Northern Alberta kimberlite province

Last updated May 27, 2023

northern Alberta kimberlite province

Location of the northern Alberta kimberlite province.

The northern Alberta kimberlite province (NAKP) consists of three groups of diatremes or volcanic pipes in north-central Alberta, Canada, most of which are kimberlites and some of which are diamondiferous. They are called the Birch Mountains (BM), Buffalo Head Hills (BHH), and the Mountain Lake cluster (ML), and they were discovered between about 1990 and 1997. Most of the diatremes were emplaced during the Late Cretaceous Epoch (Turonian to Maastrichtian stages)^[1] although a few are as young as early Paleocene.^[2]^[3]

Location

The NAKP kimberlite fields are located about 350 km (220 mi) to 450 km (280 mi) north to northwest of Edmonton in an area bounded by 55° and 57°N latitude and 115° and 118°W longitude. The area lies within the Canadian boreal forest and is sparsely settled. It includes the Buffalo Head Hills and the Birch Mountains, and is crossed by the Wabasca River and Alberta Highway 88.^[3]

Geologic setting

The NAKP kimberlite fields are aligned along a northeast–southwest trend for a distance of about 350 km (220 mi), roughly subparallel to structural discontinuities called the Great Slave Lake Shear Zone to the north and the Snowbird Tectonic Zone to the south. They lie above or marginal to a 2.0 to 2.4 billion year old Precambrian craton called the Buffalo Head Terrane, which has no surface exposure. Near the fields the Precambrian rocks are overlain by about 500 m (1,600 ft) to 2,200 m (7,200 ft) of Phanerozoic sedimentary rocks, and covered by unconsolidated glacial and post-glacial sediments.^[1]

Lithology and mineralogy

The volcanic rocks of the BHH and BM fields are classified as kimberlites. The ML rocks are not considered to be archetypal kimberilte and have been variously classified as alkaline ultramafic rocks, hybrid alkaline ultramafic rocks, alkali olivine basalt and basanite; they are difficult to classify because of strong clay alteration that has obliterated most of their original mineralogy.^[3]

All of the NAKP rocks are pyroclastic, and most represent maar-style diatremes that have a vertical-walled volcanic crater of explosive origin, surrounded by a low rim of ejecta. Pyroclastic fall and surge are the two volcanic mechanisms of deposition. There are also deposits formed by hydraulic reworking and resedimentation of material from tephra cones and/or extra-crater fall and surge deposits.^[2]^[3]

The NAKP volcanics, including the ML pipes, contain abundant lapilli and olivine supported in a fine-grained groundmass. Other minerals may include serpentine, clay minerals, carbonate minerals, phlogopite, ilmenite, perovskite, spinel, apatite, pyrite and, in some cases, diamonds.^[3]

Related Research Articles

Kimberlite is an igneous rock and a rare variant of peridotite. It is most commonly known to be the main host matrix for diamonds. It is named after the town of Kimberley in South Africa, where the discovery of an 83.5-carat (16.70 g) diamond called the Star of South Africa in 1869 spawned a diamond rush and the digging of the open-pit mine called the Big Hole. Previously, the term kimberlite has been applied to olivine lamproites as Kimberlite II, however this has been in error.

Ultramafic rocks are igneous and meta-igneous rocks with a very low silica content, generally >18% MgO, high FeO, low potassium, and are composed of usually greater than 90% mafic minerals. The Earth's mantle is composed of ultramafic rocks. Ultrabasic is a more inclusive term that includes igneous rocks with low silica content that may not be extremely enriched in Fe and Mg, such as carbonatites and ultrapotassic igneous rocks.

Volcanic activity is a major part of the geology of Canada and is characterized by many types of volcanic landform, including lava flows, volcanic plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcanoes, calderas, diatremes, and maars, along with less common volcanic forms such as tuyas and subglacial mounds.

The Phoenix pipe is a diatreme associated with the Birch Mountains kimberlite field in northern Alberta, Canada. It is thought to have formed about 75 million years ago when this part of Alberta was volcanically active during the Late Cretaceous period.

The Legend pipe is a diatreme associated with the Birch Mountains kimberlite field in northern Alberta, Canada. It is thought to have formed about 75 million years ago during the Late Cretaceous period.

The Xena pipe is a diatreme associated with the Birch Mountains kimberlite field in northern Alberta, Canada. It is thought to have formed about 75 million years ago when this part of Alberta was volcanically active during the Late Cretaceous period.

The Dragon pipe is a diatreme associated with the Birch Mountains kimberlite field in northern Alberta, Canada. It is thought to have formed about 75 million years ago when this part of Alberta was volcanically active during the Late Cretaceous period.

The Buffalo Head Hills kimberlite field is a group of kimberlitic volcanic pipes or diatremes in north-central Alberta, Canada. As of 2011, 41 kimberlite pipes, of which 28 are diamondiferous, had been identified in the field. They were emplaced during Late Cretaceous to early Paleocene time.

The Birch Mountains kimberlite field is a cluster of kimberlitic volcanic pipes or diatremes in north-central Alberta, Canada that were emplaced during a period of kimberlitic volcanism in the Late Cretaceous epoch. As of 2011, 8 diatremes had been discovered in the field, and diamonds and microdiamononds had been recovered during sampling programs.

The Kendu pipe is a diatreme associated with the Birch Mountains kimberlite field in northern Alberta, Canada. It is thought to have formed about 75 million years ago when this part of Alberta was volcanically active during the Late Cretaceous period.

K6 pipe is a diamondiferous diatreme in the Buffalo Head Hills kimberlite field of Northern Alberta, Canada. It is thought to have formed about 85 million years ago when is part of Alberta was volcanically active during the Late Cretaceous period. It is typical of melts that originated from the low mantle.

K252 pipe is a diamondiferous diatreme in the Buffalo Head Hills kimberlite field of Northern Alberta, Canada. It is thought to have formed about 85 million years ago when this part of Alberta was volcanically active during the Late Cretaceous period. It contains pyroclastic textures and is intruded into Cenomanian and Albian aged strata.

K19 pipe is a diatreme in the southwestern part of the Buffalo Head Hills kimberlite field in Northern Alberta, Canada. It is thought to have formed about 60 million years ago, making it one of the youngest volcanic formations in the Buffalo Head Hills kimberlite field and in Alberta. Unlike many other diatremes in the Buffalo Head Hills kimberlite field, it contains low diamond content.

The Mountain Lake cluster consists of two diatremes or volcanic pipes in Northern Alberta, Canada. It was emplaced during a period of kimberlite volcanism in the Late Cretaceous epoch.

Volcanism of Western Canada has produced lava flows, lava plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, greenstone belts, submarine volcanoes, calderas, diatremes and maars, along with examples of more less common volcanic forms such as tuyas and subglacial mounds.

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The Igwisi Hills are a volcanic field in Kaliua District of Tabora Region of Tanzania. Three tuff cones are found there, one of which is associated with a lava flow. They are one of the few locations of possibly kimberlitic lava flows on Earth.

The Buffalo Head Terrane (BHT) is a terrane in the western Canadian Shield in northern Alberta. It is covered by 1,600 m (5,200 ft) of Devonian and Cretaceous sediments and its centre is intruded by the 88–86 Ma kimberlites of the diamondiferous Buffalo Head Hills kimberlite province.

The geology of Nunavut began to form nearly three billion years ago in the Archean and the territory preserves some of the world's oldest rock units.

The Navajo volcanic field is a monogenetic volcanic field located in the Four Corners region of the United States, in the central part of the Colorado Plateau. The volcanic field consists of over 80 volcanoes and associated intrusions of unusual potassium-rich compositions, with an age range of 26.2 to 24.7 million years (Ma).

References

1 2 Eccles, D.R., Heaman, L.M., Luth, R.W. and Creaser, R.A. (2003). "Petrogenetic considerations for the Late Cretaceous northern Alberta kimberlite province. 8th International Kimberlite Conference, Extended Abstract, 5 p." (PDF). Archived from the original (PDF) on 26 May 2011. Retrieved 13 August 2014.{{cite web}}: CS1 maint: multiple names: authors list (link)
1 2 Boyer, L., McCandless, T., Tosdal, R. and Russell, K. 2008. Volcanic facies and eruption styles in the Cretaceous Buffalo Head Hills kimberlites, Alberta, Canada. 9th International Kimberlite Conference, Extended Abstract 9IKC-A-00367-2, 3 p.
1 2 3 4 5 Eccles, D.R. (2014). "Northern Alberta Kimberlite Province: The first 20 years. Alberta Geological Survey, ERCB/AGS Bulletin 65, 116 p." (PDF). Archived from the original (PDF) on 25 February 2012. Retrieved 19 October 2014.

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[AGS-1] 1 2 Eccles, D.R., Heaman, L.M., Luth, R.W. and Creaser, R.A. (2003). "Petrogenetic considerations for the Late Cretaceous northern Alberta kimberlite province. 8th International Kimberlite Conference, Extended Abstract, 5 p." (PDF). Archived from the original (PDF) on 26 May 2011. Retrieved 13 August 2014.{{cite web}}: CS1 maint: multiple names: authors list (link)

[Boyer-2] 1 2 Boyer, L., McCandless, T., Tosdal, R. and Russell, K. 2008. Volcanic facies and eruption styles in the Cretaceous Buffalo Head Hills kimberlites, Alberta, Canada. 9th International Kimberlite Conference, Extended Abstract 9IKC-A-00367-2, 3 p.

[BULL65-3] 1 2 3 4 5 Eccles, D.R. (2014). "Northern Alberta Kimberlite Province: The first 20 years. Alberta Geological Survey, ERCB/AGS Bulletin 65, 116 p." (PDF). Archived from the original (PDF) on 25 February 2012. Retrieved 19 October 2014.

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