A textural record of solidification and cooling in the Skaergaard Intrusion, East Greenland

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doi: 10.1093/petrology/egm064
Authors:Holness, Marian B.; Tegner, Christian; Nielsen, Troels F. D.; Stripp, Gemma; Morse, Stearns A.
Author Affiliations:Primary:
University of Cambridge, Department of Earth Sciences, Cambridge, United Kingdom
University of Aarhus, Denmark
Geological Survey of Denmark and Greenland, Denmark
University of Massachusetts, United States
Volume Title:Journal of Petrology
Source:Journal of Petrology, 48(12), p.2359-2377. Publisher: Oxford University Press, Oxford, United Kingdom. ISSN: 0022-3530
Publication Date:2007
Note:In English. 98 refs.; illus., incl. 2 plates, 3 tables, geol. sketch map
Summary:The clinopyroxene-plagioclase-plagioclase dihedral angle, Θcpp, in gabbroic cumulates records the time-integrated thermal history in the sub-solidus and provides a measure of textural maturity. Variations in Θcpp through the Layered Series of the Skaergaard intrusion, East Greenland, demonstrate that the onset of crystallization of clinopyroxene (within LZa), Fe-Ti oxides (at the base of LZc) and apatite (at the base of UZb) as liquidus phases in the bulk magma is recorded by a stepwise increase in textural maturity, related to an increase in the contribution of latent heat to the total heat loss to the surroundings and a reduction in the specific cooling rate at the crystallization front of the intrusion. The onset of both liquidus Fe-Ti oxide and apatite crystallization is marked by a transient increase in textural maturity, probably linked to overstepping before nucleation. Textural maturation at pyroxene-plagioclase-plagioclase triple junctions effectively ceases in the uppermost parts of the Layered Series as a result of the entire pluton cooling below the closure temperature for dihedral angle change, which is ≤1075°C. Solidification of the Layered Series of the Skaergaard intrusion occurred via the upwards propagation of a mush zone only a few metres thick.
Subsections:Igneous petrology
Subjects:Asthenosphere; Cooling; Crystallization; Cumulates; Intrusions; Layered intrusions; Magmas; Mantle; Partial melting; Textures; Arctic region; East Greenland; Greenland; Skaergaard Intrusion
Coordinates:N680800 N681300 W0313500 W0314500
Abstract Numbers:07M/4691
Record ID:2009021658
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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