A zircon age from gabbro-anorthosite inclusions in the gneisses of the Angmagssalik area, South-East Greenland

Rapport Grønlands Geologiske Undersøgelse ◽

10.34194/rapggu.v66.7399 ◽

1974 ◽

Vol 66 ◽

pp. 21-31

Author(s):

P.D Nunes ◽

R.H Steiger ◽

D Bridgwater

Keyword(s):

Major Part ◽

Coarse Grained ◽

Zircon Age ◽

East Greenland ◽

The North ◽

Gneiss Complex ◽

Age Determinations

Age determinations were made on 3 zircon fractions extracted from gabbroanorthosite inclusions which occur as tectonically dislocated pods in quartzofeldspathic gneisses on the eastern end of Kitak island, South-Bast Greeniand (fig. 5). The anorthosites were selected for study because they are derived from a lithologically distinctive suite of rocks found over a large part of the Archaean craton of the North AtIantic area (Bridgwater et al., 1973b). While there is no evidence that all the anorthosites of this type are contemporaneous their formation appears to require special conditions in the ernst and they are thus likely to be a useful stratigraphic tool. Furthermore the coarse-grained refractory nature of these rocks means that they retain their lithological identity during later tectonic, anatactic and metasomatic events to a far greater degree than the quartzofeldspathic, semipelitic and amphibolitic units making up the major part of the gneiss complex in which the anorthosites occur.

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

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/ggub.v186.5214 ◽

2000 ◽

pp. 42-49 ◽

Cited By ~ 2

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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Rb/Sr whole rock isochron age determinations on metamorphosed acid volcanic rocks and granitic gneisses from the Ketilidian mobile belt, South-East Greenland

Rapport Grønlands Geologiske Undersøgelse ◽

10.34194/rapggu.v66.7398 ◽

1974 ◽

Vol 66 ◽

pp. 12-20

Author(s):

S Pedersen ◽

O Larsen ◽

D Bridgwater ◽

J Watterson

Keyword(s):

Volcanic Rocks ◽

Mobile Belt ◽

High Grade ◽

East Greenland ◽

Volcanic Material ◽

Grade Metamorphism ◽

The North ◽

Acid Volcanic ◽

High Grade Metamorphism ◽

Age Determinations

The metamorphosed supracrustal rocks and paragneisses studied were collected during a reconnaissance traverse across the trend of the Ketilidian mobile belt in South-Bast Greenland (Andrews et al., 1971, 1973). All the samples are taken from gneisses regarded as derived from supracrustal material which was originally composed of acid volcanic material deposited as lavas, ignimbrites or sediments with a large volcanic component. Sample localities are shown in fig. 2. All the rocks have been affected by at least one metamorphic episode during the formation of the Ketilidian mobile belt. All are regarded as deposited after the end of regional high grade metamorphism in the Archaean block to the north (which has yielded a U/Pb zircon diffusion age of 2808 m.y.) and are intruded by a variety of synto late tectonic granites within the Ketilidian mobile belt which have yielded U/Pb diffusion and concordia ages between 1850 and 1770 m.y. in this area (Gulson & Krogh, 1972).

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Stratigraphy of the marine Lower Triassic succession at Kap Stosch, Hold with Hope, North-East Greenland

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-2017-65-07 ◽

2017 ◽

Vol 65 ◽

pp. 87-123

Author(s):

Finn Surlyk ◽

Morten Bjerager ◽

Stefan Piasecki ◽

Lars Stemmerik

Keyword(s):

Arctic Region ◽

Lower Triassic ◽

Coarse Grained ◽

The Arctic ◽

Delta Front ◽

East Greenland ◽

Fine Grained ◽

North East ◽

The North ◽

Shelf Slope

The classical marine uppermost Permian – Lower Triassic succession exposed on the north-east coast of Hold with Hope in East Greenland, south-east of Kap Stosch, is placed in the Wordie Creek Group. A new lithostratigraphic subdivision of the group is proposed here. The group comprises the revised Kap Stosch Formation overlain by the new Godthåb Golf Formation. The Kap Stosch Formation is dominated by alternating fine- and coarse-grained, cliff-forming units that constitute the basis for the erection of eight new members. They are (from below): 1. The Nebalopok Member, uppermost Permian, Hypophiceras triviale ammonoid zone, and lowermost Triassic, lower Griesbachian, Hypophiceras triviale – H. martini ammonoid zones, composed of basinal and base-of-slope siltstones and turbiditic sandstones. 2. The conglomeratic Immaqa Member (H. martini ammonoid zone), consisting of a thick clinoform-bedded unit commonly overlain by horizontally bedded deposits, representing the foreset and topset, respectively, of a Gilbert-type delta. 3. The fine-grained Fiskeplateau Member (H. martini ammonoid zone), composed of siltstones and fine-grained sandstones, representing basinal and delta front deposits. 4. The conglomerate-dominated Knolden Member (H. martini ammonoid zone), comprising a clinoform-bedded unit overlain by horizontally-bedded deposits, representing foreset and topset, respectively, of a Gilbert-type delta. 5. The fine-grained Pyramiden Member, (lower–upper Griesbachian Metophiceras subdemissum, Ophiceras commune and Wordieoceras decipiens ammonoid zones), composed of variegated siltstones and sandstones deposited in proximal basin and slope environments. 6. The Naasut Member (top Griesbachian, probably Wordieoceras decipiens ammonoid zone), dominated by thick structureless coarse-grained sandstones commonly showing clinoform bedding, deposited in slope, base-of-slope and proximal basin environments. 7. The Falkeryg Member (lowermost Dienerian, Bukkenites rosenkrantzi ammonoid zone), comprising thick, commonly pebbly sandstones deposited in shelf, slope and base-of-slope environments. 8. The Vestplateau Member (lower Dienerian, Bukkenites rosenkrantzi ammonoid zone) composed of siltstones and fine-grained sandstones deposited in basinal environments. The overlying Godthåb Golf Formation (Dienerian, Anodontophora breviformis – A. fassaensis bivalve zones) is dominated by shallow marine sandstones with several coarser grained levels. The rich ammonoid faunas of the Wordie Creek Group allow a biostratigraphic zonation which can be correlated with schemes from other parts of the Arctic region. This zonation is complemented with information on palyno, conodont, fish and isotope stratigraphy.

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Preliminary detrital zircon U-Pb Geochronology of the Wasatch Formation, Powder River Basin, Wyoming

The Mountain Geologist ◽

10.31582/rmag.mg.56.3.247 ◽

2019 ◽

Vol 56 (3) ◽

pp. 247-266

Author(s):

Ian Anderson ◽

David H. Malone ◽

John Craddock

Keyword(s):

River Basin ◽

Detrital Zircon ◽

Middle Part ◽

Detrital Zircons ◽

Powder River Basin ◽

Zircon Age ◽

Lower Eocene ◽

The North ◽

Mountain Front ◽

Fluvial Sandstone

The lower Eocene Wasatch Formation is more than 1500 m thick in the Powder River Basin of Wyoming. The Wasatch is a Laramide synorgenic deposit that consists of paludal and lacustrine mudstone, fluvial sandstone, and coal. U-Pb geochronologic data on detrital zircons were gathered for a sandstone unit in the middle part of the succession. The Wasatch was collected along Interstate 90 just west of the Powder River, which is about 50 km east of the Bighorn Mountain front. The sandstone is lenticular in geometry and consists of arkosic arenite and wacke. The detrital zircon age spectrum ranged (n=99) from 1433-2957 Ma in age, and consisted of more than 95% Archean age grains, with an age peak of about 2900 Ma. Three populations of Archean ages are evident: 2886.6±10 Ma (24%), 2906.6±8.4 Ma (56%) and 2934.1±6.6 Ma (20%; all results 2 sigma). These ages are consistent with the age of Archean rocks exposed in the northern part of the range. The sparse Proterozoic grains were likely derived from the recycling of Cambrian and Carboniferous strata. These sands were transported to the Powder River Basin through the alluvial fans adjacent to the Piney Creek thrust. Drainage continued to the north through the basin and eventually into the Ancestral Missouri River and Gulf of Mexico. The provenance of the Wasatch is distinct from coeval Tatman and Willwood strata in the Bighorn and Absaroka basins, which were derived from distal source (>500 km) areas in the Sevier Highlands of Idaho and the Laramide Beartooth and Tobacco Root uplifts. Why the Bighorn Mountains shed abundant Eocene strata only to the east and not to the west remains enigmatic, and merits further study.

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Ketilidian structure and the rapakivi suite between Lindenow Fjord and Kap Farvel, South-East Greenland

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/ggub.v186.5215 ◽

2000 ◽

pp. 50-59

Author(s):

Brian Chadwick ◽

Adam A. Garde ◽

John Grocott ◽

Ken J.W. McCaffrey ◽

Mike A. Hamilton

Keyword(s):

Coastal Region ◽

Field Work ◽

Natural Environment Research Council ◽

East Greenland ◽

The North ◽

Tectonic Processes ◽

Field Investigations ◽

North Eastern ◽

Bad Weather ◽

North Eastern Part

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Chadwick, B., Garde, A. A., Grocott, J., McCaffrey, K. J., & Hamilton, M. A. (2000). Ketilidian structure and the rapakivi suite between Lindenow Fjord and Kap Farvel, South-East Greenland. Geology of Greenland Survey Bulletin, 186, 50-59. https://doi.org/10.34194/ggub.v186.5215 _______________ The southern tip of Greenland is underlain by the Palaeoproterozoic Ketilidian orogen (e.g. Chadwick & Garde 1996; Garde et al. 1998a). Field investigations in the summer of 1999 were focused on the structure of migmatites (metatexites) and garnetiferous granites (diatexites) of the Pelite Zone in the coastal region of South-East Greenland between Lindenow Fjord and Kap Farvel (Figs 1, 2). Here, we first address the tectonic evolution in the Pelite Zone in that region and its correlation with that in the Psammite Zone further north. Then, the structure and intrusive relationships of the rapakivi suite in the Pelite Zone are discussed, including particular reference to the interpretation of the controversial outcrop on Qernertoq (Figs 2, 8). Studies of the structure of the north-eastern part of the Julianehåb batholith around Qulleq were continued briefly from 1998 but are not addressed here (Fig. 1; Garde et al. 1999). The field study was keyed to an interpretation of the Ketilidian orogen as a whole, including controls of rates of thermal and tectonic processes in convergent settings. Earlier Survey field work (project SUPRASYD, 1992–1996) had as its principal target an evaluation of the economic potential of the orogen (Nielsen et al. 1993). Ensuing plate-tectonic studies were mainly funded in 1997–1998 by Danish research foundations and in 1999 by the Natural Environment Research Council, UK. The five-week programme in 1999 was seriously disrupted by bad weather, common in this part of Greenland, and our objectives were only just achieved. Telestation Prins Christian Sund was the base for our operations (Fig. 2), which were flown with a small helicopter (Hughes MD-500).

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New insights on the north-eastern part of the Ketilidian orogen in South-East Greenland

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/ggub.v183.5201 ◽

1999 ◽

pp. 23-33 ◽

Cited By ~ 3

Author(s):

Adam A. Garde ◽

John Grocott ◽

Ken J.W. McCaffrey

Keyword(s):

Sea Ice ◽

Coastal Areas ◽

East Greenland ◽

Original Series ◽

The North ◽

North Eastern ◽

North Eastern Part ◽

Geological Research

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Garde, A. A., Grocott, J., & McCaffrey, K. J. (1999). New insights on the north-eastern part of the Ketilidian orogen in South-East Greenland. Geology of Greenland Survey Bulletin, 183, 23-33. https://doi.org/10.34194/ggub.v183.5201 _______________ During a five week period in August–September 1998 the poorly known north-eastern part of the Palaeoproterozoic (c. 1800 Ma) Ketilidian orogen between Kangerluluk and Mogens Heinesen Fjord in South-East Greenland (Fig. 1) was investigated in continuation of recent geological research in other parts of the orogen. The north-eastern part of the orogen is remote from inhabited areas. It is mountainous and comprises a wide nunatak zone which can only be reached easily by helicopter. Furthermore, access to coastal areas by boat is difficult because many parts of the coast are prone to be ice-bound even during the summer months, due to wind- and current-driven movements of the sea ice.

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Hydrothermal activity in the Upper Permian Ravnefjeld Formation of central East Greenland – a study of sulphide morphotypes

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/ggub.v180.5090 ◽

1998 ◽

pp. 81-87

Author(s):

Jesper Kresten Nielsen ◽

Mikael Pedersen

Keyword(s):

Base Metal ◽

Early Period ◽

Sedimentary Basins ◽

Hydrothermal Activity ◽

Source Rocks ◽

Upper Permian ◽

Thermal Activity ◽

East Greenland ◽

The North ◽

Alum Shale

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Kresten Nielsen, J., & Pedersen, M. (1998). Hydrothermal activity in the Upper Permian Ravnefjeld Formation of central East Greenland – a study of sulphide morphotypes. Geology of Greenland Survey Bulletin, 180, 81-87. https://doi.org/10.34194/ggub.v180.5090 _______________ Bituminous shales of the Ravnefjeld Formation were deposited in the subsiding East Greenland basin during the Upper Permian. The shales are exposed from Jameson Land in the south (71°N; Fig. 1) to Clavering Ø in the north (74°20′N) and have attracted considerable attention due to their high potential as hydrocarbon source rocks (Piasecki & Stemmerik 1991; Scholle et al. 1991; Christiansen et al. 1992, 1993a, b). Furthermore, enrichment of lead, zinc and copper has been known in the Ravnefjeld Formation on Wegener Halvø since 1968 (Lehnert-Thiel 1968; Fig. 1). This mineralisation was assumed to be of primary or early diagenetic origin due to similarities with the central European Kupferschiefer (Harpøth et al. 1986). Later studies, however, suggested base metal mineralisation in the immediately underlying carbonate reefs to be Tertiary in age (Stemmerik 1991). Due to geographical coincidence between the two types of mineralisation, a common history is a likely assumption, but a timing paradox exists. A part of the TUPOLAR project on the ‘Resources of the sedimentary basins of North and East Greenland’ has been dedicated to re-investigation of the mineralisation in the Ravnefjeld Formation in order to determine the genesis of the mineralisation and whether or not primary or early diagenetic base metal enrichment has taken place on Wegener Halvø, possibly in relation to an early period of hydrothermal activity. One approach to this is to study the various sulphides in the Ravnefjeld Formation; this is carried out in close co-operation with a current Ph.D. project at the University of Copenhagen, Denmark. Diagenetically formed pyrite is a common constituent of marine shales and the study of pyrite morphotypes has previously been successful from thermalli immature parts of elucidating depositional environment and thermal effects in the Alum Shale Formation of Scandinavia (Nielsen 1996; Nielsen et al. 1998). The present paper describes the preliminary results of a similar study on pyrite from thermally immature parts of the Ravnefjeld Formation which, combined with the study of textures of base metal sulphides in the Wegener Halvø area (Fig. 1), may provide an important step in the evaluation of the presence or absence of early thermal activity on (or below) the Upper Permian sea floor.

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Environmental impact of nutrients from nordic fish farming

Water Science & Technology ◽

10.2166/wst.1995.0364 ◽

1995 ◽

Vol 31 (10) ◽

pp. 61-71 ◽

Cited By ~ 14

Author(s):

M. Enell

Keyword(s):

Major Part ◽

Fish Farming ◽

Fish Farms ◽

Feed Composition ◽

The North ◽

Comprehensive Development ◽

The Baltic ◽

Inland Water Bodies ◽

The Impact ◽

Feed Coefficient

During the last 20 years there has been an interesting development of the Nordic fish farming, with regard to the feeding and farming technology and to the increase in production quantities. During the period 1974-1994 the production increased from 15,800 to about 250,000 tonnes/year. In 1974 the major part of the production was in Denmark, and in 1994 the major part was in Norway. The nutrient impact of fish farming on surrounding sea areas is mainly a function of the feed coefficient, the feed composition and metabolic processes in the fish. The comprehensive development of the feed composition and the feeding technology has resulted in reduced load of unmetabolized nutrients from fish farms, calculated per tonne fish produced. In 1974 the mean Nordic feed coefficient was 2.08 and in 1994 the coefficient was 1.25. Feed coefficients of 1.0-1.1 are now reported for Danish and Norwegian freshwater and marine fish farms. The nitrogen (N) and phosphorus (P) content of the feed has decreased, in addition the quality of the nutrient substances in the feed has changed, especially for N. The N content has decreased from 7.8 to 6.8% during the period 1974-1994 and the content of P has decreased from 1.7 to 0.7% during the same period. This development of the feed coefficient and the feed composition has resulted in a present load from a typical Nordic fish farm of 55 kg N and 4.8 kg P/t fish produced. The figures for 1974 were 132 kg N and 31 kg P/t fish produced. The Nordic fish farming production in 1994 resulted in a load of about 13,750 t N and about 1,200 t P on the actual recipients. The load from the Swedish, Finnish and Danish fish farming operations, with the Baltic Sea and the Skagerrak as the recipients, is negligible in comparison with other pollution sources. The quantities of N and P from the fish farming are equal to 0.5% of the atmospheric deposition on the sea surface and 3% of the atmospheric P load. Norwegian, Icelandic and the Faroe Islands fish farming operations are using the North Sea and the Norwegian Sea as the recipients. However, the nutrient load from single fish farms in certain coastal and inland water bodies can be significant and must be considered in the impact assessment together with other sources.

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