The Canadian Arctic Rift System is a major

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

n geological structure extending from the

Labrador Sea The Labrador Sea (; ) is an arm of the North Atlantic Ocean between the Labrador Peninsula and Greenland. The sea is flanked by continental shelf, continental shelves to the southwest, northwest, and northeast. It connects to the north with Baffi ...

in the southeast through

Davis Strait The Davis Strait (Danish language, Danish: ''Davisstrædet'') is a southern arm of the Arctic Ocean that lies north of the Labrador Sea. It lies between mid-western Greenland and Baffin Island in Nunavut, Canada. To the north is Baffin Bay. The ...

Baffin Bay Baffin Bay (Inuktitut: ''Saknirutiak Imanga''; ; ; ), located between Baffin Island and the west coast of Greenland, is defined by the International Hydrographic Organization as a marginal sea of the Arctic Ocean. It is sometimes considered a s ...

and the

Arctic Archipelago 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 the Danish Realm, which is, by itself, much larger ...

in the northwest. It consists of a series of interconnected

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-graben ...

s that formed during the

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...

and

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 ...

eras. Extensional stresses along the entire length of the rift system have resulted in a variety of

tectonic Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons. These processes ...

features, including

graben In geology, a graben () is a depression (geology), depressed block of the Crust (geology), crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German language, German, meaning 'ditch' or 't ...

s, half-grabens,

basins Basin may refer to: Geography and geology * Depression (geology) ** Back-arc basin, a submarine feature associated with island arcs and subduction zones ** Debris basin, designed to prevent damage from debris flow ** Drainage basin (hydrology), ...

and faults. Development of the Canadian Arctic Rift System was accompanied by two

plate tectonic Plate may refer to: Cooking * Plate (dishware), broad, mainly flat vessel commonly used to serve food * Plates, tableware, dishes or dishware used for setting a table, serving food and dining * Plate, the content of such a plate (for example: r ...

episodes that originated on opposite sides of the North American plate and were propagated toward each other. Both were strongly controlled by pre-existing structures, which either guided the propagating faults or impeded their growth. The rift system is now inactive apart from minor adjustments that are indicated by occasional

earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

s in Baffin Bay and the Labrador Sea.

Geology

The Canadian Arctic Rift System is a branch of the

Mid-Atlantic Ridge The Mid-Atlantic Ridge is a mid-ocean ridge (a Divergent boundary, divergent or constructive Plate tectonics, plate boundary) located along the floor of the Atlantic Ocean, and part of the List of longest mountain chains on Earth, longest mountai ...

that extends into the North American continent. It is an incipient structure that diminishes in degree of development northwestward, bifurcates at the head of Baffin Bay and disappears into the Arctic Archipelago. The rift system is mainly an extensional structure, which has allowed

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

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

to rotate apart and form intervening seaways. The segment extending from the Labrador Sea to Baffin Bay is sometimes referred to as the Labrador Sea–Baffin Bay rift system or the North Atlantic–Labrador Sea rift system.

Tectonic evolution

Northern Canada and Greenland Paleogene tectonics

Two rifting episodes created the Canadian Arctic Rift System. The first is referred to as the Boreal Rifting Episode which followed compression and exposure brought on by the Ellesmerian orogeny. The second is referred to as the Eurekan Rifting Episode and created most of the structures that comprise the Canadian Arctic Rift System. Both rifting episodes were active simultaneously from the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

to mid-

Tertiary Tertiary (from Latin, meaning 'third' or 'of the third degree/order..') may refer to: * Tertiary period, an obsolete geologic period spanning from 66 to 2.6 million years ago * Tertiary (chemistry), a term describing bonding patterns in organic ch ...

Boreal Rifting Episode

The Boreal Rifting Episode began in the

Late Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at million years ago ( Ma), to the beginning of the succeeding ...

and emanated southeastward from the Canada Basin into the North American continent. It caused uplift of the Pearya Geanticline and Sverdrup Rim, as well as crustal extension which led to thinning and

subsidence Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope mov ...

of the regional

lithosphere A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the lithospheric mantle, the topmost portion of the upper mantle that behaves elastically on time ...

. The rifting extended only into the area that would be occupied by the future central

Queen Elizabeth Islands The Queen Elizabeth Islands () are the northernmost cluster of islands in Canada's Arctic Archipelago, split between Nunavut and the Northwest Territories in Northern Canada. The Queen Elizabeth Islands contain approximately 14% of the global gl ...

and was aborted there due to interfering structural trends. In the extreme west, in the Banks Island area, extension of the Boreal Rifting Episode continued uninterrupted until the mid-Tertiary.

Eurekan Rifting Episode

The Eurekan Rifting Episode commenced in the Early Cretaceous as the Boreal Rifting Episode declined. Crustal stretching began at the south end of the rift system 130 million years ago, during which

supercontinent In geology, a supercontinent is the assembly of most or all of Earth's continent, continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", ...

Laurasia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pa ...

was in the process of breaking apart. Rifting began from the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

then propagated northwest where the Labrador Sea started opening in the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent 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 ''cre ...

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 ...

commenced in the southern Labrador Sea 75–60 million years ago, during which Greenland moved north relative to mainland North America. This northward movement gave rise to compressive forces between northern Greenland and the Arctic Archipelago, setting the stage for the Eurekan orogeny. Seafloor spreading reached the northern Labrador Sea 60–40 million years ago and Greenland moved simultaneously past

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 ...

along the

Nares Strait Nares Strait (; ) is a waterway between Ellesmere Island and Greenland that connects the northern part of Baffin Bay in the Atlantic Ocean with the Lincoln Sea in the Arctic Ocean. From south to north, the strait includes Smith Sound, Kane Basi ...

. Approximately of

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

separation occurred between Greenland and

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 ...

, producing

oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramaf ...

within Baffin Bay. With the commencement of active seafloor spreading in the

Norwegian Sea The Norwegian Sea (; ; ) is a marginal sea, grouped with either the Atlantic Ocean or the Arctic Ocean, northwest of Norway between the North Sea and the Greenland Sea, adjoining the Barents Sea to the northeast. In the southwest, it is separate ...

during the

Early Eocene In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

, the direction of seafloor spreading changed in both the Labrador Sea and Baffin Bay. Continued spreading in the Norwegian Sea eventually separated Greenland from

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

, resulting in the creation of the Greenland plate and the South Greenland triple junction. By this time spreading within Baffin Bay and the Labrador Sea had slowed and became oblique, eventually ceasing between 45 and 36 million years ago. The final phase of rifting was marked by continental extension in the mid-Tertiary. It breached the North American continent and reached the

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, ...

, resulting in the formation of the Parry and Nares submarine

rift valley A rift valley is a linear shaped lowland between several highlands or mountain ranges produced by the action of a geologic rift. Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics. The linear ...

s, the Queen Elizabeth Islands and the Queen Elizabeth Islands Subplate. This rifting lasted until the

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

or later.

The rift system today

Little seismicity takes place on the Canadian Arctic Rift System, indicating it is now a nearly inactive structure and that the entire system is travelling as a part of the North American plate. Several earthquakes occur, but their patterns indicate tectonic forces characteristic of plate margins are not acting directly within the Canadian Arctic today. As a result, there are questions as to whether the Greenland plate should still be considered a separate plate. The present seismic activity may be mainly an expression of readjustment of existing rift structures to a regional stress field associated with

post-glacial rebound Post-glacial rebound (also called isostatic rebound or crustal rebound) is the rise of land masses after the removal of the huge weight of ice sheets during the last glacial period, which had caused isostatic depression. Post-glacial rebound an ...

. The area between Greenland and Baffin Island is one of the most seismically active regions in eastern Canada. It was not known as a

seismic zone In seismology, a seismic zone or seismic belt is an area of seismicity potentially sharing a common cause. It can be referred to as an earthquake belt as well. It may also be a region on a map for which a common areal rate of seismicity is assume ...

until November 20, 1933, when an earthquake with a

surface-wave magnitude The surface wave magnitude (M_s) scale is one of the magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements of Rayleigh surface waves that travel along the uppermost layers of the Earth. This mag ...

of 7.3 occurred beneath Baffin Bay. This is the largest instrumentally recorded earthquake to have occurred along the

passive margin A passive margin is the transition between Lithosphere#Oceanic lithosphere, oceanic and Lithosphere#Continental lithosphere, continental lithosphere that is not an active plate continental margin, margin. A passive margin forms by sedimentatio ...

of North America and possibly the largest passive-margin earthquake worldwide. Coincidentally, it is also the largest north of the

Arctic Circle The Arctic Circle is one of the two polar circles, and the northernmost of the five major circle of latitude, circles of latitude as shown on maps of Earth at about 66° 34' N. Its southern counterpart is the Antarctic Circle. The Arctic Circl ...

. In spite of its size, the 1933 Baffin Bay earthquake did not result in any damage due to its offshore location combined with the sparse population of the adjacent onshore areas. Analysis of

seismogram A seismogram is a graph output by a seismograph. It is a record of the ground motion at a measuring station as a function of time. Seismograms typically record motions in three cartesian axes (x, y, and z), with the z axis perpendicular to the ...

s indicate

strike-slip fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

ing played a role in the occurrence of this earthquake. Earthquakes of magnitude 6.0 or greater have since been recorded in 1934, 1945, 1947 and 1957. A linear belt of medium-

amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of am ...

earthquakes known as the Labrador Sea Seismic Zone is coincident with the extinct spreading axis of the Mid-Labrador Ridge. Earthquakes as large as magnitude 5.0 have been recorded along this zone since 1982.

Structure

Faults

The Ungava Fault Zone is a major tectonic feature of Davis Strait separating the failed Labrador Sea and Baffin Bay spreading centres. It was associated with leaky transform motion related to the northward motion of Greenland relative to mainland North America during 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 fault zone has a length of roughly and an elongate north-northeast trend. A northern extension called the Ikermiut Fault Zone is dominated by

Late Paleocene The Thanetian is, in the International Commission on Stratigraphy, ICS Geologic timescale, the latest age (geology), age or uppermost stage (stratigraphy), stratigraphic stage of the Paleocene epoch (geology), Epoch or series (stratigraphy), Serie ...

to Early Eocene

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. I ...

s due to strike-slip movements between the Greenland and North American plates. Situated on Bathurst Island is the Southeast Bathurst Fault Zone, a north–south trending system of

normal fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

s forming a graben-like structure. It originally formed during the Boreal Rifting Episode, but was reactivated during a period of regional uplift and compression brought on by the Eurekan Rifting Episode. The South Cape Fault Zone to the northeast is a major east–west trending fault extending throughout much of the length of Jones Sound. It cuts across the

peninsula A peninsula is a landform that extends from a mainland and is only connected to land on one side. Peninsulas exist on each continent. The largest peninsula in the world is the Arabian Peninsula. Etymology The word ''peninsula'' derives , . T ...

s of southern Ellesmere Island. Central atlantic

Extending several hundred kilometres through Crozier Strait is the Crozier Strait Fault Zone. It lies within a north-trending

anticline In structural geology, an anticline is a type of Fold (geology), fold that is an arch-like shape and has its oldest Bed (geology), beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex curve, c ...

of the Cornwallis Fold Belt and appears to contain a lowered

fault block Fault blocks are very large blocks of rock, sometimes hundreds of kilometres in extent, created by Tectonics, tectonic and localized stresses in Crust (geology), Earth's crust. Large areas of bedrock are broken up into blocks by Fault (geology) ...

. Bathymetric data suggest it is a possible graben structure with steep, linear, north–south margins that formed during the Eurekan Rifting Episode. The faults forming the supposed graben appear to have been guided in part by the structure of the Cornwallis Fold Belt, but probably were controlled ultimately by trends in the

Precambrian The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, 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 t ...

crystalline basement. The Kaltag Fault is a northeast trending structure extending along the

continental margin A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental marg ...

northwest of the Queen Elizabeth Islands. It forms a boundary between the Canadian Arctic Rift System and other rifted structures to the northwest. The Kaltag acted as a

transform fault A transform fault or transform boundary, is a fault (geology), fault along a plate boundary where the motion (physics), motion is predominantly Horizontal plane, horizontal. It ends abruptly where it connects to another plate boundary, either an ...

with intermittent pulses of both extension and strike-slip displacement during three time intervals. Tectonism during the first time interval from

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...

was coeval with an early stage of the Boreal Rifting Episode. This was followed by a second time interval of tectonism from the latest Cretaceous to early Tertiary when the Boreal Rifting Episode was active and the Eurekan Rifting Episode was in an early stage of development. A third and final time interval of tectonism during the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58 Trending along the north side of Lancaster Sound is a major steeply dipping normal fault called the Parry Channel Fault. As much as of vertical displacement took place along this fault during the Eurekan Rifting Episode. The Northern Baffin and Admiralty faults trend along the south side of Lancaster Sound, the former of which is dominant. It extends from Admiralty Inlet in the west then trends eastward along the north coasts of Baffin and Bylot islands to Baffin Bay where it possibly connects with other rift structures. The Prince Regent Fault is a major fault that trends along the east coast of Somerset Island. It forms the southwestern boundary of the Lancaster Aulacogen and is west of the inferred Brodeur Peninsula Fault, which presumably trends along the northwest coast of Baffin Island's Brodeur Peninsula. The main evidence of the Prince Regent Fault is the straightness of Somerset Island's east coast, but the southern end of this fault also connects with a lineament that is a known fault on land. A series of

fracture zone A fracture zone is a linear feature on the ocean floor—often hundreds, even thousands of kilometers long—resulting from the action of offset mid-ocean ridge axis segments. They are a consequence of plate tectonics. Lithospheric plates on eit ...

s are present in the Labrador Sea. These include the northeasterly trending Julian Haab and Cartwright fracture zones, as well as the north-northeasterly trending Hudson, Snorri, Minna and Leif fracture zones. The change in trend corresponds with a more northerly spreading direction of the Mid-Labrador Ridge during the Eocene.

Basins

Sverdrup Basin is a Carboniferous rift basin in the Queen Elizabeth Islands that formed during the Boreal Rifting Episode. It has a northeast–southwest axis of about and a width of up to , encompassing an area of . Baffin Basin is a north-northwest trending geologic structure underlying much of central Baffin Bay. It formed as a result of seafloor spreading during the Tertiary opening of Baffin Bay around 56 million years ago. The northern extent of the basin is bounded by the Jones Sound, Lancaster Sound and Nares Strait aquatic sills below sea level while its southern extent is delimited by the Davis Strait aquatic sill roughly below sea level. Baffin Basin cross section

Lancaster Basin is a half-graben forming the eastern mouth of the larger Parry Submarine Rift Valley. It contains several block faulted structures and is filled with Mesozoic, Tertiary and

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

sediments. Barrow Basin is a prominent topographic depression and, like Lancaster Basin to the east, represents a half-graben of the Parry Submarine Rift Valley bounded on the north by high-angle normal faults. Non-marine Tertiary sediments up to approximately thick exist in the Barrow Basin. Lady Franklin Basin is one of the deepest basins offshore West Greenland. It was established during Early Cretaceous rifting and lies within a fault zone delimiting the northern end of the Labrador Sea. A thick

succession Succession is the act or process of following in order or sequence. Governance and politics *Order of succession, in politics, the ascension to power by one ruler, official, or monarch after the death, resignation, or removal from office of ...

of Cretaceous and Cenozoic sediments occupies the Lady Franklin Basin. Labrador Basin is an immense structural

trough Trough may refer to: In science * Trough (geology), a long depression less steep than a trench * Trough (meteorology), an elongated region of low atmospheric pressure * Trough (physics), the lowest point on a wave * Trough level (medicine), the l ...

between Greenland and

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 ...

that formed as a result of seafloor spreading from the Late Cretaceous to the

Late Eocene The Priabonian is, in the International Commission on Stratigraphy, ICS's geologic timescale, the latest age (geology), age or the upper stage (stratigraphy), stage of the Eocene epoch (geology), Epoch or series (stratigraphy), Series. It spans ...

. Its seabed consists of a slightly southeast trending plain that ranges below sea level. In the southeastern part of the basin are a series of

seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly a ...

s that gradually decrease in height to the northwest.

Geophysical Geophysics () is a subject of natural science concerned with the physical processes and properties of Earth and its surrounding space environment, and the use of quantitative methods for their analysis. Geophysicists conduct investigations acros ...

data suggest they are the tops of the buried Mid-Labrador Ridge, which in the southeast is conjugated with the Mid-Atlantic Ridge. The

P wave A P wave (primary wave or pressure wave) is one of the two main types of elastic body waves, called seismic waves in seismology. P waves travel faster than other seismic waves and hence are the first signal from an earthquake to arrive at any ...

velocity structure under the Labrador Basin resembles that of the Mid-Atlantic Ridge, supporting the interpretation that the Canadian Arctic Rift System is a branch of that ridge. A characteristic feature of the Labrador Basin is the Northwest Atlantic Mid-Ocean Channel. This is a

turbidity current A turbidity current is most typically an Ocean current, underwater current of usually rapidly moving, sediment-laden water moving down a slope; although current research (2018) indicates that water-saturated sediment may be the primary actor in ...

system of channels that extend southward along the axis of the basin and then into the Newfoundland Basin. Situated on Bylot Island and northern Baffin Island are a series of grabens and horsts that constitute the North Baffin Rift Zone. These structures formed intermittently from late

Proterozoic The Proterozoic ( ) is the third of the four geologic eons of Earth's history, spanning the time interval from 2500 to 538.8 Mya, and is the longest eon of Earth's geologic time scale. It is preceded by the Archean and followed by the Phanerozo ...

to early Tertiary time, with the latest period of reactivation having taken place during the Eurekan Rifting Episode.

Igneous petrology

Like many rifts worldwide, the Canadian Arctic Rift System was a site of magmatic activity during active tectonism. This activity was associated with seafloor spreading in the Baffin and Labrador basins as well as continental rifting within the Arctic Archipelago. Several episodes of intrusive and

extrusive Extrusive rock refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff. In contr ...

activity took place from the Paleozoic to Cenozoic with the emplacement of dikes, sills,

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 and

pyroclastic rock Pyroclastic rocks are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroclasts. Pyroclastic rocks are a type of volcaniclastic deposit, which are deposit ...

s. The Sverdrup Basin Magmatic Province in the east-central Sverdrup Basin is an Early Cretaceous to Paleogene

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 ...

. It consists of pyroclastic deposits, thin lava flows,

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 (geolo ...

s and central volcanoes, as well as hypabyssal sills and dikes.

Argon–argon dating Argon–argon (or 40Ar/39Ar) dating is a radiometric dating method invented to supersede Potassium-argon dating, potassiumargon (K/Ar) dating in accuracy. The older method required splitting samples into two for separate potassium and argon measur ...

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 ...

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 ...

s from the province suggests mafic magmatism peaked during two time intervals. The first time interval between 127 and 129 million years ago was characterized by the widespread intrusion of sills and dikes. Flood basalt

volcanism Volcanism, vulcanism, volcanicity, or volcanic activity is the phenomenon where solids, liquids, gases, and their mixtures erupt to the surface of a solid-surface astronomical body such as a planet or a moon. It is caused by the presence of a he ...

during the second time interval between 92 and 98 million years ago was coeval with the development of the proto-Arctic Ocean. Sills and flood basalts of the Sverdrup Basin Magmatic Province are well-exposed in the Princess Margaret Range, a north–south trending

mountain range A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have aris ...

extending across the length of Axel Heiberg Island.

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 flows occur in the Isachsen and Strand Fiord formations. Sills intrude the entire Mesozoic succession and are particularly abundant in the

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

s of the Blaa Mountain Group. A volcanic suite of Eocene age occurs in the Freemans Cove area of Bathurst Island. It is confined to the Southeast Bathurst Fault Zone, consisting of sills, dikes, agglomeratic vents and small plugs. Most of the suite consists of nephelinite or larnite-

normative Normativity is the phenomenon in human societies of designating some actions or outcomes as good, desirable, or permissible, and others as bad, undesirable, or impermissible. A Norm (philosophy), norm in this sense means a standard for evaluatin ...

nephelinites and

basanite Basanite () is an igneous, volcanic ( extrusive) rock with aphanitic to porphyritic texture. It is composed mostly of feldspathoids, pyroxenes, olivine, and calcic plagioclase and forms from magma low in silica and enriched in alkali metal ox ...

s, with rarer

olivine The mineral olivine () is a magnesium iron Silicate minerals, silicate with the chemical formula . It is a type of Nesosilicates, nesosilicate or orthosilicate. The primary component of the Earth's upper mantle (Earth), upper mantle, it is a com ...

melilite nephelinite, phonolite and tholeiitic and

alkali In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The a ...

basalt rocks. Extensive erosion has removed all traces of lava flows but lava fragments,

bombs A bomb is an explosive weapon that uses the Exothermic process, exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy. Detonations inflict damage principally through ground- and atmosphere-tra ...

and

scoria Scoria or cinder is a pyroclastic, highly vesicular, dark-colored volcanic rock formed by ejection from a volcano as a molten blob and cooled in the air to form discrete grains called clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackso ...

occur as clasts within the agglomerates. Erosional remnants of sills form the prominent

mesa A mesa is an isolated, flat-topped elevation, ridge, or hill, bounded from all sides by steep escarpments and standing distinctly above a surrounding plain. Mesas consist of flat-lying soft sedimentary rocks, such as shales, capped by a ...

s of North Mesa, Peaked Hill and Round Hill, the latter two of which consist of tholeiitic basalt and alkali basalt respectively. A major episode of Tertiary magmatism related to the opening of Baffin Bay emplaced mafic intrusions and volcanic rocks on Baffin Island and in West Greenland. Basaltic

breccia Breccia ( , ; ) is a rock composed of large angular broken fragments of minerals or Rock (geology), rocks cementation (geology), cemented together by a fine-grained matrix (geology), matrix. The word has its origins in the Italian language ...

s and lavas on Baffin Island are exposed mainly along a narrow coastal strip between Cape Dyer and Cape Searle. They have a total thickness of over and are bounded in the north by minor intrusions. The volcanic suite in West Greenland consists mainly of lava flows and occurs on Disko Island, Illorsuit Island and the

Nunavik Nunavik (; ; ) is an area in Canada which comprises the northern third of the province of Quebec, part of the Nord-du-Québec region and nearly coterminous with Kativik. Covering a land area of north of the 55th parallel, it is the homelan ...

and Nuussuaq peninsulas. A central volcano formed on Illorsuit Island with the emplacement of the Sarqâta qáqâ

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 ...

- granophyre intrusion roughly 56 million years ago. The Tertiary volcanic rocks of Baffin Island and West Greenland form part of the

North Atlantic Igneous Province The North Atlantic Igneous Province (NAIP) is a large igneous province in the North Atlantic, centered on Iceland. In the Paleogene, the province formed the Thulean Plateau, a large basaltic lava plain, which extended over at least in area and in ...

, which extends roughly eastward through

East Greenland Tunu, in Danish Østgrønland ("East Greenland"), was one of the three counties (''amter'') of Greenland until 31 December 2008. The county seat was at the main settlement, Tasiilaq. The county's population in 2005 was around 3,800. The county ...

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 ...

, 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 ...

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 ...

and

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 ...

. This large igneous province has been linked to the Iceland hotspot.

Oceanography

Extending through northern North America is a major seaway system connecting the Atlantic and Arctic oceans. This system was created by geological events of the Canadian Arctic Rift System and is still controlled by rift structures. It includes the

Northwest Passage The Northwest Passage (NWP) is the sea lane between the Atlantic and Pacific oceans through the Arctic Ocean, near the northern coast of North America via waterways through the Arctic Archipelago of Canada. The eastern route along the Arctic ...

, which cuts through the Labrador Sea, Baffin Bay, Parry Channel and other channels within and adjacent to the Arctic Archipelago. Inflow from the Atlantic Ocean and outflow from the Arctic Ocean has resulted in

ocean current An ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, sh ...

s flowing along the rifted continental margins of West Greenland, Baffin Island and Labrador.

Waterbodies

Nares Strait lies within the Nares Submarine Rift Valley between North Greenland and Ellesmere Island. It is a north-northeast trending channel connecting Baffin Bay in the south with the Arctic Ocean in the north. From south to north, the strait includes

Smith Sound Smith Sound (; ) is an Arctic sea passage between 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 ...

, Kane Basin, Kennedy Channel, Hall Basin and Robeson Channel. Parry Channel is a waterway in the Arctic Archipelago formed by the Parry Submarine Rift Valley. It consists of four waterbodies: Lancaster Sound, M'Clure Strait, Viscount Melville Sound and Barrow Strait. With a length of over , Parry Channel connects Baffin Bay in the east with

Beaufort Sea The Beaufort Sea ( ; ) is a marginal sea of the Arctic Ocean, located north of the Northwest Territories, Yukon, and Alaska, and west of the Canadian Arctic Archipelago. The sea is named after Sir Francis Beaufort, a Hydrography, hydrographer. T ...

in the west. The north and south sides of the channel are opened by a number of smaller waterways. Of these, Admiralty Inlet penetrates deep into the northwestern part of Baffin Island from the south side of Lancaster Sound. At the west end of Parry Channel, Prince of Wales Strait leads southwest from the junction of Viscount Melville Sound and M'Clure Strait into

Amundsen Gulf Amundsen Gulf is a gulf located mainly in the Inuvik Region, Northwest Territories, Canada with a small section in the Kitikmeot Region of Nunavut. It lies between Banks Island and Victoria Island (Canada), Victoria Island and the mainland. It i ...

. Jones Sound occupies a rift valley between Ellesmere Island in the north and

Devon Island Devon Island (, ) is an island in Canada and the largest desert island, uninhabited island (no permanent residents) in the world. It is located in Baffin Bay, Qikiqtaaluk Region, Nunavut, Canada. It is one of the largest members of the Arctic Ar ...

in the south. It has an east–west length of roughly and a width varying from about . Surface data and the existence of corresponding seaward-dropping fault blocks on the north coast of Devon Island and on the south coast of Ellesmere Island suggest Jones Sound may be a graben structure. Baffin Bay is a long and wide semi-enclosed sea surrounded by Ellesmere Island and Devin Island in the north, Greenland in the east and Baffin Island in the west. It is an example of a failed proto-ocean, centrally underlain by oceanic crust of the Baffin Basin which is surrounded by extended

continental crust Continental crust is the layer of igneous, metamorphic, and sedimentary rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as '' continental shelves''. This layer is sometimes called '' si ...

that varies approximately thick. Connected to the North Atlantic Ocean in the south through Davis Strait and to the Arctic Ocean in the north through Nares Strait, Jones Sound and Lancaster Sound, the ocean water in Baffin Bay is highly stratified. The surface water, of Arctic origin, is cold and fresh. Below the Arctic layer is a layer of Atlantic origin, which is warm and saline. Below the Atlantic layer are Baffin Bay Deep Water and Baffin Bay Bottom Water, both of which are cold and saline. On a net annual basis, approximately 1.7 Sv of water flows out of the Arctic Ocean through Baffin Bay, making the bay the second most important conduit between the Arctic Ocean and the rest of the world's oceans. The Labrador Sea is an arm of the North Atlantic Ocean occupying the Labrador Basin between Greenland and Labrador. It shallows and passes into Davis Strait in the north and is open to the North Atlantic Ocean in the southeast. The sea is flanked by

continental shelves A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

with banks less than deep separated by glacially eroded channels: the southern West Greenland shelf in the northeast, the Labrador shelf in the southwest and the Baffin Island shelf in the northwest. An intermediate cold water mass known as

Labrador Sea Water Labrador Sea Water is an intermediate water mass in the Labrador Sea. It is characterized by cold water, relatively low salinity compared to other intermediate water masses, and high concentrations of both oxygen and anthropogenic tracers.Pickart, ...

is formed by

convective Convection is single or multiphase fluid flow that occurs spontaneously through the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convec ...

processes in the Labrador Sea. It represents a key component of the

Atlantic Meridional Overturning Circulation The Atlantic meridional overturning circulation (AMOC) is the main ocean current system in the Atlantic Ocean.IPCC, 2021Annex VII: Glossary [Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. Masson-Delmotte, C. Méndez, S. Sem ...

, which is a major contributor to the transport and storage of heat, freshwater and other tracers in the Atlantic Ocean. Crozier Strait between Bathurst Island and Little Cornwallis Island dominates the Crozier Strait Fault Zone. It is a narrow but extremely deep body of water measuring roughly long and wide at its narrowest point. The strait, an arm of the Arctic Ocean, connects Queens Channel in the north with McDougall Sound in the south.

Prince Regent Inlet Prince Regent Inlet () is a body of water in Nunavut, Canada between the west end of Baffin Island ( Brodeur Peninsula) and Somerset Island on the west. It opens north into Lancaster Sound and to the south merges into the Gulf of Boothia. The A ...

occupies a southern branch of the Lancaster Aulacogen between Baffin Island and Somerset Island. It is a deep waterbody measuring wide at its northern end and over at its southern end. The inlet connects Lancaster Sound in the north with the Gulf of Boothia in the south. Davis Strait is a narrow and relatively shallow area connecting Baffin Bay in the north with the Labrador Sea in the south. It varies in width from to over , with the shallowest waters found along the Davis Sill. This aquatic sill is a submarine ridge below sea level extending from Baffin Island in the west to Greenland in the east. Unlike Baffin Bay and the Labrador Sea, Davis Strait is bounded by

volcanic passive margin Volcanic passive margins (VPM) and Non-Volcanic Passive Margins, non-volcanic passive margins are the two forms of transitional crust (geology), crust that lie beneath passive margin, passive continental margins that occur on Earth as the result of ...

s. Paleogene volcanic rocks are exposed on both sides of the strait: the Disko- Svartenhuk area of West Greenland in the east and near Cape Dyer on Baffin Island in the west.

Hudson Strait Hudson Strait () in Nunavut links the Atlantic Ocean and the Labrador Sea to Hudson Bay in Canada. This strait lies between Baffin Island and Nunavik, with its eastern entrance marked by Cape Chidley in Newfoundland and Labrador and Nunavut ...

– Evans Strait– Foxe Channel is a waterbody connecting

Hudson Bay Hudson Bay, sometimes called Hudson's Bay (usually historically), is a large body of Saline water, saltwater in northeastern Canada with a surface area of . It is located north of Ontario, west of Quebec, northeast of Manitoba, and southeast o ...

and Foxe Basin in the west-northwest with the Labrador Sea in the south-southeast. It comprises several half-grabens that may have developed during the initial stages of extension in the Labrador Sea. They form sub-basins that are controlled by steeply-dipping normal faults, which predominately dip toward the north.

Ocean currents

West Greenland Current originates from the movement of Atlantic water flowing around the southern point of Greenland caused by the

and Irminger currents. It transports freshwater into the Labrador Sea, influencing the formation of Labrador Sea Water. The current flows north along the coast of West Greenland, steadily losing volume through low-velocity westward branching as water is fed into the anticyclonic circulatory system of the Labrador Sea. Just south of Davis Sill, a major westward branching occurs, the remainder of the West Greenland Current continuing across Davis Sill into Baffin Bay where it eventually peters out. Baffin Island Current consists mainly of relatively fresh Arctic waters that enter northern Baffin Bay through Nares Strait, Jones Sound and Lancaster Sound. First detectable off Devon Island, the Baffin Island Current flows south along the length of western Baffin Bay and the western half of Davis Strait. It then divides at Hudson Strait; one branch sets westward along the northern half of Hudson Strait whereas another branch continues southward towards the Labrador Sea. Labrador Current is a continuation of the West Greenland and Baffin Island currents. It flows down the west side of the Labrador Sea then back into the North Atlantic Ocean where it continues southward along the east coast of

Newfoundland Newfoundland and Labrador is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region of Labrador, having a total size of . As of 2025 the population ...

and completely floods the northeastern part of the

Grand Banks The Grand Banks of Newfoundland are a series of underwater plateaus south-east of the island of Newfoundland on the North American continental shelf. The Grand Banks are one of the world's richest fishing grounds, supporting Atlantic cod, swordfi ...

. Here it divides; one branch sets southwestward along the

Avalon Peninsula The Avalon Peninsula () is a large peninsula that makes up the southeast portion of the island of Newfoundland in Canada. It is in size. The peninsula is home to 270,348 people, about 52% of the province's population, according to the 2016 Ca ...

while another and usually major branch continues southward down the east side of the Grand Banks.

References

{{North American faults Aulacogens Mid-Atlantic Ridge Seismic faults of Canada Geology of Nunavut Geology of Newfoundland and Labrador Geology of the Northwest Territories Geology of Greenland Paleozoic rifts and grabens Mesozoic rifts and grabens Cenozoic rifts and grabens Oceanic basins of the Atlantic Ocean Oceanic basins of the Arctic Ocean Landforms of Baffin Bay Labrador Sea Queen Elizabeth Islands