Pyramid Formation (British Columbia)

Last updated
Pyramid Formation
Stratigraphic range: 1.2–0.9  Ma
O
S
D
C
P
T
J
K
Pg
N
The Pyramid.jpg
The Pyramid consists of Pyramid Formation trachyte
Type Geological formation [1]
Unit of Mount Edziza volcanic complex [2]
UnderliesIce Peak Formation, Edziza Formation [1]
Overlies Nido Formation [1]
Lithology
Primary Trachyte, comendite, pantellerite [1]
Other Basalt [1]
Location
Coordinates 57°30′N130°36′W / 57.5°N 130.6°W / 57.5; -130.6 [2]
Region British Columbia [1]
CountryCanada [1]
Type section
Named for The Pyramid [1]
Named by Souther et al., 1984 [3]

The Pyramid Formation is a stratigraphic unit of Pleistocene age in northwestern British Columbia, Canada.

Contents

Naming

The Pyramid Formation takes its name from The Pyramid, a prominent pyramid-shaped lava dome on the northeastern flank of Mount Edziza. [1] [4]

Geology

Two subunits comprise the Pyramid Formation. The lower unit is a basal pyroclastic member up to 3 m (9.8 ft) thick. It contains trachytic pumice, sodic pyroxene and alkali feldspar; the latter two are present in the form of lithic clasts and crystals. This unit is rusty brown in colour and was deposited by a pyroclastic surge. The upper unit consists of a basalt member up to 65 m (213 ft) thick. It includes 6 to 10 individual basalt flows that reach thicknesses of 3–20 m (9.8–65.6 ft). They appear to have been deposited almost immediately after the pyroclastic surge was erupted. [1] Several silicic lava domes and minor lava flows of the Pyramid Formation postdate the basalt member. Among the silicic domes are Sphinx Dome, Pharaoh Dome and The Pyramid. [5]

The Pyramid Formation has a volume of 11.4 km3 (2.7 cu mi), making it the eighth most voluminous geological formation of the Mount Edziza volcanic complex after the Little Iskut Formation. [1] [2] It overlies the Nido Formation and underlies the Ice Peak and Edziza formations, all of which have formed in the last 8 million years. K–Ar dating of the Pyramid Formation has yielded ages of 1.2 ± 0.4 million years and 1.20 ± 0.03 million years for comenditic glass and 0.94 ± 0.12 million years and 0.94 ± 0.05 million years for trachyte. [1]

See also

Related Research Articles

<span class="mw-page-title-main">Mount Edziza</span> Stratovolcano in British Columbia, Canada

Mount Edziza is a volcanic mountain in Cassiar Land District of northwestern British Columbia, Canada. It is located on the Big Raven Plateau of the Tahltan Highland which extends along the western side of the Stikine Plateau. Mount Edziza has an elevation of 2,786 metres, making it the highest point of the Mount Edziza volcanic complex and one of the highest volcanoes in Canada. However, it had an elevation of at least 3,396 metres before its formerly cone-shaped summit was likely destroyed by a violent eruption in the geologic past; its current flat summit contains an ice-filled, 2-kilometre-in diameter (1.2-mile) crater. The mountain contains several lava domes, cinder cones and lava fields on its flanks, as well as an ice cap containing several outlet glaciers which extend to lower elevations. All sides of Mount Edziza are drained by tributaries of Mess Creek and Kakiddi Creek which are situated within the Stikine River watershed.

<span class="mw-page-title-main">Spectrum Range</span> Mountain range in British Columbia, Canada

The Spectrum Range, formerly gazetted as the Spectrum Mountains and the Rainbow Mountains, is a small mountain range in Cassiar Land District of northwestern British Columbia, Canada. Located at the southern end of the Tahltan Highland, it borders the Skeena Mountains in the east and the Boundary Ranges of the Coast Mountains in the west. The Spectrum Range is surrounded by the Arctic Lake Plateau in the southwest and the Kitsu Plateau in the northwest, both of which contain volcanic features such as cinder cones. It lies at the southern end of the Mount Edziza volcanic complex which includes the two neighbouring plateaus, as well as Mount Edziza and the Big Raven Plateau to the north. The mountain range is drained on all sides by streams within the Stikine River watershed and, unlike Mount Edziza to the north, contains relatively small separate glaciers. Mount Edziza Provincial Park is the main protected area surrounding the Spectrum Range.

<span class="mw-page-title-main">Coffee Crater</span> Cinder cone in British Columbia, Canada

Coffee Crater is a cinder cone in Cassiar Land District of northwestern British Columbia, Canada. It has an elevation of 2,000 metres and is one of several volcanic cones in the Snowshoe Lava Field at the southern end of the Big Raven Plateau. The cone is southeast of the community of Telegraph Creek in Mount Edziza Provincial Park, which is one of the largest provincial parks in British Columbia. Coffee Crater the source of a lava flow that travelled to the southwest; it ponded against and partially overrode stagnant ice on the Big Raven Plateau.

<span class="mw-page-title-main">Cocoa Crater</span> Cinder cone in British Columbia, Canada

Cocoa Crater, sometimes called Cocoa Cone, is a cinder cone in Cassiar Land District of northwestern British Columbia, Canada. It has an elevation of 2,117 metres and is one of several volcanic cones in the Snowshoe Lava Field at the southern end of the Big Raven Plateau. The cone is southeast of the community of Telegraph Creek in Mount Edziza Provincial Park, which is one of the largest provincial parks in British Columbia. Coffee Crater was the source of a 2-kilometre-wide (1.2-mile) lava flow that travelled to the northwest.

<span class="mw-page-title-main">Ice Peak</span> Mountain in British Columbia, Canada

Ice Peak is the prominent south peak of Mount Edziza in Cassiar Land District of northwestern British Columbia, Canada. It has an elevation of 2,500 metres and protrudes through Mount Edziza's ice cap, which is roughly 70 square kilometres in area. The peak is a pyramid-shaped horn formed by glacial erosion and is completely flanked by steep-walled, active cirques. Tencho Glacier on the southern flank is the largest outlet glacier of Mount Edziza's ice cap. The summit of Ice Peak is about 280 metres lower than that of Mount Edziza, but it still rises well above the general level of the Big Raven Plateau. Ice Peak and the surrounding area are in Mount Edziza Provincial Park, which also includes the Spectrum Range to the south.

<span class="mw-page-title-main">Big Raven Plateau</span> Plateau in British Columbia, Canada

The Big Raven Plateau is an intermontane plateau in Cassiar Land District of northwestern British Columbia, Canada. It lies on the Tahltan Highland and is surrounded by several valleys, including those of Mess Creek, Kakiddi Creek, Chakima Creek, Walkout Creek and the Klastline River. The plateau is drained by many small streams that flow into these neighbouring valleys and, unlike the valleys, it is relatively barren of vegetation. Stream erosion has resulted in the creation of canyons with intervening ridges on the eastern and western sides of the plateau, resulting in the creation of rugged terrain. The plateau is in Mount Edziza Provincial Park which is one of the largest provincial parks in British Columbia. Access to the Big Raven Plateau is mainly by aircraft or by a network of footpaths from surrounding roads.

<span class="mw-page-title-main">Kitsu Plateau</span> Plateau in British Columbia, Canada

The Kitsu Plateau is a small intermontane plateau in Cassiar Land District of northwestern British Columbia, Canada. It lies on the Tahltan Highland and is surrounded by several valleys, including those of Mess Creek, Nagha Creek and Raspberry Creek. The plateau is drained by many small streams that flow into these neighbouring valleys and, unlike the valleys, it is relatively barren of vegetation. Surrounding the Kitsu Plateau is Mount Edziza Provincial Park which is one of the largest provincial parks in British Columbia. Access to this remote plateau is mainly by aircraft since motorized vehicles are prohibited from entering Mount Edziza Provincial Park.

<span class="mw-page-title-main">Tennena Cone</span> Volcanic cone in British Columbia, Canada

Tennena Cone, alternatively Icebridge Cone, is a small volcanic cone in Cassiar Land District of northwestern British Columbia, Canada. It has an elevation of 2,390 metres and lies on the upper western flank of Ice Peak, the prominent south peak of Mount Edziza. The cone is almost completely surrounded by Mount Edziza's ice cap and is one of several volcanoes in the Snowshoe Lava Field on the Big Raven Plateau. Tennena Cone is 200 metres high, 1,200 metres long and up to 600 metres wide, its symmetrical structure resembling a black pyramid. The cone and the surrounding area are in Mount Edziza Provincial Park which also includes the Spectrum Range to the south.

<span class="mw-page-title-main">Mess Creek Escarpment</span> Escarpment in British Columbia, Canada

The Mess Creek Escarpment is a long, discontinuous cliff along Mess Creek in Cassiar Land District of northwestern British Columbia, Canada. It forms the east-central side of Mess Creek valley and consists of two segments separated about 5 kilometres by Walkout Creek valley. The northern segment extends about 8 kilometres southeast along the southwestern side of the Big Raven Plateau while the southern segment extends generally south along the northwestern, western and southwestern edges of the Kitsu Plateau for about 10 kilometres. With an elevation of more than 1,700 metres, the Mess Creek Escarpment rises more than 910 metres above the floor of Mess Creek valley. The escarpment lies within the boundaries of Mount Edziza Provincial Park.

<span class="mw-page-title-main">Volcanic history of the Northern Cordilleran Volcanic Province</span> Geologic region in British Columbia and Yukon, Canada

The volcanic history of the Northern Cordilleran Volcanic Province presents a record of volcanic activity in northwestern British Columbia, central Yukon and the U.S. state of easternmost Alaska. The volcanic activity lies in the northern part of the Western Cordillera of the Pacific Northwest region of North America. Extensional cracking of the North American Plate in this part of North America has existed for millions of years. Continuation of this continental rifting has fed scores of volcanoes throughout the Northern Cordilleran Volcanic Province over at least the past 20 million years and occasionally continued into geologically recent times.

Jack Gordon Souther was an American-born Canadian geologist, volcanologist, professor and engineer. He contributed significantly to the early understanding of recent volcanic activity in the Canadian Cordillera. Many of his publications continue to be regarded as classics in their field, even now several decades after they were written.

<span class="mw-page-title-main">Canadian Cascade Arc</span> Canadian segment of the North American Cascade Volcanic Arc

The Canadian Cascade Arc, also called the Canadian Cascades, is the Canadian segment of the North American Cascade Volcanic Arc. Located entirely within the Canadian province of British Columbia, it extends from the Cascade Mountains in the south to the Coast Mountains in the north. Specifically, the southern end of the Canadian Cascades begin at the Canada–United States border. However, the specific boundaries of the northern end are not precisely known and the geology in this part of the volcanic arc is poorly understood. It is widely accepted by geologists that the Canadian Cascade Arc extends through the Pacific Ranges of the Coast Mountains. However, others have expressed concern that the volcanic arc possibly extends further north into the Kitimat Ranges, another subdivision of the Coast Mountains, and even as far north as Haida Gwaii.

<span class="mw-page-title-main">Armadillo Formation</span> Geologic formation in British Columbia

The Armadillo Formation is a stratigraphic unit of Miocene age in northwestern British Columbia, Canada.

<span class="mw-page-title-main">Nido Formation</span> Geologic formation in British Columbia

The Nido Formation is a stratigraphic unit of Neogene age in northwestern British Columbia, Canada.

<span class="mw-page-title-main">Big Raven Formation</span> Geological formation in British Columbia, Canada

The Big Raven Formation is a stratigraphic unit of Quaternary age in northwestern British Columbia, Canada. It is the youngest and least voluminous geological formation of the Mount Edziza volcanic complex (MEVC); it overlies at least six older formations of this volcanic complex. The main volcanic rocks of the Big Raven Formation are alkali basalts and hawaiites, although a small volume of trachyte comprises the Sheep Track Member. These rocks were deposited by volcanic eruptions in the last 20,000 years during the latest magmatic cycle of the MEVC. Alkali basalt and hawaiite are in the form of lava flows and small volcanic cones while trachyte of the Sheep Track Member is mainly in the form of volcanic ejecta which covers an area of about 40 square kilometres.

The Klastline Formation is a stratigraphic unit of Pleistocene age in northwestern British Columbia, Canada.

<span class="mw-page-title-main">Volcanism of the Mount Edziza volcanic complex</span>

The Mount Edziza volcanic complex (MEVC) in British Columbia, Canada, has a history of volcanism that spans more than 7 million years. It has taken place during five cycles of magmatic activity, each producing less volcanic material than the previous one. Volcanism during these cycles has created several types of volcanoes, including cinder cones, stratovolcanoes, subglacial volcanoes, shield volcanoes and lava domes. The roughly 1,000-square-kilometre (400-square-mile) volcanic plateau forming the base of the MEVC originated from the successive eruptions of highly mobile lava flows. Volcanic rocks such as basalt, trachybasalt, benmoreite, tristanite, mugearite, trachyte and rhyolite were deposited by multiple eruptions of the MEVC; the latter six rock types are products of varying degrees of magmatic differentiation in underground magma reservoirs. Renewed effusive volcanism could block local streams with lava flows whereas renewed explosive volcanism could disrupt air traffic with volcanic ash across parts of northwestern Canada. At least 10 distinct flows of obsidian were produced by volcanism of the MEVC, some of which were exploited by indigenous peoples in prehistoric times to make tools and weaponry.

Tennaya Glacier is one of several glaciers draining the eastern side of the Mount Edziza ice cap in northwestern British Columbia, Canada. It is located southeast of the summit of Mount Edziza and northwest of Ice Peak at the head of Tennaya Creek. Meltwater from Tennaya Glacier feeds Tennaya Creek which eventually flows into Nuttlude Lake, an expansion of Kakiddi Creek.

<span class="mw-page-title-main">Edziza Formation</span> Geological formation in British Columbia, Canada

The Edziza Formation is a stratigraphic unit of Pleistocene age in northwestern British Columbia, Canada. First described in 1984, the Edziza Formation was mapped as one of several geological formations of the Mount Edziza volcanic complex. It overlies at least four other geological formations of this volcanic complex that differ in age and composition. The main volcanic rock comprising the Edziza Formation is trachyte which was deposited by volcanic eruptions at the end of the third magmatic cycle of the Mount Edziza volcanic complex 0.9 million years ago.

Idiji Ridge is a mountain ridge extending east of Tencho Glacier on the southern flank of Mount Edziza in northwestern British Columbia, Canada. It is bounded on the south by a valley containing an unnamed creek, on the east by Tennaya Creek valley and on the north by cirques extending east of Ice Peak. Idiji Ridge takes its name from the adjacent Idiji Glacier; Idiji means "it thunders" in the Tahltan language.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 Souther, J. G. (1992). The Late Cenozoic Mount Edziza Volcanic Complex, British Columbia. Geological Survey of Canada (Report). Memoir 420. Canada Communication Group. pp. 100, 129, 132, 133, 134, 246, 248, 249, 267. doi: 10.4095/133497 . ISBN   0-660-14407-7.
  2. 1 2 3 Edwards, Benjamin Ralph (1997). Field, kinetic, and thermodynamic studies of magmatic assimilation in the Northern Cordilleran Volcanic Province, northwestern British Columbia (PhD thesis). University of British Columbia. p. 10. ISBN   0-612-25005-9.
  3. "Pyramid Formation". Lexicon of Canadian Geologic Units . Government of Canada . Retrieved 2023-08-04.
  4. "The Pyramid". BC Geographical Names . Retrieved 2023-07-02.
  5. Smellie, John L.; Edwards, Benjamin R. (2016). Glaciovolcanism on Earth and Mars: Products, Processes and Palaeoenvironmental Significance. Cambridge University Press. p. 43. ISBN   978-1-107-03739-7.