Skaergaard intrusion

The Skaergaard intrusion is a layered body of solidified basaltic magma in East Greenland, famous for preserving a systematic sequence of mineral layers formed as its magma crystallized and differentiated.

Fractional crystallization: A process in which crystals are separated from cooling magma, changing the composition of the remaining melt. The intrusion’s changing mineral assemblages are a classic record of this process.
East Greenland: The eastern coastal region of Greenland, including extensive Paleogene igneous rocks. The intrusion is exposed in this region, where its geology can be studied directly.
Lawrence R. Wager: A British geologist who studied layered igneous rocks and led early investigations of the Skaergaard intrusion. His fieldwork and interpretations made the intrusion central to modern studies of magma differentiation.
Magma chamber: A subsurface reservoir or body of molten or partly molten rock beneath a volcano or within the crust. Its layered rocks preserve evidence of crystallization within a large magma body.
Gravitational crystal settling: A model in which crystals sink through magma under gravity and accumulate on the floor of an intrusion. It explains layers through crystal movement, but does not alone account for every Skaergaard feature.
Layered intrusion: A large igneous body with repeated layers of minerals formed by crystallization and accumulation from magma. The Skaergaard is a benchmark example of this broader class of igneous body.
North Atlantic Igneous Province: A broad Paleogene region of volcanic and intrusive rocks around the North Atlantic. Skaergaard formed during the magmatic episode that produced this province.
W. A. Deer: A British mineralogist and petrologist who collaborated with Lawrence Wager on the Skaergaard intrusion. Deer’s mineralogical work helped document the intrusion’s systematic changes in rock composition.
Crystal settling: The downward movement of crystals through magma under gravity. Settling has been proposed as one way to concentrate minerals into Skaergaard’s layers.
Magma mixing: The blending of two or more magmas with different compositions or temperatures. Mixing can change magma composition, unlike the fractionation model emphasized by Skaergaard’s sequence.

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