Armadillo Formation | |
---|---|
Stratigraphic range: | |
Type | Geological formation [1] |
Unit of | Mount Edziza volcanic complex [2] |
Underlies | Ice Peak Formation, Spectrum Formation, Big Raven Formation, Nido Formation [1] |
Overlies | Little Iskut Formation, Raspberry Formation [1] |
Lithology | |
Primary | Alkali basalt, comendite, trachyte [1] |
Location | |
Coordinates | 57°30′N130°36′W / 57.5°N 130.6°W [2] |
Region | British Columbia [1] |
Country | Canada [1] |
Type section | |
Named for | Armadillo Peak [1] |
Named by | Souther et al., 1984 [3] |
The Armadillo Formation is a stratigraphic unit of Miocene age in northwestern British Columbia, Canada.
The Armadillo Formation takes its name from Armadillo Peak, a volcanic peak east of Raspberry Pass in the middle of the Mount Edziza volcanic complex. [1] [4]
The Armadillo Formation has a volume of 159 km3 (38 cu mi), making it the most voluminous of the 13 geological formations comprising the Mount Edziza volcanic complex. [2] It conformably overlies the Little Iskut Formation, as well as the Raspberry Formation. It is overlain by the Ice Peak Formation, Nido Formation, Spectrum Formation and Big Raven Formation. [1]
The Armadillo Formation consists of volcanic rocks of both felsic and mafic compositions. They are the products of a long period of bimodal volcanism, having issued from multiple eruptive centres. The felsic rocks include trachyte and comenditic rhyolite which form pyroclastic deposits, lava domes and lava flows. Basalt is the main mafic rock of the Armadillo Formation and forms lava flows. [1]
K–Ar dating of the Armadillo Formation has yielded ages of 10.2 ± 1.4 million years for comendite, 6.9 ± 0.3 million years and 6.1 ± 0.1 million years for comenditic ash flows, 6.9 ± 0.3 million years for comenditic glass and 6.5 ± 0.2 million years, 6.3 ± 0.5 million years, 6.2 ± 0.1 million years and 6.1 ± 0.2 million years for hawaiite. [1] The first age is anomalously old and most likely results from excessive atmospheric argon. [3]
The Northern Cordilleran Volcanic Province (NCVP), formerly known as the Stikine Volcanic Belt, is a geologic province defined by the occurrence of Miocene to Holocene volcanoes in the Pacific Northwest of North America. This belt of volcanoes extends roughly north-northwest from northwestern British Columbia and the Alaska Panhandle through Yukon to the Southeast Fairbanks Census Area of far eastern Alaska, in a corridor hundreds of kilometres wide. It is the most recently defined volcanic province in the Western Cordillera. It has formed due to extensional cracking of the North American continent—similar to other on-land extensional volcanic zones, including the Basin and Range Province and the East African Rift. Although taking its name from the Western Cordillera, this term is a geologic grouping rather than a geographic one. The southmost part of the NCVP has more, and larger, volcanoes than does the rest of the NCVP; further north it is less clearly delineated, describing a large arch that sways westward through central Yukon.
Hoodoo Mountain, sometimes referred to as Hoodoo Volcano, is a potentially active stratovolcano in the Northern Interior of British Columbia, Canada. It is located 25 kilometres northeast of the Alaska–British Columbia border on the north side of the Iskut River opposite of the mouth of the Craig River. With a summit elevation of 1,850 metres and a topographic prominence of 900 metres, Hoodoo Mountain is one of many prominent peaks within the Boundary Ranges of the Coast Mountains. Its flat-topped summit is covered by an ice cap more than 100 metres thick and at least 3 kilometres in diameter. Two valley glaciers surrounding the northwestern and northeastern sides of the mountain have retreated significantly over the last hundred years. They both originate from a large icefield to the north and are the sources of two meltwater streams. These streams flow along the western and eastern sides of the volcano before draining into the Iskut River.
Mount Edziza, sometimes called Edziza Mountain or Edziza Peak, is a stratovolcano 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. The mountain has an elevation of 2,786 metres, making it the highest volcano of the Mount Edziza volcanic complex. However, it had an elevation of at least 3,396 metres before its original summit was likely destroyed by a violent, climactic eruption in the geologic past; its current flat summit contains an ice-filled, 2-kilometre (1.2-mile) in diameter crater. Mount Edziza contains several lava domes, cinder cones and lava fields on its flanks, as well as an ice cap that is characterized by several outlet glaciers stretching out to lower altitudes. All sides of the mountain are drained by tributaries of Mess Creek and Kakiddi Creek which are situated within the Stikine River watershed.
Level Mountain is a large volcanic complex in the Northern Interior of British Columbia, Canada. It is located 50 kilometres north-northwest of Telegraph Creek and 60 kilometres west of Dease Lake on the Nahlin Plateau. With a maximum elevation of 2,164 metres, it is the second-highest of four large complexes in an extensive north–south trending volcanic region. Much of the mountain is gently-sloping; when measured from its base, Level Mountain is about 1,100 metres tall, slightly taller than its neighbour to the northwest, Heart Peaks. The lower, broader half of Level Mountain consists of a shield-like structure while its upper half has a more steep, jagged profile. Its broad summit is dominated by the Level Mountain Range, a small mountain range with prominent peaks cut by deep valleys. These valleys serve as a radial drainage for several small streams that flow from the mountain. Meszah Peak is the only named peak in the Level Mountain Range.
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 western flank of Ice Peak, the prominent south peak of Mount Edziza. The cone is almost completely surrounded by glacial ice of Mount Edziza's ice cap which covers an area of around 70 square kilometres. 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 lies in Mount Edziza Provincial Park which also includes the Spectrum Range to the south.
The Sheep Track Member is a stratigraphic unit of the Big Raven Formation, part of the Mount Edziza volcanic complex in northwestern British Columbia, Canada. It consists of pumice from an explosive eruption that fell over an area about 40 square kilometres. The pumice is of comenditic trachyte composition and reaches a thickness of up to 2 metres along the western edge of Tencho Glacier.
The Mount Edziza volcanic complex is a group of volcanoes and associated lava flows in northwestern British Columbia, Canada. Located on the Tahltan Highland, it is 40 kilometres southeast of Telegraph Creek and 85 kilometres southwest of Dease Lake. The complex encompasses a broad, steep-sided lava plateau that extends over 1,000 square kilometres. Its highest summit is 2,786 metres in elevation, making the MEVC the highest of four large complexes in an extensive north–south trending volcanic region. It is obscured by an ice cap characterized by several outlet glaciers that stretch out to lower altitudes.
Cartoona Ridge is a mountain ridge extending east from the eastern side of the Mount Edziza volcanic complex in northwestern British Columbia, Canada. It is bounded on the north by Shaman Creek valley, on the south by Chakima Creek valley, on the east by Kakiddi Creek valley and on the west by the Big Raven Plateau. Its highest point and only named peak is Cartoona Peak at the westernmost end of the ridge with an elevation of 2,300 metres. Carttona Ridge is one of three ridges east of the Big Raven Plateau named by Canadian volcanologist Jack Souther, the other two being Idiji Ridge and Sorcery Ridge to the north.
The Little Iskut Formation is a stratigraphic unit of Miocene age in northwestern British Columbia, 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.
The Little Iskut River is a tributary of the Iskut River in the northwest part of the province of British Columbia, Canada, in Cassiar Land District. From its source at Little Ball Lake in Mount Edziza Provincial Park, the Little Iskut River flows about 45 km (28 mi), generally north to the vicinity of Mowdale Lake, then southeast and south to the Iskut River just below Cascade Falls. The Little Iskut River is part of the Stikine River drainage basin, as the Iskut River is a major tributary of the Stikine.
The Raspberry Formation is a stratigraphic unit of Miocene age in northwestern British Columbia, Canada.
The Nido Formation is a stratigraphic unit of Neogene age in northwestern British Columbia, Canada.
The Pyramid Formation is a stratigraphic unit of Pleistocene age in northwestern British Columbia, Canada.
The Mount Edziza volcanic complex (MEVC) in British Columbia, Canada, has a long history of volcanism that spans more than 6 million years. It occurred during five cycles of magmatic activity which were characterized by 13 periods of eruptive activity. This volcanism has led to the formation of several types of volcanic landforms, including cinder cones, stratovolcanoes, subglacial volcanoes, shield volcanoes, lava domes and lava fields. The 1,000-square-kilometre (390-square-mile) plateau comprising the MEVC owes its origin to 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 seven rock types are products of varying degrees of magmatic differentiation in underground magma reservoirs. 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. Renewed volcanism could produce explosive eruptions and block local streams with lava flows.
Gnu Butte is a butte in Cassiar Land District of northwestern British Columbia, Canada. It is located southeast of Telegraph Creek on the northwestern side of Raspberry Pass. The western and southern sides of the butte are surrounded by Raspberry Creek while the eastern and northern sides of the butte are surrounded by Flyin Creek. Gnu Butte lies on the Tahltan Highland between Mess Lake and Mowdade Lake in Mount Edziza Provincial Park. It bears a resemblance to flat-topped hills in parts of Africa, hence its name.
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.
Artifact Ridge is a mountain ridge extending southeast from the eastern side of the Mount Edziza volcanic complex in northwestern British Columbia, Canada. It is bounded on the north by Bourgeaux Creek valley, on the south by Artifact Creek valley, on the east by the Little Iskut River valley and on the west by the Kitsu Plateau. The ridge is at the southeastern end of Mount Edziza Provincial Park and gets its name from the knapping of obsidian tools and points by early Tahltan hunters. Destell Pass cuts north–south through the westernmost end of Artifact Ridge.
Yagi Ridge is a mountain ridge extending northwest from the middle of the Spectrum Range at the southern end of the Mount Edziza volcanic complex in northwestern British Columbia, Canada. It is bounded on the north by Nagha Glacier and Nagha Creek valley, on the south by Yeda Creek on the Arctic Lake Plateau and on the west by Mess Creek valley. Yagi Ridge reaches an elevation of 2,243 metres at the head of Nagha Glacier where its eastern end adjoins to the Spectrum Range just northwest of Yeda Peak.
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 valley, 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.