Geochronology of the Skjoldungen Alkaline province, South-East Greenland

Thomas Find Kokfelt, Kristine Thrane, Tomas Næraa, Martin Bromann Klausen, Christian Tegner

Publikation: Bog/rapportRapport (offentligt tilgængelig)


This geochronological report is based on samples that were collected during field work in 2011 and 2012 in the Skjoldungen region between c. 63 and 63º40 ́N in South East Greenland. The work was carried out within the framework of the “SEGMENT” project – a joint project between the National Geological Survey of Denmark and Greenland and The Ministry of Mineral Resources (MMR) in Greenland. The overall target of the SEGMENT project was to assess the mineral potential of South East Greenland through new field work and to do follow-up scientific research in the area. A number of reports (Klausen and Kokfelt, 2014), BSc and M.Sc. theses (Greeff, 2012; Grobbelaar, 2012; Árting, 2013; Tusch, 2013; Maarupgaard, 2015; Geldenhuys, 2015) and international research papers (Kolb et al. 2013; Bagas et al. 2013; Berger et al. 2014; Thrane and Keulen, 2015) have come out covering various geological aspects of the Skjoldungen Alkaline Province, with more to come.

This report is the first of a series of GEUS reports that presents geochronological data resulting from the SEGMENT project, with the specific focus on the Skjoldungen Alkaline Province (SAP). Subsequent geochronological GEUS reports will address the larger Skjoldungen area (c. 62º30 ́N to 64ºN) and Tasiilaq area (c. 64 to 67ºN), respectively. The SAP, situated at c. 63º30 ́N in South East Greenland, is part of the Archaean North Atlantic Craton (Figure 1). The SAP is worldwide a rare occurrence of Archaean alkaline rocks that was relatively sparsely studied prior to this project initiative (Nielsen and Rosing, 1990; Blichert-Toft, 1995; Thomsen, 1998). The province constitutes a number of mildly alkaline intrusions of mafic-ultramafic, intermediate and evolved compositions, as well as a late stage of strongly alkaline character, the nephelinitic-carbonatitic Singertât Complex (Nielsen and Rosing, 1990). The original geological mapping of the Skjoldungen area was done by GGU, mainly at a reconnaissance scale, in the late 1980’s and early 1990’s, resulting in a 1:500 000 scale geological map compiled by Escher (1990). A number of considerable more detailed field maps by Troels Nielsen and Minik Rosing also constituted a valuable map basis for the recent field work (unpublished field maps in the GEUS map archive).

The overall goals of the renewed work in the Skjoldungen area were to develop a more detailed understanding of the petrogenesis of the SAP, as well as evaluating the economic potential of the area. This was done through detailed field work within selected key areas, including (but not restricted to) the following intrusive centres: Vend Om Gabbro, Halvdans Fjord Gabbro, Hermods Vig Diorite 1 and 2, the Sfinksen, Tværdalen and Thrymheim areas, and Ruinnæsset Intrusion (Figure 1). From a research perspective, some of the specific key objectives set out included resolving the time frame for the emplacement of the SAP, as well as characterising the geological evolution and the geotectonic setting of the province. To this end we here report detailed zircon U-Pb data from 47 samples of felsic to intermediate intrusive SAP related rocks that enable us to address the defined research topics quantitatively. Included are also a few samples of basement gneisses from the same area, serving as a reference for the local crust signature, but regional age data on gneiss samples are otherwise presented in the second volume on the geochronology of the larger Skjoldungen area (Næraa et al. 2016). Hf isotope analyses on zircon and whole rock samples have also been undertaken on a subset of SAP samples and will be presented elsewhere (Kokfelt et al. 2016).
Antal sider122
StatusUdgivet - 17 mar. 2016


NavnDanmarks og Grønlands Geologiske Undersøgelse Rapport


  • Greenland


  • Programområde 4: Mineralske råstoffer


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