In 2009, CISP was one of two projects within the Swedish Deep Drilling Program (SDDP) that was granted funds for site investigations in the Swedish Research Council’s (VR) annual call for scientific projects. The project received about 1/2 of the applied funding, for the period 2010 – 2012, although the funds were available until the end of 2013.
The main objectives of CISP have been fulfilled with great success (see summary under 2012), and has led to some quite revolutionary discoveries. The new facies distribution in the Siljan area revealed by Oliver Lehnert and his group and large scale tectonic implications should be mentioned.
As expected new research questions have arisen, and following the unsuccessful application to VR 2013 it was decided by the principal investigators, in understanding with co-workers, that future research under the umbrella of the new SSDP project should take different directions.
New proposals for pilot studies under CISP management will therefore not be made, and because the main objectives have been reached the CISP project is therefore declared ended. We, the principal investigators, are extremely thankful to everyone involved for their enthusiastic and engaging participation during these years. Even though CISP ceases, research will continue in the Lockne and Siljan craters, albeit regrouped and with different specific aims.
Large impact structures are a key to understanding a diverse set of scientific problems since they record essentials about the geological history where they occur. The ambition of CISP was to characterize the large Lockne and Siljan crater structures, with decisive features in common. The Siljan structure, the largest impact structure in Western Europe, and Lockne, which is the best accessible and studied impact formed in relatively deep sea, occurred at the supposedly Himalayan-type Caledonian mountain front in Sweden. Their development therefore expresses interaction between a gigantic over-thrust plate and Baltica through about 80 Ma. The most important apparent interaction was depressing Baltica’s west flank to form the trough where both craters formed. Another was tectonic stress that influenced shape and mineralization in the craters. It is all the more important to elucidate the less understood complications that can help to understand other craters. Major issues are the importance of basement lithology and structure, depth of water or sediment cover at the time of impact.
In addition to impact tectonics, the effect on life from the impact event can be studied in the Lockne area where records of post-impact re-colonization are found. The Siljan crater, with its renowned carbonate mud mounds, also contains unique sedimentological and palaeontological records preserved solely within the crater structure.
In 2009 CISP was one of two projects within the Swedish Deep Drilling Program (SDDP) that was granted funds for site investigations in the Swedish Research Council’s (VR) annual call for scientific projects. The project received about 1/2 of the applied funding, for the period 2010 – 2012, although the funds were available until the end of 2013.
Dr. Erik Sturkell was the main applicant, with drs Jens Ormö (Centro de Astrobiología, Madrid, Spain), Christopher Juhlin (Uppsala University, Sweden), Reinhard O. Greiling (Karlsruhe Institute of Technology, Germany) and Anette Högström listed as co-workers. Administration of the project was handled by the principal investigators. The project was presented in the SDDP Science & Technology Plan in May 2010 (http://www.sddp.se/sciencetechnology), as well as in Högström et al. (2010).
Objectives and progression
The initial objective of the VR-proposal in 2009 for the project CISP was to establish reliable geological parameters for the deeper drilling of the Lockne and Siljan impact structures under the SDDP umbrella (Högström et al., 2010a).
Planned analytical approaches towards reaching this objective were:
- Shallow geophysics (resistivity and gravity in Lockne
- High resolution deep reflection seismic in Siljan
- Shallow drilling
- Study of fluid inclusions to determine composition of the fluids and constrain temperature and pressure conditions in shear zones related to the cratering
- Field reconnaissance for drill sites
- AMS studies (anisotropy of magnetic susceptibility) on basement rock
The Science and Technology Plan of SDDP lists 16 participants in CISP, which per 2011 was almost doubled.
In the initial year 2010, a general paper was published in where the project was presented (Högström et al., 2010a). During the autumn, field work was undertaken in the Siljan area near Nittsjö. Here a new section was measured of the Lower Palaeozoic sediments with a basal contact to the precambrian granites (Högström et al., 2010b). The field work was financed from sources outside CISP. The principal investigators are Oliver Lehnert (Friedrich-Alexander University Erlangen-Nürnberg, Germany), Ebbestad, Högström and Åsa Frisk (Fig. 1). Field work was also undertaken in Siljan by Holly Stein and Judith Hannah from the AIRIE Program (http://www.airieprogram.org/) at Colorado State University in partnership with the Geological Survey of Norway. This work is in collaboration with Jan Ove R. Ebbestad. The aim was to sample hydrocarbons and shales to better understand Re-Os fractionation between oil and shale on maturation. The field work was financed through grant support to the AIRIE Program. Previous preliminary studies from AIRIE include Stein et al. (2009a, b, c) and Zimmerman et al. (2009). A drilling down to 147 m was made in the Målingen structure in Lockne 2009 and 2010. This is a possible satellite crater to Lockne. The drilling was undertaken with sources outside CISP. Other field work consisted of geophysical surveys (magnetometry and gravimetry; Fig. 2). Results related to this work and other studies in Lockne were presented at meetings and in publications (Ormö et al., 2010a-d).
The main work performed during 2011 was the completion of two seismic lines on the west side of the Siljan structure. The principal investigator was Christopher Juhlin (Uppsala), and the work financed by CISP. The first line was 9 km and placed in an east-west direction just north of Mora. The second line was 12 km and placed in a north-south direction north of Orsa (Fig. 3). Each profile penetrated to about 2 km, and a number of good reflectors are evident. The seismic profile is being interpreted, and this will be the most important tool in determining the position of a deep drill hole. During field work at Nittsjö 2010, Högström and Ebbestad came in contact with personnel from the company Igrene (http://www.igrene.se/). In June 2011 Igrene extended an invitation to study three drill cores they had taken up in connection with their prospecting. Each core was about 600 m, penetrating the Palaeozoic succession and the underlying basement. The cores were taken at Solberga, Stumsnäs and Mora (Fig. 4). Oliver Lehnert, Stig Bergström (Ohio State University, Columbus, USA) and Jan Ove R. Ebbestad made initial investigations of the cores, which turned out to be extremely interesting (see Igrene’s newsletter linked here).
During October 2011 Lehnert, together with Guido Meinhold (University of Göttingen, Germany), continued a detailed logging of the core, sampling in detail for isotope- and biostratigraphy, geochemistry, thermal maturity, sediment provenance studies, and sedimentology (including detailed facies/microfacies studies). It seems that a palaeogeographical high existed to the west in Siljan, with a hiatus above the Holen Limestone. Preliminary graptolite identifications point to Silurian deposits following the Darriwilian Holen Limestone. The principal investigator is Lehnert. This work has been partly financed by CISP (Fig. 5).
Holly Stein and Judith Hannah from the AIRIE Program at Colorado State University sampled the cores for Re-Os analyses (Fig. 5). The intent was to sample both hydrocarbon and the Fjäcka and Kallholn shales. No hydrocarbon of quantity suitable for sampling was found. Several sections of Fjäcka were sampled from Solberga #1 and Stumsnäs #1. The former contains a reddish brown shale, whereas the Stumsnäs is a black shale and is more promising for Re-Os geochemistry. A starter industry-based grant to look at Re-Os fractionation in oil and shale has been secured by Stein and Hannah. A second proposal pending with NSF will augment the industry-based study by building a picture of stratigraphic ages in the Siljan region for linking with the greater CISP geoscience community (Ebbestad is the primary external collaborator). The first Re-Os results on drill core demonstrate success. A supplementary contribution of CISP funds for the Re-Os study would strengthen efforts by Stein and Hannah to raise funds external to Sweden.
During 2011 geophysical investigations have continued in the Lockne area, and field reconnaissance have been made to determine the location for two shallow drillings (50-60 m) to investigate the structural composition around the so called Tandsbyn Gully. A number of reports and papers related to the Lockne structure has been published (Asensio et al., 2011; Broman et al., 2011; Melero Asensio et al., 2011a-d, Ormö et al., 2011a, b).
One of the main objectives of the application to the Swedish Research Council in 2012 was to acquire reflection seismics in the Siljan area, and this has been achieved (Juhlin et al. 2012). Other analytical approaches like shallow geophysics (resistivity and gravity in Lockne) and AMS studies (anisotropy of magnetic susceptibility) on basement rocks (Melero Asensio et al. 2011a-e; Ormö et al. 2010a-d; Ormö et al. 2011a, b; Agarwal et al. 2012), study of fluid inclusions to determine composition of the fluids and constrain temperature and pressure conditions in shear zones relate to the cratering (Broman et al. 2011), and shallow drilling (Ormö et al. 2010c; Lehnert et al. 2012a-e) have also been fulfilled, analyses are still in progress on the wealth of data gathered. A new application for additional work was submitted in spring 2012. Despite a favourable review, this project was unfortunately not funded. Thus, major work on CISP will be suspended at the end of the year until further funding can be secured. We will try to keep continuity in the scientific work at a low level with remaining funds from the 2011 grant.
Below is a summary of activities:
The Siljan area
- A paper on the preliminary description of the Igrene drill cores in Siljan is now on line in GFF (Lehnert et al. 2012).
- A paper on the interpretation of two reflection seismic lines in the western part of the Siljan structure is now available online (Juhlin et al. 2012). This paper is open access.
- During the summer and autumn, Oliver Lehnert (Erlangen), Guido Meinhold and Arzu Arslan (both Göttingen), and lately also graptolite specialist Jörg Maletz (Berlin) worked on the three Igrene AB drill cores in Mora. The Stumsnäs core was successfully sampled and further fieldwork conducted in July. This included sampling for conodont stratigraphy in the Upper Ordovician (Hirnantian) strata of Osmundsberget with assistance of Jan Ove Ebbestad (Uppsala). Structural investigations were carried out on all cores.
- Analyses of Corg isotope measurements from the three Igrene cores and the Nittsjö trench (excavated by Ebbestad, Högström and Frisk 2009) are finished and need to be interpreted. Samples for TOC/Rock Eval are currently being analysed and whole-rock geochemical analyses (major and trace elements) will follow soon. Bentonite samples from the core are analysed in collaboration with Warren Huff (Cincinnati) who expects to have a full set of data in the beginning of next year. In addition a oil/bitumen study has been initiated with colleagues from CSIRO in Sydney (Ahmed et al. 2012).
- A status report for Igrene AB is finished.
The Lockne area
- The fieldwork in Jämtland took place at two localities and on two occasions during 2012. The main fieldwork was performed during July at both the Lockne and Målingen structures, mainly as geological mapping, levelling, and gravity measurements. Two drill sites were selected and all the landowner contacts and all other preparations for the November drilling campaign were made. During this stay, Reinhard Greiling, Agnes Kontny and a German student (Philip) from Karlsruhe joined the fieldwork for about a week (Fig. 6). In early November 2012 we made a six days visit to Lockne to supervise the core drilling in the western part of the structure.
- The geophysical fieldwork in Lockne was concentrated just north of the impact structure. An almost 5 km long profile was levelled (±1 mm accuracy) to produce heights for gravity corrections. The levelling started at the fix point “Sörviken” and followed the Marieby road for 500 m, at this point the levelling left the main road and turned into a small road. Following this small road gravity was measured at 124 sites along a 4.5 km long profile in the southwest direction. The purpose with the profile is to investigate the continuation of a shear zone that cuts the Lockne crater, and, as anticipated, the survey revealed a gravity low. During next field season a parallel profile will be made to confirm the direction of the shear zone.
- Reinhard Greiling, Agnes Kontny and a student (all Karlsruhe) sampled impact rocks for a study of anisotropy of magnetic susceptibility (AMS). The PhD student Amar Agarwal is analyzing the collected material (Agarwell et al. 2013). The Karlsruhe group was taken on an informative excursion in the Lockne area. One of the localities was the Sandbäcken creek that exposes down faulted and folded orthoceratitic limestone.
- The power plant at Högforsen was visited during the July field campaign. At Högforsen (former Högbroforsen), Häggenås, 40 km north of the Lockne impact centre, Maurits observed Loftarstone in the Håkan riverbed. This outcrop was flooded in 1985 due to the new power plant (Fig. 6). In the coming years the power plant will be overhauled after thirty years in service which will lower the water level and, hopefully, expose the Loftarstone.
- During the first four days in November a drill rig (Fig. 6B) arrived to Tandsbyn to make two short core holes. The holes (LOC10 and 11) were set on each side of the Tandsbyn gully to explore the overturned flap. Total depth was 53 and 63 m, respectively.
- In Målingen the geophysical survey continued with gravity. Målingen is situated about 15 km southwest of the 7.5 km wide Lockne crater and is a < 1 km wide structure formed almost simultaneously (within seconds) with Lockne. A 1.7 km long profile to the south of the structure was completed.
- In addition, 9 sites on islands in the Näckten Lake were included. This (hopefully) completed the gravity survey in the Målingen structure, which is now covered by 325 gravity sites. The height determination for the sites on land was done with precision levelling (±1 mm), as the expected anomaly is rather small (<0.5 mgal). For the survey on the islands (Fig. 6C), the level of the lake was determined on a calm day and during the same conditions as the height determinations of gravity sites on the island were made (using the lake level as reference surface). The accuracy for the height determination using the lake level is about ±5 mm. The survey on the islands is necessary for the determination of the regional field.
- During fieldwork, some gaps in the geological map could be filled and know outcrops were revisited. At 29 localities, extensive susceptibility measurements were performed (total 2131). These concluded the acquistion phase and evaluation, analyses and modelling is now taking over, continuing during the autumn and winter 2012/13.
- This summer Jan Ove Ebbestad (Uppsala) and Åsa Frisk (Zürich) collected nautiloid cephalopods in the Lockne structure.They will collaborate with Björn Kröger (Berlin) on analysing the ability of the shells to withstand imploding, thereby hoping to establish a depth parameter for the ocean at Lockne after the impact.
- The book (31 pages) “Locknekratern” written by Maurits Lindström (foreword by Sturkell and Ormö) tells the story about the research that led to the discovery of the marine-target Lockne impact crater. The printing costs (18 000 SEK) were shared by the Lockne crater museum and the CISP project. It is now for sale at the museum which will get the eventual profit.
- The CISP proposal for an ICDP workshop 2013 was reviewed by the ICDP. In general, ICDP was positive to the topic but suggested further preparatory work by the CISP working group before re-applying for and arranging an international workshop.
- On April 30th CISP collaborators Oliver Lehnert (Erlangen), Judith Hannah (Colorado), Holly Stein (Colorado) and Jan Ove Ebbestad (Uppsala) featured in a Science Program on Swedish national televison, where the prospecting for hydrocarbons by Igrene AB in Siljan was the focus.
- In the late summer, Chris Juhlin and Jan Ove Ebbestad (Uppsala) met with Vladimir Kutcherov (Stockholm) and Mats Budh (Mora) where possible collaboration on future seismic lines and drill cores in Siljan was discussed.
- In August, Ebbestad presented the CISP project at the Cambridge Arctic Shelf Programme (CASP), after kind invitation of Olga Bogolepova (CASP).
The original CISP project was stipulated to run between 2009 and 2012, with a proposal for continued studies of the Siljan and Lockne craters to determine the best position of deep coreholes was submitted to VR during the spring. Unfortunately, the proposal was turned down. Nevertheless, 2013 saw a number of new publications and continued studies on both craters.
Presentations of results at several meetings, including the Nordic Geological Winter Meeting in Lund, where also the principal investigators made the executive decision to declare the scope of CISP fulfilled and develop further studies of the two craters independently.
Below is a summary of activities (2013-2014).
The field activity in the Lockne crater (and surroundings) and its doublet crater the Målingen structure was performed in July, by the Madrid, Gothenburg and Karlsruhe groups. The Madrid and Gothenburg groups worked together with the following sub-projects:
- With the help from Reinhard Greiling we obtained the outcrop maps from Stefan Simon’s diploma work in 1979. In this map, various breccias were not differentiated, so we started to revisit the “breccia” outcrops, also outcrops marked uncertain (no colour) in his outcrop map was included. This work was not finished and will continue.
- The Målingen doublet crater was visited for some additional field checks for the manuscripts in production.
- In the study of the continuation of the 1.8 Ga shear zone in the area north of the crater (between Löfsåsen and Brunfloviken), a parallel (to the WSW-ENE profile from 2012) gravity profile was measured.
- Three resistivity profiles (1-3, see map, fig 2013:1), 800, 1600, 800 m long respectively, were made across the crystalline flaps (ejecta) together with Eric Hegardt (fig 2013:2) and Erik Meland from Bergab. The crystalline flaps were emplaced on different stratigraphic levels, on blown clean Pre-Cambrian peneplain and at increasing distance out from the crater on progressively higher levels in the Cambrian Alum Shale Formation. The resistivity method worked very well to establish if the high resistivity fractured granite in the flaps was underlain by the low resistivity Alum Shale. Two of the profiles, one and three, passed one drill hole each, hole 9 and 10, respectively.
- Greiling's group made additional sampling and field checks for the AMS measurements.
- Erik Sturkell took part in the opening of Geologins dag (14th of September), which took place at the Lockne crater museum and he gave one of the opening lectures. The next day on “Geologins dag” he was available for questions and discussions at the museum.
Work done on Lockne Crater in 2013 by Greilings group
The aim of this year’s study was to further increase our understanding of the effects of impact cratering on microstructural and rock magnetic properties of the target crystalline basement rocks. Orientated hand samples from the crystalline basement rocks (metavolcanic, granite and dolerite) were collected during field work in summers of 2012 and 2013 (Fig. 9). At least five cores were drilled from each hand sample for anisotropy of magnetic susceptibility (AMS) studies. Magnetic mineralogical studies like temperature dependent magnetic susceptibility (?-T), isothermal remnant magnetisation (IRM) acquisition, hysteresis and back field were also performed. Polished thin sections were prepared along the magnetic foliation and in a direction perpendicular to it for investigating effects of impact on microscopic scale. These investigations were performed under transmitted and reflected light microscopy and scanning electron microscopy (SEM). In order to identify the magnetic minerals, the thin sections were coated with a ferrofluid (produced by Institut für Angewandte Polymerchemie, FH Aachen), which is a colloidal solution of ultrafine magnetite particles. This ferrofluid sticks on the grains that generate a magnetic field giving them a brownish red colour. SEM studies were carried out with LEO 1530 of Gemini instrument and the secondary (SE) and backscattered (BSE) electrons were recorded along with energy-dispersive X-ray spectroscopy (EDX) for a qualitative elemental analysis.
From our studies so far we can conclude that the metavolcanics have the highest P’ (magnetic anisotropy) and magnetic susceptibility but lack any impact related deformational structures. AMS fabrics of these metavolcanics do not show any impact overprint. The granites have the lowest P’ and magnetic susceptibility and the magnetic fabrics are carried entirely by paramagnetic phases. They have microfabrics indicating some recrystallization of the quartz subfabric, which should have resulted in higher P’. We conclude that the low P’ in granite is due to impact related fracturing on a microscale. The dolerites have shallow dipping magnetic foliations and kmax axis, which is interpreted as a magmatic fabric. They have not suffered any post magmatic ductile deformation. Impact related brittle microfracturing is observed in granites and dolerites. These microfractures have two subsets. While the first subset is radial to the impact crater the other is concentric, similar to those developed in impact cratering experiments. Unlike the experimental studies, where radial fractures are more frequent than the concentric fractures outside the crater rim, our results show that in the Lockne area both radial and concentric micro-fractures are equally frequent.
Based on the results an abstract titled ‘Evolution of magnetic fabrics before and after the impact in the Lockne Crater, Sweden.’ has been published in Geophysical Research Abstracts. Vol. 15, EGU 2013-622, 2013. EGU General Assembly 2013. And a manuscript titled ‘Effects of cratering on crystalline target rocks: microstructural and magnetic fabric studies in the Lockne impact crater’ has been submitted in Geological Magazine.
- In June 2013, the Geophysics Program at Uppsala University under the supervision of Chris Juhlin ran sonic and temperature logs in a few of the Igrene AB boreholes in the Mora area. The sonic velocity results were quite noisy and need to be improved. Results will be distributed when this work is completed. Further investigations aim at sampling the core from one of the boreholes to obtain density values.
- In March 2013, an overview talk about the activities in the Siljan impact structure was given by Lehnert et al. at the IODP/ICDP Colloquium of the ‘Deutsche Forschungsgemeinschaft’ in Freiberg, Germany, a poster by Arslan et al. displayed the structurally complicated succession in the Stumsnäs 1 core from the southern part of the ‘Siljan Ring’ and one poster by Berner et al. showed the aspects of fluid migration within the Lower Palaeozoic strata in the ‘Siljan Ring’.
- In April 2013, gas from the Igrene borehole at Mora Högskolan was sampled by O. Lehnert for the investigation of its isotopic composition and to solve the question if the bulk of the gas is of deep mantle origin vs gas derived from the Palaeozoic shales / bacterial activity.
- In April 2013, Ulrich Berner (Statoil, Bergen; formerly BGR, Hannover) presented a talk about the hydrocarbon potential of Ordovician and Silurian rocks in the Siljan district at the DGKM Meeting in Celle, Germany.
- In June 2013, talks and posters were given at the IGCP 591 Meeting organized by members of our group (Mikael Calner & Oliver Lehnert). One oral presentation by Lehnert et al. showed interesting palaeokarst surfaces in parts of the core succession which were compared to similar surfaces in other parts of Sweden displaying times of regression and subaerial exposure. Another talk by Warren Huff et al. dealt with the record of volcanic ash beds in the core successions from the Siljan impact structure (some of these results were presented later by Huff & Lehnert also at the International Clay Conference in Rio de Janeiro in July 2013). A poster by Meinhold et al. showed the first geochemistry results from Silurian sandstones in the Mora 001 core with respect to their provenance. Berner et al. presented a poster showing the significance of organic geochemistry data from the Early Palaeozoic shales for palaeoenvironmental interpretations
- In October 2013, two new Igrene cores from the Mora area were briefly checked by O. Lehnert and G. Meinhold for future studies, one core (Vattumyren 2, Tremadocian-Katian) was logged.
- End of October 2013, Huff et al. gave a presentation of the K-bentonite record in the Ordovician and Silurian strata of the Siljan impact structure at the annual meeting of the Geological Society of America in Denver.
- In January 2014, a talk about facies distribution and model ideas about the geodynamic development of the Siljan area was presented by O. Lehnert and co-authors at the Nordic Geological Winter Meeting in Lund.
- In June 2014, an overview talk on the evolution of the Siljan area in the context of the Caledonian foreland basin will be given (Lehnert et al.) and a poster showing some results from the carbon isotope studies in the Mora 001 1 and Solberga 1 core sections will be presented by Lehnert et al. at the IGCP 591 Meeting in Tartu.
Current research in the ‘Siljan Ring’:
To support our hypotheses on the geodynamic evolution of the Siljan area in the frame of the Caledonian foreland basin development we have started studies on geochemistry and biomarkers in the organic-rich, fine-grained Upper Ordovician and Silurian siliciclastics. This will be completed by palynofacies research in the Silurian units in the near future (Vivi Vajda and Kristina Mehlqvist, Lund) to distinguish between marine conditions and brackish to lacustrine environments at certain times.
A publication of the biogeochemistry results is in preparation by Ulrich Berner (Statoil, Bergen, Norway), O. Lehnert and G. Meinhold. The geochemical data from Solberga 1 suggesting ‘lacustrine’ to brackish and marine palaeoenvironmental conditions for the Silurian shales are comparable to biomarker data from samples of crude oil and bitumen stored in large pores and vugs in the Ordovician carbonate succession (with the bulk concentrated in the voids in the Upper Ordovician mound facies) in the eastern part of the Siljan Ring (Ahmed et al. 2014). This recent study on seep oil and bitumen also displays different source characteristics for these hydrocarbons expelled from the Lower Palaeozoic shales and confirms that the Upper Ordovician and Silurian organic-rich sediments represent the source rock for oil and bitumen in the Siljan Ring. Biomarker studies showing lacustrine to brackish conditions for the sedimentation of the younger Silurian siliciclastic succession in the Mora area clearly support a depositional model for these deposits in a backbulge basin of the Caledonian foreland basin system.
A set of papers on stable isotope, K-bentonites, sedimentological and biostratigraphic studies is in preparation by Oliver Lehnert and Guido Meinhold and their cooperation partners.
Future studies in the Siljan crater:
Europe’s largest impact structure and its fill is not yet well studied and understood. Many questions arose from our investigations in the framework of CISP and some ideas on sedimentological models developed. The timing of the development of the backbulge basin formation, a tracing of the forebulge in the area and effects of the Caledonian movements in the sedimentary record of the platform to the east (regional vs global sea-level changes) still need to be investigated. Detailed investigations of additional drill cores are essential with respect to the understanding of the geological history along the western margin of Baltica. A detailed stratigraphic framework is needed for the comparison of geodynamic processes related to the Ordovician foreland basin evolution in this area with the record in the Föllinge Basin to the northwest in Jämtland and the Oslo Region, Norway, to the southwest.
A team conducted by Mikael Calner, Oliver Lehnert, Chris Juhlin, Jan Ove Ebbestad and Guido Meinhold is planning to propose a new drilling project in connection with a shallow seismic program focussed on the Siljan impact structure in 2015 under the framework of SSDP.
The CISP working group
Prof. Erik Sturkell, Gothenburg University, Sweden.
Dr. Anette S.E. Högström, Tromsø University Museum, Norway.
Prof. Stig M. Bergström, The Ohio State University, USA.
Dr. Mikael Calner, Lund University, Sweden.
Dr. Jan Ove R. Ebbestad, Uppsala University, Sweden.
Dr. Oliver Lehnert, Friedrich-Alexander University Erlangen-Nürnberg, Germany.
Dr. Jens Ormö, Centro de Astrobiología, Madrid, Spain.
Prof. Christopher Juhlin, Uppsala University, Sweden.
Prof. Reinhard O Greiling, Karlsruhe Institute of Technology, Germany.
Dr. Gudio Meinhold, Göttingen University, Germany.
Prof. Holly Stein, Colorado State University, USA.
Prof. Judith Hannah, Colorado State University, USA.
Dr. Jörg Maletz, Frei University Berlin, Germany.
Prof. Lars Holmer, Uppsala University, Sweden.
Prof. Risto Kumpulainen, Stockholm University, Sweden
Dr. Paula Lindgren, Stockholm University, Sweden.
Prof. Warren Huff, University of Cincinnati, USA.
Prof. Sven Egenhoff, Colorado State University, USA.
Dr. Arne Thorshøj Nielsen, Natural History Museum of Denmark.
Dr. Yutaro Suzuki, Shizuoka University, Japan.
Dr. Olga Bogolepova, CASP, England.
Dr. Jaak Nolvak, Tallinn University, Estland.
Dr. Thijs Vandenbroucke, Gent University, Belgium.
Dr. Åsa. M. Frisk, Zurich University, Switzerland
Dr. Arzu Arslan, Göttingen, Germany
Dr. Ulrich Berner, Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover, Germany
Ahmed, M., Lehnert, O., Fuentes, D., Sestak, S., Meinhold, G. & Gong, S. 2012. Biomarker evidence for the origin of seep oil and solid bitumen from the Late Devonian Siljan impact structure, Sweden. 17th Australian Organic Geochemistry Conference: Biogeochemistry from Deep Time through Petroleum Resources to Modern Environments. Abstract. Macquarie University, Sydney, New South Wales, Australia, 2nd - 5th December 2012.
Agarwal, A., Lied, P., Srivastava, D., Kontny, A., & Greiling, R. 2013. Evolution of magnetic fabrics before and after the impact in the Lockne Crater, Sweden. Geophysical Research Abstracts 15, EGU General Assembly 7–12 April, Vienna.
Angerer, T. & Greiling, R. 2012. Fabric evolution at basement–cover interfaces in a fold-and-thrust belt and implications for de´collement tectonics (Autochthon, Lower Allochthon, central Scandinavian Caledonides). International Journal of Earth Sciences (Geolgische Rundschau) 101, 1763–1788.
Arslan, A., Meinhold, G. & Lehnert, O., 2013. Tectonic structures in the Stumsnäs 1 core from the southern Siljan Ring, central Sweden: Ordovician sediments sandwiched between Proterozoic basement slivers. GFF, doi: http://dx.doi.org/10.1080/11035897.2013.809016.
Arslan, A., Meinhold, G., Lehnert, O., 2013. Tectonic structures in the Stumsnäs 1 core of the southern Siljan Ring, south-central Sweden. – Insights from Geochemistry. IODP/ICDP Colloquium, Freiberg, Germany, 25th – 27th March 2013. Abstractband: 27-28.
Asensio, I., Martín-Hernández, F., and Ormö, J., 2011. Evidence of ferrichromite of extraterrestrial origin by means of rock magnetic studies from the Loc-9 drill core (Lockne crater, Sweden). American Geophysical Union Fall Meeting, 5-9 December, San Francisco, USA.
Berner, U., Lehnert, O. & Meinhold, G., 2013a. Fluid Migration in Ordovician and Silurian Rocks of the Siljan Impact Structure (Sweden) – Insights from Geochemistry. IODP/ICDP Colloquium, Freiberg, Germany, 25th – 27th March 2013. Abstractband: 40-41
Berner, U., Lehnert, O. & Meinhold, G., 2013b. Hydrocarbon potential of Ordovician and Silurian rocks, Siljan Region, Sweden. DGKM Meeting, Abstract. Celle, Germany, 18th – 19th April 2013.
Berner, U., Lehnert, O. & Meinhold, G., 2013c. Depositional environments of Ordovician and Silurian sediments of the Siljan impact structure (Sweden) – Insights from organic geochemistry. In Lindskog, A. & Mehlqvist, C. (eds): Proceedings of the 3rd IGCP 591 Annual Meeting – Lund, Sweden, 9-19 June 2013: 47-48; Lund University.
Broman, C. Sturkell. E. & Fallick, A.E. 2011. Oxygen isotopes and implications for the cavitygrown quartz crystals in the Lockne impact structure, Sweden, GFF 133, 101-107.
Ebbestad, J.O.R & Högström, A.E.S. 2007. Ordovician of the Siljan District, Sweden. In Ebbestad, J.O.R., Wickström, L.M. & Högström, A.E.S. (eds.) WOGOGOB 2007. 9th meeting of the Working Group on Ordovician Geology of Baltoscandia. Field guide and Abstracts. SGU Rapporter och meddelanden 128, 7-26.
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