
Lastarria
Lastarria is a high stratovolcano that lies on the border between Chile and Argentina. It is remote, and the surroundings are uninhabited but can be reached through an unpaved road. The volcano is part of the Central Volcanic Zone, one of the ...
, the
Nevados de Payachata,
Ollagüe,
San Pablo,
San Pedro and
Socompa.
Tata Sabaya is a volcano which reaches a height of .
Five
lava flow
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...
s extend north from the summit and display levees and flow fronts, the flows reaching a maximum length of . The top of these flows is cut by a collapse scar that extends east and west of the edifice in the form of
scarps up to high. The space between the scarps is in turn filled by more recent lava flows with a blocky appearance. Farther away of the edifice, the scarp is more noticeable and reaches a height of about on the southeastern side of the volcano.
A large deposit south of the volcano, originally interpreted as a
nuee ardente deposit, is actually a
landslide
Landslides, also known as landslips, rockslips or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslides ...
deposit which extends over a length of and a width of ;
its volume is about .
The landslide incorporated material from the salar, and its rocks reflect in part the layering and structure of the pre-collapse volcano.
The deposit is one of the more conspicuous of its type, to the point that it was observed and identified on low-resolution
Landsat
The Landsat program is the longest-running enterprise for acquisition of satellite imagery of Earth. It is a joint NASA / USGS program. On 23 July 1972, the Earth Resources Technology Satellite was launched. This was eventually renamed to Lan ...
images.
It consists of material that forms
hummock-like deposits, with individual hummocks becoming smaller the farther away from the edifice they are. The deposit extends into the Salar de Coipasa where it is confined by
faults
and is in part covered by lacustrine sediments such as
tufa
Tufa is a variety of limestone formed when carbonate minerals precipitation (chemistry), precipitate out of water in ambient temperature, unheated rivers or lakes. hot spring, Geothermally heated hot springs sometimes produce similar (but less ...
.
File:Tata Sabaya debris avalanche.jpg, Outline of the debris avalanche
File:Tata Sabaya debris avalanche DEM.jpg, Debris avalanche profile
File:Tata Sabaya evolution.jpg, Profile of volcano development
Geology
Off the western coast of South America, the
Nazca Plate
The Nazca plate or Nasca plate, named after the Nazca region of southern Peru, is an oceanic list of tectonic plates, tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction, along the Peru– ...
subducts beneath the
South America Plate at a rate of about . This subduction process is responsible for the volcanism in the
Andean Volcanic Belt
The Andean Volcanic Belt is a major volcanic belt along the Andean cordillera in Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru. It is formed as a result of subduction of the Nazca plate and Antarctic plate underneath the South Americ ...
, which occurs in a
Northern Volcanic Zone in Ecuador and Colombia, a
Central Volcanic Zone in Peru, Bolivia, Chile and Argentina and a
Southern Volcanic Zone in Chile and Argentina. These volcanic zones are separated by gaps without volcanism, where the subduction process is shallower.
Several phases of tectonic and volcanic activity have been identified in the Central Volcanic Zone. An earlier phase of volcanism in the
Cordillera de la Costa commenced in the
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...
but is considered separate from the Central Volcanic Zone magmatism proper. After an erosional hiatus during the
Oligocene
The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...
,
volcanic arc
A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc ...
activity increased during the
Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
and culminated in a phase of strong
ignimbrite
Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrou ...
eruptions, which originated in
caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...
s. This phase was associated with a substantial thickening of the
crust in the Central Andes. During the
Pleistocene
The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
ignimbrite volcanism waned again and
stratovolcano
A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with ...
es began to develop.
Tata Sabaya lies along a crustal transition area which separates a younger
crust farther south from an older (
Proterozoic
The Proterozoic ( ) is the third of the four geologic eons of Earth's history, spanning the time interval from 2500 to 538.8 Mya, and is the longest eon of Earth's geologic time scale. It is preceded by the Archean and followed by the Phanerozo ...
) crust in the north, which is made up by the
Chilenia terrane
In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its d ...
and the
Arequipa-Antofalla craton
A craton ( , , or ; from "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging and rifting of contine ...
, respectively. This transition area appears to coincide with a chain of volcanoes that Tata Sabaya is part of and which extends from
Cerro Saxani in the east to
Isluga in Chile, as well as with the northern end of the
Pica gap where no recent volcanism occurs in the volcanic arc.
The basement of the volcano is formed by the ignimbritic Altos de Pica
formation, although outcrops of
granite
Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...
have been observed in the region; one of these outcrops may be a
Precambrian
The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of t ...
granite subsequently thermally modified in the
Toarcian
The Toarcian is, in the International Commission on Stratigraphy, ICS' geologic timescale, an age (geology), age and stage (stratigraphy), stage in the Early Jurassic, Early or Lower Jurassic. It spans the time between 184.2 Megaannum, Ma (million ...
.
This basement is covered by younger volcanic rocks,
alluvium
Alluvium (, ) is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluvium is also sometimes called alluvial deposit. Alluvium is ...
and sediments of the Salar de Coipasa.
Seismic tomography
Seismic tomography or seismotomography is a technique for imaging the subsurface of the Earth using seismic waves. The properties of seismic waves are modified by the material through which they travel. By comparing the differences in seismic waves ...
suggests that molten
magma
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...
exists in the regional crust.
Composition
Tata Sabaya has produced "two-
pyroxene
The pyroxenes (commonly abbreviated Px) are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents ions of calcium (Ca), sodium (Na), iron ( ...
"
andesite
Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...
and
porphyritic
Porphyritic is an adjective used in geology to describe igneous rocks with a distinct difference in the size of mineral crystals, with the larger crystals known as phenocrysts. Both extrusive and intrusive rocks can be porphyritic, meaning ...
andesite. Minerals contained within the rock are
augite
Augite, also known as Augurite, is a common rock-forming pyroxene mineral with formula . The crystals are monoclinic and prismatic. Augite has two prominent cleavages, meeting at angles near 90 degrees.
Characteristics
Augite is a solid soluti ...
,
biotite
Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron- endmember annite, and the magnesium-endmember phlogopite; more al ...
,
hornblende
Hornblende is a complex silicate minerals#Inosilicates, inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common ...
,
hypersthene
Hypersthene is a common rock-forming inosilicate mineral belonging to the group of orthorhombic pyroxenes. Its chemical formula is . It is found in igneous and some metamorphic rocks as well as in stony and iron meteorites. Many references have f ...
,
plagioclase
Plagioclase ( ) is a series of Silicate minerals#Tectosilicates, tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continu ...
and
titanomagnetite
Titanomagnetite is a mineral containing oxides of titanium and iron, with the formula Fe2+(Fe3+,Ti)2O4. It is also known as titaniferous magnetite, mogensenite, Ti-magnetite, or titanian magnetite. It is part of the spinel group of minerals. The Cu ...
with only little variation between rocks erupted during separate stages of volcanic activity. The erupted volcanites define a
potassium
Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...
-rich
calc-alkaline
The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic ...
suite. Inclusions of more
mafic
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...
rocks in the erupted material may indicate that mafic magma was injected into the
magma chamber
A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it u ...
of Tata Sabaya. The magma genesis at Tata Sabaya has been explained with magma mixing processes, which gave rise to a fairly uniform composition of the eruption products.
Climate and vegetation
The region is dry with precipitation mainly falling during southern hemisphere summer, and has little vegetation cover.
''
Polylepis tarapacana'' trees grow on the slopes of Tata Sabaya; these trees form the highest woodlands in the world.
Other aspects of regional vegetation are the so-called
puna steppe
In physical geography, a steppe () is an ecoregion characterized by grassland plains without closed forests except near rivers and lakes.
Steppe biomes may include:
* the montane grasslands and shrublands biome
* the tropical and subtropica ...
, which is characterized by grass and
shrub
A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...
vegetation.
Eruption history
Of all volcanoes in Bolivia, Tata Sabaya is the only one with Holocene activity which is not on the border with another country. The young age of the mountain has been inferred from the lack of
glaciation
A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate be ...
and
moraine
A moraine is any accumulation of unconsolidated debris (regolith and Rock (geology), rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a gla ...
s on the mountain,
unlike neighbouring summits.
The earliest activity at Tata Sabaya constructed a
pyroclastic shield
In volcanology, a pyroclastic shield or ignimbrite shield is an uncommon type of shield volcano. Unlike most shield volcanoes, pyroclastic shields are formed mostly of pyroclastic and highly explosive eruptions rather than relatively fluid basalt ...
, which crops out as a thick sequence of block-and-ash flows
fallout
Nuclear fallout is residual radioactive material that is created by the reactions producing a nuclear explosion. It is initially present in the radioactive cloud created by the explosion, and "falls out" of the cloud as it is moved by the ...
deposits and
pumice
Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of extremely vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicula ...
deposits in the northern sector of the volcano.
Effusive eruption
An effusive eruption is a type of volcanic eruption in which lava steadily flows out of a volcano onto the ground.
Overview
There are two major groupings of eruptions: effusive and explosive. Effusive eruption differs from explosive eruption ...
s then built up a volcanic cone on top of this shield; the five northerly lava flows were emplaced during this phase of activity. Some lava flows from this stage were unstable and collapsed, covering the northern parts of the volcano with debris.
This effusive activity eventually oversteepened the cone, causing its southern sector to collapse. During this collapse and
landsliding, large
toreva blocks developed from sectors of the cone which slid down undeformed, while other material from the cone formed the hummocks in the sector collapse deposit; there was no explosive eruption at the time of the collapse. The configuration of the deposit indicates that the debris entered the Salar when it was filled with water; the height of the tufa deposits imply that water levels were about above sea level. This and the lake terraces that the landslide overran marks the collapse as synchronous with the
Lake Tauca episode 12,000-12,360 years ago
when water levels in the Salar de Coipasa reached their maximum.
The onset of such collapses on volcanoes is often determined by faulting, climate change or eruption of the volcano; at Tata Sabaya earthquakes and the injection of new magma has been invoked to explain the destabilization of the edifice.
After the collapse, Holocene activity filled the scar with
lava dome
In volcanology, a lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions ...
s and lava flows, cancelling the traces of the collapse;
some of these in turn collapsed as well and gave rise to hot avalanche deposits.
Radiocarbon dating
Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for Chronological dating, determining the age of an object containing organic material by using the properties of carbon-14, radiocarbon, a radioactive Isotop ...
for a
pyroclastic flow
A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of b ...
has yielded an age of 6,000 years
before present
Before Present (BP) or "years before present (YBP)" is a time scale used mainly in archaeology, geology, and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Because ...
, implying that the volcano may be still active. Reportedly, when in 1600
Huaynaputina erupted in Peru a volcano named Sabaya erupted in
Oruro and destroyed a village.
Notes
References
Sources
*
*
*
{{Andean volcanoes
Stratovolcanoes of Bolivia
Pyroclastic shields
Subduction volcanoes
Volcanoes of Oruro Department
Five-thousanders of the Andes