The Jan Mayen Microcontinent is a fragment of

continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic 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 '' sial'' be ...

within the

oceanic Oceanic may refer to: *Of or relating to the ocean *Of or relating to Oceania **Oceanic climate **Oceanic languages **Oceanic person or people, also called "Pacific Islander(s)" Places * Oceanic, British Columbia, a settlement on Smith Island, ...

part of the western

Eurasian Plate The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and ...

lying northeast of

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 s ...

. At the onset of separation between the

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 i ...

and Eurasian plates 55 million years ago, it formed part of the eastern margin of the Greenland Plate. Propagation of a new

spreading center A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a diver ...

from the

Reykjanes Ridge The Mid-Atlantic Ridge is a mid-ocean ridge (a divergent or constructive plate boundary) located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North Am ...

separated this microcontinent from the Greenland Plate. For a short period it formed a microplate, until the

Aegir Ridge The Aegir Ridge is an extinct segment of the Mid-Atlantic Ridge in the far-northern Atlantic Ocean. It marks the initial break-up boundary between Greenland and Norway, along which seafloor spreading was initiated at the beginning of the Eocene ep ...

became inactive, after which it formed part of the Eurasian Plate. The island of

Jan Mayen Jan Mayen () is a Norwegian volcanic island in the Arctic Ocean with no permanent population. It is long (southwest-northeast) and in area, partly covered by glaciers (an area of around the Beerenberg volcano). It has two parts: larger ...

is a much younger feature, formed of

volcanic rock Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic ...

, built up at the northernmost tip of the microcontinent.

Extent

The microcontinent extends about 500 km southwards from the Jan Mayen

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 ...

. It is up to 160 km wide. The Jan Mayen Ridge separates the

Norwegian Sea The Norwegian Sea ( no, Norskehavet; is, Noregshaf; fo, Norskahavið) 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 Norway Basin) from the Greenland Sea.C.Michael Hogan. 2011. Norwegian Sea. Eds. P.Saundry & C.J.Cleveland. Encyclopedia of Earth. National Council for Science and the Environment (U.S.) Washington DC

Identification

The microcontinent was identified originally on the basis of being a bathymetric high, a positive

free-air gravity anomaly In geophysics, the free-air gravity anomaly, often simply called the free-air anomaly, is the measured gravity anomaly after a free-air correction is applied to account for the elevation at which a measurement is made. It does so by adjusting these ...

and due to the lack of

magnetic anomalies In geophysics, a magnetic anomaly is a local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying ...

, all indicating that it consisted of continental crust. This interpretation has been confirmed using wide-angle

seismic reflection Reflection seismology (or seismic reflection) is a method of exploration geophysics that uses the principles of seismology to estimate the properties of the Earth's subsurface from reflection (physics), reflected seismic waves. The method require ...

and

refraction In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenome ...

data, coupled with standard normal incidence seismic reflection data.

Make-up

The microcontinent consists of the prominent bathymetric high, the Jan Mayen Ridge and several subsidiary ridges and intervening basins towards the south and west. Investigations using seismic reflection and refraction data have identified two passive margin sequences on the two sides of the microcontinent. Faults mapped on seismic reflection data are roughly N-S trending in the northern part becoming SW-NE trending to the south. The crustal thickness reaches a maximum of 16 km on the eastern side of the main ridge.

History

At the time of the initial break-up along the North Atlantic margin (

in this area), the Jan Mayen Microcontinent formed part of the

passive margin A passive margin is the transition between oceanic and continental lithosphere that is not an active plate margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Continental rifting cre ...

developed along the East Greenland margin. Towards the end of the Eocene period, at about the time marked by chron 17 ( Middle to

Late Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "d ...

) a new spreading centre began to propagate northeastwards from the Reykjanes Ridge, forming the

Kolbeinsey Ridge The Kolbeinsey Ridge is a segment of the Mid-Atlantic Ridge located to the north of Iceland in the Arctic Ocean. It is bounded to the south by the Tjörnes Fracture Zone, which connects the submarine ridge to the on-shore Northern Volcanic Zone ri ...

. During the period when both the Kolbeinsey and Aegir ridges were active, the microcontinent underwent a 30°–50° anti-clockwise rotation. This was caused by the northeastward propagation of the Kolbeinsey Ridge, with simultaneous reduction in the rate of spreading at the southwestern end of the Aegir Ridge. An alternative but challenged model involves no rotation but the development of several short-lived fracture zones cutting through the microcontinent. With both ridges active the microcontinent was also temporarily a microplate. The Kolbeinsey Ridge reached the Jan Mayen Fracture Zone and therefore linked up to the Mohns Ridge, at about chron 6 (

Late Oligocene The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/ Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage ...

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 ...

). At this time activity on the Aegir Ridge died away and the microcontinent became part of the Eurasian Plate. The northern end of the microcontinent was affected by renewed displacement on the Jan Mayen Fracture Zone. The volcanic island of Jan Mayen only formed in the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

, possibly related to a hotspot, known as the

Jan Mayen hotspot The Jan Mayen hotspot is a proposed volcanic hotspot responsible for the volcanic activity that has formed the island of Jan Mayen in the northern Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an ...

, at the triple junction at the end of the Mohns Ridge.

Economic resources

The area around the microcontinent has recently become open for licensing for

hydrocarbon exploration Hydrocarbon exploration (or oil and gas exploration) is the search by petroleum geologists and geophysicists for deposits of hydrocarbons, particularly petroleum and natural gas, in the Earth using petroleum geology. Exploration methods Vis ...

. Licenses in the southern part, known as the northern Dreki area, have been offered by the National Energy Authority for the Icelandic government and the northern area is being assessed for future petroleum activity by the

Norwegian Petroleum Directorate The Norwegian Petroleum Directorate ( no, Oljedirektoratet) or OD is a Norwegian government agency responsible for the regulation of the petroleum resources on the Norwegian continental shelf. Based in Stavanger, its mission is to ensure that the ...

References

{{coord, 69.6, -8.2, display=title Geography of Jan Mayen Geography of Norway Geology of the Atlantic Ocean Continental fragments