The Misema Caldera is a 2,704-2,707 million year old
caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber ...
in
Ontario
Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central C ...
and
Quebec
Quebec ( ; )According to the Government of Canada, Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is ...
,
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tota ...
.
Geographic extent
It is the caldera that forms the
Blake River Megacaldera Complex
The Blake River Megacaldera Complex is a giant subaqueous caldera cluster or a nested caldera system that spans across the Ontario–Quebec border in Canada.
The caldera complex is around 2.7 billion years old, consisting of a series of overlappi ...
ASH FALL: Newsletter of the Volcanology and Igneous Petrology Division Geological Association of Canada
Retrieved on 2007-09-24 and has a diameter of 40-80 kilometres.
Composition
The caldera is also a coalescence of at least two large 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 includ ...
shield volcano
A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more v ...
es that formed more than 2703 million years ago.[Blake River Group evolution: characteristics of the subaqueous Misema and New Senator calderas](_blank)
The rim of the Misema Caldera contains a 10-15 kilometre wide inner and outer ring zone, in which many mafic ring dike complexes and subaqueous pyroclastic sediments are detected.
The mafic ring dike structures may be deeper level expressions of summit calderas related to a shield volcano phase while the pyroclastic
Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroc ...
fragments could either be associated with satellite cone
A parasitic cone (also adventive cone or satellite cone) is the cone-shaped accumulation of volcanic material not part of the central vent of a volcano. It forms from eruptions from fractures on the flank of the volcano. These fractures occur ...
s or the result of Misema caldera collapse.
The Misema Caldera is the oldest and largest caldera associated with the Blake River Megacaldera Complex and is comparable in size to the Lake Toba
Lake Toba ( id, Danau Toba) ( Toba Batak: ᯖᯀᯬ ᯖᯬᯅ; romanized: ''Tao Toba'') is a large natural lake in North Sumatra, Indonesia, occupying the caldera of a supervolcano. The lake is located in the middle of the northern part of the ...
caldera in Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
.
See also
* New Senator Caldera
* Noranda Caldera
* List of volcanoes in Canada
*Volcanism of Canada
Volcanism, Volcanic activity is a major part of the geology of Canada and is characterized by many types of volcanic landform, including lava flows, volcanic plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcano ...
*Volcanism of Eastern Canada
The volcanology of Eastern Canada includes the hundreds of volcanic areas and extensive lava formations in Eastern Canada. The region's different volcano and lava types originate from different tectonic settings and types of volcanic eruptions, ra ...
References
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Calderas of Ontario
Calderas of Quebec
Shield volcanoes
Supervolcanoes
VEI-8 volcanoes
Archean calderas
Polygenetic volcanoes
Landforms of Abitibi-Témiscamingue