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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 format ...
in the
North Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for ...
, centered on
Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...
. In the
Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...
, the province formed the Thulean Plateau, a large
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 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 (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...
, west
Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...
, the
Faroe Islands The Faroe Islands ( ) (alt. the Faroes) are an archipelago in the North Atlantic Ocean and an autonomous territory of the Danish Realm, Kingdom of Denmark. Located between Iceland, Norway, and the United Kingdom, the islands have a populat ...
, northwest
Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...
, east
Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...
,
western Norway Western Norway (; ) is the Regions of Norway, region along the Atlantic coast of southern Norway. It consists of the Counties of Norway, counties Rogaland, Vestland, and Møre og Romsdal. The region has no official or political-administrative fu ...
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 approximately 40,000 interlocking basalt columns, the result of an ancient volcano, volcanic fissure eruption, part of the North Atlantic Igneous Province active in the region during the Paleogene period. ...
and Fingal's Cave. 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 (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...
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,
Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...
, and North American 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 Fault (geology), downfaulted depression, called a graben, or more commonly ...
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 ...
between
Labrador Labrador () is a geographic and cultural region within the Canadian province of Newfoundland and Labrador. It is the primarily continental portion of the province and constitutes 71% of the province's area but is home to only 6% of its populatio ...
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 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
to early Paleocene). Studies have suggested that the modern day Iceland hotspot 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 ...
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 pale ...
, it is speculated that the present day Iceland hotspot originated as a mantle plume on the Alpha Ridge (
Arctic Ocean The Arctic Ocean is the smallest and shallowest of the world's five oceanic divisions. It spans an area of approximately and is the coldest of the world's oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, ...
) c. 130–120 Ma, migrated down
Ellesmere Island Ellesmere Island (; ) is Canada's northernmost and List of Canadian islands by area, third largest island, and the List of islands by area, tenth largest in the world. It comprises an area of , slightly smaller than Great Britain, and the total ...
, through
Baffin Island Baffin Island (formerly Baffin Land), in the Canadian territory of Nunavut, is the largest island in Canada, the second-largest island in the Americas (behind Greenland), and the fifth-largest island in the world. Its area is (slightly smal ...
, 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, ...
of the opening of the North Atlantic between Greenland and Europe. As the Earth's crust was stretched above the mantle hotspot under stress from plate rifting, fissures opened up along a line from Ireland to the
Hebrides The Hebrides ( ; , ; ) are the largest archipelago in the United Kingdom, off the west coast of the Scotland, Scottish mainland. The islands fall into two main groups, based on their proximity to the mainland: the Inner Hebrides, Inner and Ou ...
and plutonic complexes were formed. Hot
magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...
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 Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...
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 commonly defined as a vent or fissure 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 fo ...
. 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 Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...
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, produced during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to r ...
, quickly followed by vast outpourings of highly
fluid In physics, a fluid is a liquid, gas, or other material that may continuously motion, move and Deformation (physics), deform (''flow'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are M ...
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 include ...
low
viscosity Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for e ...
lava reached the surface it rapidly cooled and solidified, successive flows built up layer upon layer, each time filling and covering existing landscapes.
Hyaloclastite Hyaloclastite is a volcanoclastic accumulation or breccia consisting of glass (from the Greek ''hyalus'') fragments (clasts) formed by quench fragmentation of lava flow surfaces during submarine or subglacial extrusion. It occurs as thin marg ...
s 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 discontinu ...
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 and volcanic plugs and large amounts spread laterally to form sills.
Dike swarm A dike swarm (American English, American spelling) or dyke swarm (British English, British spelling) is a large Geology, geological structure consisting of a major group of parallel, linear, or radially oriented Magma, magmatic dike (geolo ...
s extended across the British Isles throughout the
Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...
. Individual central complexes developed with arcuate intrusions (cone sheets,
ring dike A ring dike or ring dyke is an Intrusive rock, 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 me ...
s and
stocks Stocks are feet and hand 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 de ...
), 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 a group of several microporous, crystalline aluminosilicate minerals commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ・y where is either a meta ...
minerals. Activity of the NAIP 55 million years ago may have caused the
Paleocene–Eocene Thermal Maximum The Paleocene–Eocene thermal maximum (PETM), alternatively ”Eocene thermal maximum 1 (ETM1)“ and formerly known as the "Initial Eocene" or “Late Paleocene thermal maximum", was a geologically brief time interval characterized by a ...
, 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 (4CH4·23H2O), 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 a ...
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 of East Greenland and is composed of various rocks and minerals including gabbro, olivine, apatite, and basalt. History and background The Skaergaard intrusi ...
( Early Cenozoic or about 55 million year age) is a layered
gabbro Gabbro ( ) is a phaneritic (coarse-grained and magnesium- and iron-rich), mafic intrusive igneous rock formed from the slow cooling magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is ch ...
(
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 ...
) intrusion that has mineralized rock units enriched in
palladium Palladium is a chemical element; it has symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1802 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas (formally 2 Pallas), ...
and
gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...
. In contrast, the Werner Bjerge complex is made up of potassium- and sodium-rich (alkaline)
granitic A granitoid is a broad term referring to a diverse group of coarse-grained igneous rocks that are widely distributed across the globe, covering a significant portion of the Earth's exposed surface and constituting a large part of the continental ...
rock, containing
molybdenum Molybdenum is a chemical element; it has Symbol (chemistry), symbol Mo (from Neo-Latin ''molybdaenum'') and atomic number 42. The name derived from Ancient Greek ', meaning lead, since its ores were confused with lead ores. Molybdenum minerals hav ...
. Locations of submarine central complexes within the NAIP include: * Anton Dohrn Seamount * 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 *
Mourne Mountains The Mourne Mountains ( ; ), also called the Mournes or the Mountains of Mourne, are a predominantly granite mountain range in County Down in the south-east of Northern Ireland. They include the highest mountain in all of Ulster, Slieve Donard ...
*
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 List of Irish counties by highest point, highest point in t ...
Ring of Gullion AONB * Arran * Mull *
Ardnamurchan Ardnamurchan (, ) 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 route being a single track road for much of its l ...
*
Rùm Rùm (), a Scottish Gaelic language, Scottish Gaelic name often Anglicisation, anglicised to Rum ( ), is one of the Small Isles of the Inner Hebrides, off the west coast of Scotland, in the district of Lochaber. For much of the 20th century the ...
*
Eigg Eigg ( ; ) is one of the Small Isles in the Scotland, Scottish Inner Hebrides. It lies to the south of the island of Isle of Skye, Skye and to the north of the Ardnamurchan peninsula. Eigg is long from north to south, and east to west. With ...
*
Skye The Isle of Skye, or simply 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 by the Cuillin, the rocky slopes of which provide some o ...
* St Kilda *
Rockall Rockall () is a high, uninhabitable granite islet in the North Atlantic Ocean. It is west of Soay, St Kilda, Scotland; northwest of Tory Island, Ireland; and south of Iceland. The nearest permanently inhabited place is North Uist, east in ...
Those occurrences within the
Hebrides The Hebrides ( ; , ; ) are the largest archipelago in the United Kingdom, off the west coast of the Scotland, Scottish mainland. The islands fall into two main groups, based on their proximity to the mainland: the Inner Hebrides, Inner and Ou ...
are sometimes referred to as the Hebridean Igneous Province. Other notable NAIP landform locations in the United Kingdom include: *
Giant's Causeway The Giant's Causeway () is an area of approximately 40,000 interlocking basalt columns, the result of an ancient volcano, volcanic fissure eruption, part of the North Atlantic Igneous Province active in the region during the Paleogene period. ...
– 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 (, ; 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. As of the 2021 ...
Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...
and
Neogene The Neogene ( ,) 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 million years ago. It is the second period of th ...
lava flows * Fingal's Cave on the Isle of
Staffa Staffa (, , 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 vertically pl ...
– Polygonal basalt columns eroded to form a cave *
Ailsa Craig Ailsa Craig (; ) 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 remains of a magmatic pluton formed d ...
Volcanic plug A volcanic plug, also called a volcanic neck or lava neck, is a volcano, volcanic object created when magma hardens within a Volcanic vent, vent on an active volcano. When present, a plug can cause an extreme build-up of high gas pressure if risi ...
* Cleveland Dyke, 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 English, American spelling) or dyke swarm (British English, British spelling) is a large Geology, geological structure consisting of a major group of parallel, linear, or radially oriented Magma, magmatic dike (geolo ...
s found throughout the British Isles.


Republic of Ireland

Carlingford, County Louth Carlingford (; ) 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 Lough with S ...
is the only location of a major intrusion complex within the
Republic of Ireland Ireland ( ), also known as the Republic of Ireland (), is a country in Northwestern Europe, north-western Europe consisting of 26 of the 32 Counties of Ireland, counties of the island of Ireland, with a population of about 5.4 million. ...
'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 1835 – 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. ...
. 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.


See also

*
Igneous rock Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial ...
*
Geologic province A geologic province or geological province is a spatial entity with common geologic attributes. A province may include a single dominant structural element such as a basin or a fold belt, or a number of contiguous related elements. Adjoining ...
*
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 ho ...
* Hotspot *
Oceanic plateau An oceanic or submarine plateau is a large, relatively flat elevation that is higher than the surrounding relief with one or more relatively steep sides. There are 184 oceanic plateaus in the world, covering an area of or about 5.11% of the o ...
*
Continental flood basalt A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive rock, intrusive (sill (geology), sills, dike (geology), dikes) and extrusive rock, extrusive (lava flows, tephra deposits), arising when magm ...
*
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 format ...
*
Dike swarm A dike swarm (American English, American spelling) or dyke swarm (British English, British spelling) is a large Geology, geological structure consisting of a major group of parallel, linear, or radially oriented Magma, magmatic dike (geolo ...


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