Papers by Holger Lykke-andersen
Tectonophysics, 2002
The Late Cretaceous -Cenozoic evolution of the eastern North Sea region is investigated by 3D the... more The Late Cretaceous -Cenozoic evolution of the eastern North Sea region is investigated by 3D thermo-mechanical modelling. The model quantifies the integrated effects on basin evolution of large-scale lithospheric processes, rheology, strength heterogeneities, tectonics, eustasy, sedimentation and erosion. The evolution of the area is influenced by a number of factors: (1) thermal subsidence centred in the central North Sea providing accommodation space for thick sediment deposits;
In the frame of the Priority Program 1135 of the German Research Foundation (DFG) "Dynamics ... more In the frame of the Priority Program 1135 of the German Research Foundation (DFG) "Dynamics of sedimentary systems under varying stress conditions by example of the Central European Basin System", the scientific goal of the NeoBaltic project is to describe the post-Permian to recent geological evolution of the entire western Baltic Sea region, with a special emphasis on neotectonic activity
Zeitschrift Der Deutschen Gesellschaft Fur Geowissenschaften, 2009
ABSTRACT Buried Quaternary valleys, incising several hundred metres in Tertiary sediments, are of... more ABSTRACT Buried Quaternary valleys, incising several hundred metres in Tertiary sediments, are of a glacial origin and demonstrate the immense forces acting below the glaciers by the pressurised melted water. Aside from their fascinating genesis, these valleys have a practical value because the sedimentary filling can be very permeable and can act as important aquifers for the water supply. Sustainable water management requires a detailed knowledge of the subsurface structures. Geophysical tools for the investigation and characterisation of aquifers in unconsolidated sediments are tested in six different study areas. Valleys with a width of more than 1 km and a depth of more than 200 m differ in their sedimentary environment and filling. This can be detected by gravity anomalies. Using seismic profiles, shape, internal structure and embedding in the surroundings are revealed. Airborne electromagnetic surveys map the distribution of electrical resistivity down to a depth of 300 m. In most cases the valley is clearly distinguishable from the surrounding material. The quality of the covering layers is quantified by the electrical resistivity. A reliable interpretation can be attained by combining the various methods with borehole information and expert geological knowledge.
Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science, 1997
In the EU water frame directory, groundwater/lake water interaction is recognized as playing an i... more In the EU water frame directory, groundwater/lake water interaction is recognized as playing an important part in water administration. In order to construct hydrological models that include this interaction improved spatial information, concerning the geology beneath the lake and whether seepage is occurring, is required. Conventional methods such as seepage meters, hydraulic gradients, and stable isotope measurements only give reliable
Boreas, 1993
... The GeoKat project – a study of the Late Quaternary evolution of the Kattegat Sea. HOLGER LYK... more ... The GeoKat project – a study of the Late Quaternary evolution of the Kattegat Sea. HOLGER LYKKE-ANDERSEN,; KAREN LUISE KNUDSEN,; CHRISTIAN CHRISTIANSEN. Article first published online: 16 JAN 2008. DOI: 10.1111/j.1502-3885.1993.tb00186.x. Issue. Boreas. ...
Terra Nova, 2013
ABSTRACT The formation of the Virgin Islands Basin in the north eastern part of the Caribbean is ... more ABSTRACT The formation of the Virgin Islands Basin in the north eastern part of the Caribbean is controlled by the plate boundary between the Puerto Rico-Virgin Islands Micro Plate and the stable part of the Caribbean Plate. The Puerto Rico-Virgin Islands Micro Plate is one of three micro plates located in a complex plate boundary zone in the north eastern part of the Caribbean where the Caribbean Plate borders the North American Plate. These micro plates move differently than the stable part of the Caribbean plate. There exists a lot of contradicting theories about the course of formation of the Virgin Islands Basin, including counter clockwise rotation of the micro plate and dextral or sinistral strike-slip movements between the plates. In connection with the Danish Galathea 3 expedition, the most extensive exploration of the basin to date was conducted in March 2007. Cores, CTD measurements, multi beam bathymetric data and 2D seismic data were acquired. The results from the multi beam and seismic data are presented in this study. The main observations are of extensional features, which show both on the sea bed and in the sedimentary package. Furthermore, evidence of strike-slip movements is found. Based on the observations, a tectonic model is presented. The model consists of a primary north-south to north west-south east directed extension combined with east-west trending sinistral strike-slip. It implies that the Puerto Rico-Virgin Islands Micro Plate is moving slower towards the east-north east than the stable part of the Caribbean Plate. The model is supported by the newest GPS-measurements. The Virgin Islands Basin is located in The Anegada Passage, which comprises the south eastern boundary between the Puerto Rico-Virgin Islands Micro Plate and the stable part of the Caribbean Plate.
Tectonophysics, 2007
... To the west, the Glückstadt Graben separates the NEGB from the Northwest German Basin. Sedime... more ... To the west, the Glückstadt Graben separates the NEGB from the Northwest German Basin. Sediments in the NEGB range in age from Permian to present and have a thickness of 10–12 km in the central parts (Scheck et al., 1996 and Benek et al., 1996). ...
Tectonophysics, 2006
The origin of regional sedimentary basins is being investigated by the ESTRID project (Explosion ... more The origin of regional sedimentary basins is being investigated by the ESTRID project (Explosion Seismic Transects around a Rift In Denmark). This project investigates the mechanisms of the formation of wide, regional basins and their interrelation to previous rifting processes in the Danish-Norwegian Basin in the North Sea region. In May 2004 a 143 km long refraction seismic profile was acquired along the strike direction of a suspected major mafic intrusion in the crust in central Denmark. The data confirms the presence of a body with high seismic velocity (N 6.5 km/s) extending from a depth of ∼ 10-12 km depth into the lower crust. There is a remarkable Moho relief between 27 and 34 km depth along this new along-strike profile as based on raytracing modelling of PmP reflections. The lack of PmP reflections at a zone of very high velocity in the lowest crust (7.3-7.5 km/s) suggests a possible location of a feeder channel to the batholith. The presence of volcanic rocks of Carboniferous-Permian age above the intrusion (mafic batholith) suggests a similar age of the intrusion. An older obliquely crossing profile and two new fan profiles deployed perpendicular to the main ESTRID profile, show that the batholith is about 30-40 km wide. The existence of this large mafic batholith supports the hypothesis that the origin of the Danish-Norwegian Basin is related to cooling and contraction after intrusion of large amounts of mafic melts into the crust during the late Carboniferous and early Permian. The data and interpretations from project ESTRID will form the basis for subsidence modelling. Tentatively, we interpret the formation of the Danish-Norwegian Basin as a thermal subsidence basin, which developed after widespread rifting of the region.
Tectonophysics, 2011
The origin of the topography of southwest Scandinavia is subject to discussion. Analysis of boreh... more The origin of the topography of southwest Scandinavia is subject to discussion. Analysis of borehole seismic velocity has formed the basis for interpretation of several hundred metres of Neogene uplift in parts of Denmark. Here, refraction seismic data constrain a 7.5 km long P-wave velocity model of the Chalk Group below the Stevns peninsula, eastern part of the Danish Basin. The model contains four layers in the~860 m thick Chalk Group with mean velocities of 2.2 km/s, 2.4 km/s, 3.1 km/s, and 3.9-4.3 km/s. Sonic and gamma wireline log data from two cored boreholes represent the upper~450 m of the Chalk Group. The sonic velocities are consistent with the overall seismic layering, although they show additional fine-scale layering. Integration of gamma and sonic log with porosity data shows that seismic velocity is sensitive to clay content. In intervals near boundaries of the refraction model, moderate increases in clay content correlate with reduction of porosity and increase in velocity. Higher clay contents do not further increase velocity. The reduction of porosity and increase in velocity are interpreted as clay causing increased pressure dissolution and cementation. The interpreted velocities are systematically higher than values of a chalk velocity curve determined in previous studies, and it is estimated that a significant part of the velocity anomaly may be explained by the presence of clay. The remaining velocity anomaly can be explained by 450-500 m palaeo-burial of the Chalk Group. The burial anomaly will be over-estimated by~150-200 m if the analysis is based on the average Chalk Group velocity and clay content is disregarded. Burial anomaly values of~450-600 m result if the strongest velocity contrast at 600-650 m depth is interpreted to be a result of diagenetic effects, consistent with the clay-corrected estimates within uncertainty.
Science, 1994
Glacial till, glaciomarine diamictites, and ice-rafted detritus found in marine cores collected o... more Glacial till, glaciomarine diamictites, and ice-rafted detritus found in marine cores collected off the shore of southeast Greenland record multiple Late Cenozoic glaciations beginning in the Late Miocene. Distinct rock assemblages and seismic stratigraphic control correlate the diamictites with glaciation of the southeast Greenland margin. Glaciers advanced to the sea during several intervals in the Pliocene and Pleistocene. North Atlantic glaciation may have nucleated in southern Greenland rather than further north because of the high mountains and the high levels of precipitation in this region.
Quaternary Science Reviews, 2000
A system of 100}350 m deep, overdeepened and buried valleys has been mapped in the eastern Danish... more A system of 100}350 m deep, overdeepened and buried valleys has been mapped in the eastern Danish North Sea. Individual valleys can be traced for several tens of kilometres, and valleys generally begin and terminate abruptly. A correlation to buried valleys onshore southwest Denmark is possible. The valleys post date glaciotectonic structures, and are interpreted to be Elsterian and possibly Saalian in age. The origin of valleys in the eastern Danish North Sea is explained by repeated cycles of sub-glacial down-cutting of meltwater channels and channel closure due to ice creep, eventually producing deeply incised valleys. Glacial erosion may have been signi"cant in cases where valleys are broad and shallow. The origin of overdeepened Quaternary valleys in general can be attributed to a combination of three end-member processes: (i) steady-state drainage of meltwater; (ii) catastrophic outbursts of meltwater; and (iii) glacial erosion. The main requirement for sub-glacial valley formation is the presence of a melting ice sheet overlying a poorly consolidated substrate. Permeability variations of the substrate may produce subregional variations in the pattern of valley incision, while pre-glacial rivers, faults or salt structures are of local importance only.
Quaternary Science Reviews, 2001
Quartz from late Pleistocene marine and freshwater deposits of known C age, and from a historical... more Quartz from late Pleistocene marine and freshwater deposits of known C age, and from a historically dated aeolian deposit, has been studied using multiple-aliquot and single-aliquot protocols. Comparisons are presented between equivalent doses derived using a multiple-aliquot additive-dose thermoluminescence approach, and three OSL protocols-Single aliquot regeneration and added dose (SARA; Mejdahl and B+tter-Jensen, 1994), single-aliquot additive-dose and single-aliquot regenerative-dose (Murray and Roberts, 1998). Dose rates, determined by laboratory gamma spectrometry, are compared with both field gamma scintillation measurements, and laboratory beta thermoluminescence dosimetry measurements. The agreement is satisfactory. The resulting dates are discussed in terms of absolute chronology and bleaching environment. A s rhus C, Denmark 0277-3791/99/$ -see front matter 1999 Elsevier Science Ltd. All rights reserved. PII: S 0 2 7 7 -3 7 9 1 ( 9 8 ) 0 0 0 5 0 -X
Quaternary Science Reviews, 1998
A 22.5 m long marine shelf sequence in northern Denmark covers the climatic shifts from glacial e... more A 22.5 m long marine shelf sequence in northern Denmark covers the climatic shifts from glacial environments, through interglacial and into early glacial conditions. The interglacial was interrupted by two cool intervals. Also the early glacial succession experienced oscillations of the climate, and a period with ameliorated temperature conditions has been separated as an interstadial. These results are based on a multidisciplinary high-resolution study of lithology, foraminifera, ostracods, macrofauna, diatoms and stable isotopes in a silty clay sequence from a borehole at N+rre Lyngby (70.5-48.0 m depth). The lithostratigraphy and the variations in depositional environment in the area is supported by a reflection seismic profile across the core site. The chronostratigraphy is discussed on the basis of biostratigraphical correlation and seismostratigraphy as well as Optically Stimulated Luminescence (OSL) dating and amino acid measurements. The biostratigraphy and the OSL dates suggest an Eemian age for the interglacial, while amino acid results point to an older age. If the interglacial is confirmed as Eemian, we believe that the succeeding interstadial period is likely to be correlated with the Br+rup Interstadial. The climatic changes in this eastern part of the North Sea region are closely linked with changes in the North Atlantic circulation pattern, and the environmental fluctuations at N+rre Lyngby are therefore believed to reflect fluctuations in the past regional climatic and oceanic system.
Quaternary International, 2012
Physics and Chemistry of the Earth, Parts A/B/C, 2011
Airborne electromagnetic methods (AEM) are used extensively in groundwater investigations, often ... more Airborne electromagnetic methods (AEM) are used extensively in groundwater investigations, often in combination with high-resolution seismic data. Despite the frequent use of this mapping strategy, only a few cases are found in the literature. In this study, comparisons and interpretations were made based on AEM (SkyTEM) and high-resolution seismic data from an area covering 10 km 2 in the western part of Denmark. As support for the interpretations, an exploration well was drilled to provide lithological and logging information in the form of resistivity and vertical seismic profiling. Based on the resistivity log, synthetic SkyTEM responses were calculated with a varying number of gate-times in order to illustrate the effect of the noise-level. At the exploration well geophysical data were compared to the lithological log; in general there is good agreement. The same tendency was recognised when SkyTEM results from the area were superposed onto seismic sections. Comprehensive geological knowledge is necessary in order to introduce layer boundaries from one method interactively in the data handling of the other. However, in cases where resistivity transitions are positively correlated to reflections, SkyTEM data supports the interpretation of weak reflections, and can also support the correlation of reflections both internally and between seismic lines. Besides contributing lithological information, the AEM survey provides gross three-dimensional structural information, whereas seismic data contributes with more detailed structural information in two dimensions.
Marine Micropaleontology, 2013
ABSTRACT A multiproxy study of paleoceanographic and climatic changes in Holsteinsborg Dyb on the... more ABSTRACT A multiproxy study of paleoceanographic and climatic changes in Holsteinsborg Dyb on the West Greenland shelf shows that the area is sensitive to variations in the mixing between the two components of the West Greenland Current, i.e., the Atlantic Water of the Irminger Current and the Polar Water from the East Greenland Current. A seismic profile illustrates the general development in the area since the deglaciation, and analyses of benthic foraminifera, stable isotopes (δ18O and δ13C), and X-ray fluorescence elemental counts in two cores, covering ca. 6650 and 1100 years, respectively, provide details on the oceanographic changes during the mid- and late Holocene. The chronology is based on 210Pb and AMS 14C age determinations. During the time interval of 6650–1600 cal. yr BP, the bottom waters are characterized by the presence of modified Atlantic Water, with some influence of meltwater, either local or regional. Depleted δ18O values and relatively high Si/Fe ratio suggest warmer conditions from 6650 to 3800 cal. yr BP, corresponding in time to part of the Holocene Thermal Maximum, followed by a general slight cooling with some fluctuation after 3800 cal. yr BP. At 1600 cal. yr BP, there is an abrupt change in almost all investigated proxies. The foraminiferal assemblage and the δ18O values suggest cold, low-salinity bottom-water conditions, and there is indication of seasonal sea-ice cover between 1400 and 1200 cal. yr BP, corresponding in time to the Dark Ages Cold Period and to a minimum in solar irradiance. From ca. 1150 to 580 cal. yr BP, a time interval equivalent to the historical Medieval Warm Period (MWP), the foraminiferal fauna remains indicative of cold, low-salinity bottom waters, but without any indication of sea-ice cover. The influence of Polar Water/meltwater at the sea floor during the MWP is thought to be a result of enhanced mixing of the two components of the West Greenland Current caused by an increase in wind activity during generally positive North Atlantic Oscillation conditions, maybe combined with a displacement of the Irminger Current pathway to the outer shelf. During the Little Ice Age (LIA), there is a strong influence of modified Atlantic Water at the sea floor, related to sea-ice formation and stratification of the water column. After AD 1900, the benthic foraminiferal assemblage suggests a slight increase in Polar Water influence and thereby mixing, even though the environment is not much different from that during the LIA.
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Papers by Holger Lykke-andersen