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  • 1. Chuang, T.C
    et al.
    Henkel, Herbert
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    GIS Visualization of Complex Geoscientific Data from the Björkö Structure2006In: GeoCongress 2006: Geotechnical Engineering in the Information Technology Age, Atlanta: American Society of Civil Engineers (ASCE), 2006, 2, , p. 204-209p. 204-209Conference paper (Refereed)
    Abstract [en]

    Based on the idea of Scientific Visualization, this research is aimed to visualize the complex geoscientific data to support the mapping work of the Björkö Energy Project, which has an ultimate goal to place a heat exchanging mechanism at the most suitable location in the subsurface. The production from this impact crater structure is expecting to supply the heating use for the great Stockholm area. The various point data types were compiled to diverse maps according to their characteristics. Several GIS and numerical tools are introduced integratedly to accomplish the work. The research in addition helps to streamline the data and maps processing activities carried out by the varied working groups

  • 2.
    Ekneligoda, Thushan Chandrasiri
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Henkel, Herbert
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Interactive spatial analysis of lineaments2010In: Computers & Geosciences, ISSN 0098-3004, E-ISSN 1873-7803, Vol. 36, no 8, p. 1081-1090Article in journal (Refereed)
    Abstract [en]

    An interactive software tool, here called Spatial Analysis of Lineaments (SAL), has been developed for calculating the spatial properties azimuth, length, spacing, and unidirectional frequency of lineaments which are defined by their start and end coordinates. In a series of steps the user is guided by displays of relevant statistical distributions, which can be user designed. Statistical outliers can be excluded and the total sample of lineaments can be subdivided into azimuth sets and, if required, into spatial clusters. Special attention is given to the removal of spatial outliers in an interactive way. Several rule-based decisions are made to determine the nearest lineament in the spacing calculation. As a default procedure, the program defines a window whose size depends on the mode value of the length distribution of the lineaments in the study area. The software can accept a large amount of lineaments and can analyze the spatial properties of each azimuth set avoiding the repetitive calling of the original database. A simple rule was developed to derive the unidirectional lineament frequency. The spatial properties are presented as histograms for each azimuth set together with the mode, mean, standard deviation, and number of involved lineaments. (C) 2010 Elsevier Ltd. All rights reserved.

  • 3.
    Ekneligoda, Thushan Chandrasiri
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Henkel, Herbert
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    The spacing calculator software - A Visual Basic program to calculate spatial properties of lineaments2006In: Computers & Geosciences, ISSN 0098-3004, E-ISSN 1873-7803, Vol. 32, no 4, p. 542-553Article in journal (Refereed)
    Abstract [en]

    A software tool is presented which calculates the spatial properties azimuth, length, spacing, and frequency of lineaments that are defined by their starting and ending co-ordinates in a two-dimensional (2-D) planar co-ordinate system. A simple graphical interface with five display windows creates a user-friendly interactive environment. All lineaments are considered in the calculations, and no secondary sampling grid is needed for the elaboration of the spatial properties. Several rule-based decisions are made to determine the nearest lineament in the spacing calculation. As a default procedure, the programme defines a window that depends on the mode value of the length distribution of the lineaments in a study area. This makes the results more consistent, compared to the manual method of spacing calculation. Histograms are provided to illustrate and elaborate the distribution of the azimuth, length and spacing. The core of the tool is the spacing calculation between neighbouring parallel lineaments, which gives direct information about the variation of block sizes in a given category of structures. The 2-D lineament frequency is calculated for the actual area that is occupied by the lineaments.

  • 4. Guha, D. K.
    et al.
    Henkel, Herbert
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Jacks, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Abandoned on-shore deep wells: a potential for geothermal energy resource for rural Bangladesh2005In: Proceedings of the World Geothermal Congress 2005: paper 2214, 2005Conference paper (Other academic)
  • 5.
    Henkel, Herbert
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Aaro, S.
    Geophysical investigations of the Siljan impact structure - A short review2005In: IMPACT TECTONICS / [ed] Koeberl, C; Henkel, H, 2005, p. 247-283Conference paper (Refereed)
    Abstract [en]

    Siljan in southwest Sweden is the largest impact structure in western Europe, with a present topographic diameter of ca. 75 km. Recent age determinations indicate an age of 377 Ma. The bedrock geology of the region has recently been re-mapped by the Geological Survey of Sweden in the scale of 1:50 000. There is now complete coverage with airborne geophysics. New maps of the geophysical data have been prepared for this review. In connection with the Deep Gas Project, further geophysical studies were made and two drill holes were sunk to over 6 kin depth in the central uplift of the structure. The Deep Gas Project produced a large number of reports and publications, which are listed in the summary report of Juhlin (1991). Some of the results are compiled and shortly summarized here. Digital elevation data are available with 50 in spatial resolution, and a gray tone map has been prepared with the regional trend removed. A profile of these data shows that the peak ring of the structure is still visible in the morphology.

  • 6.
    Henkel, Herbert
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Bäckström, Ann
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Bergman, Börje
    Stephansson, Ove
    Lindström, Maurits
    Geothermal energy from impact craters?: The Björkö study2005In: Proceedings of the World Geothermal Congress 2005: paper 0667, 2005Conference paper (Other academic)
  • 7.
    Henkel, Herbert
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Ekneligoda, Thushan Chandrasiri
    Aaro, Sven
    The extent of impact induced fracturing from gravity modeling of the Granby and Tvaren simple craters2010In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 485, no 1-4, p. 290-305Article in journal (Refereed)
    Abstract [en]

    The Granby and Tvaren impact structures are two of the 5 recognized early Paleozoic impact structures in Scandinavia. They have a similar diameter of ca 2 km and contain a substantial post impact fill with Paleozoic sedimentary rocks. The Granby structure represents an almost completely preserved impact crater within a Paleozoic sedimentary rock sequence - only the uppermost part of the raised crater rim might be eroded and was subsequently covered by Quaternary sediments. The Tvaren structure is eroded below the surrounding pre-impact Paleozoic cover rocks into the underlying crystalline basement and has Quaternary sediment fill. Gravity measurements have been made on land, and in the case of the Tvaren structure also on sea ice, as a basis for modeling of the extent of impact induced fracturing below and around the craters, expressed as porosity. In the models, the contributions to the gravity field from the crater fill materials seawater, Quaternary sediments and Paleozoic sedimentary rocks are accounted for. The remaining negative gravity anomaly is related to the volume of impact fractured crystalline rock indicating an outward decreasing intensity of fracturing extending beyond the morphologic crater edge to ca 1.5 km radial distance from the explosion center. The remaining porosity in the central part of this sub-crater damage zone approaches 15%. A model is suggested for the gradual change of density and the equivalent porosity with radial distance within the damage zone around simple craters. (C) 2010 Elsevier B.V. All rights reserved.

  • 8.
    Henkel, Herbert
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Piazolo, Sandra
    Wörman, Anders
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Hydraulic Engineering.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    A deep rock laboratory in the Dellen impact crater2010In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 132, no 1, p. 45-54Article in journal (Refereed)
    Abstract [en]

    The Deep Rock Lab is a platform to establish a comprehensive subsurface bedrock characterization approach, by integrating site characterization techniques applied from different disciplines of geo-mechanics, geochemistry, hydrogeology, structural geology, lithology and geophysics, with consideration of the effects of coupled geological processes of importance for the understanding of groundwater renewal, continental shield deformations, engineering issues related to geological disposal of nuclear waste and CO2, and geothermal energy retrieval in crystalline rocks. The approach will focus on the physics and chemistry of crystalline rocks and groundwater with down-the-hole measurements of relevant variables, using and developing more efficient geo-scientific site investigation techniques for deep boreholes at a chosen site, and develop more advanced down-the-hole measurements and numerical modelling methods with more advanced inversion algorithms to help integrate data interpretations and object representations. The goal is to develop this platform into a long-term research facility that can be readily used by the scientific community for both subsurface fundamental and engineering-oriented research. Such a platform will be especially important for the education of PhD students for generations to come. The integrated drilling and research facility is suggested to be located at the Dellen site. This site has an impact crater with a large range of expected physical property changes with depth, complex and multiple thermal processes that have affected the bedrock, a favorable infrastructure and local supporting activities, and a large body of existing geo-scientific data.

  • 9.
    Henkel, Herbert
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Puura, V.
    Flodén, T.
    Kirs, J.
    Konsa, M.
    Preeden, U.
    Lilljequist, R.
    Fernlund, Joanne
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Avike bay - a 10 km diameter possible impact structure at the Bothnian Sea coast of central Sweden.2005In: IMPACT TECTONICS / [ed] Koeberl, C; Henkel, H, 2005, p. 323-340Conference paper (Refereed)
    Abstract [en]

    Avike Bay is a 270 degrees degree wide near-circular, 114 in deep bay on the Swedish coast of the Bothnian Sea, northeast of Sundsvall. The structure has a diameter of about 10 km. It was classified as a probable impact structure because of its extraordinary circular topography in the overwiew of impact structures in Fennoscandia. Recent studies lend further support to this interpretation. The structure has a submarine central mound, which is elevated some 40 in above the adjacent sea floor. It has a very distinct tangential and radial on-shore fracture pattern as seen in the topographic map. Along the southwestern shore of the Bay, an enigmatic quartzite breccia of unknown age occurs as part of a larger outcrop of polymict breccia with clasts of crystalline rocks and quartzite of unknown age. In thin section, planar fractures can be observed in quartz and feldspar grains. A detailed investigation showed that in a few cases the quartz grains contained microdeformation features closely resembling PDFs.

  • 10. Lindgren, Paula
    et al.
    Ivarsson, Magnus
    Neubeck, Anna
    Broman, Curt
    Henkel, Herbert
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Holm, Nils G.
    Putative fossil life in a hydrothermal system of the Dellen impact structure, Sweden2010In: International Journal of Astrobiology, ISSN 1473-5504, E-ISSN 1475-3006, Vol. 9, no 3, p. 137-146Article in journal (Refereed)
    Abstract [en]

    Impact-generated hydrothermal systems are commonly proposed as good candidates for hosting primitive life on early Earth and Mars. However, evidence of fossil microbial colonization in impact-generated hydrothermal systems is rarely reported in the literature. Here we present the occurrence of putative fossil microorganisms in a hydrothermal system of the 89 Ma Dellen impact structure, Sweden. We found the putative fossilized microorganisms hosted in a fine-grained matrix of hydrothermal alteration minerals set in interlinked fractures of an impact breccia. The putative fossils appear as semi-straight to twirled filaments, with a thickness of 1-21 mu m, and a length between 10 and 100 mu m. They have an internal structure with segmentation, and branching of filaments occurs frequently. Their composition varies between an outer and an inner layer of a filament, where the inner layer is more iron rich. Our results indicate that hydrothermal systems in impact craters could potentially be capable of supporting microbial life. This could have played an important role for the evolution of life on early Earth and Mars.

  • 11. Liu, D W
    et al.
    Gu, D S
    Dai, T G
    Henkel, Herbert
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Analysis and calculation of thermal conductivity of rock in deep strata2005In: Journal of Central South University of Technology, ISSN 1005-9784, E-ISSN 1993-0666, Vol. 12, p. 114-119Article in journal (Refereed)
    Abstract [en]

    The thermal conductivity of rock is an important parameter for the deep mine and the geothermal development. It is often not possible to measure the thermal conductivity of the rocks present in the deep strata, and the usual approach is to calculate thermal conductivity including mineralogy and porosity. The compositions of core samples from the MID01 borehole in the Björkö area were determined, and the mineral composition was classified. The calculation of the thermal conductivity of rock in the borehole was carried out, and the main factors for the thermal conductivity of rock were analyzed. The results show that the calculated thermal conductivity of rock is reliable and useful for the design and calculation of geothermal development in the Björkö area.

  • 12.
    Olofsson, Bo
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Henkel, Herbert
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Knutsson, Stigh
    KASAM, Kärnavfallsrådet.
    Stigh, Jimmy
    Göteborgs Universitet.
    Några geologiska, geodynamiska och geofysiska undersökningsmetoder vid lokalisering av underjordsanläggningar i hårt berg2004In: Kunskapsläget på kärnavfallsområdet 2004, Stockholm: Fritzes, 2004, p. 139-207Chapter in book (Refereed)
  • 13. Ormo, Jens
    et al.
    Gomez-Ortiz, David
    McGuire, Patrick C.
    Henkel, Herbert
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Komatsu, Goro
    Rossi, Angelo Pio
    Magnetometer survey of the proposed Sirente meteorite crater field, central Italy: Evidence for uplifted crater rims and buried meteorites2007In: Meteoritics and Planetary Science, ISSN 1086-9379, E-ISSN 1945-5100, Vol. 42, no 2, p. 211-222Article in journal (Refereed)
    Abstract [en]

    The Sirente crater field consists of a 120 in wide, rimmed main depression flanked to the northwest by about 30 smaller depressions. It has been dated to the first centuries A.D. An impact origin is suggested, but not confirmed. The small size combined with the properties of the target material (carbonate mud) would neither allow shock features diagnostic of impact, nor projectile vaporization. Consequently, a meteoritic component in the sediments would be very localized. At impacts of this size the projectile most likely is an iron meteorite. Any iron meteorites on the ground surface would, in Iron Age Europe, have been removed shortly after the event. However, if the depressions are of impact origin they should contain meteorites at great depth in analogy with known craters. The magnetic properties of iron meteorites differ distinctly from the very low magnetic sediments and sedimentary rocks of the Sirente area. We have used a proton precession magnetometer/gradiometer to produce magnetic anomaly maps over four of the smaller depressions (similar to 8 in diameter), as well as two crossing profiles over a fifth depression (similar to 22 in diameter). All show distinct magnetic anomalies of about 20 nT, the larger depression up to 100 nT. Magnetic modeling shows a best fit for structures with upturned strata below their rims, excluding a karstic origin but supporting an explosive formation. The 100 nT anomaly can only be explained by highly-magnetic objects at a few meters depth. All together, the magnetic data provides a strong indication for an impact origin of the crater field.

  • 14. Oskooi, Behrooz
    et al.
    Henkel, Herbert
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Pedersen, Laust B.
    Bäckstrom, Ann
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Abedi, Maysam
    Magnetotelluric investigation on Bjorko impact structure, west of Stockholm, Sweden2016In: Arabian Journal of Geosciences, ISSN 1866-7511, E-ISSN 1866-7538, Vol. 9, no 13, article id 618Article in journal (Refereed)
    Abstract [en]

    This paper describes the application of magnetotelluric (MT) method to investigate Bjorko impact structure located at west of Stockholm, Sweden. This structure has formed in crystalline rocks ca. 1.2 Ga ago and located relatively close to the district heating infrastructure of the Stockholm region, as the largest district heating system in Europe. Since impact structures mostly contain fractured rock volumes in the form of breccia formations, the occurred brecciation zones in this region are more favorable potential targets for geothermal investigations. The main objective is evaluating the capability of the study area to have potential for geothermal resources by mapping the subsurface structure. To image electrical characteristic of underground layers, 1D and 2D bimodal inversions of TE and TM modes of MT data are performed. The results are also compared with the outputs of the inversion of the determinant data (yielding a direction independent average of the subsurface conductivity) along the same profiles, proving good accordance of the outputs. The processed resistivity sections at depth along with measuring various rock physical properties across two drilled boreholes at Bjorko and Midsommar islands localized two conductors at depths of 1 km and from 2.5 to 4.5 km, which may be attributed to be a potential zone for geothermal energy retrieval.

  • 15. Reimold, W U
    et al.
    Kelley, S P
    Sherlock, S C
    Henkel, Herbert
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Koeberl, C
    Laser argon dating of melt breccias from the Siljan impact structure, Sweden: Implications for a possible relationship to Late Devonian extinction events2005In: Meteoritics and Planetary Science, ISSN 1086-9379, E-ISSN 1945-5100, Vol. 40, no 4, p. 591-607Article in journal (Refereed)
    Abstract [en]

    In earlier studies, the 65-75 km diameter Si1jan impact structure in Sweden has been linked to the Late Devonian mass extinction event. The Siljan impact event has previously been dated by K-Ar and Ar-Ar chronology at 342-368 Ma, with the commonly quoted age being 362.7 +/- 2.2 Ma (2 sigma, recalculated using currently accepted decay constants). Until recently, the accepted age for the Frasnian/Famennian boundary and associated extinction event was 364 Ma, which is within error limits of this earlier Si1jan age. Here we report new Ar-Ar ages extracted by laser spot and laser step heating techniques for several melt breccia samples from Si1jan (interpreted to be impact melt breccia). The analytical results show some scatter, which is greater in samples with more extensive alteration; these samples generally yield younger ages. The two samples with the least alteration yield the most reproducible weighted mean ages: one yielded a laser spot age of 377.2 +/- 2.5 Ma (95% confidence limits) and the other yielded both a laser spot age of 376.1 +/- 2.8 Ma (95% confidence limits) and a laser stepped heating plateau age over 70.6% (39)Ar release of 377.5 +/- 2.4 Ma (2 sigma). Our conservative estimate for the age of Siljan is 377 2 Ma (95% confidence limits), which is significantly different from both the previously accepted age for the Frasnian/Famennian (F/F) boundary and the previously quoted age of Siljan. However, the age of the F/F boundary has recently been revised to 374.5 +/- 2.6 Ma by the International Commission for Stratigraphy, which is, within error, the same as our new age. However, the currently available age data are not proof that there was a connection between the Si1jan impact event and the F/F boundary extinction. This new result highlights the dual problems of dating meteorite impacts where fine-grained melt rocks are often all that can be isotopically dated, and constraining the absolute age of biostratigraphic boundaries, which can only be constrained by age extrapolation. Further work is required to develop and improve the terrestrial impact age record and test whether or not the terrestrial impact flux increased significantly at certain times, perhaps resulting in major extinction events in Earth's biostratigraphic record.

  • 16. Reimold, W.U.
    et al.
    Gibson, R.L.
    Henkel, Herbert
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Scientific comment on: uundja et al., 2007: Magnetic imaging of the Vredefort impact crater, South Africa, EPSL 261, 456-4682008In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 273, no 3-4, p. 393-396Article in journal (Other academic)
1 - 16 of 16
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