The New Senator Caldera is a large

Archean The Archean ( , also spelled Archaean or Archæan), in older sources sometimes called the Archaeozoic, is the second of the four geologic eons of Earth's history of Earth, history, preceded by the Hadean Eon and followed by the Proterozoic and t ...

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 ...

complex within the heart of the Blake River Megacaldera Complex,

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, ...

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 ...

. It has a diameter of 15-30 kilometers and is made of thick massive

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 ...

sequences. The caldera complex has inferred to be a subaqueous lava lake during the early stages of the caldera's development.ASH FALL: Newsletter of the Volcanology and Igneous Petrology Division Geological Association of Canada
Retrieved on 2007-09-21

Gabbro Gabbro ( ) is a phaneritic (coarse-grained and magnesium- and iron-rich), mafic intrusive igneous rock formed from the slow cooling magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is ch ...

sills represent lava lakes, which are common in mafic summit calderas. These subaqueous lava lakes are large units with a change in

grain size Grain size (or particle size) is the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials. This is different from the crystallite size, which ...

from coarse to fine grained and a

hyaloclastite Hyaloclastite is a volcanoclastic accumulation or breccia consisting of glass (from the Greek ''hyalus'') fragments (clasts) formed by quench fragmentation of lava flow surfaces during submarine or subglacial extrusion. It occurs as thin marg ...

top. The

Kiwanis Kiwanis International ( ) is an international service club founded in 1915 in Detroit, Michigan. It is headquartered in Indianapolis, Indiana, United States, and is found in more than 80 nations and geographic areas. In 1987, the organization ...

(Norands) intrusion, a high-level synvolcanic

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 ...

, intrudes

felsic In geology, felsic is a grammatical modifier, modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz.Marshak, Stephen, 2009, ''Essentials of Geology,'' W. W. Norton & Company, 3rd ed. It is contrasted ...

rocks, and is in turn cross-cut by basaltic dikes and sills. The Glenwood fault forms the eastern margin of the New Senator Caldera.

References

Calderas of Quebec Archean calderas Polygenetic volcanoes Landforms of Abitibi-Témiscamingue {{AbitibiTémiscamingue-geo-stub

See also

References