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  • 151.
    Bergmann, P.
    et al.
    Deutsches GeoForschungsZentrum GFZ.
    Jordan, M.
    Sintef.
    Querendez, E.
    Sintef.
    Romdhane, .
    Sintef.
    Eliasson, P.
    Sintef.
    Huang, F.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Zhang, F.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Ivandic, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Juhlin, C.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Towards 4D Joint Inversion for Subsurface Monitoring-Synthetic Study in the Context of the Ketzin CO2 Storage Site2015Conference paper (Refereed)
  • 152. Bergmann, Peter
    et al.
    Diersch, Magdalena
    Götz, Julia
    Ivandic, Monika
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Ivanova, Alexandra
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Kummerow, Juliane
    Liebscher, Axel
    Lüth, Stefan
    Meekes, Sjef
    Norden, Ben
    Schmidt-Hattenberger, Cornelia
    Wagner, Florian M.
    Zhang, Fengjiao
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Review on geophysical monitoring of CO2 injection at Ketzin, Germany2016In: Journal of Petroleum Science and Engineering, Vol. 139, p. 112-136Article in journal (Refereed)
    Abstract [en]

    Geophysical monitoring activities were an important component of the CO2 injection program at the Ketzin site, Germany. Here we report on the seismic and electrical resistivity tomography (ERT) measurements performed during the period of the site development and CO2 injection. Details on the site geology, the history of the CO2 injection operation, and petrophysical models relevant for the interpretation of the geophysical data are presented. The seismic measurements comprise 2D and 3D surface seismic surveys, vertical seismic profilings, and crosshole measurements. Apart from the measurements, results from advanced processing methods, such as impedance inversion and full-waveform inversion are also presented. In addition, results from crosshole ERT and surface-downhole ERT are presented. If operational efforts are taken into consideration we conclude that a combination of several geophysical methods is preferable given the demands of a spatiotemporally comprehensive monitoring program. We base this conclusion on that the different imaging characteristics and petrophysical sensitivities of different methods can complement each other. An important finding is, based on signal quality and reduced operational costs, that the use of permanent installations is promising. Generally, specific monitoring layouts will depend on site-specific characteristics, such as reservoir depth, availability of wells, petrophysical characteristics, and accessibility of surface locations. Given the comprehensive range of methods applied, the reported results are not only relevant to the operation of CO2 storage sites, but are also of interest to other monitoring projects dealing with fluid injection or production.

  • 153.
    Bergmann, Peter
    et al.
    Deutsches GeoForschungsZentrum GFZ.
    Ivandic, Monika
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Kashubin, Artem
    WesternGeco.
    Lüth, Stefan
    Deutsches GeoForschungsZentrum GFZ.
    Ivanova, Alexandra
    Deutsches GeoForschungsZentrum GFZ.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    The Relationship of Soil-moisture Saturation and Time-lapse Static Shifts-An Example from the Ketzin Pilot Site2014Conference paper (Refereed)
  • 154.
    Bergmann, Peter
    et al.
    GFZ German Research Centre for Geosciences, Centre for Geological Storage, Telegrafenberg, Potsdam, Germany.
    Ivandic, Monika
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Norden, Ben
    GFZ German Research Centre for Geosciences, Reservoir Technologies, Telegrafenberg, Potsdam, Germany..
    Rücker, Carsten
    Technical University Berlin, Department of Applied Geophysics, Berlin, Germany.
    Kiessling, D.
    Lüth, S.
    Schmidt-Hattenberger, Cornelia
    GFZ German Research Centre for Geosciences, Centre for Geological Storage, Telegrafenberg, Potsdam, Germany.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Combination of seismic reflection and constrained resistivity inversion with an application to 4D imaging of the CO2 storage site, Ketzin, Germany2014In: Geophysics, ISSN 0016-8033, E-ISSN 1942-2156, Vol. 79, no 2, p. B37-B50Article in journal (Refereed)
    Abstract [en]

    A combination of seismic and geoelectric processing was studied by means of a structurally constrained inversion approach. Structural constraints were interpreted from the seismic data and integrated into the geoelectric inversion through a local regularization, which allowed inverted resistivities to behave discontinuously across defined boundaries. This arranged seismic processing and constrained resistivity inversion in a sequential workflow, making the generic assumption that the petrophysical parameters of both methods change across common lithostructural boundaries. We evaluated the approach using a numerical example and a real data example from the Ketzin CO2 pilot storage site, Germany. The latter demonstrated the efficiency of this approach for combining 4D seismic and surface-downhole geoelectric data. In consistence with the synthetic example, the constrained resistivity inversions produced clearer delineated images along the boundary between caprock and reservoir formation. Near the CO2-flooded reservoir, the seismic and geoelectric time-lapse anomalies correlated well. At some distance to the downhole electrodes, however, the geoelectric images conveyed a notably lower resolution in comparison to the corresponding seismic images. Both methods confirm a northwesterly trend for the CO2 migration at the Ketzin site, although a rather northerly direction was initially expected. The results demonstrate the relevance of the presented approach for the combination of both methods for integrated geophysical CO2 storage monitoring.

  • 155.
    Bergmann, Peter
    et al.
    GFZ German Research Centre for Geosciences, Helmholtz Centre Potsdam, Centre for Geological Storage, Potsdam, Germany.
    Kashubin, Artem
    WesternGeco, Schlumberger House, Buckingham Gate, West Sussex, UK .
    Ivandic, Monika
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Lueth, Stefan
    GFZ German Research Centre for Geosciences, Helmholtz Centre Potsdam, Centre for Geological Storage, Potsdam, Germany.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Time-lapse difference static correction using prestack crosscorrelations: 4D seismic image enhancement case from Ketzin2014In: Geophysics, ISSN 0016-8033, E-ISSN 1942-2156, Vol. 79, no 6, p. B243-B252Article in journal (Refereed)
    Abstract [en]

    A method for static correction of time-lapse differences in reflection arrival times of time-lapse prestack seismic data is presented. These arrival-time differences are typically caused by changes in the near-surface velocities between the acquisitions and had a detrimental impact on time-lapse seismic imaging. Trace-to-trace time shifts of the data sets from different vintages are determined by crosscorrelations. The time shifts are decomposed in a surface-consistent manner, which yields static corrections that tie the repeat data to the baseline data. Hence, this approach implies that new refraction static corrections for the repeat data sets are unnecessary. The approach is demonstrated on a 4D seismic data set from the Ketzin CO2 pilot storage site, Germany, and is compared with the result of an initial processing that was based on separate refraction static corrections. It is shown that the time-lapse difference static correction approach reduces 4D noise more effectively than separate refraction static corrections and is significantly less labor intensive.

  • 156.
    Bergmann, Peter
    et al.
    Deutsches GeoForschungsZentrum GFZ.
    Kashubin, Artem
    WesternGeco.
    Ivandic, Monika
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Lüth, Stefan
    Deutsches GeoForschungsZentrum GFZ.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    4D Result Enhancement with Crosscorrelation-based Time-lapse Static Correction at Ketzin, Germany2014Conference paper (Refereed)
  • 157.
    Bergmann, Peter
    et al.
    Deutsches GeoForschungsZentrum GFZ.
    Kashubin, Artem
    WesternGeco.
    Ivandic, Monika
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Lüth, Stefan
    Deutsches GeoForschungsZentrum GFZ.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Correlation-based static correction of 4D seismic data with a demonstration at the Ketzin CO2 storage site, Germany2013Conference paper (Refereed)
  • 158.
    Bergstrand, Christoffer
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Geophysical characterization of fluid flow and hydrocarbon migration features in the SW Loppa High area, Norwegian Barents Sea2015Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
  • 159.
    Bergström, Jörgen
    Luleå tekniska universitet.
    Geophysical methods for investigating and monitoring the integrity of sealing layers on mining waste deposits1998Licentiate thesis, monograph (Other academic)
  • 160.
    Berube, Andrew P.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    A graphical 3D finite element program for modelling self-potentials generated by flow through a porous medium2007In: Journal of Environmental & Engineering Geophysics, ISSN 1083-1363, E-ISSN 1943-2658, Vol. 12, no 2, p. 185-197Article in journal (Refereed)
    Abstract [en]

    In order to provide a better understanding of the self-potentials generated by groundwater flow through real in-situ geological conditions and a tool for assisting in the interpretation of SP measurements obtained from such domains, a three-dimensional finite element computer program was written to model self-potentials generated by the flow of liquid through a porous medium. Using the program, a finite element domain is defined and each element can be assigned separate anisotropic hydraulic, electric and cross-coupling conductivity values. The hydraulic flow is defined by boundary conditions and the hydraulic conductivity distribution and is related to the electric flow through the thermodynamic theory of coupled flows.The program first determines the hydraulic potential distribution, and then calculates the electric current sources before solving for the electric potential distribution. The program was made to be quite user-friendly, versatile and fully graphical. The program was used to model seepage flow through an earth embankment dam and the results were compared to actual self-potential field measurements. It was found that the results obtained by the program were comparable with field measurements provided that sufficient knowledge of the conductive properties within the dam was available for modelling. The program successfully provides the hydraulic and electric potential distributions throughout the domain based on the input model parameters.

  • 161.
    Beyrandvand, Shahrokh
    et al.
    University of Teheran.
    Lund, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Shomali, Hossein
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Tatar, Mohammad
    International Institute of Seismology and Earthquake Engineering.
    Investigation of stress state in the Zagros region, linear versus non-linear inversion2011Conference paper (Refereed)
  • 162.
    Bhongsuwan, Tribop
    Luleå tekniska universitet.
    Research in rock magnetism and palaeomagnetism of recent sediments and palaeozoic to tertiary rocks in Thailand2000Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Rock magnetic and palaeomagnetic studies have been performed on sediments and Palaeozoic to Tertiary rocks in Thailand. The first part of the thesis includes an environmantal study based on the magnetic properties of recent sediments in one of southern Thailands largest water reservoirs, the Songkla Lake. Sediment from 21 cores collected from different parts of the lake were investigated. From the correlation with age determinations of the sediments, the sedimentation velocities could be determined and related to different parts of the lake. In an attempt to put Thailand and its geological evolution into a plate tectonic context rock magnetic and palaeomagnetic studies were performed on rock from different blocks in southern and northern Thailand. The results show that large parts of Thailand have been remagnetized due to the intrusions of Permian-Triassic granites, and that rock have been deformed in relation with a collition between Asia and India. The plate tectonic analysis shows a clear tectonic contrast between the Shan Thai and Indochina Blocks, a difference that can be related to a collition between Asia and India during the Cenozoic. The study also demonstrates that northeast Thailand, which forms a part of the Indochina Block, has been attached to the South China Block during late Jurrasic time. The presented model of the tectonic evolution for this part of Thailand supports to a large extent earlier presented geological models.

  • 163.
    Bhongsuwan, Tripob
    Luleå tekniska universitet.
    Palaeomagnetic investigations in Thailand1993Licentiate thesis, monograph (Other academic)
  • 164.
    Bispo-Santos, F.
    et al.
    Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    D'Agrella-Filho,, M S
    Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Paleomagnetism of paleoproterozoic mafic and felsic volcanic rocks of the Rio Negro-Juruena Province, Southwestern Amazonian Craton, Brazil2007Conference paper (Other academic)
    Abstract [en]

    Several paleogeographic configurations for the Amazonian Craton have been suggested along its geological history. Paleomagnetic tests for suggested configurations are however restricted due to very sparce and low quality paleomagnetic data, especially for Paleoproterozoic. In an attempt to improve our understanding of the geodynamic evolution, a paleomagnetic study was performed on felsic volcanic rocks of the Colider Suite, and associated mafic rocks in the Rio Negro-Juruena Province, southwestern Amazonian Craton. These rocks have well dated zircon U-Pb ages between 1.80-1.78 Ga. Very stable northern (southern) directions with moderate to steep negative (positive) inclinations were isolated during AF and thermal demagnetization. Rock magnetism experiments show that the magnetization, which is probably of primary origin, in the felsic rocks is carried by hematite and in the mafic rocks by Ti-poor titanomagnetite. A preliminary mean direction (D=187.4°, I=50.9°, N=16, A95=11.3°, K=11.7) yield a paleomagnetic pole located at 289.4°E, 65.4°S (A95=12.9°), which is classified with quality factor of Q=5. Paleogeographic reconstructions using key Paleoproterozoic poles suggest that Laurentia, Baltica, North China, and Amazonian Craton were located in laterally contiguous positions forming a large continental mass at 1.83-1.77 Ga ago.

  • 165. Bispo-Santos, F.
    et al.
    DÁgrella-Filho, M.S.
    Perillo, B.M.
    Tohver, E.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Janikian, L.
    Trinidade, R.I.
    Pacca, I.I.G.
    Silva, J.A.
    Barros, M.A
    Pinho, F.E.C.
    Preliminary paleomagnetic results from the Guadalupe intrusives, Amazonian craton: tectonic implications2009Conference paper (Refereed)
  • 166.
    Bispo-Santos, Franklin
    et al.
    Universidade de São Paulo.
    D’Agrella-Filho, Manoel S.
    Universidade de São Paulo.
    Pacca, Igor I.G.
    Universidade de São Paulo.
    Janikian, Liliane
    Universidade de São Paulo.
    Trindade, Ricardo I.F.
    Universidade de São Paulo.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Silva, Jesué A.
    METAMAT.
    Barros, Márcia A.S.
    Department of Mineral Resources, UFMT.
    Pinho, Francisco E.C.
    Department of Mineral Resources, UFMT.
    Columbia revisited: paleomagnetic results from the 1790 Ma colider volcanics (SW Amazonian Craton, Brazil)2008In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 164, no 1-2, p. 40-49Article in journal (Refereed)
    Abstract [en]

    In an attempt to improve our understanding of the Paleoproterozoic geodynamic evolution, a paleomagnetic study was performed on 10 sites of acid volcanic rocks of the Colider Suite, southwestern Amazonian Craton. These rocks have a well-dated zircon U-Pb mean age of 1789 +/- 7 Ma. Alternating field and thermal demagnetization revealed northern (southern) directions with moderate to high upward (downward) inclinations. Rock magnetism experiments and magnetic mineralogy show that this characteristic magnetization is carried by Ti-poor magnetite or by hematite that replaces magnetite by late-magmatic cleuteric alteration. Both magnetite and hematite carry the same characteristic component. The mean direction (Dm = 183.0 degrees, Im = 53.5 degrees, N = 10, alpha(95) = 9.8 degrees, K = 25.2) yielded a paleomagnetic pole located at 298.8 degrees E, 63.3 degrees S (alpha(95) = 10.2 degrees, K = 23.6), which is classified with a quality factor Q = 5. Paleogeographic reconstructions using this pole and other reliable Paleoproterozoic poles suggest that Laurentia, Baltica, North China Craton and Amazonian Craton were located in laterally contiguous positions forming a large continental mass at 1790 Ma ago. This is reinforced by geological evidence which support the existence of the supercontinent Columbia in Paleoproterozoic times.

  • 167.
    Bispo-Santos, Franklin
    et al.
    Universidade de São Paulo.
    D’Agrella-Filho, Manoel S.
    Universidade de São Paulo.
    Trindade, Ricardo I.F.
    Universidade de São Paulo.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Janikian, Liliane
    Universidade de São Paulo.
    Vasconcelos, Paulo M.
    University of Queensland.
    Perillo, Bruno M.
    Universidade de São Paulo.
    Pacca, Igor I.G.
    Universidade de São Paulo.
    Silva, Jesué A. da
    Companhia Matogrossense de Mineração–METAMAT.
    Barros, Márcia A.S.
    Universidade Federal de Mato Grosso.
    Tectonic implications of the 1419 Ma Nova Guarita mafic intrusives paleomagnetic pole (Amazonian Craton) on the longevity of Nuna2012In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 196-197, p. 1-22Article in journal (Refereed)
    Abstract [en]

    The Nuna supercontinent was probably assembled in the Paleoproterozoic, but its paleogeography and the timing for its demise are still a matter of debate. A paleomagnetic and geochronological study carried out on the Mesoproterozoic Nova Guarita dyke swarm (northern Mato Grosso State, SW Amazonian Craton) provides additional constraints on the duration of this supercontinent. Paleomagnetic AF and thermal treatment revealed south/southwest (northeast) magnetic directions with downward (upward) inclinations for nineteen analyzed sites. These directions are carried by PSD magnetite with high unblocking temperatures as indicated by additional magnetic tests, including thermomagnetic curves, hysteresis loops and the progressive acquisition of isothermal remanence in selected samples. A positive contact test with the host granite in one of the studied dykes further attests to the primary origin of the characteristic magnetic component. A mean site direction was calculated at Dm = 220.5°, Im = 45.9° (α95 = 6.5°, K = 27.7), which yielded a paleomagnetic pole located at 245.9°E, 47.9°S (A95 = 7.0°). 40Ar/39Ar dating carried out on biotites from four analyzed dykes yielded well-defined plateau ages with a mean of 1418.5 ± 3.5 Ma. The Nova Guarita pole precludes a long-lived Nuna configuration in which Laurentia, Baltica, North China, and Amazonia formed a long and continuous block as previously proposed for the Paleoproterozoic. It is nevertheless fully compatible with a SAMBA (Amazonia-Baltica) link at Mesoproterozoic times.

  • 168.
    Biswas, Ashis
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. University of Kalyani, India .
    Neidhardt, Harald
    Kundu, Amit K.
    Halder, Dipti
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. University of Kalyani, India .
    Chatterjee, Debashis
    Berner, Zsolt
    Jacks, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Spatial, vertical and temporal variation of arsenic in shallow aquifers of the Bengal Basin: Controlling geochemical processes2014In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 387, p. 157-169Article in journal (Refereed)
    Abstract [en]

    A detailed understanding of the geochemical processes that regulate the spatial, temporal and vertical variation of dissolved arsenic (As) in shallow aquifers (<50 m) is a prerequisite for sustainable drinking water management in the Bengal Basin. The present study conducted at Chakdaha Block of the Nadia District, West Bengal, India, combined a high resolution hydrogeochemical monitoring study over 20 months from two sets of piezometers (2 x 5) to the sediment geochemistry at areas with high (average:146 mu g/L, n = 5) and relatively low (average: 53.3 mu g/L, n = 10) dissolved As concentrations in groundwater. The determination of the isotopic composition of delta H-2 and delta O-18 in groundwater of the two sites indicated the recharge of evaporative surface water to the aquifer. The concentrations of major aqueous solutes (Ca2+, Mg2+, Na+, K+, HCO3- and Cl-) and electrical conductivity were considerably higher in wells at the high As site compared to the low As site. Additionally, at the high As site, the major ions, Fe, SO42-, electrical conductivity, delta H-2 and delta O-18 showed markedly greater enrichment in the shallowest part (<24 m) of the aquifer compared to the deeper part, reflecting vertical layering of groundwater composition within the aquifer. The oxidation of pyrites has been attributed to the high rate of mineral dissolution resulting in such greater enrichments in this part of the aquifer. In addition, the anthropogenic input with recharge water possibly increased the concentrations of Cl- in this part of the aquifer. The vertical layering of groundwater was absent in the aquifer at the low As site. The absence of such layering and relatively low major ion concentrations and electrical conductivity could be linked to the enhanced aquifer flushing and decreased water-ediment interactions influenced by local-scale groundwater abstraction. The seasonal variations of As concentrations in groundwater were observed only in the shallowest part of the aquifers (<30 m). Furthermore, the As concentrations in groundwater at the uppermost part of the shallow aquifers (<21 m) increased continuously over the monitoring period at both sites. This study supports the view that the reductive dissolution of Fe oxyhydroxides coupled with competitive PO43- sorption reactions in the aquifer sediment enriches As in groundwater of the Bengal Basin. However, the additional Fe released by the weathering of silicate minerals, especially biotite, or the precipitation of Fe as secondary mineral phases such as siderite, vivianite and acid volatile sulfides may result in the decoupling of As and Fe enrichment in groundwater. The redox zonation within the aquifer possibly regulates the vertical distribution of As in the groundwater.

  • 169.
    Bjork, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Characterizing magnetic susceptibility and remanent magnetization of magnetite and hematite rich drill-core samples at Blötberget2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Laboratory magnetic measurements are used to develop a methodology to characterize the Kiruna-type Rare Earth Elements (REE) bearing apatite iron-oxide deposits at Blötberget in central Sweden. This high-grade ore deposit is known to have sharp boundaries between lens shaped main ore bodies of magnetite-rich ore, and a complex hematite-rich ore associated with pegmatites and skarn formation. The thesis covers laboratory magnetic measurements of 37 samples originating from eight drill cores and reference samples from previously mined area. It focuses on on-covering how the samples relate in terms of magnetic susceptibility, further its dependency on temperature, frequency, field and the orientation. The results are correlated with petrographic analysis previously performed on accompanying thin sections.

    The measurements show that magnetite with strong susceptibility contribution overshadow the hematite contribution in the samples. Transition changes in susceptibility are noticeable when crossing the Verwey temperature; -153°C, Curie temperature; 580°C and Néel temperature; 680°C. The Morin temperature appears at -60°C, or is missing. Linear relationships are identified between the magnitude difference in susceptibilities across transitions at high temperature and wt% magnetite and hematite have been identified. The Blötberget skarn and hematite-rich ore samples have a higher degree of susceptibility anisotropy than the other ore-types.

    Blötberget samples are dominated by multidomain characteristics in remanence, saturation and coercivity. High temperature measurements have shown that the magnetite is close to pure. The low temperature measurements suggest hematite is impure or bears a petrological footprint. The study also shows that rich iron ore samples sometimes can be at risk of being overlooked with standard methods of measuring susceptibility

  • 170.
    Björn, Lund
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Geophysics. Geofysik.
    Effects of deglaciation on the crustal stress field and implications for endglacial faulting: A parametric study of simple Earth and ice models2005Report (Other scientific)
  • 171.
    Björn, Lund
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Geophysics.
    Glacially induced faulting2006Report (Other scientific)
  • 172.
    Björn, Lund
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Geophysics. Geofysik.
    Large earthquakes during a glacial cycle2005Report (Other scientific)
  • 173.
    Björnbom, Pehr
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Temperature lapse rates at restricted thermodynamic equilibrium in the Earth system2015In: Dynamics of atmospheres and oceans (Print), ISSN 0377-0265, E-ISSN 1872-6879, Vol. 69, p. 26-36Article in journal (Refereed)
    Abstract [en]

    Equilibrium temperature profiles obtained by maximizing the entropy of a column of fluid with a given height and-volume under the influence of gravity are discussed by using numerical experiments. Calculations are made both for the case of an ideal gas and for a liquid with constant isobaric heat capacity, constant compressibility and constant thermal expansion coefficient representing idealized conditions corresponding to atmosphere and ocean. Calculations confirm the classical equilibrium condition by Gibbs that an isothermal temperature profile gives a maximum in entropy constrained by a constant mass and a constant sum of internal and potential energy. However, it was also found that an isentropic profile gives a maximum in entropy constrained by a constant mass and a constant internal energy of the fluid column. On the basis of this result a hypothesis is suggested that the adiabatic lapse rate represents a restricted or transitory and metastable equilibrium state, which has a maximum in entropy with lower value than the maximum in the state with an isothermal lapse rate. This transitory equilibrium state is maintained by passive forces, preventing or slowing down the transition of the system to the final or ultimate equilibrium state.

  • 174. Blake, S.
    et al.
    Jones, A. G.
    Henry, T.
    Kalscheuer, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    IRETHERM Team, The
    A multi-disciplinary investigation of Irish warm springs and their potential for geothermal energy provision2015In: Proceedings World Geothermal Congress 2015, 2015, p. 11p.-Conference paper (Refereed)
  • 175. Boardsen, Scott A.
    et al.
    Sundberg, Torbjorn
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Slavin, James A.
    Anderson, Brian J.
    Korth, Haje
    Solomon, Sean C.
    Blomberg, Lars G.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Observations of Kelvin-Helmholtz waves along the dusk-side boundary of Mercury's magnetosphere during MESSENGER's third flyby2010In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 37, article id L12101Article in journal (Refereed)
    Abstract [en]

    During the third MESSENGER flyby of Mercury on 29 September 2009, 15 crossings of the dusk-side magnetopause were observed in the magnetic field data over a 2-min period, during which the spacecraft traveled a distance of 0.2 R-M (where R-M is Mercury's radius). The quasi-periodic nature of the magnetic field variations during the crossings, the characteristic time separations of similar to 16 s between pairs of crossings, and the variations of the magnetopause normal directions indicate that the signals are likely the signature of surface waves highly steepened at their leading edge that arose from the Kelvin-Helmholtz instability. At Earth, the Kelvin-Helmholtz instability is believed to lead to the turbulent transport of solar wind plasma into Earth's plasma sheet. This solar wind entry mechanism could also be important at Mercury. Citation: Boardsen, S. A., T. Sundberg, J. A. Slavin, B. J. Anderson, H. Korth, S. C. Solomon, and L. G. Blomberg (2010), Observations of Kelvin-Helmholtz waves along the dusk-side boundary of Mercury's magnetosphere during MESSENGER's third flyby, Geophys. Res. Lett., 37, L12101, doi: 10.1029/2010GL043606.

  • 176.
    Boldreel, Lars Ole
    Luleå tekniska universitet.
    An attempt based on an interpretation of multichannel reflection seismic data to delineate sedimentary sequences, structures and evolution in the part of the Western Barents Sea 72° - 74°N and 10° - 17°E1988Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is an attempt to throw further light on the structural development of the passive continental margin of the Western Barents Sea in the area from 72000'N to 74000'N and from 17000'E to 10000'E. It is based mainly on multichannel reflection seismics but available aeromagnetic, shipborne magnetic and free-air gravimetric data have also been analyzed. It seems from the results that the area between what is generally called the Senja fracture zone and the possible southernmost part of the Hornsund fault zone consists of a nonoceanic basement. The transition between the oceanic and the continental basement is placed adjacent to the Senja fracture zone and its northern continuation up to 740 N. The transition zone to the east of the Senja Fracture Zone in the area 720 50'N to 74000'N suggested in earlier works is here correlated with the development of a listric fault complex rooted in a detachment zone. The non-oceanic basement to the east of the Senja Fracture Zone is also examined and it is suggested that this basement is a stretched continental crust. A chronology for the sequences chosen has been established using the wells 711719-1 and 711719-2 located to the south of the area studied. The structural development of the margin has been dated on the basis of seven depth maps and four isopach maps of the sequences representing the time from the onset of the Tertiary to the end of the Oligocene. The main result is that the end of a major rifting phase corresponds to the beginning of the Paleocene while the onset of the sea floor spreading corresponds to the time interval from Early Eocene to Late Eocene. It appears from backstripping studies that the free-air gravity anomaly associated with the Senja Fracture Zone is probably due to the sediments loading an oceanic plate. This would mean that the Senja "Fracture Zone" is not really a fracture zone. It also seems that the seafloor spreading took place in an oblique northwards manner and that the oceanic basement closest to the Senja "Fracture Zone" and its northern continuation up to 740N is of Eocene age. If this interpretation is correct it would call for a modification of the 2-stage opening model of this area proposed in earlier works.

  • 177.
    Boldreel, Lars Ole
    Luleå tekniska universitet.
    On the structural development of the salt dome province in NW Jutland, Denmark, based on seismic studies1985In: First Break, ISSN 0263-5046, E-ISSN 1365-2397, Vol. 3, no 8, p. 15-21Article in journal (Refereed)
  • 178.
    Boldreel, Lars Ole
    Luleå tekniska universitet.
    Structural development of the salt dome province in NW-Jutland, Denmark, based on seismic studies1985In: Vol. 23, no 3, p. 424-Article in journal (Other academic)
  • 179. Borradaile, Graham
    et al.
    Almqvist, Bjarne
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Installation age of limestone masonry determined from its viscous remagnetization2006In: Geoarchaeology, ISSN 0883-6353, E-ISSN 1520-6548, Vol. 21, p. 29-60Article in journal (Refereed)
  • 180.
    Borthwick, Verity E.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Schmidt, S.
    Piazolo, Sandra
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Gundlach, C.
    Quantification of mineral behavior in four dimensions: grain boundary and substructure dynamics in salt2012In: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027, Vol. 13, p. Q05005-Article in journal (Refereed)
    Abstract [en]

    Here we present the first four dimensional (time and three dimensional space resolved) experiment on a strongly deformed geological material. Results show that even complicated microstructures with large continuous and discontinuous changes in crystallographic orientation can be resolved quantitatively. The details that can be resolved are unprecedented and therefore the presented technique promises to become influential in a wide range of geoscientific investigations. Grain and subgrain scale processes are fundamental to mineral deformation and associated Earth Dynamics, and time resolved observation of these processes is vital for establishing an in-depth understanding of the latter. However, until recently, in situ experiments were restricted to observations of two dimensional surfaces. We compared experimental results from two dynamic, in situ annealing experiments on a single halite crystal; a 2D experiment conducted inside the scanning electron microscope and a 3D X-ray diffraction experiment. This allowed us to evaluate the possible effects of the free surface on grain and subgrain processes. The extent to which surface effects cause experimental artifacts in 2D studies has long been questioned. Our study shows that, although the nature of recovery processes are the same, the area swept by subgrain boundaries is up to 5 times larger in the volume than observed on the surface. We suggest this discrepancy is due to enhanced drag force on subgrain boundaries by thermal surface grooving. Our results show that while it is problematic to derive absolute mobilities from 2D experiments, derived relative mobilities between boundaries with different misorientation angles can be used.

  • 181.
    Bosak, A.
    et al.
    European Synchrotron Radiat Facil, France.
    Krisch, M.
    European Synchrotron Radiat Facil, France.
    Chumakov, A.
    European Synchrotron Radiat Facil, France.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. National University of Science and Technology MISIS, Russia.
    Dubrovinsky, L.
    University of Bayreuth, Germany.
    Possible artifacts in inferring seismic properties from X-ray data2016In: Physics of the Earth and Planetary Interiors, ISSN 0031-9201, E-ISSN 1872-7395, Vol. 260, p. 14-19Article in journal (Refereed)
    Abstract [en]

    We consider the experimental and computational artifacts relevant for the extraction of aggregate elastic properties of polycrystalline materials with particular emphasis on the derivation of seismic velocities. We use the case of iron as an example, and show that the improper use of definitions and neglecting the crystalline anisotropy can result in unexpectedly large errors up to a few percent. (C) 2016 Elsevier B.V. All rights reserved.

  • 182. Bozic, B.
    et al.
    Fan, Huaan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Milosavljevic, Z.
    Establishment of the MGI EDM calibration baseline2013In: Survey review - Directorate of Overseas Surveys, ISSN 0039-6265, E-ISSN 1752-2706, Vol. 45, no 331, p. 263-268Article in journal (Refereed)
    Abstract [en]

    This paper deals with the estimation of the quality of the baseline for the calibration of distance measurement devices which was established by Serbian Military Geographic Institute for military use. The basic characteristics of the baseline are explained, and a plan for the checking of the baseline quality is proposed. The measurements realised so far can be grouped into two phases. The measurements have been processed, and the estimates of the distances of this length standard have been obtained. The standard deviations of the least squares estimates of the lengths were better than 0.3 mm in each epoch. This precision offers the possibility to check all measurement devices with a minimum uncertainty of the calibrations, of +/-(1 mm + 1 ppm). The stability of the pillars is also analysed. The conventional deformation analysis method was applied to three datasets and the results obtained by evaluating them are shown.

  • 183.
    Brandenburg, Axel
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Raedler, K-H
    Yoshizawa's cross-helicity effect and its quenching2013In: Geophysical and Astrophysical Fluid Dynamics, ISSN 0309-1929, E-ISSN 1029-0419, Vol. 107, no 1-2, p. 207-217Article in journal (Refereed)
    Abstract [en]

    A central quantity in mean-field magnetohydrodynamics is the mean electromotive force , which in general depends on the mean magnetic field. It may however also have a part independent of the mean magnetic field. Here we study an example of a rotating conducting body of turbulent fluid with non-zero cross-helicity, in which a contribution to proportional to the angular velocity occurs (Yoshizawa, A., Self-consistent turbulent dynamo modeling of reversed field pinches and planetary magnetic fields. Phys. Fluids B 1990, 2, 15891600). If the forcing is helical, it also leads to an effect, and large-scale magnetic fields can be generated. For not too rapid rotation, the field configuration is such that Yoshizawa's contribution to is considerably reduced compared to the case without effect. In that case, large-scale flows are also found to be generated.

  • 184.
    Braun, Martina
    et al.
    Technical University of Berlin, Dept. of Applied Geophysics, Berlin.
    Kamm, Jochen
    Technical University of Berlin, Dept. of Applied Geophysics, Berlin.
    Yaramanci, Ugur
    Technical University of Berlin, Dept. of Applied Geophysics, Berlin; Geozentrum Hannover, Leibniz Institute for Applied Geophysics, Hannover.
    Simultaneous inversion of magnetic resonance sounding in terms of water content, resistivity and decay times2009In: Near Surface Geophysics, ISSN 1569-4445, E-ISSN 1873-0604, Vol. 7, no 5-6, p. 589-598Article in journal (Refereed)
    Abstract [en]

    Magnetic resonance sounding (MRS) or surface nuclear magnetic resonance (SNMR) is used for direct groundwater exploration and for an improved aquifer characterization. Currently, it is the only geophysical method that is capable of directly determining the free water content and estimating the pore sizes of the aquifer in the subsurface. However, MRS is basically an electromagnetic method. Therefore, it is sensitive to the resistivity of the subsurface. The water content is the main target of investigation, therefore first inversion routines focused on the water content. Later on, inversion routines determining water content and decay times became available. Very recently, MRS inversion for water content and resistivity has been realized. We present here a simultaneous inversion of MRS in terms of determining the three inversion parameters - water content, resistivity and decay time - within one single inversion routine. Within the iterative inversion scheme, the extrapolated initial values are determined on the basis of the physical effective decay times in the subsurface, which are estimated within the inversion scheme. Due to an instrumental dead time, the initial values for amplitude and phase, which are related to water content and resistivity, cannot be measured directly. Therefore, the initial amplitude must be extrapolated using the decay time of the signal. The standard approach is a mono-exponential decay curve; implicitly, the phase is assumed to be time-invariant. However, multi-exponential signals are natural when considering relaxation behaviour in the underground. It originates from multi-modal pore size distributions or simply a number of differently relaxing signal contributions from the various lithological units.

  • 185.
    Brethes, Anais
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. Geological Survey of Denmark and Greenland (GEUS), Department of Petrology and Economic Geology, Denmark.
    Guarnieri, Pierpaolo
    Geological Survey of Denmark and Greenland (GEUS), Department of Petrology and Economic Geology.
    Rasmussen, Thorkild Maack
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bauer, Tobias Erich
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Interpretation of aeromagnetic data in the Jameson Land Basin, central East Greenland: Structures and related mineralized systems2018In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 724-725, p. 116-136Article in journal (Refereed)
    Abstract [en]

    This paper provides a detailed interpretation of several aeromagnetic datasets over the Jameson Land Basin in central East Greenland. The interpretation is based on texture and lineament analysis of magnetic data and derivatives of these, in combination with geological field observations. Numerous faults and Cenozoic intrusions were identified and a chronological interpretation of the events responsible for the magnetic features is proposed built on crosscutting relationships and correlated with absolute ages. Lineaments identified in enhanced magnetic data are compared with structures controlling the mineralized systems occurring in the area and form the basis for the interpretations presented in this paper. Several structures associated with base metal mineralization systems that were known at a local scale are here delineated at a larger scale; allowing the identification of areas displaying favorable geological settings for mineralization. This study demonstrates the usefulness of high-resolution airborne magnetic data for detailed structural interpretation and mineral exploration in geological contexts such as the Jameson Land Basin.

  • 186.
    Brethes, Anais
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Rasmussen, Thorkild Maack
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Guarnieri, Pierpolo
    GEUS.
    Bauer, Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    3D modelling of the base-metal mineralized Jameson Land Basin (central East Greenland) using geologically constrained inversion of magnetic data2015Conference paper (Other academic)
  • 187.
    Brethes, Anaïs
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    An integrated study of geological, magnetic and electromagnetic data for mineral exploration in the Jameson Land Basin, central East Greenland2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Jameson Land Basin, located in central East Greenland, initiated in Devonian time with the collapse of the over-thickened Caledonian Orogen. The basin developed during different phases of rifting from the late Paleozoic to the Mesozoic and has accumulated between 16-18 km of sediments. In Paleogene time, the basin was affected by intense magmatism due to the opening of the North Atlantic Ocean c. 55 Ma ago. Due to a significant uplift in Miocene time, the sedimentary sequence is well exposed along the basin margins, revealing numerous mineral occurrences hosted within almost the entire stratigraphic succession. The major types of mineralization comprise: (1) intrusion-related Mo (± Pb, Zn, Cu, Ag) mineralization associated with Paleogene intrusive complexes; (2) stratabound and/or stratiform Cu, Pb, Zn, (Ag) within Upper Permian and Triassic clastic and marine sedimentary formations; (3) stratabound and structurally controlled Pb-Zn, Cu, Ba, (Sr) mineralization in Upper Permian carbonates; and (4) structurally-controlled Pb, Zn, Cu (±Sb, Bi, Ag, Au) vein-type mineralization within Caledonian and Paleozoic rocks.

    It is well acknowledged that structures such as faults, thrusts, detachments, shear zones and associated fracture systems play an important role as fluid conduits connecting metal sources and sites of mineral precipitation. In particular, previous studies showed that mineral occurrences within the East Greenland Caledonides are closely related to lineaments and intrusions. In this context, the Crusmid-3D project was initiated in 2014, aiming at establishing the links between the crustal structures and the mineral occurrences in the Jameson Land Basin using a combination of geological and geophysical data. The interest for mineral exploration in the area led exploration companies and institutions to carry out magnetic and electromagnetic surveys, and the data derived from these constitute the base of this study.

    This thesis provides a detailed structural interpretation of aeromagnetic data in the Jameson Land Basin where several magnetic trends associated with Tertiary dikes and sills as well as with reactivated Paleozoic and Triassic faults were delineated. These data, in combination with a literature review and compilation of the mineral occurrences in the Jameson Land Basin, allowed highlighting seven prospective areas for structurally-controlled base metal mineralization.

    New structural data from geological fieldwork, drilling results and geophysical data (magnetic, electromagnetic and seismic data) along the eastern margin of the basin allowed a new interpretation of the geometry of the Triassic rift in East Greenland, represented by NE-SW-trending basins and highs segmented by NW-SE-trending transfer zones. It can be correlated with its European conjugate margin, displaying analogies with the Triassic Froan and Helgeland Basins in the Norwegian offshore and with the Papa and West Shetlands Basins north of the Shetland Islands.

    The proposed structural model of the Triassic rift was further investigated using 3D-geologically-constrained inversion of magnetic data in order to refine the architecture of the eastern margin of the Jameson Land Basin. Modelling results confirmed the presence of a shallow westward dipping peneplained crystalline basement in the southern part of the area while the northern part is characterized by faulted blocks, which accommodated relatively thick red bed sedimentary sequences, thereby representing a good potential source of base metals.

    Furthermore, Induced Polarization (IP) effects observed in airborne time-domain electromagnetic data acquired in the eastern margin of the basin were investigated using Self-Organizing Maps (SOM). The analysis of the shape and amplitude of the transient response curves using the SOM allowed identifying four areas where the transient curve patterns exhibit strong IP effects. These are shown to be collocated with Tertiary sills and dikes, clay-altered rocks as well as with a sulfide-bearing brecciated granite and with Triassic stratigraphic horizons hosting disseminated base metal sulfides.

  • 188.
    Brethes, Anaïs
    et al.
    Geological Survey of Denmark and Greenland.
    Guarnieri, Pierpaolo
    Geological Survey of Denmark and Greenland.
    Rasmussen, Thorkild Maack
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Integrating 3D photogeology with aeromagnetic data as a tool for base-metal exploration in East Greenland2014In: Geological Survey of Denmark and Greenland Bulletin, ISSN 1811-4598, E-ISSN 1604-8156, Vol. 31, p. 71-74Article in journal (Refereed)
  • 189.
    Brethes, Anaïs
    et al.
    Geological Survey of Denmark and Greenland.
    Guarnieri, Pierpaolo
    Geological Survey of Denmark and Greenland.
    Rasmussen, Thorkild Maack
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bauer, Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    3D-Modelling of the Early Triassic Base-Metal Mineralized Syn-Rift Sequence in the Jameson Land Basin (East Greenland)2015In: Mineral Resources in a Sustainable World / [ed] A.S. Andre-Mayer; M. Cathelineau; P. Muchez; E. Pirard; S. Sindern, 2015, p. 1701-1704Conference paper (Refereed)
    Abstract [en]

    The Jameson Land Basin in central East Greenland is mineralized in Pb, Zn and Cu. Mineralization occurs in several stratigraphic horizons and along structures in Upper Permian and Triassic sediments. A good understanding of the basin architecture and evolution is therefore essential for mineral exploration in this area. 3D-Photomapping from high resolution aerial photos along with a structural interpretation of aeromagnetic data, electromagnetic data, and results from fieldwork and drilling were integrated into a 3D-structural model. This data integration allowed modelling the rift architecture in the eastern margin of the Jameson Land Basin.

  • 190.
    Brethes, Anaïs
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Guarnieri, Pierpaolo
    GEUS.
    Rasmussen, Thorkild Maack
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bauer, Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geological Analysis of Aeromagnetic Data over the Blyklippen Lead-zinc Mine at Mesters Vig, Central East Greenland2016In: First Conference on Geophysics for Mineral Exploration and Mining: Near Surface Geoscience 2016, Barcelona, Spain, 4-8 September 2016, Houten, 2016, article id Mo MIN 05Conference paper (Refereed)
    Abstract [en]

    In the Mesters Vig area epithermal Pb-Zn sulphide-bearing quartz veins are associated with the border faults of a NNW-SSE elongated graben down-faulting Carboniferous to Lower Triassic sediments. The analysis of the total magnetic field, tilt derivative, vertical derivative and analytic signal allowed to define subcropping magnetic domains and identify structural trends. Doleritic dykes, sills and faults were mapped and structural relationships were established between them. Finally, aeromagnetic data allowed here to delineate structural trends along and in the vicinity of which mineralized quartz veins are mapped.

  • 191.
    Brethes, Anaïs
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Rasmussen, Thorkild Maack
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Guarnieri, Pierpaolo
    GEUS.
    Bauer, Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Mapping and characterization of Induced Polarization in airborne TEM data from central East Greenland: application of a Self-Organizing Map procedure2016Conference paper (Refereed)
    Abstract [en]

    nduced Polarization (IP) effects were observed in airborne Time Domain EM (TEM) data acquired in central East Greenland in the context of exploration for disseminated sulphides in a sedimentary basin. Some of the IP anomalies were targeted by drilling which revealed the absence of mineralization. In order to understand the possible causes of the IP effects we first identified them in the TEM data. IP indicators were extracted from the shape of the transient curves at every measurement location and were analysed by using a Self-Organizing Map (SOM) procedure. Results from K-mean clustering of the SOM are visualized on a geographical map showing the transient curves’ characteristics. Some of the clusters are clearly correlated with the geology whereas others merely reflect recordings below the noise level. In order to interpret the cause of the IP anomalies the airborne TEM data were inverted for the Cole-Cole parameters.

  • 192. Breuillard, H.
    et al.
    Le Contel, O.
    Chust, T.
    Berthomier, M.
    Retino, A.
    Turner, D. L.
    Nakamura, R.
    Baumjohann, W.
    Cozzani, G.
    Catapano, F.
    Alexandrova, A.
    Mirioni, L.
    Graham, D. B.
    Argall, M. R.
    Fischer, D.
    Wilder, F. D.
    Gershman, D. J.
    Varsani, A.
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Khotyaintsev, Yu. V.
    Marklund, G.
    Ergun, R. E.
    Goodrich, K. A.
    Ahmadi, N.
    Burch, J. L.
    Torbert, R. B.
    Needell, G.
    Chutter, M.
    Rau, D.
    Dors, I.
    Russell, C. T.
    Magnes, W.
    Strangeway, R. J.
    Bromund, K. R.
    Wei, H.
    Plaschke, F.
    Anderson, B. J.
    Le, G.
    Moore, T. E.
    Giles, B. L.
    Paterson, W. R.
    Pollock, C. J.
    Dorelli, J. C.
    Avanov, L. A.
    Saito, Y.
    Lavraud, B.
    Fuselier, S. A.
    Mauk, B. H.
    Cohen, I. J.
    Fennell, J. F.
    The Properties of Lion Roars and Electron Dynamics in Mirror Mode Waves Observed by the Magnetospheric MultiScale Mission2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 1, p. 93-103Article in journal (Refereed)
    Abstract [en]

    Mirror mode waves are ubiquitous in the Earth's magnetosheath, in particular behind the quasi-perpendicular shock. Embedded in these nonlinear structures, intense lion roars are often observed. Lion roars are characterized by whistler wave packets at a frequency similar to 100Hz, which are thought to be generated in the magnetic field minima. In this study, we make use of the high time resolution instruments on board the Magnetospheric MultiScale mission to investigate these waves and the associated electron dynamics in the quasi-perpendicular magnetosheath on 22 January 2016. We show that despite a core electron parallel anisotropy, lion roars can be generated locally in the range 0.05-0.2f(ce) by the perpendicular anisotropy of electrons in a particular energy range. We also show that intense lion roars can be observed up to higher frequencies due to the sharp nonlinear peaks of the signal, which appear as sharp spikes in the dynamic spectra. As a result, a high sampling rate is needed to estimate correctly their amplitude, and the latter might have been underestimated in previous studies using lower time resolution instruments. We also present for the first-time 3-D high time resolution electron velocity distribution functions in mirror modes. We demonstrate that the dynamics of electrons trapped in the mirror mode structures are consistent with the Kivelson and Southwood (1996) model. However, these electrons can also interact with the embedded lion roars: first signatures of electron quasi-linear pitch angle diffusion and possible signatures of nonlinear interaction with high-amplitude wave packets are presented. These processes can lead to electron untrapping from mirror modes.

  • 193. Breuillard, H.
    et al.
    Le Contel, O.
    Retino, A.
    Chasapis, A.
    Chust, T.
    Mirioni, L.
    Graham, D. B.
    Wilder, F. D.
    Cohen, I.
    Vaivads, A.
    Khotyaintsev, Yu V.
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Marklund, Göran T.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Burch, J. L.
    Torbert, R. B.
    Ergun, R. E.
    Goodrich, K. A.
    Macri, J.
    Needell, J.
    Chutter, M.
    Rau, D.
    Dors, I.
    Russell, C. T.
    Magnes, W.
    Strangeway, R. J.
    Bromund, K. R.
    Plaschke, F.
    Fischer, D.
    Leinweber, H. K.
    Anderson, B. J.
    Le, G.
    Slavin, J. A.
    Kepko, E. L.
    Baumjohann, W.
    Mauk, B.
    Fuselier, S. A.
    Nakamura, R.
    Multispacecraft analysis of dipolarization fronts and associated whistler wave emissions using MMS data2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 14, p. 7279-7286Article in journal (Refereed)
    Abstract [en]

    Dipolarization fronts (DFs), embedded in bursty bulk flows, play a crucial role in Earth's plasma sheet dynamics because the energy input from the solar wind is partly dissipated in their vicinity. This dissipation is in the form of strong low-frequency waves that can heat and accelerate energetic electrons up to the high-latitude plasma sheet. However, the dynamics of DF propagation and associated low-frequency waves in the magnetotail are still under debate due to instrumental limitations and spacecraft separation distances. In May 2015 the Magnetospheric Multiscale (MMS) mission was in a string-of-pearls configuration with an average intersatellite distance of 160km, which allows us to study in detail the microphysics of DFs. Thus, in this letter we employ MMS data to investigate the properties of dipolarization fronts propagating earthward and associated whistler mode wave emissions. We show that the spatial dynamics of DFs are below the ion gyroradius scale in this region (approximate to 500km), which can modify the dynamics of ions in the vicinity of the DF (e.g., making their motion nonadiabatic). We also show that whistler wave dynamics have a temporal scale of the order of the ion gyroperiod (a few seconds), indicating that the perpendicular temperature anisotropy can vary on such time scales.

  • 194.
    Brodic, Bojan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Multicomponent digital-based seismic land-streamer for urban underground infrastructure planning2015Licentiate thesis, comprehensive summary (Other academic)
  • 195.
    Brodic, Bojan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Three-component digital-based seismic landstreamer: Methodologies for infrastructure planning applications2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    To support urban infrastructure planning projects, along with various other near-surface applications, a multicomponent landstreamer was developed. The landstreamer was built with broadband (0-800 Hz), three-component (3C) micro-electro-mechanical system (MEMS) sensors. The digital nature of the MEMS sensors makes the developed landstreamer insensitive to electric/electromagnetic noise.

    The landstreamer’s design and its seismic imaging capabilities, along with the MEMS technical specifications, were evaluated in several studies. When comparing signals recorded with the streamer with planted MEMS sensors, no negative effects of the design were noted. Compared to different geophones tested, the streamer produced higher quality and broader signal bandwidth data. Additionally, a seismic study conducted in a tunnel demonstrated its electric/electromagnetic noise insensitivity. The streamer combined with wireless seismic recorders was used to survey logistically challenging areas for improved imaging and characterizations and avoid interference with traffic.

    For example, at the Stockholm Bypass site, the landstreamer recorded data were used for traveltime tomography with results showing a well delineated bedrock level and potential low-velocity zones matching with inferred poor-quality-class rocks. The seismic response of fractures and their extent between a tunnel and the surface was studied at the Äspö Hard Rock Laboratory site. The velocity model obtained using the traveltime tomography approach showed known well-characterized fracture systems and potential additional formerly unknown ones. Additionally, compressional- and shear-wave velocities, seismic quality factors, Vp/Vs and dynamic Poisson’s ratios of the known fracture zones were obtained. Fractures and/or weakness zones in the bedrock were imaged using refraction and reflection imaging methods at a site contaminated with a cancerogenic pollutant in southwest Sweden, illustrating the potential of the streamer for environmental-related applications. In southern Finland, the landstreamer was used for SH-wave reflection seismic imaging from a vertically oriented impact source with the results showing a well-delineated bedrock level and weak reflections correlating well with geology. At the same site, its potential for multichannel analysis of surface waves (MASW) was demonstrated. The surface-wave obtained shear-wave velocities match well with the borehole based stratigraphy of the site and are complementary to the SH-wave reflectivity and previous investigations at the site.

    Studies conducted in this thesis demonstrate the landstreamer’s potential for various near-surface applications and show the benefits and need for 3C seismic data recording. 

  • 196.
    Brodic, Bojan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Malehmir, Alireza
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Bastani, Mehrdad
    Geological Survey of Sweden.
    Mehta, Suman
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Lundberg, Emil
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Wang, Shunguo
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Multi-component digital-based seismic landstreamer and boat-towed radio-magnetotelluric acquisition systems for improved subsurface characterization in the urban environment2017In: First Break, ISSN 0263-5046, E-ISSN 1365-2397, Vol. 35, no 8, p. 41-47Article in journal (Other academic)
    Abstract [en]

    It is estimated that urban life will be the norm for around 60% of the world’s population by 2040, leading to a more centralized distribution of people and making the city as the main place of residence (Whiteley, 2009). This population centralization inherently implies rapidly expanding cities and imposes the need for more infrastructure within, around and between the present city boundaries. However, infrastructure projects nowadays have to follow strict civil engineering standards that require detailed knowledge of subsurface conditions during different stages of the construction processes. Since direct methods conventionally used for site characterization (e.g., drilling and/or core testing) are still relatively expensive the focus in the last two decades has been on non-invasive, geophysical methods. However, geophysical site characterization in urban areas is not an easy task owing to numerous challenges and various types of noise sources. Challenges such as electric/electromagnetic (EM) noise, pipelines and other subsurface objects (sometimes even unknown or undocumented), the inability to properly couple sensors because of pavement, traffic noises and limited space are common in urban environment. Since geophysical surveys need to be done with the least amount of disturbances to the environment, residents and traffic, new geophysical techniques for fast, non-invasive and high-resolution site characterization are needed. To overcome some of these challenges, a nationwide joint industry-academia project was launched in 2012 TUST GeoInfra, www.trust-geoinfra.se). As a component in the project, Uppsala University developed two new data acquisition systems. These are a fully digital MEMS-based (Micro-machined Electro-Mechanical Sensor) three component (3C) seismic landstreamer and a boat-towed radio-magnetotelluric (RMT) acquisition system. Both systems were specifically designed to address urban environments with the RMT system particularly aiming at efficient and cost-effective geophysical surveying on shallow-water bodies, which constitute 7% of Scandinavia. In this article, we will describe the two systems and present two case studies illustrating their potential. A number of published accounts are now available from the two systems showing what type of problems they can address (e.g., Bastani et al., 2015; Brodic et al., 2015; Malehmir et al., 2015a, 2015b, 2016a, 2016b, 2017; Dehghannejad et al., 2017; Maries et al., 2017; Mehta et al., 2017; Brodic et al., 2017).

  • 197.
    Brodic, Bojan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Malehmir, Alireza
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    All wave-modes converted and reflected from fracture systems: A tunnel-surface seismic experiment2015Manuscript (preprint) (Other academic)
  • 198.
    Brodic, Bojan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Malehmir, Alireza
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Bedrock and Fracture Zone Delineation UsingDifferent Near-surface Seismic Sources2017Conference paper (Other academic)
    Abstract [en]

    To delineate the bedrock surface and a fracture zone intersected by a well at c. 50 m depth, a seismic survey wasconducted using four different near-surface seismic sources. These were a 5-kg sledgehammer, a metal I-beamhit laterally, an accelerated weight drop and a prototype source tested for the first time called Udarnik. TheUdarnik source has two hammers whose impacts are initiated by an electromagnetic force of the stable coilexciting its inner moving part. Two hammers separated by a distance of approximately 50 cm successively hittwo contact plates mounted on the bottom of the source. The sweep length is adjustable and maximum 18 hitscan be made per second. In this study, we compare the performance of every source used and present reflectionseismic sections and tomography results from the high-fold (star-type acquisition was used) combinedlandstreamer and wireless recorder survey. Preliminary results indicate that bedrock was well delineated both ontomography results and stacked sections for all sources and some weak reflectivity is observed where thefracture zone is expected with most of the sources used showing the potential of the seismic methods forfracture zone imaging and near-surface characterization

  • 199.
    Brodic, Bojan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Malehmir, Alireza
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Delineating fracture zones using surface-tunnel-surfaceseismic data, P-S, and S-P mode conversions2017In: Journal of Geophysical Research - Solid Earth, ISSN 2169-9313, E-ISSN 2169-9356, Vol. 122, no 7, p. 5493-5516Article in journal (Refereed)
    Abstract [en]

    A surface-tunnel-surface seismic experiment was conducted at the Äspö Hard Rock Laboratoryto study the seismic response of major fracture systems intersecting the tunnel. A newly developedthree-component microelectromechanical sensor-based seismic landstreamer was deployed inside the noisytunnel along with conventional seismic receivers. In addition to these, wireless recorders were placed on thesurface. This combination enabled simultaneous recording of the seismic wavefield both inside the tunneland on the surface. The landstreamer was positioned between two geophone-based line segments, alongthe interval where known fracture systems intersect the tunnel. First arrival tomography produced a velocitymodel of the rock mass between the tunnel and the surface with anomalous low-velocity zones correlatingwell with locations of known fracture systems. Prominent wave mode converted direct and reflected signals,P-S and S-P waves, were observed in numerous source gathers recorded inside the tunnel. Forward traveltime and 2-D finite difference elastic modeling, based on the known geometry of the fracture systems, showthat the converted waves are generated at these systems. Additionally, the landstreamer data were used toestimate Vp/Vs, Poisson’s ratio, and seismic attenuation factors (Qp and Qs) over fracture sets that havedifferent hydraulic conductivities. The low-conductivity fracture sets have greater reductions in P wavevelocities and Poisson’s ratio and are more attenuating than the highly hydraulically conductive fracture set.Our investigations contribute to fracture zone characterization on a scale corresponding to seismicexploration wavelengths.

  • 200.
    Brodic, Bojan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Malehmir, Alireza
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Fracture System Characterization Using Wave-mode Conversions and Tunnel-surface Seismics2016Conference paper (Refereed)
    Abstract [en]

    A tunnel-to-surface experiment was conducted to test the recording capabilities of a newly developed 3C-MEMS (micro electro mechanical system) seismic landstreamer in noisy environments and to characterize the rocks in between. The tunnel portion of the seismic line was covered using a combination of 333-planted 10 Hz geophones and the 3C landstreamer. The landstreamer was located at a depth of -160 to -200 m below sea level, targeting known fracture systems intersecting the tunnel. On the surface, 75 wireless recorders connected to 10 Hz geophones and MEMS sensors were used. This setup enabled simultaneous recording of the seismic wavefield inside the tunnel and on the surface and tomographic imaging of the rockmass between the two. Geophone data recorded inside the tunnel show severe electric noise pickup, while the landstreamer data appear unaffected. First-break traveltime tomography results show decreased velocity associated with known fracture systems, indicating that high-resolution imaging of the rocks between the surface and the tunnel using this source-receiver setup is possible. Strong mode-converted energy (P-S and S-P direct- and reflected-waves) was observed from the fracture systems, suggesting significant elastic property contrasts compared to the host rock. 3D raytracing modeling supports that mode conversions originate from the fracture systems.

1234567 151 - 200 of 1312
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