Uranium data for Greenland registered by GEUS: data acquisistion, coverage and spatial uranium variation

Publikation: Bog/rapportRapport (offentligt tilgængelig)

Abstrakt

This report presents the results of a compilation of geochemical and radiometric data for uranium in Greenland stored at GEUS. Acquisition of six different data types, i.e. stream sediment fine fraction, stream sediment heavy mineral concentrate, stream water, rock, airborne gamma-spectrometry and ground scintillometry, are described, their quality is commented, and the spatial distribution of samples and recorded U data are shown in maps of entire Greenland. The data set based on systematically sampled, treated and analysed stream sediment has the most extensive coverage corresponding to c. 75 % of ice-free Greenland.

Colour symbol plots or contoured grids of U values of the individual data sets together illustrate that the background variation of U across Greenland has several clearly defined areas of uranium enrichment, with South Greenland being the most pronounced. A comparison with a map of main lithotectonic units demonstrates that elevated to high uranium values are derived from 1) parts of the Archaean basement where rocks are in amphibolite facies and are intruded by late granites and pegmatite, 2) Palaeoproterozoic supracrustal sequences with abundant migmatites and late granites, 3) Mesoproterozoic metasediments in East Greenland intruded by Palaeozoic granites, 4) Mesoproterozoic alkaline igneous complexes in South Greenland. In many cases the elevated background for U reflects occurrences of rocks with high abundance of U-bearing accessory minerals.

The highest U values in the data sets, the U anomalies, indicate where mineralisation with uraninite has occurred. Such mineralisation is known within rocks of at least three different settings and ages in South Greenland: 1) Palaeoproterozoic sediment-hosted mineralisation, 2) Vein-type mineralisation of Mesoproterozoic age hosted by Palaeoproterozoic granite, and 3) Magmatic-type uranium mineralisation associated with highly differentiated magmas of Mesoproterozoic peralkaline intrusive complexes. Elsewhere in Greenland, uraninite and secondary uranium minerals are associated with pegmatites, acid volcanic rocks and fractures or shear zones within such rock complexes. Uraniferous pyrochlore is associated with a Neoproterozoic carbonatite.
OriginalsprogEngelsk
UdgivelsesstedCopenhagen
ForlagGEUS
Antal sider52
Vol/bind2014
DOI
StatusUdgivet - 9 apr. 2014

Publikationsserier

NavnDanmarks og Grønlands Geologiske Undersøgelse Rapport
ForlagGEUS
Nr.28
Vol/bind2014

Emneord

  • Greenland

Programområde

  • Programområde 4: Mineralske råstoffer

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