The High Arctic Large Igneous Province (HALIP) is a

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

large igneous province A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive (sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The formation ...

in the Arctic. The region is divided into several smaller magmatic provinces.

Svalbard Svalbard ( , ), also known as Spitsbergen, or Spitzbergen, is a Norwegian archipelago in the Arctic Ocean. North of mainland Europe, it is about midway between the northern coast of Norway and the North Pole. The islands of the group range ...

Franz Josef Land , native_name = , image_name = Map of Franz Josef Land-en.svg , image_caption = Map of Franz Josef Land , image_size = , map_image = Franz Josef Land location-en.svg , map_caption = Location of Franz Josef ...

, Sverdrup Basin,

Amerasian Basin The Amerasia Basin, or Amerasian Basin, is one of the two major basins from which the Arctic Ocean can be subdivided (the other one being the Eurasian Basin). The triangular-shaped Amerasia Basin broadly extends from the Canadian Arctic Islands to ...

, and northern

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...

(

Peary Land Peary Land is a peninsula in northern Greenland, extending into the Arctic Ocean. It reaches from Victoria Fjord in the west to Independence Fjord in the south and southeast, and to the Arctic Ocean in the north, with Cape Morris Jesup, the north ...

) are some of the larger divisions. Today, HALIP covers an area greater than , making it one of the largest and most intense magmatic complexes on the planet. However, eroded volcanic sediments in sedimentary strata in Svalbard and Franz Josef Land suggest that an extremely large portion of HALIP volcanics have already been eroded away.

Geologic evolution

The HALIP event lasted from 130 million years ago to approximately 60 million years ago. During its active period, there were two distinct phases of volcanism. The first phase lasted from 130 million years ago to 80 million years ago and was characterized by

tholeiitic The tholeiitic magma series is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma i ...

igneous activity. During this time, numerous

dikes Dyke (UK) or dike (US) may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), a subvertical sheet-like intrusion of magma or sediment * Dike (mythology), ''Dikē'', the Greek goddess of moral justice * Dikes, ...

and sills formed, and there were eruptions of

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

ic flow. The basalts formed at this time are relatively rich in TiO₂ and have a similar composition to continental

flood basalt A flood basalt (or plateau basalt) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reach ...

s. The second phase lasted from approximately 85 million years ago to 60 million years ago and was characterized by mildly alkaline igneous activity and the eruption of flood basalts. The

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main The three types of rocks, rock types, the others being Sedimentary rock, sedimentary and metamorphic rock, metamorphic. Igneous rock ...

s formed during the second phase have a similar geochemical makeup as the intra-plate composition. The

Arctic Ocean The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately and is known as the coldest of all the oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, a ...

is a few hundred million years old, making it the youngest ocean on Earth. In the

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

, when the Arctic was located south of the Equator, the continent

Arctica Arctica or Arctida was an ancient continent which formed approximately 2.565 billion years ago in the Neoarchean era. It was made of Archaean cratons, including the Siberian Craton, with its Anabar/Aldan shields in Siberia, and the Sla ...

(or Arctida) filled the gap between the

craton A craton (, , or ; from grc-gre, κράτος "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging and ...

s that today surround the Arctic region. Arctica

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...

ed apart in the Late Precambrian (950 Ma) and was reassembled in a new configuration in the Late Paleozoic (255 Ma). Kap tegethoff gross

During the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

-Cretaceous this second continent, known as

Pangea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...

, broke apart, opening the

and the Arctic Ocean. HALIP dispersed the components of this second continent around the margins of the Arctic Ocean where they are now

terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its own ...

s and microplates embedded into fold belts or overlain by sediments. As the

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

and Arctic oceans opened during the

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

and into the

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...

, the Arctic Region underwent several stages of rifting, sedimentation, and magmatism.

Dolerite Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grained ...

s collected from Svalbard and elsewhere in the Arctic are

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 ...

intra-plate

tholeiite The tholeiitic magma series is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma i ...

s characteristic of HALIP, which indicated that the LIP formed during the opening of the Arctic Ocean around 148–70 Ma. Seismic and magnetic analyses of the seafloor produced ages of 118–83 Ma. The HALIP is widely thought to have originated from a

mantle plume A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hot ...

, and the igneous activity of the province often tracked along a similar path as the Icelandic hotspot.

Magmatic provinces

The HALIP is divided into several magmatic provinces. These provinces are divided by location, igneous rock composition, and the formations present.

Svalbard

In the Svalbard province, the HALIP is expressed as an extensive system of alkaline intrusive doleritic rocks. The

intrusion In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

s largely appear in the form of sills that can reach thicknesses of and continuously extend for up to laterally. The basaltic rocks found in Svalbard have an intra-plate composition and are thought to originate from a source near the

Alpha Ridge The Alpha Ridge is a major volcanic ridge under the Arctic Ocean between the Canada Basin (off Ellesmere Island) and the Lomonosov Ridge. It was active during the formation of the Amerasian Basin. It was discovered in 1963. The highest elevatio ...

. The Svalbard province is also closely associated with the Franz Josef Land province (discussed below). The two provinces combined cover an area of approximately .

Franz Josef Land

The Franz Josef Land province is closely associated with the Svalbard province. Franz Josef Land is located approximately east of Svalbard and contains igneous rocks of very similar composition to those of Svalbard. However, the archipelago is scattered with a prominent swarm of southeast trending dikes. Extensive sills and volcanic flows can also be found in the region, as well as a few dikes of other trends. The timing of the Franz Josef Land formations and the Svalbard formations is thought to be nearly identical, furthering the evidence for a large initial plume head model for the HALIP.

Sverdrup Basin

The Sverdrup Basin province spreads across the

Canadian Arctic Islands The Arctic Archipelago, also known as the Canadian Arctic Archipelago, is an archipelago lying to the north of the Canadian continental mainland, excluding Greenland (an autonomous territory of Denmark). Situated in the northern extremity of No ...

. The region is characterized by the presence of a radiating

dike swarm A dike swarm (American spelling) or dyke swarm (British spelling) is a large geological structure consisting of a major group of parallel, linear, or radially oriented magmatic dikes intruded within continental crust or central volcanoes ...

across the

Queen Elizabeth Islands The Queen Elizabeth Islands (french: Îles de la Reine-Élisabeth; formerly Parry Islands or Parry Archipelago) are the northernmost cluster of islands in Canada's Arctic Archipelago, split between Nunavut and the Northwest Territories in Northe ...

that seems to suggest the presence of a mantle plume beneath the Alpha Ridge. This province contains igneous rocks of both tholeiitic and alkaline composition. There are also a respectable number of sills and flood basalts in the province. The flood basalts in the Canadian Arctic Islands are similar to those of the Columbia River flood basalts in the

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...

of the United States. The Sverdrup Basin Magmatic Province covers an area of .

Amerasian Basin

The Amerasian Basin's most prominent feature is the Alpha Ridge – which is thought to be the location of the mantle plume that fed the HALIP. The ridge reaches a height of from the seafloor. Also in the region are a few basaltic dikes. The Amerasian Basin extends over .

Northern Greenland (Peary Land)

The northern Greenland province, also known as Peary Land, contains three dike swarms. The Nansen Land swarm trends SSE-SE and is the oldest of the swarms. The middle-aged swarm is known as the Erlandsen Swarm and trends SE-ESE. The J. P. Koch Swarm is the youngest of the three and trends eastward. The two younger swarms tend to have igneous rocks of alkaline composition, while the Nansen Land swarm tends to have more tholeiitic composition. The Peary Land province covers an area of over .

Barents Sea

The Barents Sea province is characterized by igneous intrusions with much similarity to Svalbard and Franz-Josef Land. This region is well known for being petroleum-rich. The Barents Sea province covers an area of .

Climatic impact

Large igneous provinces such as HALIP are thought to have caused global climate change.

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

(92–86 Ma) vertebrates, including long

champsosaur Choristodera (from the Greek χωριστός ''chōristos'' + δέρη ''dérē'', 'separated neck') is an extinct order of semiaquatic diapsid reptiles that ranged from the Middle Jurassic, or possibly Triassic, to the late Miocene (168 to ...

s, a crocodile-like reptile, found in the Canadian Arctic suggests that polar climate was much warmer during the Cretaceous when average annual temperature must have exceeded 14 °C. The BLIP intrusions could have released perhaps of carbon from the

contact aureole Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...

s which could have triggered the

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...

oceanic anoxic event (OAE1a) at 120 Ma.

References

Notes

Sources

* * * * * * * ** * * * * * * * {{Coord, 79.4488, 11.3955, region:NO-21, format=dms, display=title Large igneous provinces Cretaceous volcanism Geography of the Arctic Volcanism of Nunavut Volcanism of the Arctic Ocean Volcanism of Norway Volcanism of Russia Prehistory of the Arctic Geology of the Arctic Geology of the Arctic Ocean Geology of Russia Cretaceous Europe Cretaceous North America Cretaceous Canada Cretaceous Norway