Gaut, S., 2005: Factors influencing microbiological quality of groundwater from potable water supply wells in Norwegian crystalline bedrock aquifers. Doktor Ingeniør thesis 2005:99. Department of Geology and Mineral Resources Engineering, NTNU, 153 pp and appendices. Microbiological analyses from 195 Norwegian waterworks based on groundwater in bedrock have been examined to study the vulnerability of bedrock wells to microbiological contamination. Inspections have been carried out at 49 of the 195 waterworks to identify possible causes to the recorded microbiological contamination. It is found that groundwater derived from bedrock wells is susceptible to microbiological contamination and needs better protection. Seasonal variations in the water quality occur. Coliforms are mostly detected from June to September. Cryptosporidium, but not Giardia, is detected in the groundwater from three of twenty waterworks. The microbiological water quality is correlated to (i) wellhead completion (including the well casing), (ii) type and thickness of superficial deposits, (iii) land use and contamination sources and (iv) distance from wells to running water. Recommended wellhead completion includes a well-house and a casing of at least 5.5 m, rising 40-50 cm above ground. The gap between casing and bedrock should be sealed. Wells are least vulnerable to microbiological contamination when the superficial deposits are > 2.5 m thick and the wells are located > 100 m from farmland and not within 75-125 m of running water. Variations in parameters, such as colour, turbidity, and iron, and high levels of total organic carbon can indicate that the aquifer or the well is vulnerable to microbiological contamination. Vulnerability mapping combined with a hygienic evaluation of the well area and delineation of protection zones based on simple analytical methods is suggested as a method to protect Norwegian bedrock wells.

A palaeodepositional model and an analysis of the diagenetic evolution of the Upper Triassic Snadd Formation in the Barents Sea are here presented. Attention has especially been given to the pedogenic structures dominating the sediments. The interpretations are based on core logging and thin section analyses including three shallow, stratigraphic wells from the south- western Barents Sea area. The data from the Nordkapp Basin represent a sediment succession of only a few meter thicknesses, and the main interpretation is therefore based on data from the Bjarmeland Platform core, which covers the upper 108.9 m of the Snadd Formation of Carnian to Norian age. Sandstones are mineralogical immature, fine- grained lithic arenites. Main carbonate cements include siderite, calcite and ankerite. Iron carbonates formed early in the diagenetic evolution and a progressive decrease in the Fe- content of the system with time has been evidenced. Kaolinite is a dominating, early diagenetic mineral, and indicates an overall humid climate. Regional interpretations of the Upper Triassic palaeoclimate, are that there was a switch from arid to humid on the Triassic- Jurassic border, and this goes well with the observations made in this study. Alternating sand and mud layers dominate the Upper Triassic strata and are suggested to represent deltaic sequences formed as a consequence of autocyclic switching of lobes on the delta plain. Sedimentary structures indicate a tidally influenced environment, while thin coal deposits and abundance of root structures indicate a transitional to continental setting. In the Bjarmeland Platform core there is a switch from coarsening upward units dominated by tidal structures in the lower portions to dominantly fining upward units with rooted horizons and lack of tidal influence in the upper portion, suggesting a transition from lower delta plain to mid/upper delta plain. The Nordkapp Basin cores bear resemblance to the upper portion of the Bjarmeland Platform succession and a similar setting has been interpreted for these deposits. The depostional model correlates well with former interpretations of a large- scale delta system prograding in a westward direction in Late Triassic. Mottled sediments clearly modified by pedogenic processes are found inbetween smaller fining upward or coarsening upward sand units. The interpreted delta plain environment is a favourable setting for pedogenesis and several micro-textures e.g. carbonate-coated grains, alveolar textures, circumgranular cracking and Microcodium have been identified in the polarization microscope. Coal beds are often associated with dark grey to black carbonaceous mudrocks reflecting high water table and reducing conditions during pedogenesis. The alternations between oxidized ferruginous palaeosols with carbonate concretions and carbonaceous palaeosols most likely reflects variation in ground-water level, caused by avulsion of channels on the delta plain. Oxidized palaeosols probably formed during low-water table while carbonaceous palaeosols were formed during high ground-water table perhaps in small pools on the delta plain. The well- preserved soil profiles indicate subaerial exposure for a sufficient period of time, followed by lack of subsequent erosion. Extensive carbonate cementation at an early stage has probably enhanced the preservation of the soils.

This master thesis presents a hierarchical modelling workflow in a slope canyon of the turbidite sandstone reservoir in the Formation X at the PA field in the Gulf of Mexico. The Formation X with approximately 400 m thick was deposited during Late Paleocene to Late Middle Eocene and composed of alternating shale and sandstone intervals. Depositional lithofacies, petrophysical well characteristics, 3D seismic data and geological facies models have been used for characterizing and evaluating of this turbidite reservoir. The reservoir properties and heterogeneities are typically controlled by facies architecture. Depositional lithofacies have been interpreted using core description in few wells, and have been tried to link with the predicted electrofacies from well logs. Two main logs representing depositional heterogeneity -GR and Vsh- have been interpreted using neutron and density logs and have been used to predict electrofacies in the Formation X. Three electrofacies have been predicated and considered as facies associations. The facies associations include sand, shaly-sand and shale. The core descriptions, regional studies and seismic data are valuable data to understand the conceptual geological model that can be used a guide to distribute the facies associations between the wells. Well tops from well logs have been interpreted by variations in depositional characteristics and have been tied to seismic surfaces in order to construct the stratigraphic framework. A total of eight surface resulted in defining seven geological zones to populate reservoir properties.The geological grids have been defined according to the possible depositional heterogeneities in lateral and vertical directions. Well data including facies and porosity in a scale of 15 cm have been scaled-up to geological grids with 1 m thick. Due to uncertainty in the conceptual depositional model two different alternative facies modelling methods have been tried in order to learn the modelling processes and to understand the challenges which may influence the final results. Object-based models have been used to model the sand facies as channel, shaly-sand facies as overbank and shale facies as background. The pixel-based facies models have been built based on random distribution of the facies according to the results from data analysis in available wells.Petrophysical models have been constrained to the pixel-based facies models using random function simulation algorithm. According to data analysis and the results from modelling, the depositional facie control reservoir properties. Sand facies have higher porosity values than shaly-sand and shale facies.The result from geological description, petrophysical evaluation, seismic interpretation and property modelling has shown that the Formation X is a complex turbidite system. Such complexities results in higher uncertainty in the results and thus uncertainty assessments are necessary in this kind of reservoirs.

The mid-Norwegian Vøring and Møre margins are listed as the type example of volcanic rifted margins, with their formation usually related to the influence of the Icelandic plume. Recent studies have shown that these margins have more in common with non-volcanic rifted margins than the scientific community used to think, which opens the discussion on their architecture and evolution. As the rifting mechanisms are not yet fully constrained, a wide variety of extensional models have been proposed in the literature. The evolution of the rifting models requires updated studies based on the new concepts and the new high resolution datasets now available. Despite the large amount of geophysical data acquired on the Vøring and Møre margins during the past decades, the ambiguity with respect to the deep structures, and especially in detecting sub-basaltic basement structures, where intrusions and lava flows perturb the seismic imaging, is still a matter of concern. This study illustrates the benefit of the combination of seismic and potential field modeling results. The forward gravity and magnetic modeling significantly improves the model accuracy and provides a valuable tool to estimate sub-basaltic deep crustal structures.

No description available.

The Port Askaig Formation is a succession of Cryogenian glacial deposits found near the middle of the 25 km thick Dalradian Supergroup. On the Isle of Islay, Scotland, the Port Askaig Formation is approximately 750 mthick in the north and thins over approximately 30 km to a few tens of meters towards the southern end ofthe island. The thinning of this stratum was investigated by performing a literary review of previous works to construct six stratigraphic columns and three cross-sections across the eastern half of Islay. Two models were developed using these cross-sections and columns to explain the thinning of the Port Askaig Formation on Islay. The syndepositional model suggests that the Dalradian sediments were deposited during the late Neoproterozoic Era in an extensional basin over an array of listric normal faults with increasing tectonic activity resulting in lateral thickness changes over short distances. The synorogenic model suggeststhe Dalradian Basin was subjected to deformation in the Caledonian Orogeny during the Ordovician Period. The basin experienced both extensional and compressional stresses resulting in thickness changes throughfolding, faulting, and shearing of the Dalradian sediments. It can be concluded that the major control of thinning of the Port Askaig Formation is due to basin tectonics, followed by the folding of the Dalradian Basin by compressive stresses.

No description available.

Northern Norrbotten County is one of the three major ore producing districts in Sweden. Based on the predominance of epigenetic Cu-Au and Fe-oxide mineralization this region is regarded as a typical IOCG province. The massive to layered Viscaria Cu-deposit is proposed to be a VMS deposit of Besshi-type and is unique in deposit type of the region. The volcaniclastic rocks of the Viscaria Formation hosting the Viscaria deposit belong to the rift related Kiruna Greenstone Group. The Viscaria deposit consists of three stratiform-stratabound mineralized zones: A-, B- and D-zone. Sulphide mineralization of the D-zone differs in structural features, host rock, mineralization style and Fe-oxide dominance over Cu-sulphides compared to the main Cu-ore in the A-zone. These differences between A- and D-zone mineralization styles raise the subject that the D-zone could be of a different origin.   The Kiruna area is mainly covered by glacial-till, which contributes to limited bedrock exposure. This becomes a challenge when exploring for new deposits and highlights the importance of good geological knowledge obtained from existing deposits to carry through successful exploration programs. The objective of this study is to characterize the Fe-Cu-occurrence and the associated alteration halo of the Viscaria D-zone. Alteration halos can reach several kilometres away from the main ore zone and provides mineralogical and chemical signatures that extend the target area significantly in exploration for new deposits. Detailed core logging, optical microscopic studies, lithogeochemistry and electron microprobe analyses was utilized to contribute to a better genetic understanding of the D-zone and the associated hanging wall and footwall alteration features. The study shows that the main ore minerals of the D-zone consist of magnetite and chalcopyrite, and minor pyrite and hematite. The major alteration minerals associated with mineralization are calcite, actinolite/tremolite, epidote, chlorite and also biotite and scapolite in the hanging wall. The most prominent potential ore vector is calcite veins and biotite, as the abundance increase towards the D-zone. D-zone are further characterised by low REE concentrations, similarly to the calcic-dolomite host. The study also shows that the alteration halo of the D-zone is different in the hanging wall compared to the footwall, which is confirmed by the lithogeochemistry and mineral chemistry. The footwall is characterized by spilitization and chlorite alteration. The lithogeochemistry of the D-zone and the hanging wall reveals element mobility of Mg, Ba, Fe, Na, K, Cu and Zn. Mineral chemistry of epidote, amphibole and chlorite shows chemical changes in Fe/Al- and Mg/Fe-ratios. According to the result of this thesis and earlier studies, the D-zone mineralization is suggested to be part of the VMS system forming the stratigraphically above laying A-zone of the Viscaria Cu-deposit.

<p>In co-operation with the Geological Survey of Norway, 395 samples of topsoil, 44 bedrock samples and 24 samples of sand from sandboxes at kindergartens taken in Oslo, the capital city of Norway, were analysed for a wide range of elements. To get a measure on the bio-availability of arsenic, a five stage sequential extraction procedure was accomplished on a subset of 98 topsoil samples and on all 24 samples of sand from sandboxes. These fractions (i.e. “Exchangeable”, “Carbonate”, “Reducible substrate”, “Organic” and “Residual”) were analysed for arsenic. Bulk concentrations in a representative subset of 10 bedrock samples were determined by XRF analysis.</p><p>For the concentrations of the elements As, B, Ba, Cd, Cr, Cu, Hg, Mn, Mo, Ni, P, Pb and Zn in soil, geologic sources are important, but human activity has had a large effect on concentrations in topsoil, especially in the central districts. At least 81% of the samples contain more arsenic than the Norm value for polluted soil used by the Norwegian authorities. For chromium, zinc and lead, the percentages are 65, 74 and 25 respectively. In topsoil, up to 50% of the arsenic is extractable in the exchangeable, the carbonate and the reducible substrate fractions, but only 2% of the samples exceeded the Norm value after the three extraction stages. After four stages of extraction, 69% of the samples exceeded the Norm value.</p><p>At 24 kindergartens in the central districts of Oslo, concentrations of As, Cd, Cr, Cu, Ni, Pb and Zn in topsoil samples are higher than in samples of sand from sandpits, but differences in arsenic are low. All topsoil samples and 63% of the sandbox samples exceed the arsenic Norm value for polluted soil used by the Norwegian authorities. Concentrations of at least one of the elements Cr, Cu, Ni, Pb and Zn exceed the Norm value in the topsoil. At two kindergartens all elements, except Cd, exceed the Norm value in the topsoil.</p><p>In the samples from the sandboxes, arsenic concentrations in the exchangeable, the carbonate and the reducible substrate fractions, lie at a higher level than in topsoil samples. Leakage of arsenic compounds from impregnated and painted wood have probably caused elevated concentrations of this element in the sand. At two kindergartens the cumulative arsenic content in samples from the sandboxes exceeds the Norm value of 2 mg/kg As for polluted soil already after two fractions (i.e. the “Exchangeable” and the “Carbonate” fraction). After three fractions, the arsenic content in sand at 5 kindergartens exceeds this value. After four fractions this number was still 5. Regarding soil, no kindergartens had a cumulative arsenic content after three stages of the extraction procedure. After four stages 16 kindergartens contained more arsenic than the Norwegian Norm value of 2 mg/kg As.</p><p>Bulk concentrations of metals, in the bedrock samples, are generally higher than the acid soluble concentrations. Differences are small for copper and zinc, somewhat higher for lead and nickel and considerably different for chromium. Acid soluble chromium concentrations in soil differ little when compared with acid soluble concentrations in bedrock, but are in general much lower than bulk concentrations in rock. Chromium is probably strongly incorporated in the mineral structure of rock samples and concentrated HNO3 cannot solubilize all chromium molecules. For copper, lead and zinc, the acid soluble concentrations in soil are higher than the bulk concentrations in bedrock. The parent rock material cannot be the only source for these elements in soils and various anthropogenic sources dispersed by air or water probably have major influence.</p><p>The enrichment of nickel in topsoil near highways in Oslo might be due to the bitumen content of road dust. The enrichment of chromium and copper might be due to wear and tear of cars and engine parts. There is no enrichment of cadmium and zinc in topsoil near highways. Concentrations of zinc in topsoil in Oslo are generally high, most probably because of industry. The possible addition of zinc from traffic to the topsoil is not observed, in this study.</p>

In co-operation with the Geological Survey of Norway, 395 samples of topsoil, 44 bedrock samples and 24 samples of sand from sandboxes at kindergartens taken in Oslo, the capital city of Norway, were analysed for a wide range of elements. To get a measure on the bio-availability of arsenic, a five stage sequential extraction procedure was accomplished on a subset of 98 topsoil samples and on all 24 samples of sand from sandboxes. These fractions (i.e. “Exchangeable”, “Carbonate”, “Reducible substrate”, “Organic” and “Residual”) were analysed for arsenic. Bulk concentrations in a representative subset of 10 bedrock samples were determined by XRF analysis. For the concentrations of the elements As, B, Ba, Cd, Cr, Cu, Hg, Mn, Mo, Ni, P, Pb and Zn in soil, geologic sources are important, but human activity has had a large effect on concentrations in topsoil, especially in the central districts. At least 81% of the samples contain more arsenic than the Norm value for polluted soil used by the Norwegian authorities. For chromium, zinc and lead, the percentages are 65, 74 and 25 respectively. In topsoil, up to 50% of the arsenic is extractable in the exchangeable, the carbonate and the reducible substrate fractions, but only 2% of the samples exceeded the Norm value after the three extraction stages. After four stages of extraction, 69% of the samples exceeded the Norm value. At 24 kindergartens in the central districts of Oslo, concentrations of As, Cd, Cr, Cu, Ni, Pb and Zn in topsoil samples are higher than in samples of sand from sandpits, but differences in arsenic are low. All topsoil samples and 63% of the sandbox samples exceed the arsenic Norm value for polluted soil used by the Norwegian authorities. Concentrations of at least one of the elements Cr, Cu, Ni, Pb and Zn exceed the Norm value in the topsoil. At two kindergartens all elements, except Cd, exceed the Norm value in the topsoil. In the samples from the sandboxes, arsenic concentrations in the exchangeable, the carbonate and the reducible substrate fractions, lie at a higher level than in topsoil samples. Leakage of arsenic compounds from impregnated and painted wood have probably caused elevated concentrations of this element in the sand. At two kindergartens the cumulative arsenic content in samples from the sandboxes exceeds the Norm value of 2 mg/kg As for polluted soil already after two fractions (i.e. the “Exchangeable” and the “Carbonate” fraction). After three fractions, the arsenic content in sand at 5 kindergartens exceeds this value. After four fractions this number was still 5. Regarding soil, no kindergartens had a cumulative arsenic content after three stages of the extraction procedure. After four stages 16 kindergartens contained more arsenic than the Norwegian Norm value of 2 mg/kg As. Bulk concentrations of metals, in the bedrock samples, are generally higher than the acid soluble concentrations. Differences are small for copper and zinc, somewhat higher for lead and nickel and considerably different for chromium. Acid soluble chromium concentrations in soil differ little when compared with acid soluble concentrations in bedrock, but are in general much lower than bulk concentrations in rock. Chromium is probably strongly incorporated in the mineral structure of rock samples and concentrated HNO3 cannot solubilize all chromium molecules. For copper, lead and zinc, the acid soluble concentrations in soil are higher than the bulk concentrations in bedrock. The parent rock material cannot be the only source for these elements in soils and various anthropogenic sources dispersed by air or water probably have major influence. The enrichment of nickel in topsoil near highways in Oslo might be due to the bitumen content of road dust. The enrichment of chromium and copper might be due to wear and tear of cars and engine parts. There is no enrichment of cadmium and zinc in topsoil near highways. Concentrations of zinc in topsoil in Oslo are generally high, most probably because of industry. The possible addition of zinc from traffic to the topsoil is not observed, in this study.