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  • 1.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Rasmussen, Torklid Maack
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Project: Development, Evaluation and Optimization of Measures to Reduce the Impact on the Environment from Mining Activities in Northern Regions2016Other (Other (popular science, discussion, etc.))
    Abstract [en]

    Min-North is a transnational project financed by the Interreg Nord program and coordinated by LTU. The project is a cooperation between Geological survey of Finland, GTK, Oulo University (Finland), The Arctic University of Norway, UiT and several (>17) small and large enterprises and mining companies in the northern region with expertise within geology, waste management, geophysics and geochemistry. The overall goal is to reduce the environmental impacts of mining in the northern regions by developing, evaluating, optimizing environmental techniques. In Sweden, geophysical and geochemical techniques will be integrated to develop a 4D model for tracing pollution transport in the mine waste, mine areas and in(to) the surroundings.

  • 2.
    Andersson, Christer
    Luleå tekniska universitet.
    Regional strukturgeologisk tolkning av fjärranalysdata1985Licentiate thesis, monograph (Other academic)
  • 3.
    Autio, U.
    et al.
    Oulu Mining School, University of Oulu.
    Smirnov, Maxim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Savvaidis, Alexandros S.
    Institute of Engineering Seismology and Earthquake Engineering, Thessaloniki.
    Suopios, Pantelis
    Department of Environmental and Natural Resources Engineering, Technological Educational Institute of Crete, Chania.
    Bastani, Mehrdad
    Geological Survey of Sweden.
    Combining electromagnetic measurements in the Mygdonian sedimentary basin, Greece2016In: Journal of Applied Geophysics, ISSN 0926-9851, E-ISSN 1879-1859, Vol. 135, 261-269 p.Article in journal (Refereed)
    Abstract [en]

    We present a novel approach where time-domain electromagnetic (TEM) data are transformed and subsequently used in two-dimensional (2-D) magnetotelluric inversion of the determinant of the impedance tensor. The main idea is to integrate TEM with magnetotelluric (MT) data to produce subsurface electrical resistivity models. Specifically, we show that 2-D MT data inversion of the determinant of the impedance tensor supported by inclusion of TEM–MT-transformed data has superior resolution at the near surface and at the same time static shift afflicting the MT data can be addressed. Thus, the approach allows for practical express integration of TEM data with MT measurements as opposed to a full combined 3-D inversion, which requires significant resources. The approach is successfully applied in the Mygdonian sedimentary basin located in Northern Greece. In addition to TEM and MT data, also controlled source — and radiomagnetotelluric data are available from the Mygdonian basin, which have been subjected to 2-D analysis previously. We have extended the analysis to a full 3-D inversion using ModEM code. All obtained models are analysed and are in a good agreement.

  • 4.
    Bauer, Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skyttä, Pietari
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Dehghannejad, Mahdieh
    Uppsala University.
    Tavakoli, Saman
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geological multi-scale modelling as a tool for modern ore exploration in the Skellefte mining district, Sweden2011In: Proceedings IAMG 2011 Salzburg: Mathematical Geosciences at the crossroads of theory and practice, 2011, 759- p.Conference paper (Other academic)
    Abstract [en]

    The Palaeoproterozoic Skellefte Mining District is host to abundant ore deposits. Geological 3Dmodelling was performed using the gOcad software platform. Geological methods such as field mapping, structural analysis and facies analysis combined with geophysical techniques such as reflection seismic investigations, resistivity, magnetic, electromagnetic and gravimetric studies and analysis of potential field data provide a framework for the reconstruction of the crustal geometry and geological history of the district as a tool for modern ore exploration. Results will be furthermore utilized for kinematic 4-dimensional modelling

  • 5.
    Bauer, Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skyttä, Pietari
    Hermansson, Tobias
    Boliden Mineral AB, Luleå tekniska universitet.
    Dehghannejad, Mahdieh
    Uppsala University, Uppsala universitet, Department of Earth Sciences, Uppsala University.
    Tavakoli, Saman
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The Skellefte District2015In: 3D, 4D and Predictive Modelling of Major Mineral Belts in Europe, Encyclopedia of Global Archaeology/Springer Verlag, 2015, 93-121 p.Chapter in book (Refereed)
    Abstract [en]

    Four-dimensional geological modelling has been conducted in the Palaeoproterozoic Skellefte mining district. 3D-modelling of volcanic-hosted massive sulphide deposits and associated host-rocks has been carried out in multiple scales from deposit to regional scale and is based on a combination of geological and geophysical investigations. A conceptual model founded on unravelling the structural control on sedimentation, volcanism and mineralization and the subsequent deformation patterns, acts as a base for geological modelling. The final 3D-model provides a structural framework in which the mineralizations can be studied by improved understanding of the structural evolution in the mine areas, and by comparing the regional structural patterns versus the form and attitude of ore deposits. Additionally, uncertainty and prospectivity models were constructed showing the distribution of data and the potential of discovering new ore deposits. Subsequent 4D-modelling adds the time aspect to the 3D-models and aims at visualizing and understanding the geological history in the district and as a support for ore targeting. Moreover, adding geological time to the modelling helps gaining confidence about both the conceptual models and the 3D-models. The final 3D- and 4D-models provide a regional three-dimensional context for both industrial and academic activities in the Skellefte district, and aid the understanding of large-scale tectonic processes.

  • 6.
    Bauer, Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skyttä, Pietari
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Tavakoli, Saman
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Dehghannejad, Mahdieh
    Uppsala University, Uppsala universitet, Department of Earth Sciences, Uppsala University.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    From deposit to regional scale: 4-dimensional geological modelling in the Skellefte Mining District, Sweden2011Conference paper (Refereed)
  • 7.
    Bauer, Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skyttä, Pietari
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Tavakoli, Saman
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Hermansson, Tobias
    Boliden Mineral AB.
    Dehghannejad, Mahdieh
    Uppsala University.
    Juanatey, Maria Garcia
    Uppsala University.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Allen, Rodney
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Juhlin, Christopher
    Uppsala University.
    A regional scale 3D-model of the Skellefte mining district, northern Sweden2013In: Mineral depostits for a high-tech world: Proceedings of the 12th SGA Biennial Meeting 2013, 12-15 August 2013, Uppsala, Sweden, Uppsala: Sveriges Geologiska Undersökning , 2013, Vol. 1, 62-65 p.Conference paper (Refereed)
  • 8.
    Bauer, Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Tavakoli, Saman
    Dehghannejad, Mahdieh
    Department of Earth Sciences, Uppsala University.
    Garcia, Maria
    Department of Earth Sciences, Uppsala University.
    Weihed, Pär
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    4-dimensional geological modelling of the Skellefte district, Sweden2010In: The international archives of the photogrammetry, remote sensing and spatial information sciences, ISPRS Commission IV - Working Group 8 , 2010, Vol. XXXVIII-4, 93-96 p.Conference paper (Other academic)
  • 9.
    Beka, Thomas I.
    et al.
    Faculty of Science and Technology, UiT-The Arctic University of Norway.
    Senger, Kim
    Department of Arctic Geology, The University Centre in Svalbard.
    Autio, Uula A
    Oulu Mining School, Geophysics, University of Oulu.
    Smirnov, Maxim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Birkelund, Yngve
    Faculty of Science and Technology, UiT-The Arctic University of Norway.
    Integrated electromagnetic data investigation of a Mesozoic CO2 storage target reservoir-cap-rock succession, Svalbard2017In: Journal of Applied Geophysics, ISSN 0926-9851, E-ISSN 1879-1859, Vol. 136, 417-430 p.Article in journal (Refereed)
    Abstract [en]

    Recently acquired time-domain electromagnetic (TEM) and magnetotelluric (MT) data sets are utilized in the first electromagnetic (EM) characterization of a geological CO2 storage target site in Adventdalen, Arctic Norway. Combining the two EM data sets enabled to resolve the electrical resistivity structure of the target site better than either of the methods alone. 2D inverting the MT data in the audio period interval (0.003–1 s) with supporting input derived from the TEM data (0.01–10 ms) provided a geologically meaningful resistivity model that included information not previously evident from existing seismic and borehole data. The ca. 1.8 × 1 km 2D resistivity model displays a laterally constrained highly conductive anomaly (ca. 10 Ω m) at about 400–500 m depth, where reflectors of a parallel seismic section are concealed and core samples indicate a highly fractured décollement zone formed during Paleogene compression. The base of the permafrost is imaged at ca. 200 m depth. Synthetic inversion tests, however, suggest that this may be exaggerated by tens of meters, due to a thin conductive layer present approximately between 10 and 25 m depth. The resistivity model does not give indication for a fluid pathway we can connect to leakage, in line with water injection and leak-off tests in the reservoir and cap-rock, both of which indicate a sealing shale-dominated cap-rock separating an over-pressured compartment above the sealing shale from a severely under-pressured reservoir interval. The results we present indicate the advantage of integrating EM exploration techniques in a CO2 reservoir-cap-rock study to obtain a more complete picture.

  • 10.
    Beka, Thomas I.
    et al.
    Department of Physics and Technology, UiT-The Arctic University of Norway.
    Smirnov, Maxim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Birkelund, Yngve
    Department of Physics and Technology, UiT-The Arctic University of Norway.
    Senger, Kim
    The University Centre in Svalbard.
    Bergh, Steffen G.
    Department of Geology, UiT-The Arctic University of Norway, N-9037 Tromsø.
    Analysis and 3D inversion of magnetotelluric crooked profile data from central Svalbard for geothermal application2016In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 686, 98-115 p.Article in journal (Refereed)
    Abstract [en]

    Broadband (0.001–1000 s) magnetotelluric (MT) data along a crooked profile collected to investigate the geothermal potential on Spitsbergen could not be fully explained by two-dimensional (2D) models; hence we interpret the data with three-dimensional (3D) inversion herein. To better accommodate 3D features and nearby off profile resistivity structures, the full MT impedance tensor data together with the tipper were inverted. As a model control, a detailed bathymetry is systematically incorporated in the inversion. Our results from testing different inversion settings emphasised that appropriately choosing and tuning the starting model, data error floor and the model regularization together are crucial to obtain optimum benefit from MT field data. Through the 3D inversion, we reproduced out of quadrant impedance components and obtained an overall satisfactory data fit (RMS = 1.05). The final 3D resistivity model displays a complex geology of the near surface region (< 1.5 km), which suggests fractures, localized and regional fault systems and igneous intrusions in the Mesozoic platform cover deposits. The Billefjorden fault zone is revealed as a consistent and deep rooted (> 2 km) conductive anomaly, confirming the regional nature of the fault. The fault zone is positioned between two uplifted basement blocks (> 1000 Ωm) of presumably pre-Devonian (Caledonian) metamorphic rocks, and the fault may have been responsible for deformation in the overlying Paleozoic-Mesozoic unit. Upper crustal conductive anomalies (< 10 Ωm) below the Paleozoic-Mesozoic succession in the western part of the 3D model are interpreted as part of a Devonian basin fill. These conductors are laterally and vertically bounded by resistive rocks, suggesting a conducive environment for deep geothermal heat storage. Having this scenario in an area of a known high heat-flow, deep faults and a thinned lithosphere makes the hypothesis on finding a technologically exploitable geothermal resource close to human settlement in the area stronger.

  • 11. Berggren, Robert
    et al.
    Sandrin, Alessandro
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Physical properties of rocks and geophysical data as tools for targeting Fe-oxide Cu-Au mineralisations in northern Sweden2004In: EOS: Transactions, ISSN 0096-3941, E-ISSN 2324-9250, Vol. 85, no 47Article in journal (Other academic)
  • 12.
    Bergström, Jörgen
    Luleå tekniska universitet.
    Geophysical methods for investigating and monitoring the integrity of sealing layers on mining waste deposits1998Licentiate thesis, monograph (Other academic)
  • 13.
    Berube, Andrew P.
    Luleå University of Technology.
    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, 185-197 p.Article 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.

  • 14.
    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.

  • 15.
    Bhongsuwan, Tripob
    Luleå tekniska universitet.
    Palaeomagnetic investigations in Thailand1993Licentiate thesis, monograph (Other academic)
  • 16.
    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.

  • 17. 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)
  • 18.
    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, 40-49 p.Article 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.

  • 19.
    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, 1-22 p.Article 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.

  • 20.
    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.

  • 21.
    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, 15-21 p.Article in journal (Refereed)
  • 22.
    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, 424- p.Article in journal (Other academic)
  • 23.
    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)
  • 24.
    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, 71-74 p.Article in journal (Refereed)
  • 25.
    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, 1701-1704 p.Conference 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.

  • 26.
    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, 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.

  • 27.
    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.

  • 28.
    Buchan, K. L.
    et al.
    Geological Survey of Canada.
    Mertanen, S.
    Geological Survey of Finland.
    Park, R. G.
    Department of Earth Sciences, Keele University.
    Pesonen, L. J.
    Geological Survey of Finland.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Abrahamsen, N.
    University of Aarhus.
    Bylund, G.
    Lunds universitet.
    Comparing the drift of Laurentia and baltica in the Proterozoic: the importance of key palaeomagnetic poles2000In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 319, no 3, 167-198 p.Article in journal (Refereed)
    Abstract [en]

    Key palaeomagnetic poles are defined as those which pass basic reliability criteria and are precisely and accurately dated. They allow a more rigorous analysis of Precambrian continental drift and continental reconstructions than the traditional apparent polar wander path (APWP) approach using mostly non-key poles. Between ca. 2.45 and 2.00 Ga in the early Palaeoproterozoic, key poles define the drift of the Archaean Superior craton of Laurentia, yielding a result that is quite unlike the drift interpreted in earlier studies using the APWP method. There are no early Palaeoproterozoic key poles for the other Archaean cratons that amalgamated to form Laurentia and Baltica prior to 1.8 Ga, so that a rigorous test of early Palaeoproterozoic reconstruction models is not possible. Key poles from Laurentia between ca. 1.46 and 1.267 Ga and Baltica between 1.63 and 1.265 Ga help to define, in a preliminary fashion, the early Mesoproterozoic drift of the two shields. The key pole age match at ca. 1.265 Ga is consistent with Baltica located adjacent to eastern Greenland, and geological considerations suggest that the most reasonable fit aligns the Labradorian belt of Laurentia with the Gothian belt of Baltica. Although there is limited support from non-key poles and key poles that are not matched in age for such a fit as early as ca. 1.8 Ga, no rigorous assessment will be possible until a match in key pole ages is achieved. In the late Mesoproterozoic to Neoproterozoic, Laurentia's drift is reasonably well documented by seven key poles between 1.235 and 0.73 Ga. There are no key poles in this period from Baltica, however, so that a ≈90° clockwise rotation of Baltica relative to Laurentia between 1.265 and 1.0 Ga, widely used in the literature, cannot be confirmed.

  • 29.
    Buchan, Kenneth
    et al.
    Geological Survey of Canada.
    Ernst, Richard
    Geological Survey of Canada.
    Hamilton, Mike A.
    Geological Survey of Canada.
    Mertanen, Satu
    Geological Survey of Finland.
    Pesonen, Lauri J.
    Geological Survey of Finland.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The 1.7-0.7 Ga paleomagnetic record for Laurentia, Baltica and Siberia and its application to Rodinia reconstructions1999In: Vol. 4, no 1, 114- p.Article in journal (Other academic)
  • 30. Buchan, Kenneth L.
    et al.
    Ernst, Richard E.
    Hamilton, Michael A.
    Mertanen, Satu
    Pesonen, Lauri J.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Rodinia: the evidence from integrated palaeomagnetism and U-Pb geochronology2001In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 110, no 1-4, 9-32 p.Article in journal (Refereed)
    Abstract [en]

    Of many hundreds of well-defined palaeomagnetic poles that have been reported from cratons around the world in the 1700-500 Ma period, only a few are precisely dated. However, such ‘key' palaeopoles are a prerequisite for establishing rigorous palaeomagnetic reconstructions in order to chart the assembly, drift and breakup of the postulated late Precambrian supercontinent of Rodinia. Most key palaeopoles are derived from mafic dykes and sills that have been dated by U-Pb techniques. Most are from Laurentia, the largest and best studied of the continental fragments that are thought to have comprised Rodinia. Thirteen key Laurentia palaeopoles form an incomplete reference set that can be used for comparison with key palaeopoles from other cratons as they become available. Currently, there are four key palaeopoles for Baltica between 1700 and 500 Ma, although only one allows a direct comparison with a similar aged pole from Laurentia. The 1265 Ma match between Baltica and Laurentia is consistent with reconstructions in which Baltica is adjacent to present-day east Greenland, with the ca. 1700-1500 Ma Gothian and Labradorian belts aligned. Few key palaeopoles are yet available from other cratons. However, recent U-Pb dating of dykes, sills, or volcanic rocks in the Siberian, Australian and Kalahari cratons and in Coats Land of Antarctica constrains the ages of individual palaeopoles from each of these areas. Most of these are not key palaeopoles because they have not been conclusively demonstrated to be primary, or local tectonic rotations have not been ruled out. Nevertheless, they are useful in testing Rodinia reconstructions. In this paper, a U-Pb baddeleyite age is reported from the late Gardar magmatic rocks of southwest Greenland. Along with the previously published palaeopole for this unit, this age helps constrain the Mesoproterozoic location of southwest Greenland relative to North America.

  • 31. Bylund, G.
    et al.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Från Söderhavet till Arktis2000In: Har du tid?, Stockholm: Naturvetenskapliga forskningsrådet (NFR) , 2000, 61-74 p.Chapter in book (Other (popular science, discussion, etc.))
  • 32. Bylund, Göran
    et al.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The Dala dolerites, central Sweden, and their palaeomagnetic signature1992In: Geologiska föreningens i Stockholm förhandlingar, ISSN 0016-786X, Vol. 14, no 1, 143-153 p.Article in journal (Refereed)
    Abstract [en]

    New palaeomagnetic results are presented from nine dolerites from central Sweden. Data are also presented from four porphyry sites and one granite site. The data obtained are compared with previously published data from the area. Based on the directions of the characteristic magnetizations isolated in the various rock units a division into five groups, A-E, has been made. Group A consists of dolerites of late Sveconorwegian (c. 1050-850 Ma) age and group B comprises dolerites belonging to the Central Scandinavian Dolerite Group (c. 1250-1150 Ma). Groups C and D are less clearly defined. Group C, with a shallow negative northerly remanence inclination represents the Tuna dykes (c. 1370 Ma). The D direction, with a shallow positive northerly inclination, may represent an older generation of dolerites. The border between groups C and D is diffuse and may be the result of a prolonged mid-Proterozoic period with dolerite intrusions in Dalarna during which significant apparent polar wander occurred. Group E comprises dolerites with a steep positive inclination close to the direction of the Earth's present field. The porphyries and the granite studied carry group D and E remanence directions. This strengthens the evidence for a D-group generation of dolerites contemporary with the porphyries and the granite, c.1650 Ma ago.

  • 33.
    Bérube, Andrew Patrick
    Luleå tekniska universitet.
    Investigating the streaming potential phenomenon using electric measurements and numerical modelling with special reference to seepage monitoring in embankment dams2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A three-dimensional finite element computer program has been developed to numerically model the streaming potential phenomenon. The program can in fact calculate and display the primary and secondary potential distributions for any two coupled flows in a three dimensional domain. For streaming potentials, the primary flow is hydraulic and the secondary flow is electrical. The program operates in three separate stages. The program first determines the hydraulic potential distribution in the ground based on hydraulic conductivity values and the hydraulic driving forces, such as the pressure drop through an embankment dam. The program then calculates the geometry and magnitude of the electric current sources based on the fluid flow and cross-coupling conductivity values. Finally the electric potential distribution is solved for using these current sources and the electric conductivity distribution. Additionally, the program can incorporate external current sources, which can be used to simulate resistivity measurements in a model. The model domain can take any three-dimensional shape and can be divided into elements as desired. The individual elements can be assigned separate hydraulic, electric and cross-coupling conductivity values, creating an inhomogeneous anisotropic domain with three separate conductivity distributions. Four different types of finite element are available to choose from; two- and three-dimensional versions of isoparametric elements with either linear or quadratic interpolating polynomials. The program has been made fully graphical, allowing the user quick and easy access to information at any particular point of the domain. In order to provide a better picture of the streaming potentials in earth dams and the potential of the SP method for dam safety monitoring, SP investigations were performed on a number of embankment dams. Electric resistivity measurements were also performed on some of the dams to compliment the SP data. The resistivity data was found to be of considerable assistance for interpreting the SP measurements as well as for simulating real dam conditions with the modelling program. Three hydro-electric dams of different size on the Luleå River in northern Sweden were studied together with several dams built by mining companies for containing mine tailing reservoirs. A number of potential seepage areas were identified in several of the investigated dams.

  • 34.
    Bérubé, Andrew Patrick
    Luleå tekniska universitet.
    Geophysical methods for the investigation of subsurface flows2002Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Geophysical methods of investigating the substratum have been proven to provide quality data for a variety of applications. Despite this fact, such methods are not used in some fields to the degree that they could be. Reasons for this can include the complexity of the required measurements, the difficulties in interpreting the results, and a simple ignorance of the full potential of the various methods. One method that requires only very simple measurements with very little equipment is the self-potential or SP method, which can provide invaluable information concerning subsurface heat or liquid flows. This information could be used for example to track contaminants or to identify problem areas in or under an earth dam before they became serious. One difficulty with the SP method can be interpreting the results when the subsurface geology is complex. The first part of this thesis addresses this problem by creating a finite element computer program to model the streaming potential phenomenon for a complex domain with varying hydraulic, thermal and electrical conductivities. The second part of this thesis deals with a geophysical investigation of mining waste impoundments. Relatively simple electrical and electromagnetic methods are used to provide a thorough assessment of the impoundments' condition. Modern technological advances in both the measuring equipment and processing computers are seen to make the measurements faster and interpreting the results much easier.

  • 35.
    Chirindja, F.J.
    et al.
    Geology Department, Eduardo Mondlane University, Maputo.
    Dahlin, Torleif
    LTH, Lund, Department of Engineering Geology, Lund University.
    Perttu, Nils
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Steinbrusch, F.
    Indian Institute of Technology Madras, Chennai.
    Owen, R.
    University of Zimbabwe, Harare.
    Combined electrical resistivity tomography and magnetic resonance sounding investigation of the surface-water/groundwater interaction in the Urema Graben, Mozambique2016In: Hydrogeology Journal, ISSN 1431-2174, E-ISSN 1435-0157, Vol. 24, no 6, 1583-1592 p.Article in journal (Refereed)
    Abstract [en]

    This study focusses on the hydrogeology of Urema Graben, especially possible interactions between surface water and groundwater around Lake Urema, in Gorongosa National Park (GNP). Lake Urema is the only permanent water source for wildlife inside GNP, and there are concerns that it will disappear due to interferences in surface-water/groundwater interactions as a result of changes in the hydraulic environment. As the lake is the only permanent water source, this would be a disaster for the ecosystem of the park. The sub-surface geology in Urema Graben was investigated by 20 km of electrical resistivity tomography (ERT) and three magnetic resonance sounding (MRS) surveys. The average depth penetration was 60 and 100 m, respectively. The location of the ERT lines was decided based on general rift morphology and therefore orientated perpendicular to Urema Graben, from the transitional areas of the margins of the Barue platform in the west to the Cheringoma plateau escarpments in the east. ERT and MRS both indicate a second aquifer, where Urema Lake is a window of the first upper semi-confined aquifer, while the lower aquifer is confined by a clay layer 30–40 m thick. The location and depth of this aquifer suggest that it is probably linked to the Pungwe River which could be a main source of recharge during the dry season. If a dam or any other infra-structure is constructed in Pungwe River upstream of GNP, the groundwater level will decrease which could lead to drying out of Urema Lake.

  • 36. D´Agrella-Filho, Mabuel S.
    et al.
    Pacca, Igor I. P.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Teixeira, Wilson
    Bettencourt, Jorge Silva
    Geraldes, M.C.
    Preliminary paleomagnetic results from metabasic and sedimentary rocks from the Amazonian craton: tectonic implications for the Rodinia supercontinent2001In: Workshop on Geology of the SW Amazonian Craton: State-of- the-art. Abstracts, Instituto de Geociências-USP , 2001, 155-158 p.Conference paper (Other academic)
  • 37.
    D'Agrella-Filho, Manoel S.
    et al.
    Departamento de Geofísica, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Tohver, Eric
    School of Earth and Geographical Sciences, University of Western Australia, Crawley.
    Santos, João O.S.
    Redstone Resources Limited, Perth.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Trinidade, Ricardo I.F.
    Departamento de Geofísica, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Pacca, Igor I.G.
    Departamento de Geofísica, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Geraldes, Mauro C.
    Faculdade de Geologia, Universidade do Estado do Rio de Janeiro.
    Direct dating of paleomagnetic results from Precambrian sediments in the Amazon craton: Evidence for Grenvillian emplacement of exotic crust in SE Appalachians of North America2008In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 267, no 1-2, 188-199 p.Article in journal (Refereed)
    Abstract [en]

    We apply a new diagenetic dating technique to determine the age of magnetization for Precambrian sedimentary rocks in the SW Amazon craton. Two new palcomagnetic poles are reported from the rocks of the Aguapei Gp.: red beds of the Fortuna Fm. (P-lat = 59.8 degrees N, P-lon = 155.9 degrees E, A(95)=9.5, K= 14, 18 sites, N/n 128/115, Q=5) and the reverse-polarity mudstones of the overlying Vale da Promissao Formation (P-lat=49.5 degrees N, P-lon = 89.3 degrees E, A(95) = 12.5, K=30, 6 sites, N/n=94/80, Q=4). The Fortuna Fm. magnetization is hosted by massive, interstitial hematite cement and constitutes a post-depositional remanence. The age of diagenesis of the red beds is well-constrained by the 1149 +/- 7 Ma U-Pb age of authigenic xenotime rims on detrital zircons determined by SHRIMP analysis. The magnetite-hosted remanence of the Vale da Promissao Fm. may be detrital in origin, but the age of deposition is poorly constrained. The reliable and precisely-dated Fortuna Fun. pateomagnetic pole fixes the paleogeographic position of the Amazon craton near the SE Appalachians portion of North America at 1.15 Ga. These data demonstrate a mobile Grenvillian link between these two cratons, and support the recent identification of Amazon crust in the Blue Ridge province region of North America

  • 38.
    D'Agrella-Filho, Manoel S.
    et al.
    Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Trindade, Ricardo I.F.
    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.
    Teixeira, Wilson
    Instituto de Geociências, Universidade de São Paulo.
    Yokoyama, Elder
    Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Tohver, Eric
    School of Earth and Geographical Sciences, University of Western Australia, Crawley.
    Geraldes, Mauro C.
    Faculdade de Geologia, Universidade do Estado do Rio de Janeiro.
    Pacca, Igor I.G.
    Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Barros, Marcia A.S.
    Instituto de Ciências Exatas e da Terra, Departamento de Geologia, Universidade Federal de Mato Grosso.
    Ruiz, Amarildo S.
    Instituto de Ciências Exatas e da Terra, Departamento de Geologia, Universidade Federal de Mato Grosso.
    The 1420 Ma Indiavaí Mafic Intrusion (SW Amazonian Craton): Paleomagnetic results and implications for the Columbia supercontinent2012In: Gondwana Research, ISSN 1342-937X, E-ISSN 1878-0571, Vol. 22, no 3-4, 956-973 p.Article in journal (Refereed)
    Abstract [en]

    The configuration and the timing of assembly and break-up of Columbia are still matter of debate. In order to improve our knowledge about the Mesoproterozoic evolution of Columbia, a paleomagnetic study was carried out on the 1420 Ma Indiavaí mafic intrusive rocks that crosscut the polycyclic Proterozoic basement of the SW Amazonian Craton, in southwestern Mato Grosso State (Brazil). Alternating field and thermal demagnetization revealed south/southwest ChRM directions with downward inclinations for sixteen analyzed sites. These directions are probably carried by SD/PSD magnetite with high coercivities and high unblocking temperatures as indicated by additional rock magnetic tests, including thermomagnetic data, hysteresis data and the progressive acquisition of isothermal remanent magnetization. Different stable magnetization components isolated in host rocks from the basement 10 km NW away to the Indiavaí intrusion, further support the primary origin of the ChRM. A mean of the site mean directions was calculated at Dm = 209.8°, Im = 50.7° (α95 = 8.0°, K = 22.1), which yielded a paleomagnetic pole located at 249.7°E, -57.0°N (A95 = 8.6°). The similarity of this pole with the recently published 1420 Ma pole from the Nova Guarita dykes in northern Mato Grosso State suggests a similar tectonic framework for these two sites located 600 km apart, implying the bulk rigidity of the Rondonian-San Ignacio crust at that time. Furthermore these data provide new insights on the tectonic significance of the 1100-1000 Ma Nova Brasilândia belt –a major EW feature that cuts across the basement rocks of this province, which can now be interpreted as intracratonic, in contrast to previous interpretation. From a global perspective, a new Mesoproterozoic paleogeography of Columbia has been proposed based on comparison of these 1420 Ma poles and a 1780 Ma pole from Amazonia with other paleomagnetic poles of similar age from Baltica and Laurentia, a reconstruction in agreement with geological correlations.

  • 39.
    D’Agrella-Filho, Manoel S.
    et al.
    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.
    Yokoyama, Eder
    Universidade de São Paulo.
    Bispo-Santos, Franklin
    Universidade de São Paulo.
    A new 1.42 GA paleomagnetic pole from the Amazonian craton: implications for the Columbia supercontinent configuration2011In: Proceedings of Second Biennial Meeting of Latinmag: Tandil Argentina, November 2011, 2011Conference paper (Other academic)
    Abstract [en]

    Paleomagnetic studies carried out on the 1.42 Ga Indiavaí mafic intrusive rocks, that crop out in the SW Mato Grosso State provides a great opportunity to test the proposed paleogeographic models for Columbia. Paleomagnetic AF and thermal treatment revealed south/southwest magnetic directions with downward inclinations for sixteen analyzed sites. These directions are probably carried by SD/PSD magnetite with high coercivities and high unblocking temperatures as indicated by additional magnetic tests, including thermomagnetic curves, hysteresis loops and the IRM acquisition curves. A different magnetization obtained for host mafic rocks from the basement ca. 10 km NW away from the Indiavaí intrusive, further attests to the primary origin of the characteristic magnetic component. A mean site direction was calculated at Dm=209.8°, Im=50.7° (α95=8.0°, K=22.1), which yielded a paleomagnetic pole located at 249.7°E, -57.0°N (A95=8.6°). Comparison of this pole with other paleomagnetic poles of similar age from Baltica and Laurentia provides evidence for a link of north-northeastern Amazonian craton, southwestern Baltica and Laurentia, as previously suggested from the similar Mesoproterozoic geological evolution of their margins.

  • 40.
    D'Agrella-Filho, Manoel Souza
    et al.
    Sao Paulo University.
    Trindade, Ricardo I. Ferreira
    Sao Paulo University.
    Tohver, Eric
    University of Western Australia.
    Bispo-Santos, Franklin
    Sao Paulo University.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Pacca, Igor I. Gil
    Sao Paulo University.
    Proterozoic paleogeographic evolution of South American cratons2008Conference paper (Other academic)
    Abstract [en]

    The South American platform is composed of four major cratons (Amazonian, São Francisco, Rio de la Plata and São Luis) and other smaller continental blocks and terrains that may have taken part in supercontinental assemblages. Here, paleogeographic configurations from the Paleoproterozoic up to the Cambrian are tested by means of an updated paleomagnetic and geochronologic record of South America, including new high-quality poles from the Amazonian and São Francisco cratons. These poles are compared to those of other cratons thought to have interacted with South American units in the Proterozoic, such as Baltica and Laurentia. The oldest assemblage of continents to be addressed is the Paleoproterozoic Columbia (~1800 Ma), for which our data support a configuration aligning Laurentia, Baltica, North China and Amazonia through their Paleo-Mesoproterozoic belts. For Neoproterozoic times (~1200-1000 Ma) a connection between Laurentia and the Amazonian craton in an evolving configuration (with relative movement between the two units) is supported by a pole-to-pole comparison. In contrast, striking differences in Laurentia's drift history compared to São Francisco, São Luis (=West Africa) and Kalahari rule-out the effective participation of these cratons in Rodinia. The assembly of Gondwana has probably occurred in different steps, comprising first (~630 Ma) the connection between Sao Francisco, Rio de la Plata, other minor blocks and the African cratons, followed by the collision of these central Gondwanan blocks with the Amazonian craton and adjoining blocks by mid-Cambrian times (~530 Ma), after the opening of the Iapetus ocean basin between Laurentia and the Amazonian craton. In this scenario, the West Gondwana was not a coherent tectonic unit before the end of Precambrian times.

  • 41.
    d'Agrella-Filho, M.S.
    et al.
    University of Sao Paolo.
    Pacca, I I G
    University of Sao Paolo.
    Sigueira, R.
    University of Sao Paolo.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Teixeira, W.
    University of Sao Paolo.
    Bettencourt, J.S.
    Geraldes, M.C.
    Amazonian Proterozoic poles: implications to Rodinia paleogeography2001In: From basins to mountains: Rodinia at the turn of the century / Chris Powell Memorial Symposium / [ed] K.N. Sircombe; Z.X. Li, University of Western Australia , 2001, 27-30 p.Conference paper (Other academic)
  • 42.
    D'Agrella-Filho, M.S.
    et al.
    University of Sao Paolo.
    Pacca, Igor Gal
    University of Sao Paolo.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Trinidade, R.I.F.
    University of Sao Paolo.
    Paleomagnetic evidence for oblique collision between Amazonia and Laurentia at about 1.1 Ga2004In: International Geological Congress, Abstracts: 32nd international geological congress, Florence, Italy, Aug. 20-28, 2004, 2004, 1089- p.Conference paper (Other academic)
    Abstract [en]

    The connection between Amazonia and Laurentia at late Meso- proterozoic times through the Grenville/Sunsas-Aguapei collisional belts is a key feature of Rodinia paleogeography.However, at least three different geometries are proposed for such connection, mainly due to the paucity of paleomagnetic data for Amazonia.Connections along Greenland and Labrador were initially proposed based on the fit of geological provinces and scarse virtual geomagnetic poles.More recently, a connection through the Llano belt in Texas was proposed based on a single well dated 1.2 Ga paleopole obtained in mafic rocks from the Nova Floresta Formation. We present a series of poles obtained on sedimentary rocks of the Aguapei Group (western Matto Grosso State-Amazonian Craton) and intrusive mafic rocks, whose evolution is related to the Meso-Neoproterozoic Aguapei-Sunsas orogeny (1.3-0.9 Ga).Together with the 1.2 Ga Nova Floresta pole, they define a straight apparent polar wander path which matches the Laurentia APWP by 1.1 Ga for a connection along the (present day) Labrador region. The pole's trajectories imply a high degree of obliquity for such a collision in agreement with tectonic models put forward for the southwestern margin of Amazonia, the southeastern margin of Laurentia and the southwestern margin of Baltica.

  • 43.
    Darwesh, Ali K.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maack Rasmussen, Thorkild
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Kicks controlling techniques efficiency in term of time2017In: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 9, no 5, 482-492 p.Article in journal (Refereed)
    Abstract [en]

    Kicks are the result of under balance drilling operation. Time consumed to control the kicks will be different in depending on the controlling technique. Drilling fluid considered as a first barrier to control formation pressure and well kicks. Any advance in drilling fluids leads to more controlled operation in term of time. This paper will follow the general increasing profile of pressure before entering the reservoir. Both methods of well controlling technique; circulating techniques and non-circulating have been implemented in many oil blocks. The process of designing and casing selection, setting depth and many other issues is predominately dependent on the utilization of accurate values of formation pressure. Formation pressures used to design safe mud weights to overcome fracturing the formation and prevent well kicks. Hence the emphasis has been placed on the practical utilization of kicks pressure near the reservoir. The presented relationships will help the engineer to better understand lithological columns and reduce potential hole problems during the kick appearance. Selecting the best well controlling practical method can lead to not harming the reservoir and more production later. Changes in some drilling fluid properties have been proposed with increasing the depth without damaging the reservoir. Suggestions in relation to the casing setting point of the intermediate section are also proposed. Standard equations with proper modification for gases and safety margin have been proposed for the future drilling operation in oil fields above the reservoir.

  • 44.
    Darwesh, Ali K.
    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.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Time Optimizing near the Pay Zone2017In: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 9, no 10, 848-858 p.Article in journal (Refereed)
    Abstract [en]

    Well control techniques are used in oil and gas drilling operations to control bottom hole pressure and avoid any fluid influx from formation to the well. These techniques are highly important near the pay zone in term of time. Controlling formation fluid pressure and thereby the formations behavior in a predictable fashion will help toward more optimized environmental friendly drilling operation. Time consumed to control the formation fluid pressure will range between few hours to many days. This paper discusses hydrostatic pressure distribution and changes near the pay zone for one oil blocks in Kur- distan, in the northern part of Iraq. Obtaining homogeneous increase in some drilling fluid properties will help the engineer to better interpret sampling of the lithological columns and reduce potential hole problems and operationtime.

  • 45.
    Darwesh, Ali
    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.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Evaluation of Limestone Interval in the Drilled Surface Section of Bn-1 Oil Well2016In: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 8, no 8, 515-524 p.Article in journal (Refereed)
    Abstract [en]

    The first exploration oil well in any oil block consumes in general more time and cost than the other wells in the same block. Evaluating the drilled wells serves to improve the future operations. This paper evaluates the drilled surface section through real field data for the first exploration oil well drilled in one of the oil blocks, in Kurdistan north of Iraq. The surface section of the well was drilled with the conventional method to penetrate many different geological formations with tight intervals. Drilling efficiency and the difficulties encountered are discussed and explained using various data sources. All daily drilling reports concerning a specific interval were studied. This includes weight on bit, string rotation, mud pump flow and penetration rate. Evaluation was carried out by analyzing the used controllable drilling parameters with the formations features. Penetration of the Pila Spi formation (Middle Eocene) was the most difficult formation in the drilled section. Microsoft Office 365 Pro Plus used in making graphs and Excel tables. Evaluations showed that the conventional technology used left many negative effects, like increase in None Productive Time NPT, cost and ground water pollution. Simultaneous Casing Drilling method proposed as an alternative method for the future campaign.

  • 46. Das, U.C.
    et al.
    Parasnis, Dattatray
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Resistivity and induced polarization responses of arbitarily shaped 3-D bodies in a two-layered Earth1987In: Geophysical Prospecting, ISSN 0016-8025, E-ISSN 1365-2478, Vol. 35, no 1, 98-109 p.Article in journal (Refereed)
  • 47.
    Donadini, Fabio
    et al.
    Scripps Institution of Oceanography, La Jolla, United States of America.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Tauxe, Lisa
    Scripps Institution of Oceanography, La Jolla, United States of America.
    Paleointensity results from the 1.7 GA old hoting Gabbro, Sweden2009Conference paper (Other academic)
    Abstract [en]

    Complete text of publication follows. The Hoting Gabbro is located in the western part of the Central Svecofennian Subprovince, and dates about 1.786+-0.010 Ga. In the Hoting area, dykes intruded at around 1.6 Ga, and partly remagnetized the gabbros. Previous paleomagnetic and geochemical studies indicated that the stable characteristic remanent magnetization was acquired at about 1.7 Ga, when the slow cooling of the gabbro is taken into account. Preliminary palaeointensity studies from gabbros in the Hoting area suggested a very low field of about 5.8+-1.9 muT. Unfortunately, at that stage, only two sites out of nine yielded results. During 2008, we sampled seven sites from the Hoting area in order to perform new palaeointensity experiments. At Scripps, we applied the IZZI method on 60 specimens, and 39 yielded reliable results varying between 3 and 20 muT, and confirm the previous low results. Low field values have been associated with oxyexolution processes that might bias the palaeointensity result towards low values, and so we are currently investigating the mineralogy of the samples with SEM analyses. We will present the details of the palaeointensity and mineralogical results, and infer the evolution of the geomagnetic field during Precambrian.

  • 48.
    Donadini, Fabio
    et al.
    Institut für Geophysik, ETH Zürich.
    Elming, Sten-Åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Tauxe, Lisa
    Scripps Institution of Oceanography, University of California, San Diego.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Mineralogy.
    Paleointensity determination on a 1.786 Ga old gabbro from Hoting, Central Sweden2011In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 309, no 3-4, 234-248 p.Article in journal (Refereed)
    Abstract [en]

    Paleointensities from Precambrian rocks are rare and might be biased by remagnetization processes. Here we present new analyses of samples from a 1.786 Ga gabbro near Hoting, Central Sweden. Rock magnetic and mineralogical analyses indicate that one of the sites (site 5) may be pristine, whereas the others exhibit evidence of alteration. Characteristic remanent magnetization was determined using principal component analysis for each sample and was compared with results obtained in a previous study of Elming et al. (2009). Intensity measurements from site 5 show higher values compared to those of the other sites, suggesting that alteration processes may lead to underestimation of the field intensity. After cooling rate and anisotropy correction, the field moment at 1.786 Ga was estimated to be 25.6 ± 3.3 ZAm2 and 15.2 ± 6.1 ZAm2 from site 5 only and from all sites respectively. We consider the result from site 5 to be more accurate owing to the lack of evidence for alteration; our estimates agree well with the Proterozoic VDM values suggested by Biggin et al. (2009).

  • 49. Dyrelius, D.
    et al.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bergarters fysik1985In: Geofysik, Uppsala: Svenska fysikersamfundet , 1985Chapter in book (Other (popular science, discussion, etc.))
  • 50.
    Døssing, Arne
    et al.
    DTU Space, National Space Institute, Technical University of Denmark.
    Hopper, John R.
    Geological Survey of Denmark and Greenland (GEUS), Copenhagen.
    Olesen, Arne Vestergaard
    DTU Space, National Space Institute, Technical University of Denmark.
    Rasmussen, Thorkild Maack
    Geological Survey of Denmark and Greenland (GEUS), Copenhagen.
    Halpenny, John F.
    Natural Resources Canada, Ottawa, ON.
    New aero-gravity results from the Arctic: Linking the latest Cretaceous-early Cenozoic plate kinematics of the North Atlantic and Arctic Ocean2013In: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027, Vol. 14, no 10, 4044-4065 p.Article in journal (Refereed)
    Abstract [en]

    The tectonic history of the Arctic Ocean remains poorly resolved and highly controversial. Details regarding break up of the Lomonosov Ridge from the Barents-Kara shelf margins and the establishment of seafloor spreading in the Cenozoic Eurasia Basin are unresolved. Significantly, the plate tectonic evolution of the Mesozoic Amerasia Basin is essentially unknown. The Arctic Ocean north of Greenland is at a critical juncture that formed at the locus of a Mesozoic three-plate setting between the Lomonosov Ridge, Greenland, and North America. In addition, the area is close to the European plate, resulting in complicated interactions between all these areas that are difficult to resolve. In 2009, the 550,000 km2 LOMGRAV aero-geophysical survey produced the first collocated gravity and magnetic measurements over the area, significantly increasing the data coverage. We present an interpretation of a new free-air gravity compilation, which reveals a regionally consistent structural grain across the Lomonosov Ridge, the Ellesmere and Lincoln Sea shelves, and the Alpha Ridge. We interpret the grain as evidence of latest Cretaceous (∼80 Ma) regional extension in response to the northward propagation of Atlantic and Labrador Sea opening into the Arctic, west of Greenland. This interpretation is consistent with coincident alkaline volcanic activity evident in the borderlands of the Lincoln Sea. We further suggest that Eurekan crustal shortening contributed to the formation of the distinct Lomonosov Ridge plateau against an important fault zone north of Greenland. Our results provide new constraints for Cretaceous-Cenozoic plate reconstructions of the Arctic. Key Points Presentation of the largest aero-gravity survey acquired over the Arctic Ocean Plate tectonic link between Atlantic and Arctic spreading west of Greenland New plate reconstruction models are presented for the area north of Greenland

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