The North Atlantic Igneous Province (NAIP) is a

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

North 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 a ...

, centered on

Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its ...

. In the

Paleogene The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago ( Mya) to the beginning o ...

, the province formed the Thulean Plateau, a large

basalt Basalt (; ) is an 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 surface of a rocky planet or moon. More than 90 ...

ic lava plain, which extended over at least in area and in volume. The plateau was broken up during the opening of the North Atlantic Ocean leaving remnants preserved in north

Ireland Ireland ( ; ga, Éire ; Ulster-Scots: ) is an island in the North Atlantic Ocean, in north-western Europe. It is separated from Great Britain to its east by the North Channel, the Irish Sea, and St George's Channel. Ireland is the s ...

, west

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to ...

, the

Faroe Islands The Faroe Islands ( ), or simply the Faroes ( fo, Føroyar ; da, Færøerne ), are a North Atlantic island group and an autonomous territory of the Kingdom of Denmark. They are located north-northwest of Scotland, and about halfway bet ...

, northwest

, east

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 ...

western Norway Western Norway ( nb, Vestlandet, Vest-Norge; nn, Vest-Noreg) is the region along the Atlantic coast of southern Norway. It consists of the counties Rogaland, Vestland, and Møre og Romsdal. The region has no official or political-administrativ ...

and many of the islands located in the north eastern portion of the North Atlantic Ocean. The igneous province is the origin of the

Giant's Causeway The Giant's Causeway is an area of about 40,000 interlocking basalt columns, the result of an ancient volcanic fissure eruption. It is located in County Antrim on the north coast of Northern Ireland, about three miles (5 km) northeast of ...

and

Fingal's Cave Fingal's Cave is a sea cave on the uninhabited island of Staffa, in the Inner Hebrides of Scotland, known for its natural acoustics. The National Trust for Scotland owns the cave as part of a national nature reserve. It became known as Finga ...

. The province is also known as Brito–Arctic province (also known as the North Atlantic Tertiary Volcanic Province) and the portion of the province in the British Isles is also called the British Tertiary Volcanic Province or British Tertiary Igneous Province.

Formation

Isotopic dating indicates the most active

magmatic Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

phase of the NAIP was between and c. 54.5 Ma (million years ago) (mid-Paleocene to early Eocene) – further divided into Phase 1 (pre-break-up phase) dated to c. 62-58 Ma and Phase 2 (syn-break-up phase) dated to c. 56-54 Ma. Continuing research also indicates that tectonic plate movement (of the

Eurasian Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipela ...

, and

North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the ...

plates), regional

rifting 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-graben wi ...

events, and

seafloor spreading Seafloor spreading or Seafloor spread is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. History of study Earlier theories by Alfred Wegener a ...

between

Labrador , nickname = "The Big Land" , etymology = , subdivision_type = Country , subdivision_name = Canada , subdivision_type1 = Province , subdivision_name1 ...

and Greenland may have begun as early as c. 95-80 Ma, c. 81 Ma, and c. 63–61 Ma respectively (late

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 ...

to early Paleocene). Studies have suggested that the modern day

Iceland hotspot The Iceland hotspot is a hotspot which is partly responsible for the high volcanic activity which has formed the Iceland Plateau and the island of Iceland. Iceland is one of the most active volcanic regions in the world, with eruptions occu ...

corresponds to the earlier 'North Atlantic mantle plume' that would have created the NAIP. Through both

geochemical Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the e ...

observations and reconstructions of

paleogeography Palaeogeography (or paleogeography) is the study of historical geography, generally physical landscapes. Palaeogeography can also include the study of human or cultural environments. When the focus is specifically on landforms, the term pal ...

, it is speculated that the present day Iceland hotspot originated as a mantle plume on 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 elevation ...

(

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 ...

) c. 130–120 Ma, migrated down

Ellesmere Island Ellesmere Island ( iu, script=Latn, Umingmak Nuna, lit=land of muskoxen; french: île d'Ellesmere) is Canada's northernmost and third largest island, and the tenth largest in the world. It comprises an area of , slightly smaller than Great Br ...

, through

Baffin Island Baffin Island (formerly Baffin Land), in the Canadian territory of Nunavut, is the largest island in Canada and the fifth-largest island in the world. Its area is , slightly larger than Spain; its population was 13,039 as of the 2021 Canadia ...

, onto the west coast of Greenland, and finally arrived on the east coast of Greenland by c. 60 Ma. Extensive outpourings of lava occurred, particularly in East Greenland, which during the Paleogene was then adjacent to Britain. Little is known of the

geodynamics Geodynamics is a subfield of geophysics dealing with dynamics of the Earth. It applies physics, chemistry and mathematics to the understanding of how mantle convection leads to plate tectonics and geologic phenomena such as seafloor spreading, mo ...

of the opening of the North Atlantic between Greenland and Europe. As the Earth's crust was stretched above the

mantle A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that. Mantle may refer to: *Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear **Mantle (vesture), an Eastern Orthodox ve ...

hotspot under stress from plate rifting, fissures opened up along a line from Ireland to the

Hebrides The Hebrides (; gd, Innse Gall, ; non, Suðreyjar, "southern isles") are an archipelago off the west coast of the Scottish mainland. The islands fall into two main groups, based on their proximity to the mainland: the Inner and Outer Hebri ...

and plutonic complexes were formed. Hot

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natura ...

over 1000 °C surfaced as multiple, successive and extensive

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or ...

flows covered over the original landscape, burning forests, filling river valleys, burying hills, to eventually form the Thulean Plateau, which contained various volcanic landforms such as lava fields and

volcanoes A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...

. There was more than one period of volcanic activity during the NAIP, in between which sea levels rose and fell and

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...

took place. Volcanic activity would have started with

volcaniclastic Volcaniclastics are geologic materials composed of broken fragments ( clasts) of volcanic rock. These encompass all clastic volcanic materials, regardless of what process fragmented the rock, how it was subsequently transported, what environment it ...

accumulations, like

volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...

, quickly followed by vast outpourings of highly

fluid In physics, a fluid is a liquid, gas, or other material that continuously deforms (''flows'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shear ...

basaltic lava during successive eruptions through multiple volcanic vents or in linear fissures. As

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 in ...

low

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the int ...

lava reached the surface it rapidly cooled and solidified, successive flows built up layer upon layer, each time filling and covering existing landscapes. Hyaloclastites and

pillow lava Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava underwater, or ''subaqueous extrusion''. Pillow lavas in volcanic rock are characterized by thick sequences of discont ...

s were formed when the lava flowed into lakes, rivers and seas. Magma that did not make it to the surface as flows froze in conduits as

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

volcanic plugs A volcanic plug, also called a volcanic neck or lava neck, is a volcanic object created when magma hardens within a vent on an active volcano. When present, a plug can cause an extreme build-up of high gas pressure if rising volatile-charged ma ...

and large amounts spread laterally to form sills.

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 ...

s extended across the British Isles throughout 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 configu ...

. Individual central complexes developed with arcuate intrusions (cone sheets,

ring dike A ring dike or ring dyke is an intrusive igneous body that is circular, oval or arcuate in plan and has steep contacts. While the widths of ring dikes differ, they can be up to several thousand meters. The most commonly accepted method of ring dik ...

s and

stocks Stocks are feet restraining devices that were used as a form of corporal punishment and public humiliation. The use of stocks is seen as early as Ancient Greece, where they are described as being in use in Solon's law code. The law describing ...

), the intrusions of one centre cut through earlier centres recording magmatic activity with time. During intermittent periods of erosion and change in sea levels, heated waters circulated through the flows altering the basalts and deposited distinctive suites of

zeolite Zeolites are microporous, crystalline aluminosilicate materials commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ･y where is either a metal ion or H+. These p ...

minerals. Activity of the NAIP 55 million years ago may have caused the

Paleocene–Eocene Thermal Maximum The Paleocene–Eocene thermal maximum (PETM), alternatively (ETM1), and formerly known as the "Initial Eocene" or "", was a time period with a more than 5–8 °C global average temperature rise across the event. This climate event o ...

, where a large amount of carbon was released into the atmosphere and the Earth substantially warmed. One hypothesis is that the uplift caused by the NAIP hotspot caused

methane clathrate Methane clathrate (CH4·5.75H2O) or (8CH4·46H2O), also called methane hydrate, hydromethane, methane ice, fire ice, natural gas hydrate, or gas hydrate, is a solid clathrate compound (more specifically, a clathrate hydrate) in which a large amou ...

s to dissociate and dump 2000 gigatons of carbon into the atmosphere.

Igneous landforms

The NAIP is made up of both onshore and offshore basalt floods, sills, dykes, and plateaus. Dependent upon various regional locations, the NAIP is made up of MORB (Mid Ocean Ridge Basalt), alkali basalt, tholeiitic basalt, and

picrite basalt Picrite basalt or picrobasalt is a variety of high-magnesium olivine basalt that is very rich in the mineral olivine. It is dark with yellow-green olivine phenocrysts (20-50%) and black to dark brown pyroxene, mostly augite. The olivine-rich ...

. Basaltic volcanic rocks up to thick cover in east Greenland. Numerous intrusions related to hot-spot magmatism are exposed in the coastal region of east Greenland. The intrusions show a wide range of compositions. The

Skaergaard intrusion The Skaergaard intrusion is a layered igneous intrusion in the Kangerlussuaq area, East Greenland. It comprises various rock types including gabbro, ferro diorite, anorthosite and granophyre. Discovered by Lawrence Wager in 1931 during the B ...

( Early Cenozoic or about 55 million year age) is a layered

gabbro Gabbro () is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is ...

(

) intrusion that has mineralized rock units enriched in

palladium Palladium is a chemical element with the symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas, which was itself ...

and

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...

. In contrast, the Werner Bjerge complex is made up of potassium- and sodium-rich (alkaline)

granitic A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz- ...

rock, containing

molybdenum Molybdenum is a chemical element with the symbol Mo and atomic number 42 which is located in period 5 and group 6. The name is from Neo-Latin ''molybdaenum'', which is based on Ancient Greek ', meaning lead, since its ores were confused with lead ...

. Locations of submarine central complexes within the NAIP include: *

Anton Dohrn Seamount The Anton Dohrn Seamount is a guyot in the Rockall Trough in the northeast Atlantic. It is high and is topped with pinnacles, one of which reaches a depth of . Away from the flat top upon which the pinnacles rest, the slopes fall off steeply ...

* Rosemary Bank * Blackstones Bank * Brendan * Erlend

United Kingdom

The British portion of the NAIP, particularly West Scotland, provides relatively easy access, compared to the largely inaccessible basalt fields of West Greenland, to deeply eroded relics of the central volcanic complexes. Locations of major intrusion complexes within the British part of the NAIP include: *

Lundy Island Lundy is an English island in the Bristol Channel. It was a micronation from 1925–1969. It forms part of the district of Torridge in the county of Devon. About long and wide, Lundy has had a long and turbulent history, frequently chang ...

Mourne Mountains The Mourne Mountains ( ; ga, Beanna Boirche), also called the Mournes or Mountains of Mourne, are a granite mountain range in County Down in the south-east of Northern Ireland. They include the highest mountains in Northern Ireland, the hig ...

Slieve Gullion Slieve Gullion ( or ''Sliabh Cuilinn'', " Culann's mountain") is a mountain in the south of County Armagh, Northern Ireland. The mountain is the heart of the Ring of Gullion and is the highest point in the county, with an elevation of . At t ...

– Ring of Gullion AONB * Arran * Mull *

Ardnamurchan Ardnamurchan (, gd, Àird nam Murchan: headland of the great seas) is a peninsula in the ward management area of Lochaber, Highland, Scotland, noted for being very unspoiled and undisturbed. Its remoteness is accentuated by the main access ...

Rùm Rùm (), a Scottish Gaelic name often anglicised to Rum (), is one of the Small Isles of the Inner Hebrides, in the district of Lochaber, Scotland. For much of the 20th century the name became Rhum, a spelling invented by the former owner, Sir ...

Eigg Eigg (; gd, Eige; sco, Eigg) is one of the Small Isles in the Scottish Inner Hebrides. It lies to the south of the Isle of Skye and to the north of the Ardnamurchan peninsula. Eigg is long from north to south, and east to west. With an ar ...

Skye The Isle of Skye, or simply Skye (; gd, An t-Eilean Sgitheanach or ; sco, Isle o Skye), is the largest and northernmost of the major islands in the Inner Hebrides of Scotland. The island's peninsulas radiate from a mountainous hub dominated ...

* St Kilda *

Rockall Rockall () is an uninhabitable granite islet situated in the North Atlantic Ocean. The United Kingdom claims that Rockall lies within its exclusive economic zone (EEZ) and is part of its territory, but this claim is not recognised by Ireland ...

Those occurrences within the

are sometimes referred to as the Hebridean Igneous Province. Other notable NAIP landform locations in the United Kingdom include: *

– Polygonal basalt columns, which seen from above are large hexagonal pavements * Canna and Sanday – Basalt lava field with great thicknesses of boulder conglomerate, examples of periods of erosion by fast flowing rivers in between the lava flows. *

Rathlin Island Rathlin Island ( ga, Reachlainn, ; Local Irish dialect: ''Reachraidh'', ; Scots: ''Racherie'') is an island and civil parish off the coast of County Antrim (of which it is part) in Northern Ireland. It is Northern Ireland's northernmost point. ...

–

and

Neogene The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. ...

lava flows *

on the Isle of

Staffa Staffa ( gd, Stafa, , from the Old Norse for stave or pillar island) is an island of the Inner Hebrides in Argyll and Bute, Scotland. The Vikings gave it this name as its columnar basalt reminded them of their houses, which were built from ver ...

– Polygonal basalt columns eroded to form a cave *

Ailsa Craig Ailsa Craig (; sco, Ailsae Craig; gd, Creag Ealasaid) is an island of in the outer Firth of Clyde, west of mainland Scotland, upon which microgranite has long been quarried to make curling stones. The now-uninhabited island comprises the ...

–

Volcanic plug A volcanic plug, also called a volcanic neck or lava neck, is a volcanic object created when magma hardens within a vent on an active volcano. When present, a plug can cause an extreme build-up of high gas pressure if rising volatile-charged ma ...

Cleveland Dyke The Cleveland Dyke (or Armathwaite Dyke, Cleveland-Armathwaite Dyke or Armathwaite-Cleveland Dyke) is an igneous intrusion which extends from Galloway in southern Scotland through Cumbria and County Durham in northern England to the North York Mo ...

, North Yorkshire – Dyke swarm related to the Mull intrusive complex * The dike complexes of the NAIP contain many examples of

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-grain ...

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 ...

s found throughout the British Isles.

Republic of Ireland

Carlingford, County Louth Carlingford (; ga, Cairlinn) is a coastal town and civil parish in northern County Louth, Ireland. For the purposes of local government, the town is part of the Dundalk Municipal District. It is situated on the southern shore of Carlingford ...

is the only location of a major intrusion complex within the

Republic of Ireland Ireland ( ga, Éire ), also known as the Republic of Ireland (), is a country in north-western Europe consisting of 26 of the 32 counties of the island of Ireland. The capital and largest city is Dublin, on the eastern side of the island. ...

's part of the NAIP.

History of geological studies

The intensity of scientific investigation within the NAIP has made it one of the most historically important and deeply studied igneous provinces in the world. Basalt petrology was born in the Scottish Hebrides in 1903 led by the eminent British geologist Sir

Archibald Geikie Sir Archibald Geikie (28 December 183510 November 1924) was a Scottish geologist and writer. Early life Geikie was born in Edinburgh in 1835, the eldest son of Isabella Thom and her husband James Stuart Geikie, a musician and music critic. T ...

. From the outset Geikie studied the geology of Skye and other Western Isles taking a keen interest in volcanic geology and in 1871 he presented the Geological Society of London with an outline of the 'Tertiary Volcanic History of Britain'. Following Geikie many have tried, and continue to study and understand the NAIP, and in doing so have advanced knowledge in geology, mineralogy and in more recent decades geochemistry and geophysics.

References

External links

Map of NAIP
– from

– from

{{coord missing, Atlantic Ocean Large igneous provinces Paleocene volcanism Eocene volcanism Volcanism of the Atlantic Ocean Flood basalts Plateaus of the Atlantic Ocean Geology of Greenland Geology of Iceland Volcanism of the United Kingdom Volcanism of Northern Ireland Volcanism of Scotland Dike swarms