Greenland Plate
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,[1][2] 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[3]). The Greenland craton is made up of some of the oldest rocks on Earth. The Isua greenstone belt in southwestern Greenland contains the oldest known rocks on Earth dated at 3.7–3.8 billion years old.[4]
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 rifting 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.[5] The Labrador Sea started opening 69 million years ago[6] during the Maastrichtian period but sea-floor spreading appears to have ceased by the Oligocene period 30–35 million years ago.[7] Correlations between tectonic units in Canada and Greenland have been proposed,[8] however, the pre-drift fit of Greenland to Canada is still not accurately known.[9]
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.[10][11] 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.[12][13]
See also
References
- ↑
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- ↑ Denmark hopes to claim North Pole BBC News, 5 October 2004. Accessed 10 November 2006.
- ↑ Appel, Peter W.U., Hugh R. Rollinson, and Jacques L.R. Touret. (2001) "Remnants of an Early Archaean (>3.75 Ga) sea-floor, hydrothermal system in the Isua Greenstone Belt." Precambrian Research, Vol. 112, Issues 1–2, 15 November, pp. 27–49.
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- ↑ Hoffman, P.F. 1989: Precambrian geology and tectonic history ofNorth America. In: Bally, A.W. & Palmer, A.R. (eds): The geology of North America, 447–512. Boulder,Colorado: Geological Society of America.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Chadwick, B. & Garde, A.A. 1996: Palaeoproterozoic obliqueplate convergence in South Greenland: a reappraisal of theKetilidian Orogen. In: Brewer, T.S. (ed.): Precambrian crustalevolution in the North Atlantic region. Geological SocietySpecial Publication (London) 112, 179–196}
- ↑ Peter A. Ziegler (1990) Geological atlas of Western and Central Europe. London. Geological Society. p. 125. ISBN 978-90-6644-125-5
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