Greenland Plate
Encyclopedia
The Greenland Plate is a supposed tectonic plate bounded to the west by Nares Strait
, a probable transform fault, on the southwest by the Ungava transform underlying Davis Strait
, on the southeast by the Mid-Atlantic Ridge
, and the northeast by the Gakkel Ridge
, with its northwest border is still being explored (Danish scientists hope that the plate extends along the Lomonosov Ridge
). The Greenland
craton
is made up of some of the oldest rocks on the face of the earth. The Isua greenstone belt
in southwestern Greenland contains the oldest known rocks on Earth dated at 3.7-3.8 Billion years old.
The Precambrian basement of Greenland formed an integral part of the Laurentian Shield that is at the core of the North American continent
. Greenland was formed in two rift
ing stages from the main body of North America. The first, during the Cretaceous
period formed Baffin Bay
. Baffin Bay is the northwestern extension and terminus of the North Atlantic-Labrador Sea rift system that started forming 140 million years ago in the Early Cretaceous period. The Labrador Sea
started opening 69 million years ago during the Maastrichtian
period but sea-floor spreading appears to have ceased by the Oligocene
period 30-35 million years ago. Correlations between tectonic units in Canada
and Greenland have been proposed, however, the pre-drift fit of Greenland to Canada is still not accurately known.
Since the closure of the North Atlantic-Labrador Sea rift, Greenland has moved roughly in conjunction with North America; thus, there are questions as to whether the Greenland Plate should be still considered a separate plate at all. That said, the area between Greenland and Baffin Island is extremely seismically active, being the epicenter of many earthquakes including a 7.3 magnitude earthquake in 1933
. To date no one has been able to correlate the seismicity with particular geological structures or geophysical anomalies. It has been suggested that seismicity in the region is related to the stresses associated with post-glacial rebound
.
Nares Strait
Nares Strait is a waterway between Ellesmere Island and Greenland that is the northern part of Baffin Bay where it meets the Lincoln Sea. From south to north, the strait includes Smith Sound, Kane Basin, Kennedy Channel, Hall Basin and Robeson Channel...
, a probable transform fault, on the southwest by the Ungava transform underlying Davis Strait
Davis Strait
Davis Strait is a northern arm of the Labrador Sea. It lies between mid-western Greenland and Nunavut, Canada's Baffin Island. The strait was named for the English explorer John Davis , who explored the area while seeking a Northwest Passage....
, on the southeast by the Mid-Atlantic Ridge
Mid-Atlantic Ridge
The Mid-Atlantic Ridge is a mid-ocean ridge, a divergent tectonic plate boundary located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. It separates the Eurasian Plate and North American Plate in the North Atlantic, and the African Plate from the South...
, and the northeast by the Gakkel Ridge
Gakkel Ridge
The Gakkel Ridge is a mid-oceanic ridge, a divergent tectonic plate boundary between the North American Plate and the Eurasian Plate. It is located in the Arctic Ocean between Greenland and Siberia, and has a length of about 1,800 kilometers...
, with its northwest border is still being explored (Danish scientists hope that the plate extends along the Lomonosov Ridge
Lomonosov Ridge
The Lomonosov Ridge is an unusual underwater ridge of continental crust in the Arctic Ocean. It spans 1800 km from the New Siberian Islands, as it is part of Eurasia, over the central part of the ocean to Ellesmere Island of the Canadian Arctic Archipelago. The width of the Lomonosov Ridge varies...
). The Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
craton
Craton
A craton is an old and stable part of the continental lithosphere. Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates. They are characteristically composed of ancient crystalline basement rock, which may be covered by...
is made up of some of the oldest rocks on the face of the earth. The Isua greenstone belt
Isua greenstone belt
The Isua Greenstone Belt is an Archean greenstone belt in southwestern Greenland. The belt is aged between 3.7 and 3.8 Ga, making it among the oldest rock in the world. The belt contains variably metamorphosed mafic volcanic and sedimentary rocks...
in southwestern Greenland contains the oldest known rocks on Earth dated at 3.7-3.8 Billion years old.
The Precambrian basement of Greenland formed an integral part of the Laurentian Shield that is at the core of the North American continent
North American Plate
The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Japan and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust...
. Greenland was formed in two rift
Rift
In geology, a rift or chasm is a place where the Earth's crust and lithosphere are being pulled apart and is an example of extensional tectonics....
ing stages from the main body of North America. The first, during the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
period formed Baffin Bay
Baffin Bay
Baffin Bay , located between Baffin Island and the southwest coast of Greenland, is a marginal sea of the North Atlantic Ocean. It is connected to the Atlantic via Davis Strait and the Labrador Sea...
. Baffin Bay is the northwestern extension and terminus of the North Atlantic-Labrador Sea rift system that started forming 140 million years ago in the Early Cretaceous period. The Labrador Sea
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 shelves to the southwest, northwest, and northeast. It connects to the north with Baffin Bay through the Davis Strait...
started opening 69 million years ago during the Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
period but sea-floor spreading appears to have ceased by the Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
period 30-35 million years ago. Correlations between tectonic units in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
and Greenland have been proposed, however, the pre-drift fit of Greenland to Canada is still not accurately known.
Since the closure of the North Atlantic-Labrador Sea rift, Greenland has moved roughly in conjunction with North America; thus, there are questions as to whether the Greenland Plate should be still considered a separate plate at all. That said, the area between Greenland and Baffin Island is extremely seismically active, being the epicenter of many earthquakes including a 7.3 magnitude earthquake in 1933
1933 Baffin Bay earthquake
The 1933 Baffin Bay earthquake was a 7.3 magnitude earthquake that struck Greenland and Nunavut, and Canada at 6:21 p.m. ET on Sunday, November 20, 1933....
. To date no one has been able to correlate the seismicity with particular geological structures or geophysical anomalies. It has been suggested that seismicity in the region is related to the stresses associated with post-glacial rebound
Post-glacial rebound
Post-glacial rebound is the rise of land masses that were depressed by the huge weight of ice sheets during the last glacial period, through a process known as isostasy...
.