GEUS Bulletin (Geological Survey of Denmark and Greenland)
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Colophon, contents and preface
No full textThe Jurassic rift succession of East Greenland has been intensely studied over the last 25 years, particularly within the main outcrop areas of Jameson Land and Wollaston Forland. The more isolated and poorly known outcrops on Traill Ø, Hold with Hope, Hochstetter Forland and Store Koldewey were investigated in the late 1980s and mid-1990s in order to develop a better regional understanding of the Jurassic in eastern Greenland.
This collection of seven papers focuses on stratigraphic and depositional aspects of the Jurassic at these localities. Comprehensive descriptions of the Jurassic on Hold with Hope and south-eastern Traill Ø are accompanied by papers covering fluvial deposits and new ammonite collections from the Middle Jurassic of Traill Ø. The bulletin is concluded by studies of the dinoflagellate cyst stratigraphy of the Middle and Upper Jurassic of Hold with Hope, Hochstetter Forland and Store Koldewey
Jurassic syn-rift sedimentation on a seawards-tilted fault block, Traill Ø, North-East Greenland
No full textMiddle–Late Jurassic rifting in East Greenland was marked by westwards tilting of wide fault blocks bounded by major N–S-trending east-dipping synthetic faults. The syn-rift successions thicken westwards towards the faults and shallow marine sandstones show mainly southwards axial transport directions. An exception to this general pattern is found in south-east Traill Ø, which constitutes the E-tilted Bjørnedal Block, which is bounded to the west by the westwards-dipping antithetic Vælddal Fault. The stratigraphic development of the Jurassic succession on this block shows important differences to the adjacent areas reflecting a different tectonic development. Shallow marine sand seems initially to have filled accommodation space of the immediately adjacent block to the west. This block subsequently acted as a bypass area and much of the sediment was spilled eastwards onto the hangingwall of the east-dipping Bjørnedal Block. The succession on the Bjørnedal Block shows an eastwards proximal–distal decrease in sandstone– mudstone ratio, reflecting increasing water depth and progressive under-filling of the subbasin towards the east in agreement with the dip direction of the fault block. The transverse, mainly south-eastwards palaeocurrents, the eastwards increase in water depths and decrease in sandstone–mudstone ratio on the Bjørnedal Block are at variance with the standard picture of west-tilted blocks with southwards-directed palaeocurrents and decrease in grain size. Earlier palaeogeographic reconstructions have to be modified to account for the east-dipping hangingwall and different stratigraphic development of the area. The sea was thus open towards the east and there is no direct indication of a barrier or shoal east of Traill Ø
Jurassic dinoflagellate cysts from Hochstetter Forland, North-East Greenland
No full textThree sections in Hochstetter Forland, North-East Greenland, referred to the Jurassic Payer Dal and Bernbjerg Formations, have been analysed for dinoflagellate cysts. The dinoflagellate cysts, new finds of ammonites and previously recorded marine faunas form the basis for improved dating of the succession. The basal strata of the Payer Dal Formation at Kulhus is here dated as Late Callovian, Peltoceras athleta Chronozone, based on the presence of relatively abundant Limbicysta bjaerkei, Mendicodinium groenlandicum, Rhychoniopsis cladophora and Tubotuberella dangeardii in an otherwise poor Upper Callovian dinoflagellate assemblage. Ammonites have not been recorded from these strata. The upper Payer Dal Formation at Agnetesøelven is dated as Late Oxfordian, Amoeboceras glosense – Amoeboceras serratum Chronozones, based on the presence of Sciniodinium crystallinum, together with Cribroperidinium granuligera and Stephanelytron sp. The age is in accordance with ammonites present in the uppermost part of the formation at Søndre Muslingebjerg. New ammonites in the Bernbjerg Formation at Agnetesøelven together with dinoflagellate cysts indicate an earliest Kimmeridgian age, Rasenia cymodoce and Aulacostephanoides mutabilis Chronozones. The Upper Callovian dinoflagellate cysts from Hochstetter Forland belong to a local brackish to marginal marine assemblage, which only allows a fairly broad correlation to coeval assemblages in central East Greenland. In contrast, the Oxfordian and Kimmeridgian assemblages are fully marine and can be correlated from Milne Land in central East Greenland via Hochstetter Forland to Peary Land in eastern North Greenland
Petroleum potential of sedimentary basins in Vietnam: long-term geoscientific co-operation with the Vietnam Petroleum Institute
No full textThe Vietnam Petroleum Institute (VPI) and the Geological Survey of Denmark and Greenland (GEUS) have carried out a programme of geoscientific research and institutional capacity building since 1995. It has included geoscientific projects focused on assessment of the hydrocarbon potential of selected sedimentary basins, technology transfer and inhouse training at VPI in Hanoi and at GEUS in Copenhagen. Co-operation is continuing within the framework of a new, long-term project that aims to strengthen research capacity in Vietnam within the fields of basin analysis and modelling
The environmental changes within the seven regions through the Late Quaternary evaluated by the molluscan communities met with in the seven stages
No full textUsing the geological record to assess the changing status of Danish lakes
No full textThe Danish Nationwide Aquatic Monitoring Programme (Kristensen et al. 1991; Kronvang et al. 1996) is one of the most comprehensive in Europe and, compared with other national programmes, was put in place at an early date: the systematic monitoring of freshwater lakes began in 1989. As with all such programmes of long-term environmental monitoring, its value multiplies with time as an increasing number of scientific hypotheses can be tested and management questions addressed using the growing body of data. However, the aquatic monitoring data, as for many natural systems, are limited to the scale of decades and so may not identify important longer-term trends or be useful in the determination of ‘baseline’ (pre-industrial or pre-agricultural impact) conditions. The study of lake sediments, palaeolimnology, offers a means of extending the monitoring of lake status back in time and can be used to determine baseline conditions (e.g. for water chemistry variables), to define trends and rates of change, and to identify the causes of change (Battarbee 1999). The data obtained from palaeolimnological studies can provide a yardstick against which current and future changes may be assessed. Furthermore, restoration targets for lakes impacted by for example enhanced nutrient loading, will be aided by a knowledge of the environmental conditions of a pre-disturbance state, defining both potential targets for restoration and the limits to what a restoration project might achieve (Battarbee 1999)
Palaeoproterozoic age of a basement gneiss complex in the Charcot Land tectonic window, East Greenland Caledonides
No full textThe Charcot Land tectonic window exposes crystalline basement gneisses, which form part of the foreland of the East Greenland Caledonides. These gneisses were previously believed to be Archaean in age, on the basis of imprecise K-Ar analyses carried out in the early 1980s on hornblende from amphibolitic bands and inconclusive Rb/Sr isotope data. New U-Pb singlezircon ion microprobe analyses on the gneisses of the window yield upper intercept ages of 1916 ± 21 and 1928 ± 11 Ma, and are interpreted to represent the age of crystallisation of the igneous protolith. The foreland gneisses of the Charcot Land window are similar in age to parts of the allochthonous gneiss complexes of structurally overlying thrust sheets, but the two terranes have different lithological and structural characteristics. No Archaean rocks have been identified with certainty in any of the East Greenland Caledonian foreland windows
The Eleonore Sø and Målebjerg foreland windows, East Greenland Caledonides, and the demise of the ‘stockwerke’ concept
No full textRecognition of the Eleonore Sø and Målebjerg foreland windows during the 1997–1998 regional mapping expeditions to the East Greenland Caledonides provided critical evidence for largescale, westward-directed thrusting in the Kong Oscar Fjord region (72°–75°N), a revelation that dealt a final blow to the ‘stockwerke’ concept of an in situ highly mobile infrastructure characterised by rising fronts of Caledonian migmatisation and metasomatism. This paper reviews earlier investigations in both the Eleonore Sø and Målebjerg areas, and the misinterpretations of rock units that initially obscured recognition of their foreland affinity. The Eleonore Sø and Målebjerg windows can now be placed in context, as part of the lowest structural level of the foreland-propagating thrust pile of the Kong Oscar Fjord region
Colophon, Contents, Review of Survey activities
No full textOne of the last visible relics of the pre-fusion history of the Geological Survey of Denmark and Greenland (GEUS), the two separate Bulletin series for Greenland and Denmark, respectively, ceased to appear in late 2003. Almost a decade after the merging of the Geological Survey of Denmark (DGU) and the Geological Survey of Greenland (GGU), the two Bulletin series were merged to form the Geological Survey of Denmark and Greenland Bulletin, the first issue of which is the monumental The Jurassic of Denmark and Greenland. With the closure of the two old series, a long-standing tradition of publishing an annual Review of Greenland activities was brought to an end. Everyone in GEUS, not least those who grew up within the former DGU, agree that the Review of Greenland activities was a high-quality, enjoyable-to-read review of the new Survey s Greenland activities. It was therefore a natural progression to publish a review volume covering the full spectrum of activities of the entire institution, a Review of Survey activities intended for a professional, but not specialist, readership. In order to keep the volume to a manageable size, all articles have been restricted to a four-page limit.
Thanks to the diverse geology of Denmark and Greenland, and the reliance of society on resources hosted in the subsurface, GEUS as a survey has been generously endowed by nature. However, as for many other geological surveys in western Europe direct financial government appropriations for GEUS have decreased significantly during the past several years. Increasing funding from external scientific foundations and commercial sources has proved to be a partial compensation. Furthermore, the Survey has extended the traditional scope of its activities to also include capacity-building projects in several developing countries within the fields of institutional development, geological mapping, petroleum geology, mineral exploration and hydrogeology. Despite recent hardships, including an inevitable loss of personnel, the size, relevance and quality of the geological output of the Survey are still undergoing a healthy development.
The articles contained in this bulletin review many of the principal activities of the Survey in 2003; they reflect the diversity of our Survey, from the microbial to the plate tectonic level. Of the 23 articles, 20 measure directly the extent to which the Survey s activities have been driven by external demand, inasmuch as they describe activities which have been undertaken for external customers or rely on external sources for a significant funding contribution. Funding for these 20 projects has come from national and international research funds, from the petroleum industry, from ministries and counties, from the Bureau of Minerals and Petroleum of the Greenland Home Rule Government, and from national and international funds for aid to developing countries. It is expected that the focus on applied geological projects will also be reflected in future volumes of Review of Survey activities
Seismic and petrophysical properties of Faroe Islands basalts: the SeiFaBa project
No full textFlood basalt-covered basins exist worldwide along continental margins and are now in focus as targets for future hydrocarbon exploration. It is generally difficult to image through the basalt cover by conventional seismic reflection methods, and this is a major challenge to future petroleum exploration offshore the Faroe Islands. Long-offset profiling has proven very successful (White et al. 2003). Surprisingly, however, it is possible to image through kilometre-thick basalt sequences on some conventional profiles. Details of basalt stratigraphy are revealed on old, reprocessed seismic profiles as well as on recently acquired profiles, even though the imaging may be unsuccessful on nearby profiles (e.g. Boldreel & Andersen 1993). This stresses the need for a better understanding of the acoustic and other physical properties of basalt as well as of the degree of three-dimensional heterogeneity. The SeiFaBa project (Seismic and petrophysical properties of Faroes Basalt, 2002–2005) is funded by the Sindri Group as part of the programmes for licensees within the Faroese offshore area, and addresses these issues with special focus on the subaerially extruded flood basalts of the Faroe Islands (cf. Japsen et al. in press)