New insights from field observations of the Younger giant dyke complex and mafic lamprophyres of the gardar province on Tuttutooq island, South Greenland

• Published in: GEUS Bulletin
• Main Authors: Koopmans, Lot, Webster, Robert A., Changleng, Rory, Mathieson, Lucy, Murphy, Alasdair J., Finch, Adrian A., McCarthy, William
• Other Authors: University of St Andrews. School of Earth & Environmental Sciences, University of St Andrews. Scottish Oceans Institute, University of St Andrews. St Andrews Isotope Geochemistry
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Gardar Province; Lamprophyre; Magma chamber; Rift magmatism; Younger giant dyke complex; GE Environmental Sciences; QE Geology; Geology; NDAS; GE; QE; Courtauld; Greenland; Tuttutooq; Scott Polar Research Institute; Geological Survey of Denmark and Greenland Bulletin
• Online Access: http://hdl.handle.net/10023/23544; https://doi.org/10.34194/geusb.v47.6526; https://geusbulletin.org/index.php/geusb/article/view/6526/14176

LK, RW, RC, LM and AM received funding from the Mining Institute of Scotland, Institute of Materials, Minerals and Mining, the Edinburgh Geological Society, the Augustine Courtauld Trust and the Scott Polar Research Institute. LK received funding from the Society of Economic Geology Hickok-Radford Fund. The Gardar Province of south Greenland is defined by the products of alkaline igneous magmatism during the Mesoproterozoic. The most laterally extensive Gardar intrusions are a series of giant dyke complexes best exposed on the Tuttutooq archipelago. We present new field observations and a geological map of north-east Tuttutooq island that provide fresh insights into the temporal evolution of the Younger giant dyke complex and two associated ultramafic lamprophyres. Our data demonstrate that distinctive crystallisation regimes occurred in different sectors of the dyke complex, leading to the formation of marginal gabbros and ovoid pod-like domains displaying lamination, modal layering and/or more evolved differentiates. We infer that at least two pulses of magma contributed to the formation of the Younger giant dyke complex. In addition, the relative ages of two ultramafic lamprophyre diatremes are constrained and attributed to two distinct phases of rifting in the Gardar Province. Publisher PDF Peer reviewed