scholarly journals New hornblende and muscovite 40Ar/39Ar cooling ages in the central Rinkian fold belt, West Greenland

2006 ◽  
Vol 11 ◽  
pp. 115-124 ◽  
Author(s):  
Ann-Sofie Sidgren ◽  
Laurence Page ◽  
Adam A. Garde
Keyword(s):  
Metamorphic Grade ◽  
Fold Belt ◽  
The South ◽  
Igneous Complex ◽  
West Greenland ◽  
Structural History

The Palaeoproterozoic Rinkian fold belt in West Greenland consists of reworked Archaean basement, mainly orthogneiss, and the unconformably overlying Palaeoproterozoic Karrat Group. Both parts were intensely deformed and metamorphosed at around 1.87 Ga, at which time the crustal anatectic Prøven igneous complex was emplaced into the northern part of the belt. Seven new hornblende and muscovite 40Ar/39Ar cooling ages are presented from the central–northern parts of the Rinkian fold belt. Four 40Ar/39Ar hornblende ages ranging from 1795 ± 3 to 1782 ± 3 Ma were obtained from amphibolite and hornblendite enclaves in the Archaean orthogneiss, and two from relict dyke fragments in the latter that may be of Palaeoproterozoic age. Three 40Ar/39Ar muscovite ages of 1681 ± 6 Ma, 1686 ± 3 Ma and 1676 ± 3 Ma were obtained from samples of Karrat Group metagreywacke, andalusite schist and metasiltstone. The new 40Ar/39Ar ages, from hornblende and muscovite respectively, are very uniform and probably unrelated to local metamorphic grade and structural history, and are interpreted as regional late orogenic cooling ages. The new hornblende ages are significantly older than those previously obtained from the central and northern parts of the adjacent Nagssugtoqidian orogen to the south, and point to different uplift histories, which may suggest that the orogeny was not synchronous in the two regions.

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.

A coastal survey in the southern part of the Palaeoproterozoic Rinkian fold belt, central West Greenland

2002 ◽  
pp. 33-38 ◽  
Author(s):  
Adam A. Garde ◽  
James N. Connelly ◽  
Adam W. Krawiec ◽  
Sandra Piazolo ◽  
Kristine Thrane
Keyword(s):  
Fold Belt ◽  
The South ◽  
Original Series ◽  
West Greenland ◽  
Field Investigations ◽  
Logistic Support

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article. Garde, A. A., Connelly, J. N., Krawiec, A. W., Piazolo, S., & Thrane, K. (1). A coastal survey in the southern part of the Palaeoproterozoic Rinkian fold belt, central West Greenland. Geology of Greenland Survey Bulletin, 191, 33-38. https://doi.org/10.34194/ggub.v191.5109 A brief but potentially important part of the 2001 field investigations in the Precambrian of West Greenland (van Gool et al. 2002, this volume) was devoted to the southernmost part of the Palaeoproterozoic Rinkian fold belt east of Disko Bugt (Fig. 1). From 9–17 August the five authors carried out a reappraisal of critical Archaean and Proterozoic relationships and collected samples for precise geochronological studies. The principal aims are to date the main Rinkian tectonic and metamorphic events in this region as precisely as possible and compare them with the evolution of the Nagssugtoqidian orogen to the south (see van Gool et al. 2002, this volume, fig. 1). The vessel M/S Søkongen provided logistic support; a helicopter provided transport to Nunatarsuaq.

The Archaean Atâ intrusive complex (Atâ tonalite), north-east Disko Bugt, West Greenland

1999 ◽  
pp. 103-112
Author(s):  
Feiko Kalsbeek ◽  
Lilian Skjernaa
Keyword(s):  
Intrusive Complex ◽  
The South ◽  
Original Series ◽  
Early Proterozoic ◽  
West Greenland ◽  
North East ◽  
The North ◽  
Southern Border ◽  
Area North ◽  
Igneous Layering

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Kalsbeek, F., & Skjernaa, L. (1999). The Archaean Atâ intrusive complex (Atâ tonalite), north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 103-112. https://doi.org/10.34194/ggub.v181.5118 _______________ The 2800 Ma Atâ intrusive complex (elsewhere referred to as ‘Atâ granite’ or ‘Atâ tonalite’), which occupies an area of c. 400 km2 in the area north-east of Disko Bugt, was emplaced into grey migmatitic gneisses and supracrustal rocks. At its southern border the Atâ complex is cut by younger granites. The complex is divided by a belt of supracrustal rocks into a western, mainly tonalitic part, and an eastern part consisting mainly of granodiorite and trondhjemite. The ‘eastern complex’ is a classical pluton. It is little deformed in its central part, displaying well-preserved igneous layering and local orbicular textures. Near its intrusive contact with the overlying supracrustal rocks the rocks become foliated, with foliation parallel to the contact. The Atâ intrusive complex has escaped much of the later Archaean and early Proterozoic deformation and metamorphism that characterises the gneisses to the north and to the south; it belongs to the best-preserved Archaean tonalite-trondhjemite-granodiorite intrusions in Greenland.

Surficial geochemical and mineralogical signatures of Ni-Cu-PGE deposits in glaciated terrain: examples from the South Range of the Sudbury Igneous Complex, Ontario, Canada

2021 ◽  
pp. 104301
Author(s):  
Sarah Hashmi ◽  
Matthew I. Leybourne ◽  
Daniel Layton-Matthews ◽  
Stewart Hamilton ◽  
M. Beth McClenaghan ◽  
...  
Keyword(s):  
The South ◽  
Igneous Complex ◽  
Sudbury Igneous Complex

The Metamorphosed Limestones and Associated Contaminated Igneous Rocks of the Carlingford District, Co. Louth

1932 ◽  
Vol 69 (5) ◽  
pp. 209-233 ◽  
Author(s):  
G. D. Osborne
Keyword(s):  
Igneous Rocks ◽  
The South ◽  
Ordnance Survey ◽  
Igneous Complex ◽  
North East ◽  
The North ◽  
South West ◽  
Carboniferous Limestone ◽  
Contamination Effects

THE Carlingford-Barnave district falls within the boundaries of Sheet 71 of the Ordnance Survey of Ireland, and forms part of a broad promontory lying between Carlingford Lough on the north-east and Dundalk Bay on the south-west. The greater part of this promontory is made up of an igneous complex of Tertiary age which has invaded the Silurian slates and quartzites and the Carboniferous Limestone Series. This complex has not yet been investigated in detail, but for the purposes of the present paper certain references to it are necessary, and these are made below. The prevalence of hybrid-relations and contamination-effects between the basic and acid igneous rocks of the region is a very marked feature, and because of this it has been difficult at times to decide which types have been responsible for the various stages of the metamorphism.

The Laurentia – West Greenland connection at 1.9 Ga: New insights from the Rinkian fold belt

2017 ◽  
Vol 51 ◽  
pp. 289-309 ◽  
Author(s):  
Mary Sanborn-Barrie ◽  
Kristine Thrane ◽  
Natasha Wodicka ◽  
Nicole Rayner
Keyword(s):  
Fold Belt ◽  
West Greenland

The geochronology of uraniferous minerals in the Witwatersrand Triad; an interpretation of new and existing U-Pb age data on rocks and minerals from the Dominion Reef, Witwatersrand and Ventersdorp Supergroups

1977 ◽  
Vol 286 (1336) ◽  
pp. 567-583 ◽  
Keyword(s):  
Thermal Effects ◽  
Free State ◽  
The South ◽  
Witwatersrand Basin ◽  
Simple Interpretation ◽  
Igneous Complex ◽  
Radiogenic Lead ◽  
Sedimentary Sequences ◽  
Age Patterns ◽  
Bushveld Igneous Complex

Uranium and lead analyses of rock samples from the Witwatersrand, Ventersdorp, and Transvaal supergroups give mainly discordant ages. Samples from the Upper Witwatersrand of the Orange Free State give 207 Pb/ 206 Pb ages of ca. 3000 Ma. These data when considered together with earlier total conglomerate U -Pb analyses from the Dominion Reef Supergroup lead to the conclusion that the uraniferous minerals of the Dominion Reef, Witwatersrand, Ventersdorp and Transvaal conglomerates are 3050 ± 50 Ma old. In the northern parts of the Witwatersrand Basin the parent uraniferous minerals experienced a major reworking at 2040 ± 100 Ma which brought about the partial or complete resetting of the original 3050 Ma age. Radiogenic lead released during this reworking crystallized as galena in veins and fissures which cut across the uraniferous conglomerate horizons. This reworking appears to have had little effect in the Orange Free State to the south. Its age and geographical extent suggest it was caused by thermal effects which accompanied the emplacement of the Bushveld Igneous Complex at 1950 ± 150 Ma. Samples from the south, which were relatively unaffected by the ca. 2040 Ma reworking generally show the effects of recent uranium loss. In the northern part of the basin discordant age patterns characteristic of lead loss have been imposed on uranium-lead systems which were generally reset (partially or completely) by the ca. 2040 Ma event. The presence of 3050 Ma old minerals in sedimentary sequences which are probably younger than ca. 2740 Ma suggests the simple interpretation that the uraniferous minerals are predominantly detrital.

scholarly journals Volcanic centres between Frigg Fjord and Midtkap, eastern North Greenland

1981 ◽  
Vol 106 ◽  
pp. 69-75
Author(s):  
I Parsons
Keyword(s):  
Fault Zone ◽  
Fold Belt ◽  
The South ◽  
The North ◽  
Rock Types ◽  
South West ◽  
North Greenland

A series of smal! volcanic centres cut Ordovician turbidites of Formation A in the southem part of Johannes V. Jensen Land between Midtkap and Frigg Fjord (Map 2). Their general location and main rock types were described by Soper et al. (1980) and their nomenclature is adopted here for fig. 22 with the addition of the small pipe B2. A further small intrusion, south-west of Frigg Fjord, was described by Pedersen (1980). The centres lie 5-10 km south of, and parallel to, the important Harder Fjord fault zone (fig. 22) which traverses the southern part of the North Greenland fold belt and shows substantial downthrow to the south (Higgins et al., this report).

scholarly journals Suitability of surficial media for Ni-Cu-PGE exploration in an established mining camp: a case study from the South Range of the Sudbury Igneous Complex, Canada

2021 ◽  
pp. geochem2021-051
Author(s):  
Sarah Hashmi ◽  
Matthew I. Leybourne ◽  
Stewart Hamilton ◽  
Daniel Layton-Matthews ◽  
M. Beth McClenaghan
Keyword(s):  
Anthropogenic Contamination ◽  
The South ◽  
Aqua Regia ◽  
Content Type ◽  
Igneous Complex ◽  
Sudbury Igneous Complex ◽  
Geochemical Study ◽  
Pge Mineralization ◽  
Supplementary Material

A geochemical study over the southwestern part of the South Range of the Sudbury Igneous Complex (SIC) was completed to assess the suitability of surficial media (humus, B-horizon soil and C-horizon soil) for delineating geochemical anomalies associated with Ni-Cu-PGE mineralization. Another objective was to test whether Na pyrophosphate can eliminate the effects of anthropogenic contamination in humus. Results of this study suggest that the natural geochemical signature of humus is strongly overprinted by anthropogenic contamination. Despite no indication of underlying or nearby mineralization, metal concentrations in humus samples by aqua regia collected downwind from smelting operations are higher compared to background, including up to 13 times higher for Pt, 12 times higher for Cu and 9 times higher for Ni. The high anthropogenic background masks the geogenic signal such that it is only apparent in humus samples collected in the vicinity of known Ni-Cu-PGE deposits. Results of this study also demonstrate that anthropogenically-derived atmospheric fallout also influences the upper B-horizon soil; however, lower B-horizon soil (at > 20 cm depth) and C-horizon soil (both developed in till) are not affected. Glacial dispersal from Ni-Cu-PGE mineralization is apparent in C-horizon till samples analyzed in this study. Compared to the background concentrations, the unaffected C-horizon till samples collected immediately down-ice of the low-sulfide, high precious metal (LSHPM) Vermilion Cu-Ni-PGE deposit are enriched over 20 times in Pt (203 ppb), Au (81 ppm) and Cu (963 ppm), and over 30 times in Ni (1283 ppm).Supplementary material:https://doi.org/10.6084/m9.figshare.c.5691080

Sign in / Sign up

Export Citation Format

Share Document