Papers by Bodil W Lauridsen
Bulletin of The Geological Society of Denmark, Oct 12, 2023
Understanding of the shallow shelf system in the Danish Basin during the Early Cretaceous has ben... more Understanding of the shallow shelf system in the Danish Basin during the Early Cretaceous has benefitted significantly from studying the previously overlooked Hauterivian-Aptian section of the Vedsted Formation of the Vinding-1 drill core. The presence of chalks in this section demonstrates that carbonate-rich pelagic sediment accumulated locally in the siliciclastic-dominated Danish Basin and that benthic carbonate production was insignificant. The area was not a carbonate platform in the Early Cretaceous and does not indicate any reworked carbonate supply from platform environments in the vicinity. The scarcity of benthic macrofossils in the cored section is due to the lack of a specialised boreal chalk fauna at that time, and the adjacent nearshore environment apparently did not support any substantial benthic carbonate production. A revised biostratigraphy of the cored section is presented based primarily on calcareous nannofossils, supported by foraminifera, ostracods, and belemnites. Four lithofacies describe the spectrum from marlstone to slightly marly chalk, and the facies succession characterises four depositional units recording two discrete transgressive-regressive cycles. The study provides a depositional record that permits sequence stratigraphic correlation to the Valdemar and Adda Fields in the Central Graben.
Palaeogeography, Palaeoclimatology, Palaeoecology, 2008
Chalk-marl cyclicity is a common and characteristic feature of the Upper Cretaceous Chalk Group o... more Chalk-marl cyclicity is a common and characteristic feature of the Upper Cretaceous Chalk Group of NW Europe. The mainly small-sized benthic fauna from an upper Maastrichtian cyclic chalk-marl succession at Rørdal, Denmark, is analysed in order to interpret the composition and structure of the benthic fauna, and to test if faunal density, diversity, composition, and mode of life substrate were controlled by changes in lithology. The material comprises 21 bulk samples weighing 5 kg each, collected from all chalk and marl half-cycles. The samples were washed and sieved and yielded a total of 25,974 specimens. These are referred to at least 75 species and 15 bryozoan morphotypes and form the basis for the establishment of 10 guilds. The lithological cyclicity is not reflected by the distribution of individual species or by changes in average adult size, but there is generally a higher species diversity and density in chalk compared to marl. The chalk thus represents times of more favourable living conditions, higher environmental stability, and probably higher nutrient influx. No changes in guilds between marl and chalk are found. The variation in substrate character between the two lithologies was thus too small to have exerted any significant influence on the mode of life of the benthic fauna in spite of a difference in clay content, averaging 10%. Two different fossil associations are recognized, each covering one to two chalk-marl cycles and characterized by a distinct fauna with similar ecological requirements. If the chalk-marl couplets represent precession cycles within the Milankovitch band, then the change from one association to the other and back again may represent the 100,000 years eccentricity cycle based on a calculated sedimentation rate of 6 cm ka − 1 .
Cretaceous Research, 2011
Trace fossils from an upper Maastrichtian cyclic chalkemarl succession, the Rørdal Member, expose... more Trace fossils from an upper Maastrichtian cyclic chalkemarl succession, the Rørdal Member, exposed in the Rørdal quarry, Denmark, are analysed in order to test whether the changes in substrate lithology exerted any control over the ichnodiversity, tiering complexity, and density of the infauna. The cyclicity is interpreted as caused by orbital changes within the Milankovitch frequency band. The carbonate content varies between 71 and 82 weight% in the marl and 82e92 weight% in the chalk beds. The material is based on 19 samples collected from six chalk and marl beds. The investigated bedding-normal sample surfaces vary in area between 29 and 155 cm 2. Eight ichnogenera and two undetermined ichnogenera are recognised. The member is characterised by three ichnofabrics (A, B and C). The ichnofabric analysis is based on texture and internal structure of the sediments resulting from bioturbation. Ichnofabric A is found only in chalk samples and shows a poor preservation of trace fossils, whereas ichnofabric C is found in a few chalk and all marl samples and comprises a very dense, diverse and well preserved ichnofauna representing a high tiering complexity. Ichnofabric B represents an intermediate situation between ichnofabrics A and C and occurs in chalk samples immediately adjacent to marl beds. The observed changes in ichnofabrics between chalk and marl are related to the amount of clay in the samples and the differences in the occurrence of trace fossils are interpreted as due to differences in the visibility of traces between chalk and marl and not due to differences in ecological stress upon the endobenthic community of the two lithologies. The study thus provides an excellent example of how the effect of taphonomic factors may give a misleading and biased impression of apparent differences in the endobenthic community between chalk and marl.
Cretaceous Research, 2012
High-resolution carbon isotope stratigraphy of the upper CampanianeMaastrichtian is recorded in t... more High-resolution carbon isotope stratigraphy of the upper CampanianeMaastrichtian is recorded in the Boreal Realm from a total of 1968 bulk chalk samples of the Stevns-1 core, eastern Denmark. Isotopic trends are calibrated by calcareous nannofossil bio-events and are correlated with a lower-resolution d 13 C profile from Rørdal, northwestern Denmark. A quantitative approach is used to test the reliability of Upper Cretaceous nannofossil bio-events and provides accurate biohorizons for the correlation of d 13 C profiles. The CampanianeMaastrichtian boundary (CMB) is identified through the correlation of dinoflagellate biostratigraphy and d 13 C stratigraphy between Stevns-1 and the Global boundary Standard Stratotype-section and Point at Tercis les Bains (SW France), allowing the identification of new chemical and biostratigraphic markers that provide a precise placement of the stage boundary on a regional scale. The boundary interval corresponds to the third phase of a stepwise 0.8& negative d 13 C excursion, lies in calcareous nannofossil subzone UC16d BP , and encompasses the last occurrence of nannofossil Tranolithus stemmerikii and first occurrence of nannofossil Prediscosphaera mgayae. Fifteen d 13 C events are defined and correlated to sixteen reliable nannofossil biohorizons, thus providing a well-calibrated standard high-resolution d 13 C curve for the Boreal Realm.
Journal of Sedimentary Research
The Cenomanian–Danian Chalk Group of NW Europe is characterized by distinct trace-fossil assembla... more The Cenomanian–Danian Chalk Group of NW Europe is characterized by distinct trace-fossil assemblages dominated by Thalassinoides isp., Planolites isp., Zoophycos isp., and Chondrites isp., whereas ichnogenera such as Taenidium and Phycosiphon are rare. The trace fossils form a complex tiering arrangement, which reflects burrowing activities of diverse benthic associations that operate at different levels in the sediment column, dynamic sedimentation rates, and changes in substrate hardness during progressive burial, forming intricate ichnofabrics. In the Danish Basin, studies of chalk ichnofabrics have focused mainly on the Maastrichtian. Studies of the shallower, grain-rich Danian chalk have revealed similar trace-fossil assemblages, whereas the ichnology of the fine-grained, deeper-water Danian deposits is poorly known. Based on detailed facies and ichnofabric analysis of a mid-Danian silica-rich, pelagic chalk located in the central, deeper shelf area of the Danish Basin, four fa...
As societies gradually shift from oil and gas to renewable energy, many offshore wells will be pl... more As societies gradually shift from oil and gas to renewable energy, many offshore wells will be plugged and abandoned, while some will be transformed to facilitate carbon storage (CCS). In order to mitigate any methane leakage associated with abandonment, it is necessary to understand whether the leakage has a natural or anthropogenic origin. During exploration and production, emphasis is almost exclusively on the reservoir, while post abandonment monitoring programs generally focus on the water column. Thus, only little attention has been given to the shallow subsurface, how it has been influenced by hydrocarbon production, and to which degree the geology facilitates or inhibits fluid migration. In order to monitor and evaluate future leakage of hydrocarbons to the marine environment, it is crucial to understand the natural seepage through the seabed both locally at platforms and regionally. For CCS, understanding the shallow subsurface is equally important as monitoring cannot be c...
Bulletin of the Geological Society of Denmark
Understanding of the shallow shelf system in the Danish Basin during the Early Cretaceous has ben... more Understanding of the shallow shelf system in the Danish Basin during the Early Cretaceous has benefitted significantly from studying the previously overlooked Hauterivian–Aptian section of the Vedsted Formation of the Vinding-1 drill core. The presence of chalks in this section demonstrates that carbonate-rich pelagic sediment accumulated locally in the siliciclastic-dominated Danish Basin and that benthic carbonate production was insignificant. The area was not a carbonate platform in the Early Cretaceous and does not indicate any reworked carbonate supply from platform environments in the vicinity. The scarcity of benthic macrofossils in the cored section is due to the lack of a specialised boreal chalk fauna at that time, and the adjacent nearshore environment apparently did not support any substantial benthic carbonate production. A revised biostratigraphy of the cored section is presented based primarily on calcareous nannofossils, supported by foraminifera, ostracods, and bele...
Spreadsheet containing all the data collected and used for this study.
Palaeogeography, Palaeoclimatology, Palaeoecology, 2021
Abstract Fossil cold-water coral mound ecosystems are rare in geological history. One of the best... more Abstract Fossil cold-water coral mound ecosystems are rare in geological history. One of the best known examples are the Danian coral mounds of Faxe comprising a complex interplay between corals, bryozoans, and a diverse associated fauna. The Baunekule facies is a special type of weakly consolidated coral rudstone to floatstone found in the Faxe Formation. The facies has a rich fauna of 220 species that are extremely well-preserved due to an early diagenetic recrystallization of aragonite to calcite prior to dissolution and is regarded as a fossil conservation Lagerstatten. The fauna lived between dead and living coral fragments on the flank of a growing Dendrophyllia coral mound. The fauna is authocthonous and dominated by small gastropods, polychaete tubeworms, bivalves and brachiopods. The fauna from Baunekule facies are compared to other parts of the Faxe Formation which have experienced a significantly different diagenesis. More than 57% of the fauna are not described from others parts of the Faxe Fm. More than 80% of the studied species from the coral limestone are unknown from other parts of Danian localities worldwide. The study of the Baunekule facies compares well with data from modern living coral mounds of Lophelia with a low species richness of framebuilding corals and a high species richness of the associated highly specialised fauna that show a dominance of attached suspension feeders, mobile carnivores, and grazers. The small gastropods are apparently lacking on the modern mounds, probably related to the sampling methods in the deep ocean. In general, there is agreements between the ecology of the fossil and the modern cold-water coral ecosystems with evidence for similar environments from Danian to modern time. The fossil cold-water coral mounds probably acted as diversity hotspots in the outer shelf – slope settings in the Danian epicontinental sea.
Geological Survey of Denmark and Greenland Map Series, 2018
The geological map sheet of Kilen in 1:100 000 scale covers the south-eastern part of the Carboni... more 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 ...
Chemical Geology, 2016
Past marine environmental conditions can be reconstructed from geochemical signatures of both ben... more Past marine environmental conditions can be reconstructed from geochemical signatures of both benthic and planktic organisms and particularly brachiopods have been extensively used for this purpose. However, it is seldom possible to investigate the links between environmental conditions and shell geochemistry in monospecific records over extended periods of time. Here, we present geochemical data from the~100 m thick, brachiopodrich upper Campanianupper Maastrichtian chalk (~73.8-68.6 Ma) of the Rørdal-1 drill core (northern Denmark). Two species that lived attached to small substrate (Argyrotheca bronnii Roemer and Gisilina jasmundi Steinich) and one secondarily free-living species (Magas chitoniformis Schlotheim) have been studied for element concentrations as well as C and O isotope signatures. Each species has a unique chemical signature, with M. chitoniformis showing lowest Mg and Mn concentrations, A. bronnii the highest Mn concentrations and G. jasmundi the highest Sr concentrations. All three species display decreasing Mg/Ca ratios throughout the studied interval and distinct Mn enrichments in the Campanian-Maastrichtian boundary (CMB) interval. In the Campanian part of the succession, the three species are slightly enriched in 13 C (median Δ 13 C values of +0.0 to +0.5‰) and 18 O (median Δ 18 O values of +0.3 to +0.6‰) with respect to coeval chalk. In the course of the Maastrichtian, the two attached species acquire progressively lighter isotopic compositions with A. bronnii reaching δ 13 C and δ 18 O values N 1.0‰ lower than coeval chalk. The secondarily free-living species M. chitoniformis, on the other hand, becomes isotopically heavier and reaches δ 13 C and δ 18 O enrichments of~1.0‰ at the top of the core. The observed differences between the species illustrate species-specific signatures of biomineralisation, diagenesis and response to environmental change. This geochemical complexity illustrates that a comprehensive geochemistry-based picture of the Late Cretaceous Chalk Sea can only be painted using detailed multi-species and multi-proxy datasets.
Bulletin of the Geological Society of Denmark
Kilen, Kronprins Christian Land, contains the thickest and stratigraphically most complete Jurass... more 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 biostratigraphic studies, and builds on the earlier stratigraphic work conducted mainly in the 1980s and 1990s. According to the new stratigraphic scheme, the more than 500 m thick Jurassic succession is divided into four formations. The poorly dated Gletscherport Formation comprises lagoonal heterolithic sandstones. The Mågensfjeld and Birkelund Fjeld Formations consist of shallow marine fine-grained sandstones of Bajocian–Bathonian and Kimmeridgian age, respectively. The Kuglelejet Formation comprises mainly shallow marine sandy mudstone and sandstone of Volgian age and includes the mudstone-dominated Splitbæk Member. The Lower Cretaceous ...
Bulletin of the Geological Society of Denmark
The diverse brachiopod fauna from the middle Danian cool-water coral mounds of the Faxe Formation... more The diverse brachiopod fauna from the middle Danian cool-water coral mounds of the Faxe Formation, Denmark, includes the new genus Obliquorhynchia that exhibits an asymmetric folding of the frontal commissure, a rare feature in brachiopods. Two of the most abundant brachiopod species found in the Faxe Formation, ‘Rhynchonella’ flustracea and ‘Rhynchonella’ faxensis, are considered conspecific and are both referred to Obliquorhynchia. In the literature, the species name flustracea has been ascribed to von Schlotheim. However, the original species name proposed by von Schlotheim in his catalogue (1832, 65, no 62) was lustraceus. This remained a nomen nudum until von Buch (1834) published a description based on the material of von Schlotheim and changed the name to flustracea. The species is thus ascribed to von Buch. A lectotype for Obliquorhynchia flustracea (von Buch 1834) is designated and illustrated here.
Geological Survey of Denmark and Greenland (GEUS) Bulletin
The chemical composition of chalk and marl reflects the mixture of carbonate particles and clasti... more The chemical composition of chalk and marl reflects the mixture of carbonate particles and clastic input deposited on the seabed together with growth of authigenic minerals and diagenesis. The Rørdal quarry in Jylland (Fig. 1) is known for its alternating chalk–marl succession (Surlyk et al. 2010) and the aim of this article is to investigate how this cyclicity is reflected in the geochemical signature of the sequence and test if this has implications for the interpretation of the depositional environment as well as the chemostratigraphy in the chalk.
Geological Survey of Denmark and Greenland (GEUS) Bulletin
This catalogue of 194 gastropod taxa is based on the collection of Danian gastropods from the Bau... more This catalogue of 194 gastropod taxa is based on the collection of Danian gastropods from the Baunekule facies, Faxe Formation in eastern Denmark. The gastropod fauna is extremely rich and well preserved. Most of the gastropods (106 species) are referred to genus level only, 9 morphotypes to even higher taxonomical levels and 79 gastropods are referred to species level. The gastropods are classified following Bouchet & Rocroi (2005) as 4 different clades: Vetigastropoda (represented by 26 species and 10 superfamilies), Caenogastropoda (represented by 142 species and 17 superfamilies), Heterobranchia (represented by 23 species and 5 superfamilies) and Opisthobranchia (represented by 1 species and 1 superfamily). The new species Zaclys? nuetzeli n. sp. is introduced. The Faxe Formation is recognised as a cold-water coral ecosystem with interfingering smaller bryozoan mounds. The Baunekule facies is found in the upper part of the coral mound complex of the Faxe Formation, where it form...
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Papers by Bodil W Lauridsen