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 is ...

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 Ca ...

and

Quebec Quebec ( ; )According to the 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 one of the thirteen ...

Canada Canada is a country in North America. Its Provinces and territories of Canada, 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 ...

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 incl ...

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 vi ...

es that formed more than 2703 million years ago.Blake River Group evolution: characteristics of the subaqueous Misema and New Senator calderas
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 cones 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 i ...

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 ...

References

{{coord, 48.39, N, 79.45, W, display=title Calderas of Ontario Calderas of Quebec Shield volcanoes Supervolcanoes VEI-8 volcanoes Archean calderas Polygenetic volcanoes Landforms of Abitibi-Témiscamingue

Geographic extent

Composition

See also

References