- Skaergaard intrusion
The Skaergaard
intrusion is a layeredgabbro complex in EastGreenland , located at coord|68.1683|N|31.7169|W|.Discovered by
Lawrence Wager [Brooks, CK (2005) "The Skaergaard intrusion: from icon to precious metal deposit". Geology Today, v. 21, p. 218-221.] in1931 during the BritishArctic Air Route Expedition led byGino Watkins , the intrusion has been important to the development of key concepts in igneouspetrology , includingmagma differentiation [Wager, LR, Deer, WA (1939) "Geological investigations in East Greenland Part III. Thepetrology of the Skaergaard Intrusion, Kangerdlugssuaq". Meddelselser om Grønland, v. 105, 346 pp.] [McBirney, AR (1975) "Differentiation of the Skaergaard intrusion". Nature, v. 253, p. 691-694.] and the development of layering. [Wager, LR, Brown, GM (1967) Layered Igneous Rocks. WH Freeman,San Francisco , 588 pp.] [McBirney, AR, Noyes, RM (1975) "Crystallization and Layering of the Skaergaard Intrusion". Journal of Petrology, v. 20, p. 487-554.] The Skaergaard intrusion formed when tholeiitic magma was emplaced about 55 million years ago, [Brooks, CK, Gleadow, AJW (1977) "A fission-track age for the Skaergaard intrusion and the age of the East Greenland basalts". Geology, v. 5, p. 539-540.] during the initial opening of theNorth Atlantic Ocean . The body represents essentially a single pulse of magma, which crystallized from the bottom upward and the top downward. The intrusion is characterized by exceptionally well-developed layering defined by variations in the abundance of crystallizingolivine ,pyroxene ,plagioclase andmagnetite . The Skaergaard is perhaps the simplest and smallest of a group of gabbroic complexes of similar age that occur along the central coast of East Greenland, which together with coeval flood basalts are part of the North AtlanticLarge igneous province .References
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