TY - JOUR
T1 - Geochronology of Archaean and Proterozoic events in the Ammassalik area, South-East Greenland, and comparisons with the Lewisian of Scotland and the Nagssugtoqidian of West Greenland
AU - Kalsbeek, F.
AU - Austrheim, H.
AU - Bridgwater, D.
AU - Hansen, B.T.
AU - Pedersen, S.
AU - Taylor, P. N.
N1 - Funding Information:
We thank the heads and staff of the various laboratories involved in this study for support and technical assistance, and many collegues for help and fruitful discussions on the geology of the Amassalik area. Stuart Watt (GGU), Robin Gill (University of London), Stephen Moorbath and Martin Whitehouse (University of Oxford) reviewed the manuscript and gave helpful comments. The figures were drawn by Lis Duegaard (GGU). The laboratories in Copenhagen are supported by the Danish Natural Science Research Council (SNF) who also supported part of the field work. Publication of this paper was authorised by GGU.
PY - 1993/6
Y1 - 1993/6
N2 - The Ammassalik area in South-East Greenland forms a link between the Precambrian terrains of West Greenland and northwest Scotland. It consists mainly of Archaean orthogneisses reworked during a Proterozoic tectonothermal event. Proterozoic ortho- and paragneisses, major leuconorite-charnockite complexes, suites of metadolerite dykes and posttectonic granites also occur. SmNd, RbSr, PbPb and zircon UPb isotope data yield ages of ∼ 3.0-2.8 Ga for Archaean basement gneisses, 2.2-2.1 (?) Ga for Proterozoic gneisses, 1.9-1.8 Ga for the Proterozoic reworking, 1.89 Ga for the leuconorite-charnockite complexes, and 1.7-1.6 Ga for the late granites. Proterozoic reworking has disturbed most Archaean isotope systems, and contamination with Archaean material makes dating of Proterozoic rocks difficult. In several cases discordant dates are obtained from different isotope systems. The chronologies of the Lewisian complex of Scotland and the West Greenland Nagssugtoqidian mobile belt compare closely with that of the Ammassalik area, and support the correlation between these areas suggested by earlier studies. There are, however, also major differences between the Nagssugtoqidian and the mobile belt in the Ammassalik area, and precise correlation across the Inland Ice of Greenland is still ambiguous.
AB - The Ammassalik area in South-East Greenland forms a link between the Precambrian terrains of West Greenland and northwest Scotland. It consists mainly of Archaean orthogneisses reworked during a Proterozoic tectonothermal event. Proterozoic ortho- and paragneisses, major leuconorite-charnockite complexes, suites of metadolerite dykes and posttectonic granites also occur. SmNd, RbSr, PbPb and zircon UPb isotope data yield ages of ∼ 3.0-2.8 Ga for Archaean basement gneisses, 2.2-2.1 (?) Ga for Proterozoic gneisses, 1.9-1.8 Ga for the Proterozoic reworking, 1.89 Ga for the leuconorite-charnockite complexes, and 1.7-1.6 Ga for the late granites. Proterozoic reworking has disturbed most Archaean isotope systems, and contamination with Archaean material makes dating of Proterozoic rocks difficult. In several cases discordant dates are obtained from different isotope systems. The chronologies of the Lewisian complex of Scotland and the West Greenland Nagssugtoqidian mobile belt compare closely with that of the Ammassalik area, and support the correlation between these areas suggested by earlier studies. There are, however, also major differences between the Nagssugtoqidian and the mobile belt in the Ammassalik area, and precise correlation across the Inland Ice of Greenland is still ambiguous.
UR - https://www.scopus.com/pages/publications/0027385640
U2 - 10.1016/0301-9268(93)90024-V
DO - 10.1016/0301-9268(93)90024-V
M3 - Article
AN - SCOPUS:0027385640
SN - 0301-9268
VL - 62
SP - 239
EP - 270
JO - Precambrian Research
JF - Precambrian Research
IS - 3
ER -