The Blake River Megacaldera Complex is a giant subaqueous

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 ...

cluster or a nested caldera system that spans across the

Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...

–

Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...

border in

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, making it the world's List of coun ...

. The caldera complex is around 2.7 billion years old, consisting of a series of overlapping

s of various ages and sizes. It lies within the southern zone of the Abitibi greenstone belt of the

Superior Craton The Superior Craton is a stable fault block, crustal block covering Quebec, Ontario, and southeast Manitoba in Canada, and northern Minnesota in the United States. It is the biggest craton among those formed during the Archean period. A craton is a ...

and has an area of . The Blake River Megacaldera Complex has been a centre of major interest since 2006 with numerous excursions at the international, national and local level.ASH FALL: Newsletter of the Volcanology and Igneous Petrology Division Geological Association of Canada
Retrieved on 2007-09-21 It is a world-class metallotect with respect to both hydrothermal Cu- Zn massive sulfides and

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-rich massive sulfides.

Structure and geographical extent

The Blake River Megacaldera Complex consists of mainly mafic to intermediate volcanic flows and less abundant felsic volcanic flows and intercalated pyroclastic rocks, which underwent three stages of major volcanic activity. * The first phase resulted in the creation of the long, wide, east-west striking Misema Caldera which has been dated to 2704–2707 Ma. It is a coalescence of at least two large mafic shield volcanoes that formed more than 2703 million years ago. * The second phase resulted in the creation of the long, wide, northwest–southeast trending New Senator Caldera which formed 2701–2704 Ma. Its formation consists of thick massive mafic sequences which has inferred to be a subaqueous lava lake during the early stages of the caldera's development. * The third phase of activity constructed the classic east-northeast striking 2696 Ma Noranda Caldera which contains a 7-to-9-km-thick succession of mafic and felsic rocks erupted during five major series of activity. The Blake River Megacaldera Complex is considered a supervolcano due to its great size and its multiple dikes and vents. The Misema Caldera is in the order of , making the complex similar to the Yellowstone Caldera in

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

, Lake Toba in

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and strikingly similar in structure to the Olympus Mons caldera on

Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...

. As a result, the Blake River Group is best categorized as a meganested caldera complex.Blake River Group evolution: characteristics of the subaqueous Misema and New Senator calderas
Retrieved on 2008-01-23

References

{{Clear Calderas of Ontario Calderas of Quebec Supervolcanoes Volcanic groups Archean calderas Polygenetic volcanoes Landforms of Abitibi-Témiscamingue

Structure and geographical extent

See also

References