The year in focus, 2001

2002 ◽  
pp. 9-12
Author(s):  
Kai Sørensen
Keyword(s):  
Sedimentary Rocks ◽  
Crystalline Basement ◽  
Boundary Zone ◽  
Systematic Mapping ◽  
Aeromagnetic Survey ◽  
East Greenland ◽  
West Greenland ◽  
North West ◽  
North East ◽  
Lower Palaeozoic

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, e.g.: Sørensen, K. (2002). The year in focus, 2001. Geology of Greenland Survey Bulletin, 191, 9-12. https://doi.org/10.34194/ggub.v191.5057 Field activities in Greenland by the Geological Survey of Denmark and Greenland (GEUS) in 2001 were again many and varied. They included economic investigations of crystalline basement and sedimentary rocks in North-West Greenland, and a systematic mapping project combined with resource evaluation in the boundary zone of the Nagssugtoqidian and Rinkian mobile belts of central and southern West Greenland. In addition, studies of the Vendian to Lower Palaeozoic successions in North-East Greenland and of the Palaeogene sediments of central East Greenland were carried out, a major aeromagnetic survey was flown in central West Greenland, and investigations of Holocene lake sediments in southern West Greenland were continued.

Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland

1999 ◽  
pp. 65-78
Author(s):  
Henrik Rasmussen ◽  
Lars Frimodt Pedersen
Keyword(s):  
Tectonic Setting ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
West Greenland ◽  
North West ◽  
North East ◽  
Metavolcanic Rocks ◽  
Arc Setting ◽  
Area North ◽  
Back Arc

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, H., & Frimodt Pedersen, L. (1999). Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 65-78. https://doi.org/10.34194/ggub.v181.5114 _______________ Two Archaean supracrustal sequences in the area north-east of Disko Bugt, c. 1950 and c. 800 m in thickness, are dominated by pelitic and semipelitic mica schists, interlayered with basic metavolcanic rocks. A polymict conglomerate occurs locally at the base of one of the sequences. One of the supracrustal sequences has undergone four phases of deformation; the other three phases. In both sequences an early phase, now represented by isoclinal folds, was followed by north-west-directed thrusting. A penetrative deformation represented by upright to steeply inclined folds is only recognised in one of the sequences. Steep, brittle N–S and NW–SE striking faults transect all rock units including late stage dolerites and lamprophyres. Investigation of major- and trace-element geochemistry based on discrimination diagrams for tectonic setting suggests that both metasediments and metavolcanic rocks were deposited in an environment similar to a modern back-arc setting.

scholarly journals Lithostratigraphy of the continental Devonian sediments in North-East Greenland

1993 ◽  
Vol 165 ◽  
pp. 1-108
Author(s):  
H Olsen ◽  
P.H Larsen
Keyword(s):  
Sedimentary Rocks ◽  
East Greenland ◽  
North East ◽  
Genetic Stratigraphy

A new lithostratigraphy is erected for the continental Devonian sedimentary rocks in North-East Greenland based on genetic stratigraphy.

scholarly journals Field investigations in the Precambrian terrain of the Thule district, North-West Greenland

1979 ◽  
Vol 95 ◽  
pp. 14-22
Author(s):  
P.R Dawes
Keyword(s):  
Field Work ◽  
Crystalline Basement ◽  
Field Mapping ◽  
West Greenland ◽  
North West ◽  
Field Investigations ◽  
Precambrian Terrain ◽  
Outer Coast ◽  
Three Phases

The field mapping of the Precambrian crystalline basement and overlying Thule Group of the Thule district aimed at the production of a 1:500000 map sheet between 75°15'N and 78°N was continued in July and August (fig. 5). The field work was split up, due to the varying availability of transport facilities, into three phases. (1) The charter of a Bell 204 helicopter from Thule Air Base enabled mapping in western Inglefield Land, and in the nunatak terrain of Prudhoe Land and Melville Bugt. (2) Investigation of the outer coast of western Melville Bugt was carried out with the aid of GGU cutter K. J. V. Steenstrup. (3) Detailed stratigraphical work in the middle and upper part of the Thule Group was based on foot traverses from Thule Air Base.

scholarly journals Reaction of Precambrian high-grade gneisses to mid-crustal ductile deformation in western Dove Bugt, North-East Greenland

1994 ◽  
Vol 162 ◽  
pp. 53-70
Author(s):  
B Chadwick ◽  
C.R.L Friend
Keyword(s):  
Shear Zones ◽  
Ductile Deformation ◽  
Small Scale ◽  
High Grade ◽  
East Greenland ◽  
North West ◽  
North East ◽  
Basin Development ◽  
Ductile Shear Zones ◽  
Partial Melts

Mid-crustal deformation of an Early Proterozoic high-grade gneiss complex in western Dove Bugt gave rise to at least two sets of nappes. Structures in mylonites in low-angle ductile shear zones associated with the younger nappes indicate north-easterly-directed displacements. The nappes and mylonites are folded by upright to inclined folds that verge north-west and which appear to be associated with decollements that dip south-east. Hornblende, sillimanite and anatectic partial melts that developed with the nappes, mylonites and younger folds show that deformation took place under amphibolite facies conditions. Several lines of evidence suggest that the younger nappes, the mylonites and the upright to inclined folds formed during the Caledonian orogeny. Some pre-Caledonian deformation may be represented by the oldest isoclinal folds. Numerous, small-scale, ductile extensional shear zones and more brittIe fractures that were superimposed across the Caledonian structures are believed to have formed during orogen-parallel collapse which may be related IO Devonian basin development farther south in central East Greenland. Younger fauIts and major joints are correlated with Carboniferous, Mesozoic and Tertiary basin development in North-East Greenland.

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.

Lower–Middle Ordovician stratigraphy of North-East Greenland

2002 ◽  
pp. 117-125 ◽  
Author(s):  
Svend Stouge ◽  
W. Douglas Boyce ◽  
Jørgen L. Christiansen ◽  
David A.T. Harper ◽  
Ian Knight
Keyword(s):  
Passive Margin ◽  
East Greenland ◽  
Middle Ordovician ◽  
North East ◽  
Upper Proterozoic ◽  
Iapetus Ocean ◽  
Rodinia Supercontinent ◽  
Lower Palaeozoic ◽  
Early Palaeozoic ◽  
Laurentian Margin

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Stouge, S., Boyce, W. D., Christiansen, J. L., Harper, D. A., & Knight, I. (2002). Lower–Middle Ordovician stratigraphy of North-East Greenland. Geology of Greenland Survey Bulletin, 191, 117-125. https://doi.org/10.34194/ggub.v191.5138 _______________ The Upper Proterozoic (Riphean) to Lower Palaeozoic succession in North-East Greenland is exposed in a broad N–S-trending belt in the fjord region between 71°38´ and 74°25´N (Fig. 1). The succession comprises mainly marine sediments accumulated during the later stages of the break-up of the Rodinia supercontinent, the subsequent opening of the Iapetus Ocean and formation of the passive margin along the edge of the Laurentian palaeocontinent. Investigations of the sedimentary succession were initiated on Ella Ø in the summer of 2000 as part of a project to investigate the development of the Laurentian margin facing the Iapetus Ocean in the Early Palaeozoic, when studies of the uppermost formations of the Riphean Eleonore Bay Supergroup to the Lower Ordovician Antiklinalbugt Formation on Ella Ø were undertaken (Stouge et al. 2001). Ella Ø was revisited during the summer of 2001, with the focus on the Ordovician formations. In addition, investigations were undertaken in the Albert Heim Bjerge area where the uppermost part of the Ordovician succession is preserved (Fig. 1).

New constraints on the tectonic activity of the “Tellian Domain” from Northern Tunisia: preliminary paleomagnetic results.

2020 ◽  
Author(s):  
Philippe Robion ◽  
Marwen Arfaoui ◽  
Riadh Ahmadi ◽  
Mohamed El Messaoud Derder ◽  
Mohamed Amena ◽  
...  
Keyword(s):  
Rock Magnetism ◽  
Kinematic Model ◽  
Sedimentary Rocks ◽  
Vertical Axis ◽  
Geometric Constraints ◽  
Tectonic Activity ◽  
North West ◽  
North East ◽  
Magnetization Intensity ◽  
Characteristic Component

<p>In this study, we present preliminary results on paleomagnetic data collected in the Tunisian Tellian domain in both magmatic and sedimentary rocks of middle to lat Miocene ages from the Nefza-Mogods province, North-West of Tunisia. About 320 cores distributed over twenty one sites were collected both in magmatic rocks (16 sites) and in sedimentary rocks (5 sites), in order to obtain geometric constraints to establish a kinematic model along the North-East African margin. The sampled rocks are distributed between basanites, rhyodacites and microgranites. Some samples were taken from host sedimentary rocks host rocks in lacustrine limestones and jaspilites. Demagnetization process and Rock-Magnetism studies revealed a diversified magnetic mineralogy. In basalts, magnetite with an unblocking temperature of 580 °C is identified. In rhyodacites, the mineralogy is mixed with three types of minerals: a mineral with an unblocking temperature around 350°-400°C attributed either to a sulfide or to titanomagnetite, magnetite with unblocking temperature at 580°C, and a high temperature mineral with unblocking temperature between 600°C and 680°C attributed to hematite or titanohematite. The limestones, having a low magnetization intensity, are characterized by the presence of magnetite and the jaspilites by hematite. Basalts, which have been mainly demagnetized by AF process , show a characteristic component demagnetized between 20mT and 100mT. For rhyodacites, some sites have a characteristic component demagnetized between 400°C and 580°C and others up to 670°C. Although their low magnetization intensity, the lacustrine limestones show a magnetic component between 20mT and 140 mT. The first result indicate that the mean directions associated to the younger magmatic (basalts and rhyodacite) rocks (8 Ma, Tortonian) and their sedimentary host deposits are very close to the expected magnetic field after tilting in paleogeographic coordinates. By contrast, the older microgranites and rhyodacites(-12 Ma) display a vertical axis clockwise rotation of about 30°. This result suggests a significant tectonic phase between 12 Ma and 8 Ma, linked to the implementation of the Tell nappes.</p>

scholarly journals An investigation of the igneous rocks on Hareøen and western Nûgssuaq, West Greenland

1971 ◽  
Vol 35 ◽  
pp. 11-13
Author(s):  
N Hald
Keyword(s):  
East Coast ◽  
Geological Mapping ◽  
Igneous Rocks ◽  
South Coast ◽  
The South ◽  
West Greenland ◽  
North West ◽  
North East ◽  
The North ◽  
Basaltic Lavas

Hareøen is an island north-west of Disko in western Greenland. It has the form of a plateau, whose highest point - 512 metres - is found near the south coast. Like the neighbouring parts of Nugssuaq and Disko, Hareøen consists chiefly of Tertiary basaltic lavas. The island first attracted attention on account of the presence of interbasaltic, coal-bearing sediments on the north-east coast. These were already examined by Giesecke in 1811 (Giesecke, 1910) and later among others by Steenstrup (1874) and B.E. Koch (1959). A petrographie investigation of the basalts was first undertaken by Holmes (1919), who described loose fragments rich in K2O. Lavas from the south coast, colleeted and analysed by Pedersen (1970), also have a high content of potash. V. Miinther in the years 1948-49 untertook geological mapping of the island, on which the present investigation is supported (Miinther, in press).

scholarly journals Eastern North Greenland 1993-1995 - a new 1:500 000 mapping project

1994 ◽  
Vol 160 ◽  
pp. 47-51
Author(s):  
N Henriksen
Keyword(s):  
Field Work ◽  
Geological Survey ◽  
East Greenland ◽  
West Greenland ◽  
North West ◽  
General Overview ◽  
North Greenland

The Geological Survey of Greenland (GGU) initiated in 1964 a 1:500000 mapping programme to produce a general overview of the onshore geology of all the ice-free areas of Greenland. So far 10 of a total of 14 planned map sheets have been published, and one additional sheet for which field work has been completed is under compilation. Most of Greenland is therefore now covered by map sheets of this series and only three areas remain to be covered: in North-West Greenland (sheet 6), in eastern North Greenland (sheet 9) and in East Greenland (sheet 11). Eastern North Greenland (map sheet no. 9; Fig. 1) is the target of the present project, with planned field work from 1993–1995. The first season (1993) was used for logistical preparation and geological reconnaissance in advance of the more intensive field work in the two following seasons (1994–95).

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