Marine Impacts and Environmental Consequences—Drilling of the Mjølnir Structure, the Barents Sea

In September 2007, thirty-three scientists attended an international workshop in Longyearbyen (Svalbard, Norway) to discuss impacts of extraterrestrial bodies into marine environment and to prepare for the drilling of the 142-Ma-old Mjølnir impact structure in the Barents Sea (Fig. 1; Gudlaugsson, 1993; Dypvik et al., 1996, Tsikalas et al., 1998). A field trip visited the ejecta layer in the Janusfjellet Mountain in Isfjorden, just outside Longyearbyen (Fig. 2). The workshop focused on two topics: 1) mechanisms of marine impact cratering including ejecta formation and distribution, geothermal reactions, and the formation of tsunami, and 2) environmental effects of marine impacts. Both topics are highly relevant to the Mjølnir event and the geological evolution of the Arctic, as well as to the biological changes at the Jurassic-Cretaceous boundary. Against thisbackground were a) concrete drilling targets formulated, b) plans outlined for compiling data from existing geological and geophysical surveys as the basis for Integrated Ocean Drilling Program (IODP) and International Continental Scientific Drilling Program (ICDP) drilling proposals, and c) a steering group and science teams established for compiling old and new material as a foundation for the developmentof drilling proposal

Shaking and splashing—A case study of far-field effects of the Mjølnir asteroid impact on depositional environments in the Barents Sea

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ExoMars Raman Laser Spectrometer RLS, a tool for the potential recognition of wet target craters on Mars

In the present work, NIR, LIBS, Raman and XRD techniques have been complementarily used to carry out a comprehensive characterization of a terrestrial analogue selected from the Chesapeake Bay Impact Structure (CBIS). The obtained data clearly highlight the key role of Raman spectroscopy in the detection of minor and trace compounds, through which inferences about geological processes occurred in the CBIS can be extrapolated. Beside the use of commercial systems, further Raman analyses were performed by the Raman Laser Spectrometer (RLS) ExoMars Simulator. This instrument represents the most reliable tool to effectively predict the scientific capabilities of the ExoMars/Raman system that will be deployed on Mars in 2021. By emulating the analytical procedures and operational restrictions established by the ExoMars mission rover design, it was proved that the RLS ExoMars Simulator is able to detect the amorphization of quartz, which constitutes an analytical clue of the impact origin of craters. On the other hand, the detection of barite and siderite, compounds crystallizing under hydrothermal conditions, helps to indirectly confirm the presence of water in impact targets. Furthermore, the RLS ExoMars Simulator capability of performing smart molecular mappings was also evaluated. According to the obtained results, the algorithms developed for its operation provide a great analytical advantage over most of the automatic analysis systems employed by commercial Raman instruments, encouraging its application for many additional scientific and commercial purposes

The Ritland impact crater - Appearance and mechanisms of formation 2013

The objectives of the project will be met by detailed studies in the field, laboratory analyses and numerical modelling. The field studies will cover the impact rocks, the fractured basement rocks and the post-impact crater infill sequence, including search for ejected material. We will utilise the 3-dimensional erosional cut and the excellent exposures of the Ritland crater to reconstruct the original crater shape and the history of crater infilling by applying petroleum industry software (Petrel). This reconstruction will be the base for modeling the mechanics of crater formation (Shuvalov). The basement fracturing will be documented in sections with continuous detailed photographic coverage. Using the crater model, the sections can then be analysed with reference to their original xyz location relative to the pre-erosional crater structure. Geochemical studies will be carried out on samples of the impact rocks with suevite-like textures, as well as on selected post-impact sediments from the lowermost part of the crater structure. If the new field-work succeeds in finding ejecta material, this will also be included. Analyses of the platinum group elements as well as Os and Cr isotopes will be carried out at the University of Vienna, to obtain information about the impactor. We will also look into the possibility of radiometric dating of glass samples. The excellent exposures of fractured basement and crater fill of the Ritland Crater are complementary to, and will be compared with the Gardnos Crater, which is larger, more complex and with more scattered exposures. Elin Kalleson will finish her PhD on Gardnos in 2008 and her experience will be important for a flying start of this project. It is an objective to document the Ritland Crater as a reference area for future scientific studies. The project also aims to use the Ritland rater to develop interest for geology and natural sciences in the local community and the region. Data from the project are presented in several papers. See references below

Tab. 1: Semi-quantitative estimations of mineral composition

Paleontological and petrological studies of clay beds in the Basilika Formation (Tertiary age) are the subject of this paper. The petrology of the beds indicates that their main constituents were derived from volcanic activity and represent bentonites. Differing composition of the beds may suggest several spatially separated eruptions. The volcanic source area probably lay towards the north of the present Tertiary outcrops of Svalbard. Two foraminiferal assemblages are found in the bentonites: the lower is dominated by arenaceous forms while the upper consists of calcareous species

Late Jurassic/Early Cretaceous phosphates of Nordvik, North Siberian Basin

Late Jurassic and Early Cretaceous calcite-rich phosphate (fluor/hydroxy apatite) concretions in the North Siberian basin (Nordvik) have been analysed. Their mineralogical and geochemical (major, trace and rare earth element) characteristics are presented in a sedimentological context. Low oxygen conditions prevailed along large parts of the seafloor of this wide epicontinental sea. In the Nordvik region this, in combination with slow and very fine-grained clastic sedimentation, and high algal production, resulted in the formation of phosphatic concretions. The concretions mainly consist of microcrystalline to ultracrystalline apatite and calcite, with traces of sphalerite, pyrite, kaolinite, quartz and albite. The clastic composition of the concretions is comparable with the surrounding Nordvik shales. Dysoxic–anoxic conditions in the last precipitating pore-water phases (early diagenetic) are reflected in enrichments in, for example, vanadium, uranium and the rare earth elements in the concretions

The Lower Miocene Nukhul Formation (Gulf of Suez, Egypt): microfacies and reservoir characteristics

The Lower Miocene Nukhul Formation was deposited early during early stages of Gulf of Suez rifting. Outcrop of this Formation at Gebel el Zeit, Egypt is up to 100 m (328 ft) thick and consist of lower sandstone-dominated and upper carbonate-dominated units. Samples were collected from the Nukhul Formation outcrop to describe the lithofacies, mineralogy, and petrographic characteristics to better understand the hydrocarbon reservoir potential for the unit. The investigations showed that the lower part of Nukhul Formation at North Gebel el Zeit consists of poorly sorted, dolomitic sandstone and sandy dolomite which were deposited in a shallow-marine setting. The presence of polycrystalline and crushed quartz grains in Nukhul strata indicates that these strata were sourced by recycled sediments associated with local uplift tied to rifting. The upper Nukhul consists of dolomitized carbonates with preservation of primary textures; primary limestone depositional textures include the following: intraclast packstone, rudstone, and coral-algal boundstone, wackestone, and grainstone with minor floatstone. Carbonate rock strata were deposited in shallow marine, peritidal to subtidal environments that developed on fault-block highs. The presence of zoned saddle dolomite suggests some component of fault-controlled fluid flow. The reservoir characteristic of the Lower Miocene Nukhul Formation at the Gebel el Zeit indicates favorable properties for reservoir development in both the lower siliciclastic-dominated dolomite and the upper dolomitized carbonate portions of the formation

Fluid inclusions and quartz cementation in Jurassic sandstones from Haltenbanken, offshore Mid-Norway

Fluid inclusions have been examined in quartz overgrowth from the Middle-Lower Jurassic sandstones of the Haltenbanken area, offshore Mid-Norway, in order to determine the chemical composition and temperatures of fluids associated with quartz cementation, which appears to be late diagenetic and closely related to stylolitization. The examined fluid inclusions occur within the quartz overgrowths and along the "dust rims" of detrital quartz grains ; they contain essentially aqueous solutions with salinities of 3-4 equivalent weight % NaCl and densities of 0.96-0.97 g/cm3. Traces of hydrocarbon, presumably mainly methane, are present in some inclusions. The data indicate that quartz overgrowth occurred at a late stage in the diagenetic history, during the circulation of low-salinity aqueous fluids at temperatures of + 140 °C to + 170 °C and at depths of burial of 3 500-4 500 m. Considering the burial history these conditions can only have been attained during the Late Tertiary. An average geothermal gradient of about 40 °C/km is suggested by the fluid inclusion data.Les inclusions fluides des silicifications diagénétiques des grès, d'âge jurassique moyen et inférieur, ont été étudiées pour déterminer les compositions chimiques et les températures de piégeage des fluides associés. La silicification diagénétique semble liée aux processus de stylolitisation. Les fluides sont essentiellement des solutions aqueuses avec des salinités de 3 % équivalent-poids NaCl et des densités de 0,96 à 0,97 g/cm3. Des traces d'hydrocarbures (principalement méthane) sont présentes dans quelques inclusions. Les résultats microthermométriques indiquent que la silicification diagénétique s'est déroulée entre + 140 °C et + 170 °C et à 3 500-4 500 m de profondeur. D'après l'histoire sédimentaire, ces conditions n'ont pu être réalisées qu'à la fin du Tertiaire. Un paléogradient thermique de 40 °C/km est compatible avec les caractéristiques des inclusions fluides.Konnerup-Madsen Jens, Dypvik Henning. Fluid inclusions and quartz cementation in Jurassic sandstones from Haltenbanken, offshore Mid-Norway. In: Bulletin de Minéralogie, volume 111, 3-4, 1988. Inclusions fluides. IXth symposium on fluid inclusions. University of Oporto – May 1987

Jurassic and Cretaceous palaeogeography and stratigraphic comparisons in the North Greenland-Svalbard region

We present sedimentological comparisons and stratigraphical correlations of the Jurassic and Cretaceous epicontinental shelf deposits of Svalbard and updated descriptions of the shallow-marine North Greenland sediments of East Peary Land and Kronprins Christians Land (Kilen). The Callovian to Volgian Agardhfjellet Formation of Svalbard is correlated to the lower part of the Ladegårdsåen Formation on East Peary Land, and to the Birkelund Fjeld, Splitbæk, and Kuglelejet formations of Kronprins Christian Land (Kilen). The Berriasian to Hauterivian Rurikfjellet Formation (Svalbard) correlates with the Dromledome and Lichen Ryg formations from Kilen and the middle part of the Ladegårdsåen Formation from East Peary Land. The Galadriel Fjeld Formation from Kilen and the upper part of the Ladegårdsåen Formation (East Peary Land) are comparable to the Helvetiafjellet and Carolinefjellet formations of Svalbard. These comparisons between Svalbard and North Greenland are combined with stratigraphical information from neighbouring regions in palaeogeographical reconstructions. Five selected time slices are presented within a setting of the most recent plate tectonic reconstructions for the area

Effects of geological heterogeneity on CO2 distribution and migration – A case study from the Johansen Formation, Norway

In characterizing subsurface reservoirs for CO2 storage, the geological heterogeneity distribution is of importance with respect to the injectivity and migration paths. The object of this study is a saline aquifer of Jurassic age; the Johansen Formation of the Northern North Sea. Through scenario modeling the effect of site-typical geological heterogeneities of depositional origin have been tested. The existence of laterally continuous calcite cemented layers and draping mud layers of low permeability in association with flooding events, could compartmentalize the reservoir. This is not necessarily a disadvantage; however, as the sweep efficiency becomes higher when the plume is spread out, potentially increasing the effect of trapping mechanisms