scholarly journals New insights from field observations of the Younger giant dyke complex and mafic lamprophyres of the Gardar Province on Tuttutooq island, South Greenland

Author(s):  
Lot Koopmans ◽  
Robert A. Webster ◽  
Rory Changleng ◽  
Lucy Mathieson ◽  
Alasdair J. Murphy ◽  
...  

The Gardar Province of south Greenland is defined by the products of alkaline igneous magmatism during the Mesoproterozoic. The most laterally extensive Gardar intrusions are a series of giant dyke complexes best exposed on the Tuttutooq archipelago. We present new field observations and a geological map of north-east Tuttutooq island that provide fresh insights into the temporal evolution of the Younger giant dyke complex and two associated ultramafic lamprophyres. Our data demonstrate that distinctive crystallisation regimes occurred in different sectors of the dyke complex, leading to the formation of marginal gabbros and ovoid pod-like domains displaying lamination, modal layering and/or more evolved differentiates. We infer that at least two pulses of magma contributed to the formation of the Younger giant dyke complex. In addition, the relative ages of two ultramafic lamprophyre diatremes are constrained and attributed to two distinct phases of rifting in the Gardar Province.

1920 ◽  
Vol 57 (11) ◽  
pp. 500-503 ◽  
Author(s):  
J. W. Gregory ◽  
Ethel Currie

THE Geological Department of Glasgow University has recently received from Dr. W. R. Smellie and Mr. J. V. Harrison some fossils collected by them which throw further light on the age of the limestones of the Persian arc at the north-western end of Luristan, about 100 miles north-east of Baghdad. The locality, Gilan, is on a tributary of the Diala, about 30 miles south-east of Kasr-i-Shirin, a well-known station on the main road from Baghdad to Teheran. The geology of this part of the Persian frontier has been investigated by J. de Morgan (Miss. Sci. Perse, vol. iii, pt. i, Étud. Géol., 1905, pp. 71–112), who has given a geological map (ibid., pl. xix) of an area about 60 miles south-east of Gilan. De Morgan has identified there a folded series of Cretaceous and Eocene limestones, with lacustrine and gypsiferous Miocene beds. The locality at which the fossils were collected by Messrs. Smellie and Harrison is in line with the strike of the rocks in the area of de Morgan's map.


1995 ◽  
Vol 165 ◽  
pp. 53-58
Author(s):  
N Henriksen

The second field season of the Geological Survey of Greenland's (GGU) mapping project in eastern North Greenland (1993–95) was carried out according to plan and with full accomplishment of all geoscientific goals. The programme aims at producing a general overview of the onshore geology of the Jokelbugten to Kronprins Christian Land region (78–81 °N) in eastern North Greenland (Fig. 1) to be compiled as sheet no. 9 in GGU's 1:500 000 geological map sheet series; this is the last remaining incomplete map sheet at this scale in North and North-East Greenland. The field work was initiated in 1993 with limited reconnaissance work (Henriksen, 1994a), and in 1994 the first of two more intensive field campaigns was carried out. In addition to establishing a general overview of the regional geology the work aims at obtaining an evaluation of the economic geological potential of the region, in respect of both minerals and hydrocarbons. Two glaciological programmes were fully integrated with the project: one was carried out by the Alfred Wegener Institute (AWi), Bremerhaven, Germany, while the other was partly based on a special grant from the Nordic Council of Ministers.


1990 ◽  
Vol 148 ◽  
pp. 16-20
Author(s):  
N Henriksen

A three-year field mapping programme was initiated in 1988 aiming at regional geological studies and geological mapping in North-East Greenland between latitudes 75° and 78°N. This region encompasses relatively little known parts of the Caledonian fold belt and the overlying post-Caledonian sequences, which lie north of the better known regions of central East Greenland (Henriksen, 1989). Major aims of the programme include compilation a 1:500 000 geological map, and an understanding of the general geology of the region.


2021 ◽  
pp. 101-110 ◽  
Author(s):  
Lusmeilia Afriani ◽  
Gatot Eko Susilo ◽  
Sri Nawangrini ◽  
Iswan Iswan

Research in this paper discusses shrinking and consolidation of flood embankments soil in swamp irrigation areas. The flood embankments are made from swampy soil materials. The focus of this research is the reduction of dyke embankment height that occurs due to soil shrinkage and soil consolidation. Investigations about the time of consolidation and land subsidence that occurred on the embankment at certain periods after the embankment established were also carried out in this study. The research sites are some swamp irrigation areas in the Tulang Bawang Watershed, around North-East Lampung, Indonesia. This research was carried out by conducting laboratory tests on soil samples and field observations on the reduction in height of flood embankments in the study area. The research shows that the main cause of total decrease on the embankment is due to linear shrinkage, consolidation of soil under the embankment, an immediate subsidence, and the subsidence of the embankment themselves. Their contribution to total decrease of embankment is 42.51%, 34.48%, 18.32%, and 4.62%, respectively. Results also indicate that the ratio between the percentage of embankment consolidation in downstream area happen faster than the one in upstream area of the river.


2007 ◽  
Vol 144 (6) ◽  
pp. 897-908 ◽  
Author(s):  
B. O'Driscoll

AbstractDetailed remapping of the Palaeogene Ardnamurchan Centre 3 gabbros, NW Scotland, suggests that this classic sequence of ring-intrusions forms a composite layered lopolith. The area mapped by previous studies as the Great Eucrite gabbro intrusion comprises 70% by area of Centre 3. Field observations suggest that most of the other smaller ring-intrusions of Centre 3 (interior to the Great Eucrite) constitute either distinct petrological facies of the same intrusion, or included country-rock or peridotite blocks. These observations, together with syn-magmatically deformed inward-dipping modal layering, are used here to support the interpretation that significant central sagging occurred in the intrusion at a late stage in its crystallization history.


1991 ◽  
Vol 1 (1) ◽  
pp. 1-9 ◽  
Author(s):  
A. T. Juniper ◽  
C. Yamashita

SummarySpix's Macaw Cyanopsitta spixii has always been a very poorly known species from the arid interior of north-east Brazil. Previous views that its habitat is buriti palm swamp appear mistaken, as the most recent field observations and the testimony of local people suggest that Tabebuia caraiba gallery woodland along seasonal creeks is a critical habitat component. Owing to widespread destruction of such woodland, during a survey in June/July 1990 only three good patches were found, all failing to regenerate; one held a single bird, and another held birds up to last year.A Ararinha-azul Cyanopsitta spixii sempre foi uma espécie pouco conhecida no interior árido do nordeste do Brasil. Opiniōes anteriores que o seu habitat é buritizais parecem erradas porque as observações de campo mais recentes e o testimônio dos habitantes locais sugestem que matas de Tabebuia caraiba ao longo de riachos estacionais são um crítico componente do habitat. Devido à destruição extensa deste tipo de mata, durante um levantamento em junho/julho 1990 somente tres áreas boas foram achadas, todas sem regeneração; uma abrigava um único pássaro, e uma outra abrigava pássaros até o ano passado.


2005 ◽  
Vol 2 ◽  
pp. 111-116 ◽  
Author(s):  
A. Barrera ◽  
M. Barriendos ◽  
M. C. Llasat

Abstract. In this paper the catastrophic and extraordinary floods occurring in Barcelona County (Catalonia, NE Spain) are studied, in order to characterise the temporal evolution of extreme flash floods in that area and their main features. These events usually cause economical losses and major problems for undertaking daily activity in Barcelona city. This kind of floods is a very common feature in the North-east of Spain and they are recorded every year in some point of Catalonia. This contribution also shows the frequency of those events, within the framework of all the floods that have occurred in Barcelona since the 14th century, but also describes the flooded area, urban evolution, impacts and the weather conditions for any of most severe events. The evolution of flood occurrence shows the existence of oscillations in the earlier and later modern age periods that can be attributed to climatic variability, evolution of the perception threshold and changes in vulnerability. A great increase of vulnerability can be assumed for the period 1850-1900. The analysis of the time evolution for the Barcelona rainfall series (1854-2000) shows that no trend exists, although, due to the changes in urban planning, flash-floods impact has changed over this time. The number of catastrophic flash floods has diminished, although the extraordinary ones have increased.


Author(s):  
Kristian Svennevig ◽  
Peter Alsen ◽  
Pierpaolo Guarnieri ◽  
Jussi Hovikoski ◽  
Bodil Wesenberg Lauridsen ◽  
...  

The geological map sheet of Kilen in 1:100 000 scale covers the south-eastern part of the Carboniferous– Palaeogene Wandel Sea Basin in eastern North Greenland. The map area is dominated by the Flade Isblink ice cap, which separates several minor isolated landmasses. On the semi-nunatak of Kilen, the map is mainly based on oblique photogrammetry and stratigraphical field work while in Erik S. Henius Land, Nordostrundingen and northern Amdrup Land the map is based on field data collected during previous, 1:500 000 scale regional mapping. Twenty-one Palaeozoic–Mesozoic mappable units were identified on Kilen, while the surrounding areas comprise the Late Cretaceous Nakkehoved Formation to the north-east and the Late Carboniferous Foldedal Formation to the south-west. On Kilen, the description of Jurassic–Cretaceous units follows a recently published lithostratigraphy. The Upper Palaeozoic–lowermost Cretaceous strata comprise seven formations and an informal mélange unit. The overlying Lower–Upper Cretaceous succession comprises the Galadriel Fjeld and Sølverbæk Formations, which are subdivided into six and five units, respectively. In addition, the Quaternary Ymer Formation was mapped on south-east Kilen. The Upper Palaeozoic to Mesozoic strata of Kilen are faulted and folded. Several post-Coniacian NNW–SSE-trending normal faults are identified and found to be passively folded by a later N–S compressional event. A prominent subhorizontal fault, the Central Detachment, separates two thrust sheets, the Kilen Thrust Sheet in the footwall and the Hondal Elv Thrust Sheet in the hanging wall. The style of deformation and the structures found on Kilen are caused by compressional tectonics resulting in post-extensional, presumably Early Eocene, folding and thrusting and basin inversion. The structural history of the surrounding areas and their relation to Kilen await further studies.


Author(s):  
Kristian Svennevig ◽  
Peter Alsen ◽  
Pierpaolo Guarnieri ◽  
Jussi Hovikoski ◽  
Bodil Wesenberg Lauridsen ◽  
...  

NOTE: This Map Description was published in a former series of GEUS Bulletin. Please use the original series name when citing this series, for example: Svennevig, K., Alsen, P., Guarnieri, P., Hovikoski, J., Wesenberg Lauridsen, B., Krarup Pedersen, G., Nøhr-Hansen, H., & Sheldon, E. (2018). Descriptive text to the Geological map of Greenland, 1:100 000, Kilen 81 Ø.1 Syd. Geological Survey of Denmark and Greenland Map Series 8, 1-29. https://doi.org/10.34194/geusm.v8.4526 _______________ The geological map sheet of Kilen in 1:100 000 scale covers the south-eastern part of the Carboniferous–Palaeogene Wandel Sea Basin in eastern North Greenland. The map area is dominated by the Flade Isblink ice cap, which separates several minor isolated landmasses. On the semi-nunatak of Kilen, the map is mainly based on oblique photogrammetry and stratigraphical field work while in Erik S. Henius Land, Nordostrundingen and northern Amdrup Land the map is based on field data collected during previous, 1:500 000 scale regional mapping. Twenty-one Palaeozoic–Mesozoic mappable units were identified on Kilen, while the surrounding areas comprise the Late Cretaceous Nakkehoved Formation to the north-east and the Late Carboniferous Foldedal Formation to the south-west. On Kilen, the description of Jurassic–Cretaceous units follows a recently published lithostratigraphy. The Upper Palaeozoic–lowermost Cretaceous strata comprise seven formations and an informal mélange unit. The overlying Lower–Upper Cretaceous succession comprises the Galadriel Fjeld and Sølverbæk Formations, which are subdivided into six and five units, respectively. In addition, the Quaternary Ymer Formation was mapped on south-east Kilen. The Upper Palaeozoic to Mesozoic strata of Kilen are faulted and folded. Several post-Coniacian NNW–SSE-trending normal faults are identified and found to be passively folded by a later N–S compressional event. A prominent subhorizontal fault, the Central Detachment, separates two thrust sheets, the Kilen Thrust Sheet in the footwall and the Hondal Elv Thrust Sheet in the hanging wall. The style of deformation and the structures found on Kilen are caused by compressional tectonics resulting in post-extensional, presumably Early Eocene, folding and thrusting and basin inversion. The structural history of the surrounding areas and their relation to Kilen await further studies.


1955 ◽  
Vol 92 (2) ◽  
pp. 127-140 ◽  
Author(s):  
G. D. Nicholls

AbstractField observations collected on a short expedition to Jan Mayen indicate that ankaramite was extruded at three different periods at the north-eastern end of the island, either as lava flows or pyroclastic deposits. Cycles of volcanic activity, in which the earlier lavas are ankaramite and the later ones trachybasaltic, have been recognized.


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