Archean and Proterozoic crust in North-West Greenland: evidence from Rb–Sr whole-rock age determinations

1988 ◽  
Vol 25 (9) ◽  
pp. 1365-1373 ◽  
Author(s):  
Peter R. Dawes ◽  
Ole Larsen ◽  
Feiko Kalsbeek
Keyword(s):  
Ellesmere Island ◽  
Isotopic Age ◽  
Sr Isotope ◽  
Isotopic Data ◽  
Igneous Complex ◽  
West Greenland ◽  
North West ◽  
Devon Island ◽  
Age Determinations

The geochronological understanding of the Precambrian crystalline shield of North-West Greenland (75–79°N) is at a rudimentary stage. Isotopic data from three major rock complexes—the Etah meta-igneous complex, the Kap York meta-igneous complex, and the Kivioq Havn gneiss and supracrustal complex—all show scatter indicating disturbed Rb–Sr isotope systems. This may reflect widespread reactivation of the crust in Proterozoic (Hudsonian) time. However, the majority of the samples define errorchrons that are regarded as geologically significant, and although the ages are poorly constrained, the data demonstrate the presence of both Archean and Proterozoic terranes.The Etah complex is Proterozoic in age (errorchron age ca. 1850 Ma), whereas the Kap York and Kivioq Havn complexes represent late Archean material (errorchron age ca. 2700 Ma). These ages compare favourably with isotopic age information from adjacent Canada in southeast Ellesmere Island and Devon Island, where correlatable Archean and Proterozoic rock complexes occur.

scholarly journals Mapping in the Fiskefjord area, southern West Greenland

1982 ◽  
Vol 110 ◽  
pp. 55-57
Author(s):  
A.A Garde ◽  
V.R McGregor
Keyword(s):  
Granulite Facies ◽  
Amphibolite Facies ◽  
Isotopic Age ◽  
Supracrustal Rock ◽  
Granulite Facies Metamorphism ◽  
West Greenland ◽  
Facies Metamorphism ◽  
Geological Work ◽  
Age Determinations

Previous geological work on the 1:100000 map sheet 64 V.l N (fig. 15) includes published maps of smaller areas by Berthelsen (1960, 1962) and Lauerma (1964), mapping by Kryolitselskabet Øresund A/S (Bridgwater et al., 1976) and mapping by GGU geologists for the 1:500000 map sheet Frederikshåb Isblink - Søndre Strømfjord (Allaart et al., 1977, 1978). The Amltsoq and Niik gneisses and Malene supracrustal rock units south and east of Godthåbsfjord have not so far been correlated with rocks in the Fiskefjord area. Godthåbsfjord separates the granulite facies gneisses in Nordlandet from amphibolite facies Nûk gneisses on Sadelø and Bjørneøen; the granulite facies metamorphism occurred at about 2850 m.y. (Black et al., 1973), while no published isotopic age determinations from the Fiskefjord area itself are available.

scholarly journals Comparative note on the Precambrian basement of southern Inglefield Land and eastern Ellesmere Island

1981 ◽  
Vol 105 ◽  
pp. 14-18
Author(s):  
T Frisch
Keyword(s):  
Crystalline Basement ◽  
Ellesmere Island ◽  
Geological Survey ◽  
Precambrian Basement ◽  
West Greenland ◽  
North West ◽  
Comparative Note

A one-week visit to southem Inglefield Land, by the GGU motor cutter K. J. V. Steenstrup in conjunction with P. R. Dawes's geological studies in North-West Greenland, provided an opportunity to examine the Precambrian crystalline basement between Sunrise Pynt and Kap Alexander (fig. 4). The basement exposures face those on eastem Ellesmere Island, no more than 70 km away across Smith Sound, which were mapped by the writer in 1977 for the Geological Survey of Canada (Frisch et al., 1978). This note briefly compares the two areas.

scholarly journals Etah meta-igneous complex and the Wulff structure: Proterozoic magmatism and deformation in Inglefield Land, North-West Greenland

1988 ◽  
Vol 139 ◽  
pp. 1-24
Author(s):  
P.R Dawes
Keyword(s):  
Large Scale ◽  
Mobile Belt ◽  
Magmatic Complex ◽  
Igneous Complex ◽  
West Greenland ◽  
North West ◽  
High Deformation ◽  
Precambrian Geology ◽  
North East ◽  
The North

A hitherto uninvestigated collection of crystalline rocks from north-eastem Inglefield Land (c. 79°N) allowanew interpretation of the Precambrian geology of the region. The majority of the samples - high-grade basic, intermediate and granitoid rocks - are referred to the Etah meta-igneous complex, which has been shown to be mid-Proterozoic in age in the type area in south-western Inglefield Land. In areas of high deformation there is a gradation from massive rocks of igneous aspect into folded and variably migmatised gneisses. Thus the magmatic complex provides a gauge of the nature and intensity of Proterozoic (Hudsonian) deformation and metamorphism. In Inglefield Land Proterozoic deformation produced different structural styles; thus in the north-east the Wulff structure - a large-scale refolded isoclinal structure - characterises a region that lacks an obvious preferred regional foliation direction, while in the south-west, linear E-W trending belts with steep dips dominate the structural pattem. The Proterozoic evolution is outlined from the formation of the Etah Group, a supracrustal sequence that pre-dates the Etah meta-igneous complex, to uplift, peneplanation, deposition and magmatism in the late Proterozoic. Inglefield Land is not part of the Rinkian mobile belt of West Greenland, and it is stressed that the obvious continuation of the Proterozoic geology is into Ellesmere Island.

scholarly journals Rb-Sr whole-rock measurements of the Kap York meta-igneous complex, Thule district, North-West Greenland

1980 ◽  
Vol 100 ◽  
pp. 30-33
Author(s):  
F Kalsbeek ◽  
P.R Dawes
Keyword(s):  
Igneous Rocks ◽  
High Grade ◽  
Precambrian Basement ◽  
The South ◽  
Igneous Complex ◽  
Basic Composition ◽  
West Greenland ◽  
North West ◽  
Geological Map ◽  
Rock Suite

The Precambrian basement af the Kap York - Melville Bugt region is high-grade gneiss, composed af both orthogneisses and paragneisses, in which several units af metasedimcntary and meta-igneous rocks occur. The largest Occurrence af igneous rocks that has rctaincd magmatic aspect is the Kap York meta-igncous complcx which is composed af a rock suite af acidic to basic composition occupying thc wholc af the Kap York peninsula (fig. 8). On the Tectonic/Geological map of Greenland (Escher, 1970) the Kap York rocks were included in the Prolcrozoic Nagssugtoqidian orogenic complex which, elsewhere to the south in Greenland, yields K-Ar ages between 1790 and 1650 m.y.

scholarly journals Discordant U-Pb isotopic system in zircons from a granite north-west of Frederikshåbs Isblink, Fiskenæsset region

1973 ◽  
Vol 51 ◽  
pp. 28-30
Author(s):  
R.T Pidgeon
Keyword(s):  
Laboratory Work ◽  
Isotopic Age ◽  
North West ◽  
Preliminary Results ◽  
Rock Types ◽  
Isotopic System ◽  
Field Season ◽  
Age Determinations

Extensive sampling was carried out in parts of the Fiskenæsset region during the 1971 field season with the aim of providing suitable matenal for isotopic age determinations. The total area covered by the mapping programme was so large and the geological problems so varied that it was decided to initiate this study by looking in detail at a small number of rock types in one or two sub-areas. Once isotopic relationships are known in these areas it is hoped to extend the work to embrace other problems in the region. The laboratory work is in progress at present and already some preliminary results have been obtained (Feb. 1972).It is the purpose of this report to discuss the age relationships of zircons extracted from a single 100 kg sample of granite from the mapping area of Hopgood (see plate 1).

scholarly journals New K/Ar age determinations from southern West Greenland

1969 ◽  
Vol 19 ◽  
pp. 68-71
Author(s):  
R.St.J Lambert ◽  
J.G Simons
Keyword(s):  
Granulite Facies ◽  
Amphibolite Facies ◽  
Isotopic Age ◽  
West Greenland ◽  
Gneiss Complex ◽  
Major Scale ◽  
Age Determinations

The following four samples are from the pre-Ketilidian/pre-Nagssugtoqidian central gneiss complex of west Greenland (Pulvertaft, 1968), in which there are several amphibolite facies linear belts with conformable greenschist layers that contrast on a major scale with the complexly folded granulite facies complexes (Windley, in press). The following dates together with those published by Armstrong (1963) and Larsen and Møller (1968) suggest that the linear belts have an isotopic age in the range 2410-2710 m. y., whilst the granulite facies complex in the Fiskenæsset region has an age of at least 3210 m. y. There was also plutonic activity in the period 1940-1820 m. y. expressed by a weak metamorphism in late supracrustal rocks only preserved within the Godthåb-Isua linear belt and in the pegmatites around the Qôrqut granite (Larsen and Møller, op. cit.).

Episodic tectono-thermal activity in the southern part of the East Greenland Caledonides

2000 ◽  
pp. 42-49 ◽  
Author(s):  
A. Graham Leslie ◽  
Allen P. Nutman
Keyword(s):  
Thermal Activity ◽  
Isotopic Data ◽  
Zircon Age ◽  
East Greenland ◽  
Original Series ◽  
Age Determinations

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Leslie, A. G., & Nutman, A. P. (2000). Episodic tectono-thermal activity in the southern part of the East Greenland Caledonides. Geology of Greenland Survey Bulletin, 186, 42-49. https://doi.org/10.34194/ggub.v186.5214 _______________ Isotopic data from the Renland augen granites of the Scoresby Sund region (Figs 1, 2) provided some of the first convincing support for relicts of potentially Grenvillian tectono-thermal activity within the East Greenland Caledonides. In Renland, Chadwick (1975) showed the presence of major bodies of augen granite (Fig. 2) interpreted by Steiger et al. (1979), on the basis of Rb–Sr whole rock and U–Pb zircon age determinations, to have been emplaced about 1000 Ma ago.

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