Karen Dybkjaer

Karen Dybkjaer
Geological Survey of Denmark and Greenland · Department of Stratigraphy

PhD

About

94
Publications
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Introduction
Senior research geologist/palynologist with more than 25 years experience in biostratigraphy and palaeoenvironmental interpretation based on fossil spores, pollen, dinoflagellate cysts and palynofacies analyses. Specialised in uppermost Triassic, Jurassic and lowermost Cretaceous successions from the North Sea Basin (Danish and Norwegian sectors) and the Norwegian-Danish Basin and in Miocene successions onshore Denmark and in the North Sea Basin.
Additional affiliations
February 1990 - present
Geological Survey of Denmark and Greenland
Position
  • Senior Researcher

Publications

Publications (94)
Article
The Hanoi Trough in northern Vietnam forms the landward extension of the large Song Hong Basin in the South China Sea. Several gas and condensate discoveries have been made in the offshore part while exploration in the Hanoi Trough has been less successful. Encountered hydrocarbons suggest a terrigenous source rock, the most likely candidate being...
Article
A cored section (North Jens-1) in the Danish Central Graben spans the ‘Base Cretaceous Unconformity’ (BCU) in a seismically conformable situation in a basin-centre setting. Multidisciplinary analysis of the core revealed that the apparent simplicity of the boundary in seismic profiles at this location disguises a complex, dynamic geological history...
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The Paleocene–Eocene Thermal Maximum (PETM) was a period of geologically-rapid carbon release and global warming ~56 million years ago. Although modelling, outcrop and proxy records suggest volcanic carbon release occurred, it has not yet been possible to identify the PETM trigger, or if multiple reservoirs of carbon were involved. Here we report e...
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Permian to Triassic outcrops in East Greenland diminish significantly northwards. Understanding the northward extent, and nature, of the Permian and Triassic successions has implications for regional palaeogeographic reconstructions and exploration in adjacent offshore basins. Examining the structural relationships between the basement, Permian, Tr...
Conference Paper
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The Miocene climate was dynamic, oscillating between major glaciation events and greenhouse conditions (the so-called Miocene Climatic Optimum or MCO). However, forcing factors responsible for climatic transitions from one state to another are not fully understood, partly because palaeoclimatological records from northern mid to high latitudes are...
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Here, we present an updated stratigraphic subdivision of the Oligocene to Pleistocene succession (880–610 m) in the newly proposed type well for the Molo Formation, the industrial 6407/9-5 well, located on the continental shelf in the eastern Norwegian Sea. Furthermore, new data from the Danish North Sea wells Nora-1, Vagn-2, and Tove-1 are present...
Article
Evaluation of the regional geotectonic impact of the High Arctic Large Igneous Province (HALIP) in the present‐day northern Atlantic region has been hindered by poor correlation between the Svalbard – Barents Shelf region and eastern North Greenland. New sedimentological and biostratigraphic data from Peary Land and Kronprins Christian Land (Kilen)...
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The early Miocene was an important period for the development of the eastern North Sea. Tectonism in North-West Europe resulted in uplift of the Scandinavian mountains, reactivation of salt structures, inversion of old graben structures and deposition of the most coarse-grained deposits in the Danish pre-Quaternary succession. Some of these deposit...
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The Miocene epoch witnessed major changes in climate. The marine oxygen isotope record, our best single continuous representation of the time interval, contains large shifts indicating substantial changes in the glaciation of Antarctica and/or deep ocean temperatures, with the interval of the most depleted isotopic composition occurring between ~ 1...
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Strontium (Sr) isotope data from cores and ditch-cutting samples from hydrocarbon wells from Pleistocene sediments from four areas on the Norwegian continental shelf have been compared with previously published biostratigraphic, lithostratigraphic, seismic and new micropaleontological and palynological data. The aim for this paper is also to provid...
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The Danish part of the Central Graben (DCG) is one of the petroliferous basins in the offshore region of north-western Europe. The source rock quality and maturity is here reviewed, based on 5556 Rock-Eval analyses and total organic carbon (TOC) measurements from 78 wells and 1175 vitrinite reflectance (VR) measurement from 55 wells, which makes th...
Conference Paper
This was a presentation on ongoing work on the end-Triassic mass extinction. We were supposed to present some new results but unfortunately, due to COVID-19 analyses were postponed to a later date. The presentation is a review of what we know so far. You can see the presentation at: https://meetingorganizer.copernicus.org/EGU2020/EGU2020-20732.html
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Growth of fibrous illite may destroy an otherwise promising sandstone reservoir, even sandstones characterized by microquartz coatings. Therefore detailed petrographical and diagenetic investigations were performed in order to understand the factors that control illite precipitation and other factors affecting the reservoir properties in the Upper...
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Seven side-wall core samples from the lower part of the Molo Formation in exploration well 6610/3–1 off Vestfjorden/Lofoten have been reanalysed for marine palynomorphs. Description of new species from other studies and access to reference successions from nearby sites with an independent chronostratigraphy have enabled a more reliable depositional...
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The almost complete, mainly deltaic, upper Paleogene and Neogene succession in Jylland, Denmark, was previously investigated for 87Sr/86Sr atios in 143 samples from 18 localities. In the present paper, strontium-isotope data from the Upper Oligocene–Lower Miocene parts and foraminiferal and pyritised diatoms data from 94 of these samples were used...
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During the past 600 million years of Earth history, four of five major extinction events were synchronous with volcanism in large igneous provinces. Despite improved temporal frameworks for these events, the mechanisms causing extinctions remain unclear. Volcanic emissions of greenhouse gases, SO 2 , and halocarbons are generally considered as majo...
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The reconstruction of former ice sheets is important for testing Earth system models that can assess interactions between polar ice sheets and global climate, but information retrieved from contemporary glaciated margins is sparse. In particular, we need to know when ice sheets began to form marine outlets and the mechanisms by which they advance a...
Article
Correct interpretations of depositional environments are fundamental for evaluating the geological history of a sedimentary basin. Palynofacies analyses are a valuable supplement to sedimentological and seismic studies. In order to develop a palynofacies reference dataset for fluvio-deltaic and shelfal successions, a study of the assemblages of sed...
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A large, well-preserved vertebrate coprolite found in the clay pit Sofienlund Lergrav, Jylland, is identified as crocodilian due to its size and morphology. The coprolite consists of several concentric layers wrapped around a more homogeneous core. Weak constriction marks are present on the surface. Di-noflagellate cyst contents of the coprolite in...
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In recent years there has been an increased interest in Neogene hydrocarbon accumulations in the North Sea. The production of gas from Pliocene–Quaternary deposits in the Dutch sector, the discovery of oil-bearing Miocene sands in the Lille John area and oil accumulation in middle Miocene deposits in the T-1 well in the northern part of the Danish...
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Kilen, Kronprins Christian Land, contains the thickest and stratigraphically most complete Jurassic and Cretaceous sediment succession in North Greenland. This study revises and formalises the lithostratigraphic framework of these deposits. The work is based on recent extensive stratigraphic field work supplemented by photogeological mapping and bi...
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This paper presents the results of a cross-border study of the Middle Jurassic-Early Cretaceous rift phase in the Danish-German-Dutch Central Graben area. Based on long-distance correlations of palynologically interpreted wells, a stepwise basin evolution pattern was determined. Four phases are defined and described as tectonostratigraphic mega-seq...
Article
Understanding the end-Triassic mass extinction event (201.36 Ma) requires a clear insight into the stratigraphy of boundary sections, which allows for long-distance correlations and correct distinction of the sequence of events. However, even after the ratification of a Global Stratotype Section and Point, global correlations of TJB successions are...
Article
A motorway was constructed in 2010–2016 through the suburbs of the city of Silkeborg (Fig. 1). The Danish Road Directorate wished to climate-proof the motorway against adverse future climate changes. The directorate collaborated with the Geological Survey of Denmark and Greenland (GEUS) to study the hydrological conditions. Studies of historical an...
Article
In a terrestrial Triassic–Jurassic boundary succession of southern Sweden, perfectly zoned sphaerosiderites are restricted to a specific sandy interval deposited during the end-Triassic event. Underlying and overlying this sand interval there are several other types of siderite micromorphologies, i.e. poorly zoned sphaerosiderite, spheroidal (ellip...
Conference Paper
The end-Triassic biotic crisis is generally explained by massive input of CO2 and/or methane to the atmosphere linked to the formation of the large igneous province called the Central Atlantic Magmatic Province (CAMP). Such massive volcanism can be compared to industrial pollution releasing large amounts of the greenhouse gases CO2 and SO2 to the a...
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Multiple levels of earthquake-induced soft-sediment deformations (seismites) are concentrated in the end-Triassic mass extinction interval across Europe. The repetitive nature of the seismites rules out an origin by an extraterrestrial impact. Instead, this intense seismic activity is linked to the formation of the Central Atlantic magmatic provinc...
Conference Paper
Full-text available
The end-Triassic biotic crisis is generally explained by massive input of CO2 and/or methane to the atmosphere linked to the formation of the Central Atlantic Magmatic Province. Such massive volcanism can be compared to industrial pollution releasing large amounts of the greenhouse gases CO2 and SO2 to the atmosphere. Indeed, the fossil record prov...
Article
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One hundred and fifty-six 87Sr/86Sr analyses have been performed on 129 samples from 18 outcrops and boreholes in Oligocene–Miocene deposits from Jylland, Denmark. These analyses were mainly conducted on mollusc shells but foraminiferal tests, Bolboforma and one shark tooth were also analysed. The main purpose of the study is to compare ages of the...
Conference Paper
Aiming at predicting reservoir quality of Heno Formation sandstones, a study of its main authigenic phases has been carried out. Lowest porosities and permeabilities are found in intensively carbonate cemented sandstones. The carbonate cement can typically be described as either; early concretionary calcite cement, later patchy calcite cement or Fe...
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In order to be able to predict the distribution of reservoir sands and of grainsize and porosity trends in a hydrocarbon province, it is essential to understand the basin evolution in detail. In this study, an attempt is made to reconstruct the complex basin evolution of the southern Central Graben area by careful correlation of sedimentary success...
Chapter
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The focus of this study is the lower Eocene to lower Miocene succession in ODP Site 643A. The site is located in the Norwegian Sea, at the base of the Outer Vøring Plateau (OVP). We analysed dinocyst assemblages and calculated the relative input of soil organic matter using an organic proxy, the branched/isoprenoid tetraether (BIT) index. Our resul...
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A multidisciplinary study of the Oligocene/Miocene (O/M) transition was carried in two boreholes (Harre-1 and Horn-1) from the Danish land area in order to improve the understanding of the paleoclimatological and environmental changes across the Mi-1 the earliest Miocene cooling event. Dinoflagellate cyst (dinocyst) biostratigraphy, supported by re...
Article
The recent paper by Gołędowski et al. (2012) is a contribution to the ongoing debate regarding the possible processes involved in the geological evolution of the North Sea basin and adjacent hinterlands during the Cenozoic. Their major conclusions state (1) that the prominent seismic feature called the ‘mid-Miocene unconformity’ (MMU) is a diachron...
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Lower Miocene strata from boreholes and, in particular, at outcrops in the Lillebælt and Limfjorden areas of Jylland provide a natural laboratory for studying the drowning of a major delta system during a period of global warming. Detailed studies of sedimentary structures, fossil algae, spores and pollen give information about depositional environ...
Article
For the first time a combined palynological and δ13C-isotope study has identified the Oligocene–Miocene boundary — and thus the base of the Neogene — within the North Sea Basin. The type section, the Lemme–Carrosio section in northern Italy, is correlated with the Frida-1 well in the eastern (Danish) part of the North Sea Basin using a combination...
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Profound changes in both marine and terrestrial biota during the end-Triassic mass extinction event and associated successive carbon cycle perturbations across the Triassic-Jurassic boundary (T-J, 201.3 Ma) have primarily been attributed to volcanic emissions from the Central Atlantic Magmatic Province and/or injection of methane. Here we present a...
Article
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This study presents a detailed continental palaeoclimate record for the Neogene of Northwestern Europe. Palynomorph samples from continental to marginal marine deposits in 5 correlated sections from the Lower Rhine Basin (NW Germany) covering the time-span from Burdigalian to Zanclean are analysed. Independent time-control in the sections is provid...
Conference Paper
Here we present the results of a multiproxy study of the uppermost Oligocene to lowermost Miocene succession from the Danish land area. The study includes dinoflagellate cysts (dinocyst) stratigraphy, organic geochemistry, magnetostratigraphy, stable carbon isotope (δ13C) analysis and palynofacies analysis of sediment cores from two boreholes (Harr...
Article
A palynological investigation has been conducted on Lower–Upper Miocene sediments from Jylland, Denmark, corresponding to the time interval of about 19 to 8 Ma. The sediments, derived from the Sdr. Vium drill core, were deposited in marine to marginal-marine environments, as shown by the relatively high abundance of dinoflagellate cysts in all samp...
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This paper presents a revised lithostratigraphic scheme for the uppermost Upper Oligocene - Miocene succession of Denmark. The marine Oligocene Brejning Clay Member is upgraded to formation status and includes the Sydklint Member and the Øksenrade Member (new). The shallow marine and deltaic deposits of mainly Early Miocene age are included in the...
Article
A chemostratigraphic study of Upper Jurassic sandstones in the northern Danish Central Graben has been undertaken within the framework of a well-defined stratigraphic/sedimentological model based particularly on cored well sections. Two reservoir sandstone units are recognised, the transgressive marginal marine to shoreface sandstone of the Gert Me...
Article
Regional uplift of structural highs took place in the greater North Sea region in early Middle Jurassic times, resulting in a change from marine shelf deposition in the Early Jurassic to widespread emergence, erosion and localized deposition in grabens. The Middle Jurassic Bagå Formation exposed on the island of Bornholm in the Baltic Sea was depos...
Article
A dinocyst zonation for the Neogene succession in the eastern part of the North Sea Basin (Denmark) is presented. The zonation is based on an extensive database comprising data from more than fifty onshore and offshore boreholes and about twenty five outcrops. Most of the nineteen dinocyst zones described and defined herein, are new. The zonation i...
Article
Asynchronous changes in carbon cycling and vegetation over an expanded Triassic-Jurassic boundary succession
Article
The end-Triassic mass-extinction on land was characterized by the widespread dieback of gymnospermous forests across the northern hemisphere and their transient replacement by ferns and fern allies. These floral changes are thought to have been triggered by the eruption of 2 million kubic kilometers of basalt belonging to the Central Atlantic Magma...
Article
Two exposures in Jylland, Denmark, encompassing beds of latest Oligocene to earliest Miocene age (latest Chattian–early Aquitanian) yielded well-preserved palynofloras. The assemblages indicate that Jylland was covered by extensive Taxodiaceae swamp forests in the mid-Cenozoic. Besides a Taxodiaceae–Cupressaceae association, which was overwhelmingl...
Chapter
Recently available well data from the northern part of the Danish Central Graben have been analysed to further understand the basin development, biostratigraphy, depositional models and palaeogeography of Upper Jurassic reservoir sandstones, which are the primary exploration targets in this basin. Notably, the discovery of the Hejre accumulation in...
Article
Full-text available
Absolute abundances (concentrations) of dinoflagellate cysts are often determined through the addition of Lycopodium clavatum marker-grains as a spike to a sample before palynological processing. An inter-laboratory calibration exercise was set up in order to test the comparability of results obtained in different laboratories, each using its own p...
Article
Full-text available
Absolute abundances (concentrations) of dinoflagellate cysts are often determined through the addition of Lycopodium clavatum marker-grains as a spike to a sample before palynological processing. An inter-laboratory calibration exercise was set up in order to test the comparability of results obtained in different laboratories, each using its own p...
Article
Variability of the organic C-isotope record across the Triassic-Jurassic boundary of the Danish and German basins
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Full-text available
The Triassic – lower Cretaceous sedimentary succession of the Norwegian–Danish Basin has for a long time been of exploration interest, and numerous studies have been carried out. However, high-resolution correlation within the basin remains necessary, especially between the Danish and Nor - we gian parts of the basin. A variety of litho- and biostr...
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Lycopodium clavatum tablets are commonly added as a spike to determine dinoflagellate cyst concentrations in sediments. In this study we investigate the effects of different processing techniques on dinoflagellate cyst concentrations using well-mixed sediment samples from Saanich Inlet, British Columbia, Canada. At the onset of any dinoflagellate c...
Article
Full-text available
Absolute abundances (concentrations) of dinoflagellate cysts are often determined through the addition of Lycopodium clavatum marker-grains as a spike to a sample before palynological processing. An inter-laboratory calibration exercise was set up in order to test the comparability of results obtained in different laboratories, each using its own p...
Article
In Denmark most of the water used in private households, in the industry and for irrigation in agriculture comes from subsurface aquifers. Some of the most important aquifers in Jylland, western Denmark, are sand layers deposited from 23 to 15 Ma ago, in the Early Neogene (Early to Middle Miocene). About 23 Ma ago, in the Early Miocene, the coastli...
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Full-text available
Schiøler, P., Andsbjerg, J., Clausen, O.R., Dam, G., Dybkjær, K., Hamberg, L., Heilmann-Clausen, C., Johannessen, E.P., Kristensen, L.E., Prince, I. & Rasmussen, J.A. 2007: Lithostratigraphy of the Palaeogene – Lower Neogene succession of the Danish North Sea. Geological Survey of Denmark and Greenland Bulletin 12, 77 pp. + 5 plates. As a result of...