Nazko Cone

Nazko Cone /ˈnæzkoʊ/ is a small potentially active basaltic cinder cone in central British Columbia, Canada, located 75 km west of Quesnel and 150 kilometers southwest of Prince George. It is considered the easternmost volcano in the Anahim Volcanic Belt. The small tree-covered cone rises 120 m above the Chilcotin-Nechako Plateau and rests on glacial till. It was formed in three episodes of activity, the first of which took place during the Pleistocene interglacial stage about 340,000 years ago. The second stage produced a large hyaloclastite scoria mound erupted beneath the Cordilleran Ice Sheet during the Pleistocene. Its last eruption produced two small lava flows that traveled 1 km to the west, along with a blanket of volcanic ash that extends several km to the north and east of the cone.

Nazko Cone
Nazko Cone, British Columbia
Nazko Cone, the easternmost and youngest volcano overlying the Anahim hotspot
Highest point
Elevation1,230 m (4,040 ft)
ListingList of volcanoes in Canada
Coordinates52°55′38″N 123°44′2″W / 52.92722°N 123.73389°WCoordinates: 52°55′38″N 123°44′2″W / 52.92722°N 123.73389°W
Geography
LocationBritish Columbia, Canada
Geology
Age of rockPleistocene
Mountain typeCinder cone
Volcanic arc/beltAnahim Volcanic Belt
Last eruption5220 BCE ± 100 years

Geology and history

Origins

Anahim Volcanic Belt-en
Location of Anahim hotspot in millions of years ago, including the Anahim Volcanic Belt

Nazko Cone probably began erupting about 340,000 years ago and has grown steadily since then. Like all of the Anahim volcanoes, Nazko Cone has its origins in the Anahim hotspot—a plume of magma rising from deep in the Earth's mantle. The hotspot remains in a fixed position, while the North American Plate drifts over it at a rate of 2 to 3.3 centimetres per year. The upwelling of the hot magma creates volcanoes, and each individual volcano erupts for a few million years before the movement of the plate carries it away from the rising magma.

The hotspot has existed for at least 13 million years, and the Anahim Volcanic Belt stretches almost 600 kilometres (400 mi) away from the hotspot. Currently, the hotspot lies under Nazko Cone, which is the youngest volcano in the Anahim Volcanic Belt.

7200 BP Eruption of Nazko Cone

The eruptive cycle of Nazko Cone 7200 years ago started with the eruption of two different progressions of fluid lava flows, an older grey basalt overlain by a younger, darker black basalt. The passive eruptions were followed by a period of explosive eruptions.[1] This explosive activity built three overlapping cinder cones near the end of the explosive phase of activity. The last phase of explosive activity spread tephra to the north and east of the cones. The deepest deposits near the cones are over 3 m deep and thin to less than a few centimetres only a few kilometres away, which suggests that the explosive eruptions at Nazko Cone were fairly small. However, the last eruption from Nazko Cone could have started forest fires, since there is charcoal inside the tephra layer.[1]

Recent activity

The volcano has been dormant since the 7200 BP eruption. On October 10, 2007, a small swarm of earthquakes appeared 20 kilometres west of Nazko Cone.[2] Most of these earthquakes were magnitude 1.0 or less; some as strong as M 3.1 or 3.2 were centered 25 kilometres below the surface. The cause of this seismic activity is believed to be the upwelling of magma because the area is not close to any faults or tectonic plate boundaries.[2]

Hazards

Future eruptions from Nazko Cone are unlikely to cause many fatalities, due to the region's remoteness. There is active logging and ranching in the region, and people engaged in these activities are at some risk. Lava flows are likely to flow only a few kilometres from the volcano which could possibly start forest fires in the dry region. Any future eruption is likely to affect low flying air traffic only, since eruptions would likely be in the form of Hawaiian eruption- lava fountains that create small cinder cones and lava flows rather than voluminous ash clouds.

Monitoring

Nazko Cone has been an intensively monitored volcano by the Geological Survey of Canada since October 10, 2007.[2]

One of the most important tools is seismometry. About 5 seismometers were set up around Nazko Cone to enable scientists to measure the intensities and locations of hundreds of small earthquakes every day. Since then, there have been more than 1000 small earthquakes recorded. Earthquakes can begin to increase years before an eruption actually starts.

Another type of seismic activity occurs in the hours preceding an eruption. So-called harmonic tremor is a continuous "rumble" which contrasts with the normal seismic activity of sudden shocks and is believed to be caused by the rapid movement of magma underground. Volcanic tremor normally indicates an imminent eruption, although it may also be caused by shallow intrusions of magma which do not reach the surface.

Another important indicator of what is happening underground is the shape of the volcano. Tiltmeters measure very small changes in the profile of the volcano, and sensitive equipment measures distances between points on the volcano. As magma fills the shallow reservoirs below the summit, the mountain inflates.

Recent history

Nazko Cone was staked for mining its cinder and scoria in the early 1990s by the Canadian Pumice Corporation, and has since been steadily reduced to produce red industrial aggregate for landscaping.

Before mining, the Nazko Cone was also a unique ecosystem. The vegetation included a complex of species. Very large old Douglas fir trees were common, growing in some of the more soil-like ash and lava. White spruce was surprisingly common, although severely stunted, whereas lodgepole pine was not.

There were some shallow caves and hollows below the volcano. To the west, following the lava flow mentioned above, is a unique wetland which appears to be saturated ash. What makes it unique is the fact that normally wetlands are saturated organic material such as peat moss. The wetland at Nazko Cone, however, is mixed organic and lava or ash, and the resultant ecosystem is quite unexpected.

Geothermal Potential

High heat flow in the Nazko Cone area is being evaluated as a potential source of geothermal heating.

See also

References

  1. ^ a b Natural Resources Canada: Nazko Cone Archived 2008-06-15 at the Wayback Machine
  2. ^ a b c Chronology of Events in 2007 at Nazko Cone Archived 2007-12-05 at Archive.today

External links

  • "Nazko". Global Volcanism Program. Smithsonian Institution.
  • Volcano World description
2007–2008 Nazko earthquakes

The 2007–2008 Nazko earthquakes were a series of small volcanic earthquakes measuring less than 4.0 on the Richter magnitude scale. They took place in the sparsely populated Nazko area of the Central Interior of British Columbia, Canada starting on October 9, 2007 and ending on June 12, 2008. They occurred just west of Nazko Cone, a small tree-covered cinder cone that last erupted about 7,200 years ago.

No damage or casualties resulted from the Nazko earthquakes, which were too small to be felt by people, but local seismographs recorded them. The earthquake swarm occurred at the eastern end of a known volcanic zone called the Anahim Volcanic Belt. This is an east-west trending line of volcanic formations extending from the Central Coast to the Central Interior of British Columbia.

Anahim Volcanic Belt

The Anahim Volcanic Belt is a 600 km (373 mi) long volcanic belt, stretching from just north of Vancouver Island to near Quesnel, British Columbia, Canada. The Anahim Volcanic Belt has had three main magmatic episodes: 15–13 Ma, 9–6 Ma, and 3–1 Ma. The volcanoes generally become younger eastward at a rate of 2 cm (0.8 in) to 3.3 cm (1.3 in) a year. The Nazko Cone, which last erupted only 7,200 years ago, is the youngest Anahim volcano. These volcanoes are thought to have formed as a result of the North American Plate sliding westward over a long-lived center of upwelling magma called the Anahim hotspot. The hotspot is thought to be similar to the one feeding the Hawaiian Islands.

Future volcanism is most likely in the form of basaltic cinder cones, but eruptions of less mafic magma, typical of the eastern portions of the belt, cannot be ruled out. A series of earthquakes began October 9, 2007 in the vicinity of Nazko Cone which was related to intense subterranean volcanic activity in the area.

The volcanic belt is defined by 37 Quaternary basalt centers and three large shield volcanoes called the Rainbow Range, Ilgachuz Range and the Itcha Range. These three large volcanoes have built up dome-like piles of lava and fragmental rocks to a height of 8,130 feet (2,478 m) at Tsitsutl Peak in the Rainbow Range, 7,873 feet (2,400 m) at Far Mountain in the Ilgachuz Range, and 7,760 feet (2,365 m) at Mount Downton in the Itcha Range. The Rainbow Range is a low dome-like cone about 20 miles (32 km) diameter, with Anahim Peak an obsidian plug on its north-east flank. The Ilgachuz Range is 15 miles (24 km) or more in diameter, and the Itcha Range is 10 miles (16 km) wide and about 40 miles (64 km) long. All have been dissected by late Tertiary, pre-Pleistocene stream erosion.

Major volcanoes of the Anahim Volcanic Belt include:

Ilgachuz Range, 2,410 metres (7,907 ft)

Itcha Range, 2,368 metres (7,769 ft)

Rainbow Range, 2,478 metres (8,130 ft)

Anahim hotspot

The Anahim hotspot is a volcanic hotspot located in the West-Central Interior of British Columbia, Canada. One of the few hotspots in North America, the Anahim plume is responsible for the creation of the Anahim Volcanic Belt. This is a 300 km (190 mi) long chain of volcanoes and other magmatic features that have undergone erosion. The chain extends from the community of Bella Bella in the west to near the small city of Quesnel in the east. While most volcanoes are created by geological activity at tectonic plate boundaries, the Anahim hotspot is located hundreds of kilometres away from the nearest plate boundary.

This hotspot's existence was first proposed in the 1970s by three scientists who used John Tuzo Wilson's classic hotspot theory. This theory proposes that a single, fixed mantle plume builds volcanoes that then, cut off from their source by the movement of the North American Plate, become increasingly inactive and eventually erode over millions of years. A more recent theory, published in 2001 by the Geological Society of America, suggests that the Anahim hotspot might be supplied by a mantle plume from the upper mantle rather than a deep-seated plume proposed by Wilson. The plume has since been tomographically imaged, showing it to be roughly 400 km (250 mi) deep. This measurement, however, could be an underestimate as the plume might originate deeper within Earth.

Volcanism as early as 14.5 million years ago has been linked to the Anahim hotspot, with the latest eruption having taken place in the last 8,000 years. This volcanic activity has produced rocks that show a bimodal distribution in composition. While these rocks were being deposited, the hotspot coincided with periods of crustal extension and uplift. Activity in modern times has been limited to earthquakes and volcanic gas emissions.

Bella Bella and Gale Passage dike swarms

The Bella Bella and Gale Passage dike swarms are two parallel dike swarms on the Central Coast of British Columbia, Canada. They range in age from 14.5 to 12.5 million years old. They are both chemically bimodal, consisting of rocks such as basalt, trachyte and comendite. They form the westernmost extent of the Anahim Volcanic Belt on Athlone Island, Dufferin Island and Denny Island.The Bella Bella and Gale Passage dike swarms are petrographically similar to the shield complexes in the central Anahim Volcanic Belt. As a result, the swarms are thought to represent the roots of a peralkaline magma system in which they are the magma conduits connecting the underlying magma chamber to the volcanic centre at the surface, which has been extensively eroded to remnants of eruptive breccia.

Far Mountain

Far Mountain is the highest of over 13 peaks in the Ilgachuz Range in the Anahim Volcanic Belt in British Columbia, Canada. The Ilgachuz Range is one of the three major shield volcanoes that formed the Anahim Volcanic Belt when the North American Plate moved over a hotspot (the Anahim hotspot). This is similar to the one which feeds the Hawaiian Islands. The mountain is located in the western part of Itcha Ilgachuz Provincial Park.

Geology of British Columbia

The geology of British Columbia is a function of its location on the leading edge of the North American continent. The mountainous physiography and the diversity of rock types and ages hint at the complex geology, which is still undergoing revision despite a century of exploration and mapping.

The country's most prominent geological features are mountain ranges, including the North American Cordillera, which stretches from Southern Mexico to Alaska.

Geology of the Pacific Northwest

The geology of the Pacific Northwest includes the composition (including rock, minerals, and soils), structure, physical properties and the processes that shape the Pacific Northwest region of the United States and Canada. The region is part of the Ring of Fire: the subduction of the Pacific and Farallon Plates under the North American Plate is responsible for many of the area's scenic features as well as some of its hazards, such as volcanoes, earthquakes, and landslides.

The geology of the Pacific Northwest is vast and complex. Most of the region began forming about 200 million years ago as the North American Plate started to drift westward during the rifting of Pangaea. Since that date, the western edge of North America has grown westward as a succession of island arcs and assorted ocean-floor rocks have been added along the continental margin.

There are at least five geologic provinces in the area: the Cascade Volcanoes, the Columbia Plateau, the North Cascades, the Coast Mountains, and the Insular Mountains. The Cascade Volcanoes are an active volcanic region along the western side of the Pacific Northwest. The Columbia Plateau is a region of subdued geography that is inland of the Cascade Volcanoes, and the North Cascades are a mountainous region in the northwest corner of the United States, extending into British Columbia. The Coast Mountains and Insular Mountains are a strip of mountains along the coast of British Columbia, each with its own geological history.

Ilgachuz Range

The Ilgachuz Range is a name given to an extinct shield volcano in British Columbia, Canada. It is not a mountain range in the normal sense, because it was formed as a single volcano that has been eroded for the past 5 million years. It lies on the Chilcotin Plateau, located some 350 kilometres (220 mi) north-northwest of Vancouver and 30 km north of Anahim Lake. The highest peak of the range is Far Mountain. The range supports a unique grassland ecosystem. This type of grassland has not been seen anywhere else in central and southern British Columbia. The climate is cool and dry; typical of higher elevations of the Interior Plateau.

The 280 kilometres (174 mi) long West Road River rises in the Ilgachuz Range and flows east to its confluence with the Fraser River between Prince George and Quesnel. It drains an area of approximately 12,000 km2 and loses over 900 m elevation before joining the Fraser.

Itcha Mountain

Itcha Mountain is one of the two named volcanic peaks of the Itcha Range, which is located in the Chilcotin District of the Central Interior of British Columbia, Canada. It is in the Anahim Volcanic Belt, which formed when the North American Plate moved over a hotspot, similar to the one feeding the Hawaiian Islands. The Anahim Volcanic Belt includes other immediately nearby ranges, the Rainbow and Ilgachuz Ranges. Itcha Mountain is located 42 km (26 mi) northeast of Anahim Lake and 2 km (1 mi) northeast of Mount Downton, another peak of the Itcha Range. Both of these peaks are located within Itcha Ilgachuz Provincial Park, as is Far Mountain, the park's highest peak.

This mountain is the namesake for the Itcha Range, which is one of the several large shield volcanoes that stands all by itself.

Itcha Range

The Itcha Range, also known as the Itchas, is a small isolated mountain range in the West-Central Interior of British Columbia, Canada. It is located 40 km (25 mi) northeast of the community of Anahim Lake. With a maximum elevation of 2,375 m (7,792 ft), it is the lowest of three mountain ranges on the Chilcotin Plateau extending east from the Coast Mountains. Two mountains are named in the Itcha Range; Mount Downton and Itcha Mountain. A large provincial park surrounds the Itcha Range and other features in its vicinity. More than 15 animal species are known to exist in the Itcha Range area, as well as a grassland community that is limited only to this location of British Columbia. The Itcha Range is within territory which has been occupied by aboriginal peoples for millennia. This area has a relatively dry environment compared to the Coast Mountains in the west.

In contrast to most mountain ranges in British Columbia, the Itcha Range represents an inactive shield volcano. This highly dissected volcanic edifice consists of a variety of rock types, including basanite, hawaiite, trachyte, rhyolite, phonolite and alkali olivine basalt. They were deposited by different types of volcanic eruptions characterized by passive lava flows and explosivity. Two stages of eruptive activity have been identified at the volcano along with three sub-phases that are limited only to the first stage of development. The main body of the Itcha Range is between 3.8 and 3.0 million years old and thus over two million years ago it passed the most active shield stage of life. A period of dormancy lasting for almost a million years followed, which was interrupted by the post-shield stage of volcanism 2.2 to 0.8 million years ago. More recent volcanic activity in and around the Itcha Range might have occurred in the last 340,000 years to produce cinder cones.

The Itcha Range is part of an east-west trending volcanic zone called the Anahim Volcanic Belt. This consists of large shield volcanoes, small cinder cones, lava domes and lava flows that become progressively younger from west to east. Several explanations have been made regarding the creation of this feature, each citing a different geologic process. If volcanic activity were to resume at the Itcha Range, Canada's Interagency Volcanic Event Notification Plan (IVENP) is prepared to notify people threatened by eruptions.

King Island Pluton

The King Island Pluton is a mid-to-late Miocene intrusion of syenite and alkali granite on the Central Coast of British Columbia, Canada. It is over 20 km (12 mi) long and 2.5 km (1.6 mi) wide, extending from King Island in the west to the mainland in the east. The pluton is exposed in 1,000 m (3,300 ft) cliffs along the Dean and Burke channels west of Bella Coola.The King Island Pluton is petrographically similar to the shield complexes in the central Anahim Volcanic Belt. As a result, the pluton is thought to represent the magma chamber of an extinct volcanic centre that has since eroded away. At the time of its formation, the pluton was emplaced 2 to 5 km (1.2 to 3.1 mi) below the surface.

List of cinder cones

A list of cinder cones is shown below.

Mount Downton

Mount Downton is the highest summit of the 10 km (6 mi) diameter Itcha Range, located 40 km (25 mi) northeast of Anahim Lake and 33 km (21 mi) east of Far Mountain in the Chilcotin District of the Central Interior of British Columbia, Canada. It lies within Itcha Ilgachuz Provincial Park.

Nazko

Nazko is a small ranching and logging community, including an historic First Nations community located 100 km west of Quesnel on the Nazko River in the Central Interior of British Columbia, Canada. Nazko means, "river flowing from the south".Nazko is the gateway to the Nuxalk Carrier Grease-Alexander Mackenzie Heritage Trail. It has a sizeable Indian reserve, home to the Nazko First Nation, and is well known in ranching history.

The first schools were built in 1950 by the ranchers and homesteaders and in 1960 by the government of Canada. In 1984 BC Hydro brought electricity to the area and the following year the road from Quesnel to Nazko was paved.Nazko is not far from the Nazko Cone which last erupted 7,200 years ago. From 2007 to 2008, a swarm of earthquakes occurred just 30 km (19 mi) west of Nazko Cone.

Population: est. 200

Nazko (disambiguation)

Nazko may refer to:

Nazko, a community in the Central Interior region of British Columbia

Nazko Cone, a volcano in the Central Interior of British Columbia, Canada

Nazko River, a river in the Central Interior of British Columbia

Nazko First Nation

Satah Mountain

Satah Mountain is a cinder cone, located 35 km (22 mi) east-northeast of Nimpo Lake in central British Columbia, Canada. It areas to the south form a N-S-trending chain of cinder cones of Pleistocene and Holocene age. It lies on the Chilcotin Plateau.

Satah Mountain occupies the high point of the Satah Mountain volcanic field. This consists of a long ridge of trachytic lava domes and flows and basaltic and trachybasaltic cinder cones that extend south from the felsic Itcha Range volcanic complex.

Satah Mountain volcanic field

The Satah Mountain volcanic field (SMVF) is an extensive north-south trending volcanic chain in the Central Interior of British Columbia that stretches south of the Itcha Range shield volcano to northeast of Nimpo Lake. The chain is located on the Chilcotin Plateau, a major subdivision of the Interior Plateau that includes other nearby volcanic features. It forms a segment of the east-west trending Anahim Volcanic Belt, whose volcanic activity ranges in age from Miocene-to-Holocene. Volcanic features in the Satah Mountain field include lava domes, cinder cones and lava flows. Its name originates from Satah Mountain, the highest volcano, located 35 km (22 mi) northeast of Nimpo Lake.Lava domes and flows are composed of trachyte and the cinder cones consist of basaltic and trachybasaltic lava. The most recently formed cone is well preserved and might have a similar age to the 7,200‑year‑old Nazko Cone at the easternmost end of the Anahim Volcanic Belt. However, recent (2015) argon-argon dating by Kuehn et al. found that the youngest SMVF feature was a 1.43 million year old plug of basaltic trachyandesite.

Tsitsutl Peak

Tsitsutl Peak is the highest volcanic peak of the Rainbow Range in British Columbia, Canada, located within Tweedsmuir South Provincial Park, 43 km (27 mi) northwest of Anahim Lake and 44 km (27 mi) northeast of Thunder Mountain.

Whitetop Mountain (British Columbia)

Whitetop Mountain is a forested hill in the West-Central Interior of British Columbia, Canada. It is on the northwest side of junction of the Chilcotin River and Downton Creek. Whitetop is a volcanic cone of the Chilcotin Plateau and Anahim Volcanic Belt.

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