Niels Springer | GEUS Geological Survey of Denmark and Greenland (original) (raw)
Papers by Niels Springer
All Days, Oct 22, 1995
A new technique for obtaining water-oil capillary pressure curves, based on nuclear magnetic reso... more A new technique for obtaining water-oil capillary pressure curves, based on nuclear magnetic resonance ͑NMR͒ imaging of the saturation distribution in flooded cores is presented. In this technique, a steady-state fluid saturation profile is developed by flooding the core at a constant flow rate. At the steadystate situation where the saturation distribution no longer changes, the local pressure difference between the wetting and nonwetting phases represents the capillary pressure. The saturation profile is measured using an NMR technique and for a drainage case, the pressure in the nonwetting phase is calculated numerically. This paper presents the NMR technique and the procedure for calculating the pressure distribution in the sample. Inhomogeneous samples produce irregular saturation profiles, which may be interpreted in terms of variation in permeability, porosity, and capillary pressure. Capillary pressure curves for North Sea chalk obtained by the new technique show good agreement with capillary pressure curves obtained by traditional techniques.
Elsevier eBooks, 2003
The IEA Weyburn CO 2 Monitoring and Storage Project is a collaborative investigation involving ge... more The IEA Weyburn CO 2 Monitoring and Storage Project is a collaborative investigation involving geoscientists from North America and Europe, and is co-ordinated by the Petroleum Technology Research Centre (PTRC) in Regina, Canada. The IEA Weyburn CO 2 Monitoring and Storage Project is currently analyzing the effects of a miscible CO 2 flood into a carbonate reservoir rock at a mature onshore Canadian oilfield. Anthropogenic CO 2 is being injected as part of an enhanced oil recovery operation. The European contribution includes the analysis of the long-term safety and performance of CO 2 storage via construction of features, events and processes (FEP) database. This will allow the integrity of deep storage of CO 2 in sedimentary rocks to be investigated objectively. Initial work has also been focused on better understanding the pre-injection hydrogeological and geochemical conditions in the reservoir to recognize changes resulting from injection of the CO 2 . The CO 2 distributions are irregular and reflect anthropogenic or near surface phenomena and seasonal variations in CO 2 fluxes are present. There are no correlations between gas anomalies and injection wells or pipelines. Changes from these baseline conditions as a result of CO 2 injection are also under investigation and will be the focus of future activities. Geochemical experiments, predictive computer modeling, microseismic monitoring, and soil gas surveys will be carried out to investigate CO 2 migration pathways and the rate and extent of chemical reactions of the injected CO 2 with the host formation and adjacent strata.
Measurement of Archie's Resistivity Index 'RI' and saturation exponent 'n' can be very time consu... more Measurement of Archie's Resistivity Index 'RI' and saturation exponent 'n' can be very time consuming for low permeable core samples using the established porous plate techniques. An evaporation technique circumventing the porous plate difficulties has been developed, and is demonstra ted for the tight Lower Cretaceous carbonates in the Danish North Sea. Samples are saturated with a diluted formation brine and by evaporation water is removed from the diluted brine in the samples until the original brine concentration has been restored and the samples has attained a water saturation < 1. By this technique any water saturation down to approximately 0.1 can be imposed on the sample in less than a week. The movement of water in the sample during desaturation is documented by a tracer technique and core scanning, and data from the Lower Cretaceous carbonates are presented.
SPE reservoir evaluation & engineering, Apr 1, 1999
A new technique for obtaining water-oil capillary pressure curves, based on nuclear magnetic reso... more A new technique for obtaining water-oil capillary pressure curves, based on nuclear magnetic resonance ͑NMR͒ imaging of the saturation distribution in flooded cores is presented. In this technique, a steady-state fluid saturation profile is developed by flooding the core at a constant flow rate. At the steadystate situation where the saturation distribution no longer changes, the local pressure difference between the wetting and nonwetting phases represents the capillary pressure. The saturation profile is measured using an NMR technique and for a drainage case, the pressure in the nonwetting phase is calculated numerically. This paper presents the NMR technique and the procedure for calculating the pressure distribution in the sample. Inhomogeneous samples produce irregular saturation profiles, which may be interpreted in terms of variation in permeability, porosity, and capillary pressure. Capillary pressure curves for North Sea chalk obtained by the new technique show good agreement with capillary pressure curves obtained by traditional techniques.
Proceedings of SPE Annual Technical Conference and Exhibition, Oct 1, 1995
A new technique for obtaining water-oil capillary pressure curves, based on nuclear magnetic reso... more A new technique for obtaining water-oil capillary pressure curves, based on nuclear magnetic resonance ͑NMR͒ imaging of the saturation distribution in flooded cores is presented. In this technique, a steady-state fluid saturation profile is developed by flooding the core at a constant flow rate. At the steadystate situation where the saturation distribution no longer changes, the local pressure difference between the wetting and nonwetting phases represents the capillary pressure. The saturation profile is measured using an NMR technique and for a drainage case, the pressure in the nonwetting phase is calculated numerically. This paper presents the NMR technique and the procedure for calculating the pressure distribution in the sample. Inhomogeneous samples produce irregular saturation profiles, which may be interpreted in terms of variation in permeability, porosity, and capillary pressure. Capillary pressure curves for North Sea chalk obtained by the new technique show good agreement with capillary pressure curves obtained by traditional techniques.
DGU serie, Oct 31, 1984
The volume deals with the lithostratigraphy of Zechstein domal evaporites and a geochemical study... more The volume deals with the lithostratigraphy of Zechstein domal evaporites and a geochemical study of Zechstein 1 and 2 rock salt.
Petrophysics, Feb 1, 2017
Mercury injection capillary pressure (MICP) measurements are frequently considered as part of rou... more Mercury injection capillary pressure (MICP) measurements are frequently considered as part of routine core analysis (RCA) programmes, and a fair number of MICP samples are then taken from each core brought to surface. MICP data in combination with log data are used in building saturation-height functions that in turn are necessary to calculate STOIIP and initialise reservoir simulation models. From a physics point of view, MICP has a resemblance to porous plate (PP) measurements: at a preselected number of pressure steps the amount of injected fluid is measured after equilibration, that is, when fluid movement has come to a standstill. It is well known that PP experiments, just like other special core analysis (SCAL) measurement methods are subject to interference between capillary forces and viscous forces due to relative permeability. For that reason, state-of-the-art SCAL data are extracted from experiments through interpretation-by-simulation. In SCAL relative permeability experiments, the impact of such interpretation is often significant (e.g. residual oil saturations may reduce by 10 to 15 units). Some 40 samples have been investigated by MICP, under various measurement protocols, to study a possible saturation shift due to an interference with relative permeability similar to what is observed in other SCAL experiments. The measurements were designed using an adapted version of the license-free SCAL simulator SCORES. In line with the simulations, the experiments show that mainly recordings of the saturations of the plateau of the capillary pressure curve do not reach equilibrium conditions in conventional MICP measurements. The plateau values should be shifted to lower wetting phase saturations by 10 to 15 units. In hydrocarbon reservoirs with an extensive transition zone, the transition zone may be significantly reduced and a sizeable effect on STOIIP and therefore on reserves can be expected. The paper presents detailed information on an improved MICP measurement protocol.
Canadian Journal of Earth Sciences, Feb 1, 1994
Established isotopic sediment-dating techniques have been used to date the time of deformation an... more Established isotopic sediment-dating techniques have been used to date the time of deformation and metamorphism of the lower Palaeozoic rocks within the North Greenland fold belt. Fine mineral fractions < 2 μm have been separated from pelitic sediments at widely distributed localities and analysed using X-ray diffraction, isotope, and geochemical techniques.The mineralogical study identified two slightly different mineral parageneses of low greenschist facies. One assemblage without the sodium mica paragonite is confined to calcareous lithologies of the Amundsen Land and Vølvedal groups. The second assemblage includes paragonite and is found in noncalcareous lithologies of the Polkorridoren Group.Rb–Sr isotope dating of the mineral fractions yielded isochron ages in the range 318–346 Ma, which shows that final uplift and cooling associated with Ellesmerian tectonism in North Greenland occurred in the Mississippian. The results suggest that, although the metamorphism was of regional scale, recrystallization and isotopic homogenization occurred in closed systems of local extent.
Elsevier eBooks, 2003
Publisher Summary This chapter summarizes results of the geochemical work carried out as part of ... more Publisher Summary This chapter summarizes results of the geochemical work carried out as part of the “Saline Aquifer CO2 Storage” (SACS) project, a European research project that aims to monitor the injection operations at Sleipner. The objective of the geochemical work within the SACS project was to determine the potential for chemical reactions between injected CO2, formation water and the reservoir rock, as these reactions may affect injection operations and long term CO2 storage potential. The chemical reactivity of CO2 with a host formation has to be assessed in any CO2 geological sequestration project, as it may affect injection operations and long term CO2 storage potential. At the Sleipner gas field (Norwegian sector of the North Sea), CO2 has been injected since 1996 into a deep saline aquifer (Utsira formation) approximately 1 km below the bed of the North Sea. This can enhance the CO2 storage capacity and have consequences on CO2 migration or immobilization. A direct approach was used, based on laboratory experiments reacting samples of Utsira sand and formation water with CO2 under simulated reservoir conditions for timescales up to 24 months. Laboratory investigations are particularly useful for the study of shorter-term processes. Although limited in scale and timeframe, laboratory experiments have the advantage that they can help to identify the key geochemical reactions on actual rock material under actual reservoir conditions, which is very important as such reactions are known to be highly site-specific. They are also helpful to test the ability of geochemical codes to reproduce the experimental observations before using them to make long term predictions over experimental timescales up to thousands of years.
Cement & Concrete Composites, Sep 1, 2008
Pozzolanic submicron-sized silica fume and the non-pozzolanic micron- and nano-sized layer silica... more Pozzolanic submicron-sized silica fume and the non-pozzolanic micron- and nano-sized layer silicates (clay minerals) kaolinite, smectite and palygorskite have been used as additives in Portland cement pastes and mortars. These layer silicates have different particle shape (needles and plates), surface charge, and size (micron and nano). The structure of the resulting cement pastes and mortars has been investigated by atomic
67th EAGE Conference & Exhibition, 2005
H026 Mineralogical and textural control on chalk background velocity and porosity Introduction 1 ... more H026 Mineralogical and textural control on chalk background velocity and porosity Introduction 1 IDA L. FABRICIUS 1 LARS GOMMESEN 2 DAN OLSEN 3 NIELS SPRINGER 3 PETER JAPSEN 3 FINN JAKOBSEN 3 CHRISTIAN SCHIOTT 4 1 Technical University of Denmark (ER 2 Odegaard A/S Copenhagen Denmark; 3 GEUS Copenhagen Denmark; 4 Amerada Hess Copenhagen Denmark. In order to evaluate the variation in background velocity in chalk for seismic interpretation we need to address the influence of mineralogy and texture. For this purpose we sampled cores from the water zone of eight wells
Contributions to Mineralogy and Petrology, 1983
An example of diffusion in a natural solid rock is described using STSr as a tracer. The distribu... more An example of diffusion in a natural solid rock is described using STSr as a tracer. The distribution of excess radiogenic aTSr across the contact of a metamorphosed basic dyke in a granodioritic gneiss is shown to fit closely to a mathematically modelled theoretical diffusion curve. It is suggested that the excess radiogenic Sr was generated by the breakdown of older Rb-rich biotite in the country rock to form chlorite during a late-stage greenschist facies metamorphism, and then taken up into a fluid phase migrating along the country rock-dyke interface. This fluid introduced silica, alkalies, light REE, HzO, CO z, N and C1 into the marginal zone of the dyke, probably during fluid migration along grain boundaries. The present irregular distribution of the volatile constituents across the contact and in the dyke excludes a diffusion controlled distribution. The distribution of volatiles probably reflects the influence of the existing mineralogy on the geochemical anomaly actually recorded from a post magmatic process. Evidence is presented that the diffusivity of radiogenic Sr was enhanced by the presence of a volatile phase.
Clay Minerals, 2011
In the Upper Cretaceous-Danian North Sea chalk, silica composed of nano-size quartz spheres is di... more In the Upper Cretaceous-Danian North Sea chalk, silica composed of nano-size quartz spheres is dispersed in the chalk matrix, and quartz is present in bands and nodules of flint. In the present investigation of the North Sea Danian chalk the nano-quartz in the chalk matrix is compared with the silica in the flint. Samples of chalk and flint layers from four North Sea wells have been investigated. Atomic Force Microscopy (AFM) has been applied to image the quartz in the chalk and in the flint. X-ray diffraction (XRD), including analysis of the positions and profiles of hkl reflections in powder diffraction patterns, has been applied to characterize the lattice of the quartz in both the chalk matrix and in the flint. The quartz in the chalk matrix and in the flint is composed of nano-quartz spheres having identical cell parameters. Based on the results we propose a new model for formation of flint in North Sea chalk: (1) The nano-quartz in the flint, like the nano-quartz in the chalk ...
Rapport Grønlands Geologiske Undersøgelse, 1981
This report presents the first Rb-Sr age determinations obtained on low-grade metasediments withi... more This report presents the first Rb-Sr age determinations obtained on low-grade metasediments within the eastern part of the North Greenland fold belt. Samples were collected during the 1979 field mapping in eastem Johannes V. Jensen Land, the results ofwhich have been published elsewhere (Soper et al., 1980). Material selected for this study was taken from moderately folded rocks of the Polkorridoren Group and from the northem part of the fold belt where deformation is intense and sedimentary structures are rarely preserved (fig. 23). The principles and methods of isotopic dating of sedimentary rocks applied in this study have been treated in a recent paper by Clauer (1979).
All Days, Oct 22, 1995
A new technique for obtaining water-oil capillary pressure curves, based on nuclear magnetic reso... more A new technique for obtaining water-oil capillary pressure curves, based on nuclear magnetic resonance ͑NMR͒ imaging of the saturation distribution in flooded cores is presented. In this technique, a steady-state fluid saturation profile is developed by flooding the core at a constant flow rate. At the steadystate situation where the saturation distribution no longer changes, the local pressure difference between the wetting and nonwetting phases represents the capillary pressure. The saturation profile is measured using an NMR technique and for a drainage case, the pressure in the nonwetting phase is calculated numerically. This paper presents the NMR technique and the procedure for calculating the pressure distribution in the sample. Inhomogeneous samples produce irregular saturation profiles, which may be interpreted in terms of variation in permeability, porosity, and capillary pressure. Capillary pressure curves for North Sea chalk obtained by the new technique show good agreement with capillary pressure curves obtained by traditional techniques.
Elsevier eBooks, 2003
The IEA Weyburn CO 2 Monitoring and Storage Project is a collaborative investigation involving ge... more The IEA Weyburn CO 2 Monitoring and Storage Project is a collaborative investigation involving geoscientists from North America and Europe, and is co-ordinated by the Petroleum Technology Research Centre (PTRC) in Regina, Canada. The IEA Weyburn CO 2 Monitoring and Storage Project is currently analyzing the effects of a miscible CO 2 flood into a carbonate reservoir rock at a mature onshore Canadian oilfield. Anthropogenic CO 2 is being injected as part of an enhanced oil recovery operation. The European contribution includes the analysis of the long-term safety and performance of CO 2 storage via construction of features, events and processes (FEP) database. This will allow the integrity of deep storage of CO 2 in sedimentary rocks to be investigated objectively. Initial work has also been focused on better understanding the pre-injection hydrogeological and geochemical conditions in the reservoir to recognize changes resulting from injection of the CO 2 . The CO 2 distributions are irregular and reflect anthropogenic or near surface phenomena and seasonal variations in CO 2 fluxes are present. There are no correlations between gas anomalies and injection wells or pipelines. Changes from these baseline conditions as a result of CO 2 injection are also under investigation and will be the focus of future activities. Geochemical experiments, predictive computer modeling, microseismic monitoring, and soil gas surveys will be carried out to investigate CO 2 migration pathways and the rate and extent of chemical reactions of the injected CO 2 with the host formation and adjacent strata.
Measurement of Archie's Resistivity Index 'RI' and saturation exponent 'n' can be very time consu... more Measurement of Archie's Resistivity Index 'RI' and saturation exponent 'n' can be very time consuming for low permeable core samples using the established porous plate techniques. An evaporation technique circumventing the porous plate difficulties has been developed, and is demonstra ted for the tight Lower Cretaceous carbonates in the Danish North Sea. Samples are saturated with a diluted formation brine and by evaporation water is removed from the diluted brine in the samples until the original brine concentration has been restored and the samples has attained a water saturation < 1. By this technique any water saturation down to approximately 0.1 can be imposed on the sample in less than a week. The movement of water in the sample during desaturation is documented by a tracer technique and core scanning, and data from the Lower Cretaceous carbonates are presented.
SPE reservoir evaluation & engineering, Apr 1, 1999
A new technique for obtaining water-oil capillary pressure curves, based on nuclear magnetic reso... more A new technique for obtaining water-oil capillary pressure curves, based on nuclear magnetic resonance ͑NMR͒ imaging of the saturation distribution in flooded cores is presented. In this technique, a steady-state fluid saturation profile is developed by flooding the core at a constant flow rate. At the steadystate situation where the saturation distribution no longer changes, the local pressure difference between the wetting and nonwetting phases represents the capillary pressure. The saturation profile is measured using an NMR technique and for a drainage case, the pressure in the nonwetting phase is calculated numerically. This paper presents the NMR technique and the procedure for calculating the pressure distribution in the sample. Inhomogeneous samples produce irregular saturation profiles, which may be interpreted in terms of variation in permeability, porosity, and capillary pressure. Capillary pressure curves for North Sea chalk obtained by the new technique show good agreement with capillary pressure curves obtained by traditional techniques.
Proceedings of SPE Annual Technical Conference and Exhibition, Oct 1, 1995
A new technique for obtaining water-oil capillary pressure curves, based on nuclear magnetic reso... more A new technique for obtaining water-oil capillary pressure curves, based on nuclear magnetic resonance ͑NMR͒ imaging of the saturation distribution in flooded cores is presented. In this technique, a steady-state fluid saturation profile is developed by flooding the core at a constant flow rate. At the steadystate situation where the saturation distribution no longer changes, the local pressure difference between the wetting and nonwetting phases represents the capillary pressure. The saturation profile is measured using an NMR technique and for a drainage case, the pressure in the nonwetting phase is calculated numerically. This paper presents the NMR technique and the procedure for calculating the pressure distribution in the sample. Inhomogeneous samples produce irregular saturation profiles, which may be interpreted in terms of variation in permeability, porosity, and capillary pressure. Capillary pressure curves for North Sea chalk obtained by the new technique show good agreement with capillary pressure curves obtained by traditional techniques.
DGU serie, Oct 31, 1984
The volume deals with the lithostratigraphy of Zechstein domal evaporites and a geochemical study... more The volume deals with the lithostratigraphy of Zechstein domal evaporites and a geochemical study of Zechstein 1 and 2 rock salt.
Petrophysics, Feb 1, 2017
Mercury injection capillary pressure (MICP) measurements are frequently considered as part of rou... more Mercury injection capillary pressure (MICP) measurements are frequently considered as part of routine core analysis (RCA) programmes, and a fair number of MICP samples are then taken from each core brought to surface. MICP data in combination with log data are used in building saturation-height functions that in turn are necessary to calculate STOIIP and initialise reservoir simulation models. From a physics point of view, MICP has a resemblance to porous plate (PP) measurements: at a preselected number of pressure steps the amount of injected fluid is measured after equilibration, that is, when fluid movement has come to a standstill. It is well known that PP experiments, just like other special core analysis (SCAL) measurement methods are subject to interference between capillary forces and viscous forces due to relative permeability. For that reason, state-of-the-art SCAL data are extracted from experiments through interpretation-by-simulation. In SCAL relative permeability experiments, the impact of such interpretation is often significant (e.g. residual oil saturations may reduce by 10 to 15 units). Some 40 samples have been investigated by MICP, under various measurement protocols, to study a possible saturation shift due to an interference with relative permeability similar to what is observed in other SCAL experiments. The measurements were designed using an adapted version of the license-free SCAL simulator SCORES. In line with the simulations, the experiments show that mainly recordings of the saturations of the plateau of the capillary pressure curve do not reach equilibrium conditions in conventional MICP measurements. The plateau values should be shifted to lower wetting phase saturations by 10 to 15 units. In hydrocarbon reservoirs with an extensive transition zone, the transition zone may be significantly reduced and a sizeable effect on STOIIP and therefore on reserves can be expected. The paper presents detailed information on an improved MICP measurement protocol.
Canadian Journal of Earth Sciences, Feb 1, 1994
Established isotopic sediment-dating techniques have been used to date the time of deformation an... more Established isotopic sediment-dating techniques have been used to date the time of deformation and metamorphism of the lower Palaeozoic rocks within the North Greenland fold belt. Fine mineral fractions < 2 μm have been separated from pelitic sediments at widely distributed localities and analysed using X-ray diffraction, isotope, and geochemical techniques.The mineralogical study identified two slightly different mineral parageneses of low greenschist facies. One assemblage without the sodium mica paragonite is confined to calcareous lithologies of the Amundsen Land and Vølvedal groups. The second assemblage includes paragonite and is found in noncalcareous lithologies of the Polkorridoren Group.Rb–Sr isotope dating of the mineral fractions yielded isochron ages in the range 318–346 Ma, which shows that final uplift and cooling associated with Ellesmerian tectonism in North Greenland occurred in the Mississippian. The results suggest that, although the metamorphism was of regional scale, recrystallization and isotopic homogenization occurred in closed systems of local extent.
Elsevier eBooks, 2003
Publisher Summary This chapter summarizes results of the geochemical work carried out as part of ... more Publisher Summary This chapter summarizes results of the geochemical work carried out as part of the “Saline Aquifer CO2 Storage” (SACS) project, a European research project that aims to monitor the injection operations at Sleipner. The objective of the geochemical work within the SACS project was to determine the potential for chemical reactions between injected CO2, formation water and the reservoir rock, as these reactions may affect injection operations and long term CO2 storage potential. The chemical reactivity of CO2 with a host formation has to be assessed in any CO2 geological sequestration project, as it may affect injection operations and long term CO2 storage potential. At the Sleipner gas field (Norwegian sector of the North Sea), CO2 has been injected since 1996 into a deep saline aquifer (Utsira formation) approximately 1 km below the bed of the North Sea. This can enhance the CO2 storage capacity and have consequences on CO2 migration or immobilization. A direct approach was used, based on laboratory experiments reacting samples of Utsira sand and formation water with CO2 under simulated reservoir conditions for timescales up to 24 months. Laboratory investigations are particularly useful for the study of shorter-term processes. Although limited in scale and timeframe, laboratory experiments have the advantage that they can help to identify the key geochemical reactions on actual rock material under actual reservoir conditions, which is very important as such reactions are known to be highly site-specific. They are also helpful to test the ability of geochemical codes to reproduce the experimental observations before using them to make long term predictions over experimental timescales up to thousands of years.
Cement & Concrete Composites, Sep 1, 2008
Pozzolanic submicron-sized silica fume and the non-pozzolanic micron- and nano-sized layer silica... more Pozzolanic submicron-sized silica fume and the non-pozzolanic micron- and nano-sized layer silicates (clay minerals) kaolinite, smectite and palygorskite have been used as additives in Portland cement pastes and mortars. These layer silicates have different particle shape (needles and plates), surface charge, and size (micron and nano). The structure of the resulting cement pastes and mortars has been investigated by atomic
67th EAGE Conference & Exhibition, 2005
H026 Mineralogical and textural control on chalk background velocity and porosity Introduction 1 ... more H026 Mineralogical and textural control on chalk background velocity and porosity Introduction 1 IDA L. FABRICIUS 1 LARS GOMMESEN 2 DAN OLSEN 3 NIELS SPRINGER 3 PETER JAPSEN 3 FINN JAKOBSEN 3 CHRISTIAN SCHIOTT 4 1 Technical University of Denmark (ER 2 Odegaard A/S Copenhagen Denmark; 3 GEUS Copenhagen Denmark; 4 Amerada Hess Copenhagen Denmark. In order to evaluate the variation in background velocity in chalk for seismic interpretation we need to address the influence of mineralogy and texture. For this purpose we sampled cores from the water zone of eight wells
Contributions to Mineralogy and Petrology, 1983
An example of diffusion in a natural solid rock is described using STSr as a tracer. The distribu... more An example of diffusion in a natural solid rock is described using STSr as a tracer. The distribution of excess radiogenic aTSr across the contact of a metamorphosed basic dyke in a granodioritic gneiss is shown to fit closely to a mathematically modelled theoretical diffusion curve. It is suggested that the excess radiogenic Sr was generated by the breakdown of older Rb-rich biotite in the country rock to form chlorite during a late-stage greenschist facies metamorphism, and then taken up into a fluid phase migrating along the country rock-dyke interface. This fluid introduced silica, alkalies, light REE, HzO, CO z, N and C1 into the marginal zone of the dyke, probably during fluid migration along grain boundaries. The present irregular distribution of the volatile constituents across the contact and in the dyke excludes a diffusion controlled distribution. The distribution of volatiles probably reflects the influence of the existing mineralogy on the geochemical anomaly actually recorded from a post magmatic process. Evidence is presented that the diffusivity of radiogenic Sr was enhanced by the presence of a volatile phase.
Clay Minerals, 2011
In the Upper Cretaceous-Danian North Sea chalk, silica composed of nano-size quartz spheres is di... more In the Upper Cretaceous-Danian North Sea chalk, silica composed of nano-size quartz spheres is dispersed in the chalk matrix, and quartz is present in bands and nodules of flint. In the present investigation of the North Sea Danian chalk the nano-quartz in the chalk matrix is compared with the silica in the flint. Samples of chalk and flint layers from four North Sea wells have been investigated. Atomic Force Microscopy (AFM) has been applied to image the quartz in the chalk and in the flint. X-ray diffraction (XRD), including analysis of the positions and profiles of hkl reflections in powder diffraction patterns, has been applied to characterize the lattice of the quartz in both the chalk matrix and in the flint. The quartz in the chalk matrix and in the flint is composed of nano-quartz spheres having identical cell parameters. Based on the results we propose a new model for formation of flint in North Sea chalk: (1) The nano-quartz in the flint, like the nano-quartz in the chalk ...
Rapport Grønlands Geologiske Undersøgelse, 1981
This report presents the first Rb-Sr age determinations obtained on low-grade metasediments withi... more This report presents the first Rb-Sr age determinations obtained on low-grade metasediments within the eastern part of the North Greenland fold belt. Samples were collected during the 1979 field mapping in eastem Johannes V. Jensen Land, the results ofwhich have been published elsewhere (Soper et al., 1980). Material selected for this study was taken from moderately folded rocks of the Polkorridoren Group and from the northem part of the fold belt where deformation is intense and sedimentary structures are rarely preserved (fig. 23). The principles and methods of isotopic dating of sedimentary rocks applied in this study have been treated in a recent paper by Clauer (1979).