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Publications (10 of 13) Show all publications
Simon, H., Buske, S., Hedin, P., Juhlin, C., Krauss, F. & Giese, R. (2019). Anisotropic Kirchhoff pre-stack depth migration at the COSC-1 borehole, central Sweden. Geophysical Journal International, 219(1), 66-79
Open this publication in new window or tab >>Anisotropic Kirchhoff pre-stack depth migration at the COSC-1 borehole, central Sweden
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2019 (English)In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 219, no 1, p. 66-79Article in journal (Refereed) Published
Abstract [en]

A remarkably well preserved representation of a deeply eroded Palaeozoic orogen is found in the Scandinavian Caledonides, formed by the collision of the two palaeocontinents Baltica and Laurentia. Today, after 400 Ma of erosion along with uplift and extension during the opening of the North Atlantic Ocean, the geological structures in central western Sweden comprise far transported allochthonous units, the underlying Precambrian crystalline basement, and a shallow west-dipping decollement that separates the two and is associated with a thin layer of Cambrian black shales. These structures, in particular the Seve Nappes (upper part of the Middle Allochthons), the Lower Allochthons and the highly reflective basement are the target of the two approximately 2.5 km deep fully cored scientific boreholes in central Sweden that are part of the project COSC (Collisional Orogeny in the Scandinavian Caledonides). Thus, a continuous 5 km tectonostratigraphic profile through the Caledonian nappes into Baltica's basement will be recovered. The first borehole, COSC-1, was successfully drilled in 2014 and revealed a thick section of the seismically highly reflective Lower Seve Nappe. The Seve Nappe Complex, mainly consisting of felsic gneisses and mafic amphibolites, appears to be highly anisotropic. To allow for extrapolation of findings from core analysis and downhole logging to the structures around the borehole, several surface and borehole seismic experiments were conducted. Here, we use three long offset surface seismic profiles that are centred on the borehole COSC-1 to image the structures in the vicinity of the borehole and below it. We applied Kirchhoff pre-stack depth migration, taking into account the seismic anisotropy in the Seve Nappe Complex. We calculated Green's functions using an anisotropic eikonal solver for a VTI (transversely isotropic with vertical axis of symmetry) velocity model, which was previously derived by the analysis of VSP (Vertical Seismic Profile) and surface seismic data. We show, that the anisotropic results are superior to the corresponding isotropic depth migration. The reflections appear significantly more continuous and better focused. The depth imaging of the long offset profiles provides a link between a high-resolution 3-D data set and the regional scale 2-D COSC Seismic Profile and complements these data sets, especially in the deeper parts below the borehole. However, many of the reflective structures can be observed in the different data sets. Most of the dominant reflections imaged originate below the bottom of the borehole and are situated within the Precambrian basement or at the transition zones between Middle and Lower Allochthons and the basement. The origin of the deeper reflections remains enigmatic, possibly representing dolerite intrusions or deformation zones of Caledonian or pre-Caledonian age.

Place, publisher, year, edition, pages
OXFORD UNIV PRESS, 2019
Keywords
Composition and structure of the continental crust, Controlled source seismology, Crustal imaging, Seismic anisotropy, Crustal structure
National Category
Geophysics
Identifiers
urn:nbn:se:uu:diva-394185 (URN)10.1093/gji/ggz286 (DOI)000484124800004 ()
Funder
German Research Foundation (DFG), BU1364/10-1German Research Foundation (DFG), GI982/2-1
Available from: 2019-10-09 Created: 2019-10-09 Last updated: 2019-10-09Bibliographically approved
Yan, P., Garcı́a Juanatey, M. A., Kalscheuer, T., Juhlin, C., Hedin, P., Savvaidis, A., . . . Kück, J. (2017). A magnetotelluric investigation of the Scandinavian Caledonides in western Jämtland, Sweden, using the COSC borehole logs as prior information. Geophysical Journal International, 208(3), 1465-1489
Open this publication in new window or tab >>A magnetotelluric investigation of the Scandinavian Caledonides in western Jämtland, Sweden, using the COSC borehole logs as prior information
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2017 (English)In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 208, no 3, p. 1465-1489Article in journal (Refereed) Published
Abstract [en]

In connection with the Collisional Orogeny in the Scandinavian Caledonides (COSC) project, broad-band magnetotelluric (MT) data were acquired at 78 stations along a recent ca. 55km- long NW-SE directed reflection seismic profile (referred to as the COSC Seismic Profile; CSP), with the eastern end located similar to 30 km to the west of the orogenic Caledonian front. The MT component of the project aims at (i) delineating the highly conductive (similar to 0.1 Omega . m) alum shales that are associated with an underlying main decollement and (ii) calibrating the MT model to borehole logs. Strike and distortion analyses of the MT data show a 3-D structure in the western 10 km of the profile around the 2.5 km deep COSC-1 borehole (IGSN: ICDP5054EHW1001) and a preferred strike angle of N34 degrees E in the central and eastern parts of the profile. 2-D modelling of MT impedances was tested using different inversion schemes and parameters. To adjust the resistivity structure locally around the borehole, resistivity logging data from COSC-1 were successfully employed as prior constraints in the 2-D MT inversions. Compared with the CSP, the model inverted from the determinant impedances shows the highest level of structural similarity. A shallow resistor (> 1000 Omega . m) in the top 2-3 km depth underneath the western most 10 km of the profile around COSC-1 corresponds to a zone of high seismic reflectivity, and a boundary at less than 1 km depth where the resistivity decreases rapidly from > 100 to < 1 Omega . m in the central and eastern parts of the profile coincides with the first seismic reflections. The depth to this boundary is well constrained as shown by 1-D inversions of the MT data from five selected sites and it decreases towards the Caledonian front in the east. Underneath the easternmost part of the profile, the MT data show evidence of a second deeper conductor (resistivity < 1 Omega . m) at > 3 km depth. Based upon the COSC-1 borehole logs, the CSP reflection seismic image, and the surface geologic map, the MT resistivity models were interpreted geologically. In the vicinity of COSC-1, the resistor down to 2-3 km depth pertains to the metamorphic Middle Allochthon. The up to 1000-m-thick shallow resistor in the central and eastern parts of the profile is interpreted to overly an imbricated unit at the bottom of the Lower Allochthon that includes the alum shales. In the MT resistivity model, the 300-500 m thick imbricated unit masks the main Caledonian decollement at its bottom. A second possible interpretation, though not favoured here, is that the decollement occurs along a much deeper seismic reflection shallowing from 4.5 km depth in the west to similar to 600 m depth in the east. An additional borehole (COSC-2) is planned to penetrate the Lower Allochthon and the main decollement surface in the central part of the profile and can provide information to overcome this interpretational ambiguity. Using a synthetic study, we evaluate how resistivity logs from COSC-2 can improve the 2-D inversion model.

Keywords
Inverse theory, Downhole methods, Magnetotellurics, Continental tectonics: compressional, Europe
National Category
Geophysics
Identifiers
urn:nbn:se:uu:diva-303495 (URN)10.1093/gji/ggw457 (DOI)000396818900016 ()
Funder
Swedish Research Council, 2013-5780The Geological Survey of Sweden (SGU)
Available from: 2016-09-20 Created: 2016-09-20 Last updated: 2017-04-27Bibliographically approved
Simon, H., Buske, S., Krauss, F., Giese, R., Hedin, P. & Juhlin, C. (2017). The derivation of an anisotropic velocity model from a combined surface and borehole seismic survey in crystalline environment at the COSC-1 borehole, central Sweden. Geophysical Journal International, 210(3), 1332-1346
Open this publication in new window or tab >>The derivation of an anisotropic velocity model from a combined surface and borehole seismic survey in crystalline environment at the COSC-1 borehole, central Sweden
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2017 (English)In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 210, no 3, p. 1332-1346Article in journal (Refereed) Published
Abstract [en]

The Scandinavian Caledonides provide a well-preserved example of a Palaeozoic continent-continent collision, where surface geology in combination with geophysical data provides information about the geometry of parts of the Caledonian structure. The project COSC (Collisional Orogeny in the Scandinavian Caledonides) investigates the structure and physical conditions of the orogen units and the underlying basement with two approximately 2.5 km deep cored boreholes in western Jamtland, central Sweden. In 2014, the COSC-1 borehole was successfully drilled through a thick section of the Seve Nappe Complex. This tectonostratigraphic unit, mainly consisting of gneisses, belongs to the so-called Middle Allochthons and has been ductilely deformed and transported during the collisional orogeny. After the drilling, a major seismic survey was conducted in and around the COSC-1 borehole with the aim to recover findings on the structure around the borehole from core analysis and downhole logging. The survey comprised both seismic reflection and transmission experiments, and included zero-offset and multiazimuthal walkaway Vertical Seismic Profile (VSP) measurements, three long offset surface lines centred on the borehole, and a limited 3-D seismic survey. In this study, the data from the multiazimuthal walkaway VSP and the surface lines were used to derive detailed velocity models around the COSC-1 borehole by inverting the first-arrival travel-times. The comparison of velocities from these tomography results with a velocity function calculated directly from the zero-offset VSP revealed clear differences in velocities for horizontally and vertically travelling waves. Therefore, an anisotropic VTI (transversely isotropic with vertical axis of symmetry) model was found that explains first-arrival traveltimes from both the surface and borehole seismic data. The model is described by a vertical P-wave velocity function derived from zero-offset VSP and the Thomsen parameters tau = 0.03 and delta = 0.3, estimated by laboratory studies and the analysis of the surface seismic and walkaway VSP data. This resulting anisotropic model provides the basis for further detailed geological and geophysical investigations in the direct vicinity of the borehole.

National Category
Geophysics
Identifiers
urn:nbn:se:uu:diva-337146 (URN)10.1093/gji/ggx223 (DOI)000411213800004 ()
Available from: 2017-12-20 Created: 2017-12-20 Last updated: 2018-01-24Bibliographically approved
Yan, P., Kalscheuer, T., Hedin, P. & Juanatey, M. d. (2017). Two-dimensional magnetotelluric inversion using reflection seismic data as constraints and application in the COSC project. Geophysical Research Letters, 44(8), 3554-3563
Open this publication in new window or tab >>Two-dimensional magnetotelluric inversion using reflection seismic data as constraints and application in the COSC project
2017 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 44, no 8, p. 3554-3563Article in journal (Refereed) Published
Abstract [en]

We present a novel 2-D magnetotelluric (MT) inversion scheme, in which the local weights of the regularizing smoothness constraints are based on the envelope attribute of a reflection seismic image. The weights resemble those of a previously published seismic modification of the minimum gradient support method. We measure the directional gradients of the seismic envelope to modify the horizontal and vertical smoothness constraints separately. Successful application of the inversion to MT field data of the Collisional Orogeny in the Scandinavian Caledonides (COSC) project using the envelope attribute of the COSC reflection seismic profile helped to reduce the uncertainty of the interpretation of the main decollement by demonstrating that the associated alum shales may be much thinner than suggested by a previous inversion model. Thus, the new model supports the proposed location of a future borehole COSC-2 which is hoped to penetrate the main decollement and the underlying Precambrian basement.

Place, publisher, year, edition, pages
AMER GEOPHYSICAL UNION, 2017
National Category
Geophysics
Identifiers
urn:nbn:se:uu:diva-324629 (URN)10.1002/2017GL072953 (DOI)000401847500015 ()
Funder
Swedish Research Council, 2013-5780
Available from: 2017-06-16 Created: 2017-06-16 Last updated: 2017-06-16Bibliographically approved
Hedin, P., Almqvist, B., Berthet, T., Juhlin, C., Buske, S., Simon, H., . . . Alm, P.-G. (2016). 3D reflection seismic imaging at the 2.5 km deep COSC-1 scientific borehole, central Scandinavian Caledonides. Tectonophysics, 689, 40-55
Open this publication in new window or tab >>3D reflection seismic imaging at the 2.5 km deep COSC-1 scientific borehole, central Scandinavian Caledonides
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2016 (English)In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 689, p. 40-55Article in journal (Refereed) Published
Abstract [en]

The 2.5 km deep scientific COSC-1 borehole (ICDP 5054-1-A) was successfully drilled with nearly complete core recovery during spring and summer of 2014. Downhole and on-core measurements through the targeted Lower Seve Nappe provide a comprehensive data set. An observed gradual increase in strain below 1700 m, with mica schists and intermittent mylonites increasing in frequency and thickness, is here interpreted as the basal thrust zone of the Lower Seve Nappe. This high strain zone was not fully penetrated at the total drilled depth and is thus greater than 800 m in thickness.

To allow extrapolation of the results from downhole logging, core analysis and other experiments into the surrounding rock and to link these with the regional tectonic setting and evolution, three post-drilling high-resolution seismic experiments were conducted in and around the borehole. One of these, the first 3D seismic reflection land survey to target the nappe structures of the Scandinavian Caledonides, is presented here. It provides new information on the 3D geometry of structures both within the drilled Lower Seve Nappe and underlying rocks down to at least 9 km.

The observed reflectivity correlates well with results from the core analysis and downhole logging, despite challenges in processing. Reflections from the uppermost part of the Lower Seve Nappe have limited lateral extent and varying dips, possibly related to mafic lenses or boudins of variable character within felsic rock. Reflections occurring within the high strain zone, however, are laterally continuous over distances of a kilometer or more and dip 10–15° towards the southeast. Reflections from structures beneath the high strain unit and the COSC-1 borehole can be followed through most of the seismic volume down to at least 9 km and have dips of varying degree, mainly in the east–west thrust direction of the orogen.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
3D reflection seismic, continental scientific deep drilling, borehole geophysics, collisional orogeny in the Scandinavian Caledonides, Seve Nappe Complex, shear zones
National Category
Geophysics
Research subject
Geophysics with specialization in Solid Earth Physics
Identifiers
urn:nbn:se:uu:diva-261087 (URN)10.1016/j.tecto.2015.12.013 (DOI)000387522100005 ()
Projects
Collisional Orogeny in the Scandinavian Caledonides (COSC)
Funder
Swedish Research Council, 2013-5780Swedish Research Council, 2013-94German Research Foundation (DFG), BU1364/10-1German Research Foundation (DFG), GI982/2-1
Available from: 2015-08-29 Created: 2015-08-29 Last updated: 2017-12-04Bibliographically approved
Wenning, Q., Almqvist, B., Hedin, P. & Zappone, A. (2016). Seismic anisotropy in mid to lower orogenic crust: Insights from laboratory measurements of Vp and Vs in drill core from central Scandinavian Caledonides. Tectonophysics, 692(Part A), 14-28
Open this publication in new window or tab >>Seismic anisotropy in mid to lower orogenic crust: Insights from laboratory measurements of Vp and Vs in drill core from central Scandinavian Caledonides
2016 (English)In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 692, no Part A, p. 14-28Article in journal (Refereed) Published
Abstract [en]

Recent drilling of the first Collisional Orogeny in the Scandinavian Caledonides scientific borehole (COSC-1) near Are, Sweden permitted a laboratory investigation of seismic anisotropy on high metamorphic grade and highly deformed core samples. The 2.5 km deep borehole crosscuts the amphibolite-grade Lower Seve Nappe and-intersects a high-strain shear zone in the lowermost 800 m. Measurements of ultrasonic compressional (V-p) and shear (V-s) velocities are conducted at room temperature and pressures ranging from room conditions up to 260 MPa on six core sections that represent the most abundant lithologies in the borehole. The core sections consist of two amphibolites, a calc-silicate gneiss, a felsic gneiss, an amphibole-rich gneiss, and a garnet-bearing micaschist from the shear zone. Three mutually perpendicular samples were taken to characterize the anisotropy induced by the clear foliation and lineation. The intrinsic (crack-free velocities) V(p)0 and V(s)0 in the direction perpendicular to foliation ranges from 5.51 to 6.67 km/s and 3.31 to 4.13 km/s, respectively. In the direction parallel to foliation the V(p)0 and V(s)0 ranges from 6.31 to 7.25 km/s and 3.53 to 4.35 km/s,respectively. V-p anisotropy ranges from3% in the calc-silicate gneiss to 19% in the micaschist. In the upper crustal seismic reflection survey around the COSC-1 borehole, reflection coefficient analysis suggests that reflectors occur due to impedance contrast between commonly occurring amphibolites and gneisses in the upper 1800 m and the micaschists below. When extrapolated to mid-crustal levels the analysis indicates that both rock types can produce reflection coefficients between adjacent lithologies in excess of 0.1. Similarities in lithologies, shear zone thickness, and reflectivity pattern in the Central Scandinavian Caledonides compared to other orogens (e.g., the Himalaya) demonstrate the importance of these measurements as a proxy for in-situ strongly anisotropic shear zones in the middle crust.

National Category
Geophysics
Identifiers
urn:nbn:se:uu:diva-299169 (URN)10.1016/j.tecto.2016.07.002 (DOI)000390742100003 ()
Available from: 2016-07-15 Created: 2016-07-15 Last updated: 2017-08-08Bibliographically approved
Juhlin, C., Hedin, P., Gee, D., Lorenz, H., Kalscheuer, T. & Yan, P. (2016). Seismic imaging in the eastern Scandinavian Caledonides: Siting the 2.5 km deep COSC-2 borehole, central Sweden. Solid Earth, 7(3), 769-787
Open this publication in new window or tab >>Seismic imaging in the eastern Scandinavian Caledonides: Siting the 2.5 km deep COSC-2 borehole, central Sweden
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2016 (English)In: Solid Earth, ISSN 1869-9510, E-ISSN 1869-9529, Vol. 7, no 3, p. 769-787Article in journal (Refereed) Published
Abstract [en]

The Collisional Orogeny in the Scandinavian Caledonides (COSC) project, a contribution to the International Continental Scientific Drilling Program (ICDP), aims to provide a deeper understanding of mountain belt dynamics. Scientific investigations include a range of topics, from subduction-related tectonics to the present-day hydrological cycle. COSC investigations and drilling activities are focused in central Scandinavia where rocks from the mid to lower crust of the orogen are exposed near the Swedish-Norwegian border. Here, rock units of particular interest occur in the Seve Nappe Complex (SNC) of the so-called Middle Allochthon and include granulite facies migmatites (locally with evidence of ultra-high pressures) and amphibolite facies gneisses and mafic rocks. This complex overlies greenschist facies metasedimentary rocks of the dolerite-intruded Särv Nappes and underlying, lower grade Jämtlandian Nappes (Lower Allochthon). Reflection seismic profiles have been an important component in the activities to image the sub-surface structure in the area. Sub-horizontal reflections in the upper 1-2 km are underlain and interlayered with strong west- to northwest-dipping reflections, suggesting significant east-vergent thrusting. Two 2.5 km deep fully cored boreholes are a major component of the project which will improve our understanding of the sub-surface structure and tectonic history of the area. Borehole COSC-1 (IGSN: http://hdl.handle.net/10273/ICDP5054EEW1001), drilled in the summer of 2014, targeted the subduction-related Seve Nappe Complex and the contact with the underlying allochthon. The COSC-2 borehole will be located further east and investigate the lower grade, mainly Cambro-Silurian rocks of the Lower Allochthon, the Jämtlandian décollement and penetrate into the crystalline basement rocks to identify the source of some of the northwest-dipping reflections. A series of high resolution seismic profiles have been acquired along a composite c. 55 km long profile to help locate the COSC drill holes. We present here the results from this COSC-related composite seismic profile (CSP), including new interpretations based on previously unpublished data acquired between 2011 and 2014. These seismic data, along with shallow drill holes in the Caledonian thrust front and previously acquired seismic, magnetotelluric, and magnetic data, are used to identify two potential drill sites for the COSC-2 borehole.

Keywords
reflection seismic, collisional orogeny, Scandinavian Caledonides, COSC, scientific drilling
National Category
Geophysics
Research subject
Geophysics with specialization in Solid Earth Physics
Identifiers
urn:nbn:se:uu:diva-261094 (URN)10.5194/se-7-769-2016 (DOI)000379431700004 ()
Projects
COSC
Funder
Swedish Research Council, 2013-5780
Available from: 2015-08-30 Created: 2015-08-30 Last updated: 2017-12-04Bibliographically approved
Hedin, P. (2015). Geophysical studies of the upper crust of the central Swedish Caledonides in relation to the COSC scientific drilling project. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Geophysical studies of the upper crust of the central Swedish Caledonides in relation to the COSC scientific drilling project
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The Collisional Orogeny in the Scandinavian Caledonides (COSC) project aims to provide a deeper understanding of mountain belt dynamics through scientific deep drilling in the central parts of the mountain belt of western Sweden. The main targets include a subduction related allochthon, the basal orogenic detachment and the underlying partially subducted Precambrian basement. Research covered by this thesis, focusing primarily on reflection seismic data, was done within the framework of the COSC project.

The 55 km long composite COSC Seismic Profile (CSP) images the upper crust in high resolution and established the basis for the selection of the optimum location for the two 2.5 km deep COSC boreholes. Together with potential field and magnetotelluric data, these profiles allowed the construction of a constrained regional interpretation of the major tectonic units. Non-conventional pseudo 3D processing techniques were applied to the 2D data prior to the drilling of the first borehole, COSC-1, to provide predictions about the 3D geometry of subsurface structures and potential zones of interest for the sampling programs.

COSC-1 was drilled in 2014 and reached the targeted depth with nearly complete core recovery. A continuous geological section and a wealth of information from on-site and off-site scientific investigations were obtained. A major post-drilling seismic survey was conducted in and around the borehole and included a 3D reflection seismic experiment. The structurally and lithologically complex Lower Seve Nappe proved difficult to image in detail using standard processing techniques, but its basal mylonite zone and underlying structures are well resolved. The 3D data, from the surface down to the total drilled depth, show good correlation with the initial mapping of the COSC-1 core as well as with preliminary results from on-core and downhole logging.  

Good correlation is also observed between the 2D and 3D reflection seismic datasets. These will provide a strong link between the two boreholes and a means to extrapolate the results from the cores and boreholes into the surrounding rock. Ultimately, they will contribute to the deeper understanding of the tectonic evolution of the region, the Scandinavian Caledonides and the formation of major orogens. 

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. p. 87
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1281
Keywords
reflection seismic, collisional orogeny, Scandinavian Caledonides, COSC, scientific drilling, geophysical logging, gravity, magnetics
National Category
Geophysics
Research subject
Geophysics with specialization in Solid Earth Physics
Identifiers
urn:nbn:se:uu:diva-261112 (URN)978-91-554-9320-2 (ISBN)
Public defence
2015-10-16, Hambergsalen, Geocentrum, Villavägen 16, Uppsala, 10:00 (English)
Opponent
Supervisors
Projects
Collisional Orogeny in the Scandinavian Caledonides
Funder
Swedish Research Council, 2009-4413Swedish Research Council, 2013-5780
Available from: 2015-09-25 Created: 2015-08-30 Last updated: 2016-08-16Bibliographically approved
Hedin, P., Malehmir, A., Gee, D. G., Juhlin, C. & Dyrelius, D. (2014). 3D interpretation by integrating seismic and potential field data in the vicinity of the proposed COSC-1 drill site, central Swedish Caledonides. Geological Society Special Report, 390, 301-319
Open this publication in new window or tab >>3D interpretation by integrating seismic and potential field data in the vicinity of the proposed COSC-1 drill site, central Swedish Caledonides
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2014 (English)In: Geological Society Special Report, ISSN 0309-670X, Vol. 390, p. 301-319Article in journal (Refereed) Published
Abstract [en]

The scientific drilling project COSC (Collisional Orogeny in the Scandinavian Caledonides), designed to study key questions concerning orogenic processes, aims to drill two fully cored boreholes to depths of c. 2.5 km each at carefully selected locations in west-central Sweden. The first of these, COSC-1, is scheduled for start late spring 2014 and will target the Seve Nappe Complex, characterized by inverted metamorphism and with parts that have evidently been subjected to hot ductile extrusion. In this study available seismic sections have been combined with surface geology to produce a 3D interpretation of the tectonic structures in the vicinity of the COSC-1 borehole. Constrained 3D inverse gravity modelling over the same area supports the interpretation, and the high-density Seve Nappe Complex stands out clearly in the model. Interpretation and models show that the maximum depth extent of the Seve Nappe Complex is less than 2.5 km, consistent with reflection seismic data. The gravity modelling also requires underlying units to comprise low-density material, consistent with the Lower Allochthon, but the modelling is unable to discern the décollement separating the allochthons from the crystalline Precambrian basement.

Place, publisher, year, edition, pages
Geological Society, 2014
National Category
Geophysics
Research subject
Geophysics with specialization in Solid Earth Physics
Identifiers
urn:nbn:se:uu:diva-213662 (URN)10.1144/SP390.15 (DOI)
Projects
Collisional Orogeny in the Scandinavian Caledonides
Funder
Swedish Research Council, 2009-4413
Available from: 2014-01-02 Created: 2014-01-02 Last updated: 2017-12-06Bibliographically approved
Hedin, P. & Juhlin, C. (2014). 3D Seismic Processing of Crooked Line 2D Data in the Vicinity of the COSC 2.5 km Deep Scientific borehole. In: : . Paper presented at 76th EAGE Conference & Exhibition, Amsterdam, The Netherlands.
Open this publication in new window or tab >>3D Seismic Processing of Crooked Line 2D Data in the Vicinity of the COSC 2.5 km Deep Scientific borehole
2014 (English)Conference paper, Published paper (Refereed)
National Category
Geophysics
Research subject
Geophysics with specialization in Solid Earth Physics
Identifiers
urn:nbn:se:uu:diva-289145 (URN)10.3997/2214-4609.20140522 (DOI)
Conference
76th EAGE Conference & Exhibition, Amsterdam, The Netherlands
Projects
Collisional Orogeny in the Scandinavian Caledonides
Funder
Swedish Research Council
Available from: 2016-04-29 Created: 2016-04-29 Last updated: 2017-01-25
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1963-2588

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