scholarly journals Early Tertiary flood basalts from Hareøen and western Nûgssuaq, West Greenland

1976 ◽  
Vol 120 ◽  
pp. 1-36
Author(s):  
N Hald
Keyword(s):  
Thin Layers ◽  
Igneous Rocks ◽  
Chemical Analyses ◽  
Flood Basalts ◽  
The West ◽  
West Greenland ◽  
Basaltic Rocks ◽  
Magmatic Rocks ◽  
Incompatible Elements ◽  
Early Tertiary

In central West Greenland flood basalts were erupted in the Early Tertiary. On Hareøen and western Nûgssuaq the upper part of the volcanic sequence predominates reaching a thickness of more than 3 km. In these two areas tholeiitic, olivine porphyritic basalts and picritic basalts are followed by tholeiitic basalts with plagioclase as the dominant phenocryst. The content of incompatible elements in the plagioclase porphyritic basalts is low in the early stages, as is the case in most of the older olivine porphyritic lavas in the province; however, after a pause in the volcanic activity, the concentration of these elements is increased by a factor of 3-6. A few thin layers of peralkaline, rhyolitic tuffs are found in the upper part of the plagioclase porphyritic sequence. The tholeiitic lavas are intruded by dykes. Most of these are petrographically the equivalent of the extrusive rocks, but dykes of transitional olivine basalts are presumed to represent a younger magmatic episode from which no lavas are known. The youngest igneous rocks in the area – and perhaps the youngest lavas in all of the West Greenland basalt province – are olivine porphyritic, alumina enriched transitional basalts deposited unconformably on the tholeiitic sequence on Hareøen. Forty-three new chemical analyses of the magmatic rocks are presented as well as micro-probe data on phenocryst and groundmass phases. The diversity of basaltic rocks cannot be explained by low pressure crystal fractionation alone, and it is suggested that the chemical evolution of the lavas and dyke rocks reflect chemical variations in batches of olivine rich magmas injected into the crust from the mantle.

scholarly journals Lithostratigraphy of the early Tertiary volcanic rocks of central West Greenland

1975 ◽  
Vol 69 ◽  
pp. 17-24
Author(s):  
N Hald ◽  
A.K Pedersen
Keyword(s):  
Marine Sediments ◽  
Volcanic Rocks ◽  
Igneous Rocks ◽  
Metamorphic Rocks ◽  
Flood Basalts ◽  
West Greenland ◽  
Early Tertiary ◽  
Volcanic Sequence ◽  
Geological Map

A sequence of flood basalts, in places more than 8-10 km thick, was erupted during the Early Tertiary in the central part of West Greenland between latitudes 69° and 73°N. The volcanic rocks rest on Precambrian metamorphic rocks and non-marine and marine sediments from the Cretaceous and Paleocene. The lower part of the volcanic sequence is dominated by tholeiitic olivinerich basalts and picrite basalts, whereas the upper part is characterized by tholeiitic basalts with plagioclase as the dominant phenocryst mineral; transitional and alkaline lavas and tuffs are found, especially in the upper part of the sequence. The geology of the Tertiary igneous rocks has been summarized by Munck & Noe-Nygaard (1957), Rosenkrantz & Pulvertaft (1969) and Clarke & Pedersen (in press). However, until now no formal lithostratigraphy has been established. A geological map at scale 1:100 000 covering the greater part of Nugssuaq (sheet Agatdal-70 V. 1 Nord) has been published by GGU.

scholarly journals Investigations of Tertiary volcanic rocks along the south coast of Nûgssuaq and in eastern Disko, 1987

1988 ◽  
Vol 140 ◽  
pp. 28-32
Author(s):  
L.M Larsen ◽  
A.K Pedersen
Keyword(s):  
Volcanic Rocks ◽  
Field Work ◽  
South Coast ◽  
The West ◽  
West Greenland ◽  
Early Tertiary ◽  
Composite Section ◽  
Greenland Basin ◽  
Volcanic Facies ◽  
Integrated Study

As a continuation of an integrated study of sedimentary and volcanic facies in the Cretaceous to Tertiary West Greenland basin (G. K.Pedersen, 1987; A. K. Pedersen & Larsen, 1987) early Tertiary volcanic rocks were studied in 1987 along a NW-SE trending composite section, about 120 km in length; on Niigssuaq and Disko. The study attempts to establish and describe lithostratigraphic volcanic units in the Tertiary volcanic formations, and through a combination of field mapping, photogrammetry and geochemistry to establish chronostratigraphic horizons through the early Tertiary deposits of the region. In this respect it is essential to identify the same eruptive units as subaeriallava facies and as subaqueous lava or hyaloclastite facies, and to trace subaerial tufts throughout the area. In the first part of the season localities along the Vaigat coast of Nûgssuaq from Kugssinerssuaq in the east to Nûssap qâqarssua in the west were investigated. In the second part of the season very poorly known areas in the western and southem part ofthe Kvandalen region on east Disko were investigated. The field work was supported by the Arctie Station in Godhavn and its cutter Porsild as well as by GGU's cutter J. F. Johnstrup.

scholarly journals Early Tertiary, low-potassium tholeiites from exploration wells on the West Greenland shelf

1987 ◽  
Vol 136 ◽  
pp. 1-25
Author(s):  
N Hald ◽  
J.G Larsen
Keyword(s):  
Baffin Island ◽  
Quaternary Sediments ◽  
The South ◽  
The West ◽  
Baffin Bay ◽  
West Greenland ◽  
Early Tertiary ◽  
Davis Strait ◽  
Low Potassium

Data on the Tertiary basalts in the Davis Strait region are reported from two exploration wells drilled by Arco and Mobil on the West Greenland shelf. Hellefisk 1 (67°53 'N, 56°44'W), situated only 60 km east of the mid-line in Davis Strait, penetrated the upper 690 m of a subaeriallava sequence continuous with the onshore volcanics of Disko and situated beneath 2.3 km of Paleocene to Quaternary sediments. The lavas are feldspar microporphyritic tholeiites and mostly unmetamorphosed despite the presence of laumontite and prehnite in the vesicular top zones. Nukik 2 (65°38'N, 54°46'W) penetrated 150 m of hyaloclastites and tholeiitic olivine dolerite sheets, presumably sills, some 200 km further to the south. These vo1canics are also deeply buried and are of unknown extension. The drilled rocks, except for the much altered hyaloclastites in the Nukik 2 well, have low contents of Ti02 (0.99-2.03%), K2O (0.09-0.18%) and P2O5 (0.08-0.21%), La/Sm ratios less than one and 87Sr/86Sr ratios of 0.7032 to 0.7044. Chemically they are related to the MORB-like picrites of Baffin Island rather than the less depleted tholeiites of West Greenland. In both areas the MORB affinity may be related to eruptions through a strongly attenuated lithosphere associated with the opening of Baffin Bay and Davis Strait.

Chapter 10 Magmatism (1.6–1.4 Ga) and Mesoproterozoic sedimentation related to intracratonic rifting coeval with distal accretionary orogenesis

2020 ◽  
Vol 50 (1) ◽  
pp. 269-288 ◽  
Author(s):  
Magnus Ripa ◽  
Michael B. Stephens
Keyword(s):  
Tectonic Setting ◽  
Northern Europe ◽  
Isotopic Data ◽  
Flood Basalts ◽  
The West ◽  
North Central ◽  
Continental Flood Basalts ◽  
Magmatic Rocks ◽  
Tectonic Development ◽  
Siliciclastic Rocks

AbstractSeparate pulses of magmatic activity involving the emplacement of plutons with predominantly granitic or bimodal granitic and gabbroic composition, as well as dolerite dykes, occurred in a cratonic setting in eastern Sweden at c. 1.59–1.58 Ga, c. 1.53–1.50 Ga and c. 1.47–1.44 Ga; anorthosite, monzodiorite and syenitoid rocks are locally present. Most of the granites have been compared with rapakivi granites in Finland and elsewhere. Isotopic data (Hf in zircons and ɛNd values) from the plutons in north-central Sweden show contamination by an Archean source. Siliciclastic rocks dominated by aeolian or deltaic sandstones overlie c. 1.58 Ga or c. 1.50 Ga plutons, are intercalated with 1.46 Ga basaltic lavas and were deposited prior to the emplacement of 1.27–1.25 Ga dolerites. The magmatic rocks are subalkaline (tholeiitic) to alkaline and the mafic components have been compared with continental flood basalts, suggesting an intracratonic, rift-related tectonic setting for the magmatism and sand deposition. These rocks constitute the westerly part of a late Paleoproterozoic to early Mesoproterozoic magmatic province in northern Europe, located along roughly north–south- and WSW–ENE-trending linear belts. This tectonic development was coeval with accretionary orogenic activity further to the west and SW.

scholarly journals Lithostratigraphy of the Tertiary Vaigat Formation on Disko, central West Greenland

1985 ◽  
Vol 124 ◽  
pp. 1-30
Author(s):  
A.K Pedersen
Keyword(s):  
Igneous Rocks ◽  
West Greenland ◽  
Native Iron ◽  
Early Tertiary

The lithostratigraphy of the early Tertiary Vaigat Formation on Disko is presented. The formation is divided into six members: Naujanguit Member, Asuk Member, Kûgánguaq Member, Qordlortorssuaq Member, Ordlingassoq Member and Manítdlat Member. The members were formed by two major igneous events. The first event gave rise to the vo!canic rocks from the Naujånguit Member and two minor vo!canic systems enclosed therein: the Asuk and Kiigånguaq Members. The basalts of the Qordlortorssuaq Member constitute the waning phase of the first igneous event. The second igneous event gave rise to the vo!canic rocks of the Ordlingassoq Member within which are enclosed the alkaline basalts of the Manitdlat Member. The members are composed of the folIowing igneous rocks: Naujanguit Member: tholeiitic picrites, minor silicic basalts and olivine-poor tholeiitic basalts; Asuk Member: silicic basalts and magnesian andesites, many rocks carry native iron; Kfigånguaq Member: silicic basalts and magnesian andesites; Qordlortorssuaq Member: olivine-poor tholeiitic basalts; Ordlingassoq Member: tholeiitic picrites, minor alkaline picrites; Manitdlat Member: alkaline picrites and alkaline basalts.

IV.—The Late Palæzoic Alkaline Igneous Rocks of the West of Scotland

1912 ◽  
Vol 9 (2) ◽  
pp. 69-80 ◽  
Author(s):  
G. W. Tyrrell
Keyword(s):  
Royal Society ◽  
Igneous Rocks ◽  
Chemical Analyses ◽  
The West ◽  
Abundant Evidence ◽  
Preliminary Account ◽  
The Government ◽  
Government Grant ◽  
The Postponement ◽  
Detailed Work

Of late years it has become manifest that the igneous rocks of the Carboniferous in Central Scotland have a distinct alkaline facies. Such rocks as monchiquite, nepheline-basalt, mugearite, kulaite, phonolite, essexite, and teschenite have been described from the Lothians; whilst in the western counties nepheline-phonolite, theralite, mugearite, and teschenite are already known. There is abundant evidence, however, that in the West the alkaline phase is of later date than in the Lothians, and of late Carboniferous or Permian age. In Arran it probably extended into the Triassic, assuming that the stratigraphy which assigns certain rocks to the Triassic is correct. A general account of this connected suite of alkaline rocks, together with the lavas in the Mauchline Basin, to which they can be shown to be genetically related, is given in this paper, which deals only with rocks demonstrably later than the volcanics of the Calciferous Sandstone. The work on which this paper is based was commenced in 1908, and was assisted in 1909 by a grant from the Government Grant Committee of the Royal Society, for which grateful acknowledgment is made. An unfortunate breakdown in health, however, necessitated the postponement of the investigation for nearly a year. It is still incomplete owing to the difficulty of obtaining adequate chemical analyses, without which it is impossible accurately to determine the affinities of some of the rocks. Pending the completion of the detailed work it has been thought advisable to present this preliminary account of an igneous suite of extraordinary variety and interest.

scholarly journals Early Tertiary lavas and sills on Traill Ø and Geographical Society Ø, northern East Greenland: petrography and geochemistry

1996 ◽  
Vol 171 ◽  
pp. 29-43
Author(s):  
N Hald
Keyword(s):  
Genetic Relationship ◽  
Rift Zone ◽  
Flood Basalts ◽  
East Greenland ◽  
Geographical Society ◽  
Incompatible Elements ◽  
Early Tertiary

The Early Tertiary extrusion of flood basalts in East Greenland was accompanied by intrusion of numerous sills in the Upper Palaeozoic arid Mesozoic sediments of the N–S trending East Greenland rift zone. With a few exceptions the lavas and sills have low contents of Ti and other incompatible elements, indicating a genetic relationship with the lavas and sills north of Kejser Franz Joseph Fjord rather than with the lavas in the Scoresby Sund area. Two sills are described in greater detail. The first, from Geographical Society Ø, is 60 m thick and homogeneous throughout. The second, from southern Traill Ø, is more than 150 m thick and atypical as it ranges in composition from low-Ti tholeiite to diorite.

scholarly journals VII.—The Late Palæozoic Alkaline Igneous Rocks of the West of Scotland

1912 ◽  
Vol 9 (3) ◽  
pp. 120-131 ◽  
Author(s):  
G. W. Tyrrell
Keyword(s):  
Thin Section ◽  
Basic Type ◽  
Igneous Rocks ◽  
The West ◽  
Fine Grained ◽  
Late Palaeozoic

2. Essexite. (a) Carskeoch type.—A small boss of essexite, of rather basic type, pierces the agglomerate of the Carskeoch vent, near Patna, Ayrshire. Macroscopically it is light grey, compact, and fine-grained. In thin section it shows a plexus of fluxionally-arranged plagioclase laths of the composition Ab An, the interstices being filled with subhedral augite of a nearly colourless variety, and fresh olivine. Here and there minute angular interspaces are occupied with turbid isotropic matter, the form and arrangement of the particles of which suggest the former presence of nepheline. A few broad plates of pale augite and crystals of olivine interrupt the general trachytoid fabric. Ilmenite and biotite occur sparsely, and a little orthoclase may be detected on the margins of the plagioclases, extending irregularly into the interspaces. This rock has a distinct individuality, and resembles neither the essexites of Lochend and Craigleith in the Lothians, nor the Crawfordjohn type described below. It is poor in alkali-felspars and felspathoids, is devoid of purple augite, and has a well-developed trachytoid fabric.

scholarly journals Genetic mixed-stock analysis disentangles spatial and temporal variation in composition of the West Greenland Atlantic Salmon fishery

2016 ◽  
Vol 73 (9) ◽  
pp. 2311-2321 ◽  
Author(s):  
Ian R. Bradbury ◽  
Lorraine C. Hamilton ◽  
Timothy F. Sheehan ◽  
Gerald Chaput ◽  
Martha J. Robertson ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
North American ◽  
Temporal Stability ◽  
Spatial And Temporal Variation ◽  
Published Data ◽  
The West ◽  
West Greenland ◽  
Archived Samples ◽  
Mixed Stock ◽  
Salmon Fishery

Abstract The West Greenland Atlantic Salmon (Salmo salar) fishery represents the largest remaining mixed-stock fishery for Atlantic Salmon in the Northwest Atlantic and targets multi-sea-winter (MSW) salmon from throughout North America and Europe. We evaluated stock composition of salmon harvested in the waters off West Greenland (n = 5684 individuals) using genetic mixture analysis and individual assignment to inform conservation of North American populations, many of which are failing to meet management targets. Regional contributions to this fishery were estimated using 2169 individuals sampled throughout the fishery between 2011 and 2014. Of these, 22% were identified as European in origin. Major North American contributions were detected from Labrador (∼20%), the Southern Gulf/Cape Breton (29%), and the Gaspe Peninsula (29%). Minor contributions (∼5%) were detected from Newfoundland, Ungava, and Quebec regions. Region-specific catches were extrapolated using estimates of composition and fishery catch logs and harvests ranged from 300 to 600 and 2000 to 3000 individuals for minor and major constituents, respectively. To evaluate the temporal stability of the observed fishery composition, we extended the temporal coverage through the inclusion of previously published data (1995–2006, n = 3095) and data from archived scales (1968–1998, n = 420). Examination of the complete time-series (47 years) suggests relative stability in stock proportions since the late 1980s. Genetic estimates of stock composition were significantly associated with model-based estimates of returning MSW salmon (individual years r = 0.69, and overall mean r = 0.96). This work demonstrates that the analysis of both contemporary and archived samples in a mixed-stock context can disentangle levels of regional exploitation and directly inform assessment and conservation of Atlantic Salmon in the West Greenland interceptory Atlantic Salmon fishery.

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