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  • 101.
    Burchardt, S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Koyi, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Strain pattern in and around anhydrite blocks sinking within a salt structures2010Conference paper (Refereed)
  • 102.
    Burchardt, Steffi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    New insights into the mechanics of sill emplacement provided by field observations of the Njardvik Sill, Northeast Iceland2008In: Journal of Volcanology and Geothermal Research, ISSN 0377-0273, E-ISSN 1872-6097, Vol. 173, no 3-4, p. 280-288Article in journal (Refereed)
    Abstract [en]

    Sills are concordant sheet-like bodies of magma. Their mechanics of emplacement is an important but still not fully understood topic. The well-exposed basaltic Njardvik Sill in the extinct Tertiary Dyrfjöll Volcano in Northeast Iceland offers exceptionally clear insights into the mechanism of sill emplacement. The sill is multiple and consists of at least 7 units (sills) all of which were emplaced along a sharp contact between a rhyolitic intrusion and adjacent basaltic lava flows. Each sill unit was supplied with magma from an inclined sheet. The contacts between the sheets and the sill units are very clear and show that the sill units are much thicker than their feeder sheets. Since the Njardvik Sill consists of separate units, it obviously did not evolve into a homogeneous magma body. Nevertheless, the abrupt change in dip and thickness from inclined sheets to horizontal sills at this particular locality indicates that the earlier sills were influencing the stress field in their vicinity during the subsequent sheet injections. The local stresses around the newly formed sill units forced each of the subsequently injected sheets to change into sills. The Njardvik Sill can be followed laterally in a coastal section for 140 m until it ends abruptly at a fault that cuts the sill. Using these field observations as a basis, a numerical model shows how an inclined sheet opens up the contact between the felsic intrusion and the basaltic lava pile, along which the sill emplacement takes place. The results suggest that sill emplacement is primarily the result of stress rotation at contacts between layers of contrasting mechanical properties. There, the orientation of the maximum principal compressive stress σ1 is horizontal. Hence, such contacts can represent interfaces along which sill emplacement is encouraged. Once a sill has been emplaced, it extends the stress field with a horizontal orientation of σ1. Consequently, inclined sheets and dykes injected near the sill will be deflected into sills. The injection frequency of further sill units controls if the sill can grow into a larger magma body by mixing of the newly supplied with the initially injected magma. In case of the Njardvik Sill, the injection frequency was low, so subsequently emplaced sill units can be distinguished.

  • 103.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Galland, O.
    Hallot, E.
    Mourgues, R
    Dykes versus cone sheets in volcanic systems– two sides of the same coin?2013Conference paper (Refereed)
    Abstract [en]

    Subvertical dykes and inclined cone-sheets represent the two main types of magmatic sheet intrusions in volcanic systems. Despite their coexistence in the same volcanoes and seemingly common source, the intrusion dynamics of dykes and cone sheets has often been addressed through distinct models, such that we cannot predict under which condition either of the two forms. We present a series of scaled laboratory experiments that reproduce the emplacement of sheet intrusions into the brittle crust. A cohesive silica flour was used as model crust, and some vegetable oil as a low viscosity magma. The experiments comprised the injection of the oil at constant flow rate into the flour through an inlet. Through 46 experiments, we varied independently the depth (h) and the diameter (d) of the inlet, as well as the injection velocity (v). Our experiments produced sheet intrusions exhibiting either dyke or cone sheet morphologies. Dykes were characterized by a sub-vertical, slightly elliptic shape that often split into two branches to form a "boat"- shaped intrusion at very shallow depths. Cone sheets resembled inverted cones with rims that flattened from depth to the surface. Some of experiments produced hybrid intrusions with a dyke-like lower part feeding complex conical sheet intrusion higher up. Combining our systematic parametric study with a dimensional analysis, we show that the formation of dykes and cone sheets is controlled by two dimensionless parameters. One is geometrical ( 1 = h=d) and the other is dynamical ( 2 = v=Cd), where is the viscosity of the vegetable oil and C the flour cohesion. In a plot of 1 vs. 2, the experiments organise into two distinct fields, separated by a transition line that can be described by a power law. The hybrid intrusions produced in our experiments fall along the transition line in between the dyke and cone-sheet regimes. These results show that at high 1 values, dykes are favoured and originate from magma sources that are relatively deep in relation to their size. In contrast, cone sheets preferentially form from shallow sources and are favoured at large 2 values, i.e. for fast injection rates. These results compare fairly well to relevant geological data from magmatic sheet intrusions in various geological settings. Cone sheet and dyke emplacement can thus be explained by a single, unified mechanical model for sheet intrusions.

  • 104.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Koyi, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    The influence of viscosity contrasts on the strain pattern in and around anhydrite blocks sinking within a salt structure2010Conference paper (Refereed)
  • 105.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Schmeling, Harro
    Strain pattern within and around denser blocks sinking within Newtonian salt structures2011In: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 33, no 2, p. 145-153Article in journal (Refereed)
    Abstract [en]

    Blocks of dense material, such as anhydrite, entrained in salt structures have been proposed to sink through their host material. Here, we present the results of numerical models that analyse strain patterns within and around initially horizontal anhydrite blocks (viscosity 10(21) Pa s) sinking through Newtonian salt with a viscosity of 10(17) Pa s. In addition, the influence of the block aspect ratio (thickness to width ratio; AR) is analysed. The model results show that the blocks are folded and marginally sheared to approach streamlined shapes. The effectiveness of this process is a function of the block AR and influences the sinking velocity of the blocks significantly. Final sinking velocities are in the range of ca. 1.7 -3.1 mm/a. Around the block in the salt, an array of folds and shear zones develops during block descent, the structure of which is principally the same independent of the block AR. However, the size and development of the structures is a function of the block size. Monitoring of strain magnitudes demonstrates that the salt is subject to extremely high strains with successively changing stress regimes, resulting in closely-spaced zones of high adjacent to low strain. In comparison to the anhydrite blocks, strain magnitudes in the salt are up to one order of magnitude higher.

  • 106.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Schmeling, Harro
    The influence of viscosity contrasts on the strain pattern and magnitude within and around dense blocks sinking through Newtonian salt2012In: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 35, p. 102-116Article in journal (Refereed)
    Abstract [en]

    Dense inclusions in salt cover a wide range of materials and therefore material properties, depending on their origin. We have modelled the deformation associated with gravity-driven sinking of horizontal, initially rectangular blocks of dense material through Newtonian salt. Our two-dimensional Finite Differences models analyse the influence and interaction of two parameters: (1) the size, i.e. the aspect ratio (AR), of the block and (2) the viscosity contrast between the salt and the more viscous block over four orders of magnitude. The results demonstrate that during gravity-driven sinking the blocks are folded and sheared. The strain magnitude within the block increases with increasing block AR and decreases with increasing viscosity contrast. Sinking velocities of the blocks are in the range of <2 and >6 mm a−1 and are a function of block and salt deformation that depend on the block mass and AR, as well as on the viscosity contrast. Salt deformation is characterised by the development of an array of characteristic structures that include folds and shear zones, as well as a zone characterised by extreme vertical stretching above the block, termed entrainment channel. Strain in the salt is locally more than two orders of magnitude higher than in the block and increases with increasing block AR and viscosity contrast. Salt deformation is distributed in closely-spaced high- and low-strain zones concentrated in the block vicinity and the entrainment channel.

  • 107.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Tanner, David C.
    Leibniz Institute for Applied Geophysics, Hannover, Germany.
    Troll, Valentin R
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Krumbholz, Michael
    Geoscience Center, Georg-August University Göttingen, Göttingen, Germany.
    Gustafsson, Ludvik E.
    Association of Local Authorities in Iceland, Reykjavik, Iceland.
    Three-dimensional geometry of concentric intrusive sheet swarms in the Geitafell and the Dyrfjoll volcanoes, eastern Iceland2011In: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027, Vol. 12, no 7, p. Q0AB09-Article in journal (Refereed)
    Abstract [en]

    Sheet intrusions (inclined sheets and dykes) in the deeply eroded volcanoes of Geitafell and Dyrfjoll, eastern Iceland, were studied at the surface to identify the location, depth, and size of their magmatic source(s). For this purpose, the measured orientations of inclined sheets were projected in three dimensions to produce models of sheet swarm geometries. For the Geitafell Volcano, the majority of sheets converge toward a common focal area with a diameter of at least 4 to 7 km, the location of which coincides with several gabbro bodies exposed at the surface. Assuming that these gabbros represent part of the magma chamber feeding the inclined sheets, a source depth of 2 to 4 km below the paleoland surface is derived. A second, younger swarm of steeply dipping sheets crosscuts this gabbro and members of the first swarm. The source of this second swarm is estimated to be located to the SE of the source of Swarm 1, below the present-day level of exposure and deeper than the source of the first swarm. For the Dyrfjoll Volcano, we show that the sheets can be divided into seven different subsets, three of which can be interpreted as swarms. The most prominent swarm, the Njardvik Sheet Swarm, converges toward a several kilometers wide area in the Njardvik Valley at a depth of 1.5 to 4 km below the paleoland surface. Two additional magmatic sources are postulated to be located to the northeast and southwest of the main source. Crosscutting relationships indicate contemporaneous, as well as successive activity of different magma chambers, but without a resolvable spatial trend. The Dyrfjoll Volcano is thus part of a complex volcanic cluster that extends far beyond the study area and can serve as fossil analog for nested volcanoes such as Askja, whereas in Geitafell, the sheet swarms seem to have originated from a single focus at one time, thus defining a single central volcanic complex, such as Krafla Volcano.

  • 108.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Tanner, David C.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Krumbholz, Michael
    Gustafsson, Ludvik E.
    Three-dimensional geometry of concentric intrusive sheet swarms in the Geitafell and the Dyrfjöll Volcanoes, Eastern Iceland2011In: Geochemistry Geophysics Geosystems, ISSN 1525-2027, E-ISSN 1525-2027, Vol. 12, no 7, p. Q0AB09-Article in journal (Refereed)
    Abstract [en]

    Sheet intrusions (inclined sheets and dykes) in the deeply eroded volcanoes of Geitafell and Dyrfjöll,eastern Iceland, were studied at the surface to identify the location, depth, and size of their magmaticsource(s). For this purpose, the measured orientations of inclined sheets were projected in three dimensionsto produce models of sheet swarm geometries. For the Geitafell Volcano, the majority of sheetsconverge toward a common focal area with a diameter of at least 4 to 7 km, the location of which coincideswith several gabbro bodies exposed at the surface. Assuming that these gabbros represent part of the magmachamber feeding the inclined sheets, a source depth of 2 to 4 km below the paleoland surface is derived.A second, younger swarm of steeply dipping sheets crosscuts this gabbro and members of the first swarm.The source of this second swarm is estimated to be located to the SE of the source of Swarm 1, below thepresent‐day level of exposure and deeper than the source of the first swarm. For the Dyrfjöll Volcano,we show that the sheets can be divided into seven different subsets, three of which can be interpretedas swarms. The most prominent swarm, the Njardvik Sheet Swarm, converges toward a several kilometerswide area in the Njardvik Valley at a depth of 1.5 to 4 km below the paleoland surface. Two additionalmagmatic sources are postulated to be located to the northeast and southwest of the main source. Crosscuttingrelationships indicate contemporaneous, as well as successive activity of different magma chambers,but without a resolvable spatial trend. The Dyrfjöll Volcano is thus part of a complex volcanic cluster thatextends far beyond the study area and can serve as fossil analog for nested volcanoes such as Askja, whereasin Geitafell, the sheet swarms seem to have originated from a single focus at one time, thus defining a singlecentral volcanic complex, such as Krafla Volcano.

  • 109.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Tanner, David Colin
    Krumbholz, Michael
    Mode of emplacement of the Slaufrudalur Pluton, Southeast Iceland inferred from three-dimensional GPS mapping and model building2010In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 480, p. 232-240Article in journal (Refereed)
  • 110.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology. Univ Gottingen, Geosci Ctr, D-37077 Gottingen, Germany.
    Tanner, D.C.
    Univ Gottingen, Geosci Ctr, D-37077 Gottingen, Germany.
    Krumbholz, Michael
    Univ Gottingen, Geosci Ctr, D-37077 Gottingen, Germany; Leibniz Inst Appl Geophys, D-30655 Hannover, Germany.
    The Slaufrudar pluton, southeast Iceland: An example of shallow magma emplacement by coupled cauldron subsidence and magmatic stoping2011In: Geological Society of America Bulletin, ISSN 0016-7606, E-ISSN 1943-2674, Vol. 124, no 1-2, p. 213-227Article in journal (Refereed)
    Abstract [en]

    The Tertiary Slaufrudalur pluton is the largest granitic intrusion exposed in Iceland. Five glacial valleys cut through the uppermost 900 m of the pluton, exposing spectacular sections through its roof, walls, and interior. The wall contacts are subvertical and sharp. Only in the northeast and southwest is the wall contact characterized by brittle faulting. The pluton roof is smooth at map scale, so that the overall cross-sectional shape of the pluton and its internal layering indicate emplacement by incremental floor sinking through cauldron subsidence. A pronounced elongation of the pluton, parallel to the trend of regional fissure swarms, and its angular shape in map view indicate strong tectonic control on horizontal ring-fault propagation, whereas faulted wall contacts represent step-over structures between the earlier-formed ring faults. On outcrop scale, the roof contact exhibits numerous steps, faults, and apophyses associated with conjugate fracture sets that are parallel and perpendicular to the strike of the length of the pluton. These structures were presumably formed by sequential inflation and deflation of the pluton during episodic magma intrusion and therefore are closely coupled to cauldron subsidence. As a result of roof fracturing and magma injection along the fractures, roof material is found partly or completely detached within the granite. The Slaufrudalur pluton therefore provides new insight into the coupling of the emplacement mechanisms of cauldron subsidence and magmatic stoping in the upper crust.

  • 111.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Mathieu, L.
    Donaldson, C.H.
    3 or 1? 3D cone-sheet architecture provides insight into the centre(s) of Ardnamurchan2013Conference paper (Refereed)
    Abstract [en]

    The Palaeogene Ardnamurchan igneous centre, NW Scotland, was a defining place for the development of classic concepts of cone-sheet, ring-dyke, and dyke emplacement. It holds therefore an iconic status among geologists and has influenced our understanding of subvolcanic structures fundamentally. We have used historic geological maps ofArdnamurchan to project the underlying three-dimensional (3D) cone-sheet structure. The results illustrate that a single elongate magma chamber likely acted as the source of the cone-sheet swarms, instead of the traditionally accepted model of three successive centres. Our finding is moreover consistent with recent sedimentological, geochemical, geophysical, and structural investigations that all support a ridge-like morphology for the Ardnamurchan volcano. This challenges the static model of cone-sheet emplacement that involves successive but independent centres in favour of a dynamical one that involves a single, but elongate magma chamber that is progressively evolving. The latter model reduces the lifetime required for the Ardnamurchan centre considerably.

  • 112.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Mathieu, Lucie
    Emeleus, Henry C.
    Donaldson, Colin H.
    Ardnamurchan 3D cone-sheet architecture explained by a single elongate magma chamber2013In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 3, p. 2891-Article in journal (Refereed)
    Abstract [en]

    The Palaeogene Ardnamurchan central igneous complex, NW Scotland, was a defining place for the development of the classic concepts of cone-sheet and ring-dyke emplacement and has thus fundamentally influenced our thinking on subvolcanic structures. We have used the available structural information on Ardnamurchan to project the underlying three-dimensional (3D) cone-sheet structure. Here we show that a single elongate magma chamber likely acted as the source of the cone-sheet swarm(s) instead of the traditionally accepted model of three successive centres. This proposal is supported by the ridge-like morphology of the Ardnamurchan volcano and is consistent with the depth and elongation of the gravity anomaly underlying the peninsula. Our model challenges the traditional model of cone-sheet emplacement at Ardnamurchan that involves successive but independent centres in favour of a more dynamical one that involves a single, but elongate and progressively evolving magma chamber system.

  • 113.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Schmeling, Harro
    Goethe Univ Frankfurt, Fac Earth Sci, Altenhoferallee 1, D-60438 Frankfurt, Germany..
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Blythe, Lara
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Erupted frothy xenoliths may explain lack of country-rock fragments in plutons2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 34566Article in journal (Refereed)
    Abstract [en]

    Magmatic stoping is discussed to be a main mechanism of magma emplacement. As a consequence of stoping, abundant country-rock fragments should occur within, and at the bottom of, magma reservoirs as "xenolith graveyards", or become assimilated. However, the common absence of sufficient amounts of both xenoliths and crustal contamination have led to intense controversy about the efficiency of stoping. Here, we present new evidence that may explain the absence of abundant country-rock fragments in plutons. We report on vesiculated crustal xenoliths in volcanic rocks that experienced devolatilisation during heating and partial melting when entrained in magma. We hypothesise that the consequential inflation and density decrease of the xenoliths allowed them to rise and become erupted instead of being preserved in the plutonic record. Our thermomechanical simulations of this process demonstrate that early-stage xenolith sinking can be followed by the rise of a heated, partially-molten xenolith towards the top of the reservoir. There, remnants may disintegrate and mix with resident magma or erupt. Shallow-crustal plutons emplaced into hydrous country rocks may therefore not necessarily contain evidence of the true amount of magmatic stoping during their emplacement. Further studies are needed to quantify the importance of frothy xenolith in removing stoped material.

  • 114.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Troll, Valentin R
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Schmeling, Harro
    Faculty of Earth Sciences, J. W. Goethe Universität, Altenhöferallee 1, 60438 Frankfurt am Main, Germany.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Blythe, Lara
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Sink or swim: The fate of crustal xenoliths in shallow magma chambersIn: Article in journal (Other academic)
  • 115.
    Burchardt, Steffi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Walter, Thomas
    Propagation, linkage, and interaction of caldera ring-faults: Comparison between analogue experiments and caldera collapse at Miyakejima, Japan, in 20012009In: Bulletin of Volcanology, ISSN 0258-8900, E-ISSN 1432-0819, Vol. 72, no 3, p. 297-308Article in journal (Refereed)
  • 116. Burliga, S.
    et al.
    Koyi, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Chemia, Z.
    Analogue and numerical modelling of salt supply to a diapiric structure rising above an active basement fault2012In: Geological Society of London, Special Publication, Vol. 363, p. 395-408Article in journal (Refereed)
    Abstract [en]

    Salt diapirs preferably rise above basement faults in extensional basins. A series of analogue and numerical models were developed in order to assess the supply of salt from the footwall and hanging wall to a diapir and to study the influence of basin inversion on the diapir development. The modelling scenario was based on the Kłodawa Salt Structure evolution (central Poland). The experiments show that the ductile material derived from the footwall constitutes the dominant portion of the diapir developed due to model extension, and this material occurs both in the footwall and hanging wall parts of the diapir. Shortening of the analogue models resulted in thinning of the diapir and shifting its stem onto the footwall. Ductile material become redistributed inside the diapir, however footwall material still prevails in the diapir structure. Results from the numerical models show that the magnitude of the basement fault governs the amount of salt supply to a diapir across the fault and that there is a differential salt supply from the hanging wall and footwall with time.

  • 117. Burliga, S.
    et al.
    Koyi, H.A
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Solid Earth Geology. berggrundsgeologi.
    Krzywiec, P.
    Gutowski, J.
    Influence of diapisrism on faulting in inverted basin infill. Analogue modelling results.2007In: Deformation in the Desert, Geological Society of Australia, 2007, p. 59-Conference paper (Other scientific)
  • 118. Burliga, S.
    et al.
    Koyi, H.A
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Solid Earth Geology. Berggrundsgeologi.
    krzywiec, P.
    Gutowski, J.
    Prediction of future evolution of the Klodawa Salt Structure (Poland) based on geological record and analogue modelling data.2007In: 6th Conference on the mechanical behavior of salt (Hannover): http://www.bgr.bund.de/cln_030/nn_895252/EN/Themen/Geotechnik/Downloads/Abstracts__saltmech6,templateId=raw,property=publicationFile.pdf/Abstracts_saltmech6.pdf, 2007Conference paper (Other scientific)
  • 119. Burliga, Stanislaw
    et al.
    Koyi, Hemin A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Krzywiec, Piotr
    Modelling cover deformation and decoupling during inversion, using the Mid-Polish Trough as a case study2012In: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 42, p. 62-73Article in journal (Refereed)
    Abstract [en]

    Seismic sections across the NW part of the Polish Basin show that thrust faults developed in the sedimentary units above the Zechstein evaporite layer during basin inversion. These cover thrust faults have formed above the basement footwall. Based on the evolution of the basin, a series of scaled analogue models was carried out to study interaction between a basement fault and cover sediments during basin extension and inversion. During model extension, a set of normal faults originated in the sand cover above the basement fault area. The distribution and geometry of these faults were dependent on the thickness of a ductile layer and pre-extension sand layer, synkinematic deposition, the amount of model extension, as well as on the presence of a ductile layer between the cover and basement. Footwall cover was faulted away from the basement only in cases where a large amount of model extension and hanging-wall subsidence were not balanced by synkinematic deposition. Model inversion reactivated major cover faults located above the basement fault tip as reverse faults, whereas other extensional faults were either rotated or activated only in their upper segments, evolving into sub-horizontal thrusts. New normal or reverse faults originated in the footwall cover in models which contained a very thin pre-extension sand layer above the ductile layer. This was also the case in the highly extended and shortened model in which synkinematic hanging-wall subsidence was not balanced by sand deposition during model extension. Model results show that inversion along the basement fault results in shortening of the cover units and formation of thrust faults. This scenario happens only when the cover units are decoupled from the basement by a ductile layer. Given this, we argue that the thrusts in the sedimentary infill of the Polish Basin, which are decoupled from the basement tectonics by Zechstein evaporites, developed due to the inversion of the basement faults during the Late Cretaceous-Early Tertiary. (C) 2012 Elsevier Ltd. All rights reserved.

  • 120. Byrne, P. K.
    et al.
    Holohan, E. P.
    Kervyn, M.
    de Vries, B. van Wyk
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Murray, J. B.
    A sagging-spreading continuum of large volcano structure2013In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 41, no 3, p. 339-342Article in journal (Refereed)
    Abstract [en]

    Gravitational deformation strongly influences the structure and eruptive behavior of large volcanoes. Using scaled analog models, we characterize a range of structural architectures produced by volcano sagging and volcano spreading. These arise from the interplay of variable basement rigidity and volcano-basement (de-)coupling. From comparison to volcanoes on Earth (La Reunion and Hawaii) and Mars (Elysium and Olympus Montes), the models highlight a structural continuum in which large volcanoes throughout the Solar System lie.

  • 121. Byrne, Paul K.
    et al.
    de Vries, Benjamin van Wyk
    Murray, John B.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    The geometry of volcano flank terraces on Mars2009In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 281, no 1-2, p. 1-13Article in journal (Refereed)
    Abstract [en]

    Flank terraces are subtle, expansive structures on the slopes of many large Martian shield volcanoes. Several terrace formation hypotheses - including self-loading, lithospheric flexure, magma chamber tumescence, volcano spreading, and shallow gravitational slumping - have been suggested. Terraces are not readily visible on photogeological data; consequently, terrace geometry has not yet been comprehensively described. Terrace provenance, therefore, is poorly understood. We used three-dimensional Mars Orbiter Laser Altimeter (MOLA) data to characterise the geometry of these elusive structures, with a view to   understanding better the role that flank terraces play in the tectonic evolution of volcanoes on Mars. Terraces have a broad, convex-upward profile in section, and a systematic "fish scale" imbricate stacking pattern in plan. They are visible at all elevations, on at least nine   disparate Martian volcanoes. Terrace-like features also occur on three shield volcanoes on Earth, an observation not recorded before. Analysis of a suite of morphometric parameters for flank terraces showed that they are scale-invariant. with similar proportions to thrust faults on Earth. We compared predicted formation geometries to our terrace observations, and found that only lithospheric flexure can fully account for the morphology, distribution, and timing of terraces. As a volcano flexes into the lithosphere beneath it, its upper surface will  experience a net reduction in area, resulting in the formation of outward verging thrusts. We conclude, therefore, that flank terraces are fundamental volcanotectonic structures, that they are the surface expressions of thrust faults, probably formed by lithospheric flexure. and that they are not restricted to Mars.

  • 122. Byrne, P.K.
    et al.
    Holohan, E.P.
    Kervyn, M.
    van Wyk de Vries, B.
    Murray, J.B.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    A Sagging-Spreading Continuum for the Structure of Large Volcanoes on Terrestrial Planets2011Conference paper (Other academic)
  • 123. Byrne, P.K.
    et al.
    Van Wyk de Vries, B.
    Murray, J.B.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    A Volcanotectonic Survey of Ascraeus Mons, Mars2011In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 117Article in journal (Refereed)
    Abstract [en]

    Ascraeus Mons is one of the largest volcanoes on Mars. It is replete with well-preserved features that can be used to understand its volcanotectonic evolution. Previous studies of this volcano focused on specific features, and were limited by the quality and coverage of contemporary data. Our objective is to review and enhance the existing developmental model for Ascraeus by considering all endogenic surface features on the volcano. We surveyed the volcano's caldera complex, flank terraces, pit structures, sinuous rilles, arcuate grabens, and small vents. We report the spatial and temporal distributions of these features, appraise their proposed formation mechanisms in light of our mapping results, and propose a detailed geological history for Ascraeus Mons. An initial shield-building phase was followed by the formation of a summit caldera complex and small parasitic cones, while compression due to flexure of the supporting basement led to extensive terracing of the shield flanks. An eruptive hiatus followed, ending with the construction of expansive rift aprons to the northeast and southwest. Against later, extensive flank resurfacing in the late Amazonian, continued flexure formed arcuate grabens concentric to the edifice. Localized eruption and surface flow of a fluid agent (lava and/or water) from within the volcano then produced a population of rilles on the lower flanks. Finally, in a change of flank tectonic regime from compression to extension, pit crater chains and troughs developed on the main shield and rift aprons, eventually coalescing to form large embayments at the northeast and southwest base of the volcano.

  • 124. Caja, M.
    et al.
    Marfil, R.
    Garcia, D.
    Remacha, W.E.
    Morad, Sadoon
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Mansurbeg, Howri
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Amorosi, A.
    Martınez-Calvonn, C.
    Lahoz-Beltrá, R.
    Provenance of  siliciclastic and hybrid turbiditic arenites of the Eocene Hecho Group,Spanish Pyrenees: implications for the tectonic evolution of a foreland basin2010In: Basin Research, ISSN 0950-091X, E-ISSN 1365-2117, Vol. 22, no 2, p. 157-180Article in journal (Refereed)
    Abstract [en]

    The Eocene Hecho Group turbidite system of the Aínsa-Jaca foreland Basin (southcentral Pyrenees) provides an excellent opportunity to constrain compositional variations within the context of spatial and temporal distribution of source rocks during tectonostratigraphic evolution of foreland basins. The complex tectonic setting necessitated the use of petrographic, geochemical and multivariate statistical techniques to achieve this goal. The turbidite deposits comprise four unconformity-bounded tectonostratigraphic units (TSU), consisting of quartz-rich and feldspar-poor sandstones, calclithites rich in extrabasinal carbonates and hybrid arenites dominated by intrabasinal carbonates. The sandstones occur exclusively in TSU-2, whereas calclithites and hybrid arenites occur in the overlying TSU-3, TSU-4 and TSU-5. The calclithites were deposited at the base of each TSU and hybrid arenites in the uppermost parts. Extrabasinal carbonate sources were derived from the fold-and-thrust belt (mainly Cretaceous and Palaeocene limestones). Conversely, intrabasinal carbonate grains were sourced from foramol shelf carbonate factories. This compositional trend is attributed to alternating episodes of uplift and thrust propagation (siliciclastic and extrabasinal carbonates supplies) and subsequent episodes of development of carbonate platforms supplying intrabasinal detrital grains. The quartz-rich and feldspar-poor composition of the sandstones suggests derivation from intensely weathered cratonic basement rocks during the initial fill of the foreland basin. Successive sediments (calclithites and hybrid arenites) were derived from older uplifted basement rocks (feldspar-rich and, to some extent, rock fragments-rich sandstones), thrust-and-fold belt deposits and from coeval carbonate platforms developed at the basin margins. This study demonstrates that the integration of tectono-stratigraphy, petrology and geochemistry of arenites provides a powerful tool to constrain the spatial and temporal variation in provenance during the tectonic evolution of foreland basins.

  • 125. Carracedo, J. C.
    et al.
    Fernandez-Turiel, J. L.
    Gimeno, D.
    Guillou, H.
    Kluegel, A.
    Krastel, S.
    Paris, R.
    Perez-Torrado, F. J.
    Rodriguez-Badiola, E.
    Rodriguez-Gonzalez, A.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Walter, T. R.
    Wiesmaier, S.
    Comment on "The distribution of basaltic volcanism on Tenerife, Canary Islands: Implications on the origin and dynamics of the rift systems" by A. Geyer and J. Marti. Tectonophysics 483 (2010) 310-3262011In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 503, no 3-4, p. 239-241Article in journal (Other academic)
  • 126. Carracedo, J. C.
    et al.
    Guillou, H.
    Nomade, S.
    Rodriguez-Badiola, E.
    Perez-Torrado, F. J.
    Rodriguez-Gonzalez, A.
    Paris, R.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Wiesmaier, S.
    Delcamp, A.
    Fernandez-Turiel, J. L.
    Evolution of ocean-island rifts: The northeast rift zone of Tenerife, Canary Islands2011In: Geological Society of America Bulletin, ISSN 0016-7606, E-ISSN 1943-2674, Vol. 123, no 3-4, p. 562-584Article in journal (Refereed)
    Abstract [en]

    The northeast rift zone of Tenerife presents a superb opportunity to study the entire cycle of activity of an oceanic rift zone. Field geology, isotopic dating, and magnetic stratigraphy provide a reliable temporal and spatial framework for the evolution of the NE rift zone, which includes a period of very fast growth toward instability (between ca. 1.1 and 0.83 Ma) followed by three successive large landslides: the Micheque and Guimar collapses, which occurred approximately contemporaneously at ca. 830 ka and on either side of the rift, and the La Orotava landslide (between 690 +/- 10 and 566 +/- 13 ka). Our observations suggest that Canarian rift zones show similar patterns of development, which often includes overgrowth, instability, and lateral collapses. Collapses of the rift flanks disrupt established fissural feeding systems, favoring magma ascent and shallow emplacement, which in turn leads to magma differentiation and intermediate to felsic nested eruptions. Rifts and their collapses may therefore act as an important factor in providing architectural and petrological variability to oceanic volcanoes. Conversely, the presence of substantial felsic volcanism in rift settings may indicate the presence of earlier landslide scars, even if concealed by postcollapse volcanism. Comparative analysis of the main rifts in the Canary Islands outlines this general evolutionary pattern: (1) growth of an increasingly high and steep ridge by concentrated basaltic fissure eruptions; (2) flank collapse and catastrophic disruption of the established feeder system of the rift; (3) postcollapse centralized nested volcanism, commonly evolving from initially ultramafic-mafic to terminal felsic compositions (trachytes, phonolites); and (4) progressive decline of nested eruptive activity.

  • 127. Carracedo, J.C.
    et al.
    Guillou, H.
    Badiola, E. Rodriguez,
    Perez-Torrado, F.J.
    Gonzalez, A. Rodriguez
    Paris, R.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Wiesmaier, S.
    Delcamp, A.
    Rernandez-Turiel, J.L
    The NE Rift of Tenerife: towards a model on the origin and evolution of ocean island rifts2009In: Estudios Geologicos, Vol. 65, no 1, p. 5-47Article in journal (Refereed)
    Abstract [en]

    The NE Rift of Tenerife is an excellent example of a persistent, recurrent rift, providing important evidence of the origin and dynamics   of these major volcanic features. The rift developed in three  successive, intense and relatively short eruptive stages (a few hundred   ka), separated by longer periods of quiescence or reduced activity: A  Miocene stage (7266 +/- 156 ka), apparently extending the central Miocene shield of Tenerife towards the Anaga massif; an Upper Pliocene   stage (2710 +/- 58 ka) and the latest stage, with the main eruptive   phase in the Pleistocene. Detailed geological (GIS) mapping, geomagnetic reversal mapping and stratigraphic correlation, and radioisotopic (K/Ar) dating of volcanic   formations allowed the reconstruction of the latest period of rift   activity. In the early phases of this stage the majority of the   eruptions grouped tightly along the axis of the rift and show reverse polarity (corresponding to the Matuyama chron). Dykes are of normal and   reverse polarities. In the final phase of activity, eruptions are more   disperse and lavas and dykes are consistently of normal polarity   (Brunhes chron). Volcanic units of normal polarity crossed by dykes of   normal and reverse polarities yield ages apparently compatible with   normal subchrons (M-B Precursor and Jaramillo) in the Upper Matuyama   chron. Three lateral collapses successively mass-wasted the rift: The   Micheque collapse, completely concealed by subsequent nested volcanism,   and the Guimar and La Orotava collapses, that are only partially   filled. Time occurrence of collapses in the NE rift apparently   coincides with glacial stages, suggesting that giant landslides may be   finally triggered by sea level changes during glaciations. Pre-collapse   and nested volcanism is predominantly basaltic, except in the Micheque   collapse, where magmas evolved towards intermediate and felsic   (trachytic) compositions.   Rifts in the Canary Islands are long-lasting, recurrent features,   probably related to primordial, plume-related fractures acting   throughout the entire growth of the islands. Basaltic volcanism forms   the bulk of the islands and rift zones. However, collapses of the   flanks of the rifts disrupt their established fissural feeding system,   frequently favouring magma accumulation and residence at shallow   emplacements, leading to differentiation of magmas, and intermediate to felsic nested eruptions. Rifts and their collapse may therefore act as an important factor in providing petrological variability to oceanic   volcanoes. Conversely, the possibility exists that the presence of  important felsic volcanism may indicate lateral collapses in oceanic shields and ridge-like volcanoes, even if they are concealed by post-collapse volcanism or partially mass-wasted by erosion.

  • 128.
    Carracedo, J.C.
    et al.
    University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
    Pérez-Torrado, F.
    University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
    Rodríguez-González, A.
    University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
    Klügel, A.
    Universität Bremen, Bremen, Germany.
    Troll, Valentin R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Wiesmeier, S.
    Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich, Germany.
    The Ongoing Volcanic Eruption of El Hierro, Canary Islands2012In: Transaction of the American Geophysical Union, EOS, Vol. 93, p. 89-90Article in journal (Other academic)
    Abstract [en]

    El Hierro, the youngest of the Canary Islands (Spain), is no stranger to hazards associated with volcanic activity or to efforts to minimize the effects of these hazards on local communities. As early as 1793, administrative records of El Hierro indicate that a swarm of earthquakes was felt by locals; fearing a greater volcanic catastrophe, the first evacuation plan of an entire island in the history of the Canaries was prepared. The 1793 eruption was probably submarine with no appreciable consequences other than that the earthquakes were felt [Carracedo, 2008]; over the next roughly 215 years the island was seismically quiet. Yet seismic and volcanic activity are expected on this youngest Canary Island due to its being directly above the presumed location of the Canary Island hot spot, a mantle plume that feeds upwelling magma just under the surface, similar to the Hawaiian Islands. Because of this known geologic activity, the Spanish Instituto Geográfco Nacional (IGN) has managed geophysical monitoring of the island since the beginning of the 1990s.

  • 129.
    Carracedo, Juan Carlos
    et al.
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Rodriguez-Gonzalez, Alejandro
    Pérez-Torrado, Francisco José
    Departamento de Física-Geología, Universidad de Las Palmas de Gran Canaria, 35017 Las Palmas de Gran Canaria, Spain.
    Fernandez-Turiel, J-L.
    Institute of Earth Sciences Jaume Almera, ICTJA-CSIC, Barcelona, Spain.
    Paris, Raphaël
    Université Blaise Pascal, UMR 6524, Clermont-Ferrand & CNRS, France.
    Rodríguez-Badiola, E.
    Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain.
    Pestana-Pérez, G.
    Consejería de Agricultura, Ganadería, Pesca y Alimentación, Gobierno de Canarias, Spain.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Wiesmaier, Sebastian
    Departamento de Física (GEOVOL), Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary, Islands, Spain.
    Geological Hazards in the Teide Volcanic Complex2013In: Teide Volcano: Geology and Eruptions of a Highly Differentiated Oceanic Stratovolcano, Springer Berlin/Heidelberg, 2013, p. 249-272Chapter in book (Refereed)
    Abstract [en]

    The island of Tenerife displays contrasted densities of population, from the densely occupied coastal zones (including tourist resorts, airport, energy facilities, etc.) to the sparsely populated forests and mountainous highlands, where most of the recent volcanic events are located. Considering the low frequency of historical eruptions (compared to Hawaii or Reunion Island for example), the assessment of geological hazards must also rely on the analysis and interpretation of prehistorical events, going back to at least the Late Quaternary. In this chapter, we review the hazards related to Teide’s volcanism, but also those from increased seismicity and from slope instability. We discuss the origin of low magnitude earthquakes, and particularly the 2004 episode of unrest. New estimates on cumulative volumes for resurfacing by lava flows during the last few thousand years are provided to serve as a tool for building a lava flow hazard map of Tenerife. Hazards related to explosive activity are also considered and although possible, with phreatomagmatic eruptions being the most likely style anticipated, explosive events are of relatively low probability at Teide in the near future.

  • 130.
    Carracedo, Juan Carlos
    et al.
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    From Myth to Science: The Contribution of Mount Teide to the Advancement of Volcanology2013In: Teide Volcano: Geology and eruptions of a highly differentiated oceanic stratovolcano, Springer Berlin/Heidelberg, 2013, p. 1-21Chapter in book (Refereed)
    Abstract [en]

    This chapter outlines the progress of geological research into the origin and evolution of the Teide Volcanic Complex within the framework of Tenerife Island, the Canary Islands, and oceanic volcanism in general. Initially considered to relate to either the entrance to ‘Hell’ or to mythical Atlantis, for von Buch, von Humboldt, Lyell and the other great eighteenth and nineteenth century naturalists Teide eventually helped to shape a new, and at that time revolutionary concept; the origin of volcanic rocks from solidified magma. This school of thought slowly cast aside Neptunism and removed some of the last barriers for the development of modern Geology and Volcanology as the sciences we know today. Despite the volcanic nature of the Canaries having been already recognised by the twentieth century, modern geological understanding of the archipelago progressed most significantly with the advent of plate tectonics. While some authors still maintain a link between the Canaries and the Atlas tectonic regime (see also Chap.​ 2), geological research truly advanced in the Canaries through comparison with hotspot-derived archipelagos, particularly the Hawaiian Islands. This approach, initiated in the 1970s, provided a breakthrough in the understanding of Canary volcanism, demonstrating Tenerife and Teide to be one of the world’s most interesting, complex and to many, one of the most iconic of oceanic volcanoes.

  • 131.
    Carracedo, Juan Carlos
    et al.
    Estación Volcanológica de Canarias, IPNA-Consejo Superior de Investigaciones Científicas (CSIC), La Laguna, 38206, Tenerife, Spain.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Structural and Geological Elements of Teide Volcanic Complex: Rift Zones and Gravitational Collapses2013In: Teide Volcano: Geology and eruptions of a highly differentiated oceanic stratovolcano, Springer, 2013, p. 57-74Chapter in book (Refereed)
    Abstract [en]

    Initially recognised in the Hawaiian Islands, volcanic rift zones and associated giant landslides have been extensively studied in the Canaries, where several of their more significant structural and genetic elements have been established. Almost 3,000 km of water tunnels (galerías) that exist in the western Canaries provide a unique possibility to access the deep structure of the island edifices. Recent work shows that rift zones to control the construction of the islands, possibly from the initial stages of island development, form the main relief features (shape and topography), and concentrate eruptive activity, making them crucial elements in defining the distribution of volcanic hazards on ocean islands.

  • 132.
    Cerny, P
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Chapman, R
    Ferreira, K
    Smeds, S-A
    Geochemistry of oxide minerals of Nb, Ta, Sn and Sb in the Varuträsk granitic pegmatite, Sweden2004In: Am. Mineralogist, Vol. 89, p. 505-518Article in journal (Refereed)
  • 133.
    Chadwick, J.P.
    et al.
    Department of Petrology, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
    Troll, Valentin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Waight, T.E.
    Department of Geography and Geology, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen, Denmark.
    van der Zwan, F.M.
    Department of Petrology, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
    Schwarzkopf, L.M.
    GeoDocCon, Unterpferdt 8, 95176 Konradsreuth, Germany.
    Petrology and geochemistry of igneous inclusions in recent Merapi deposits: a window into the sub-volcanic plumbing system2013In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 165, no 2, p. 259-282Article in journal (Refereed)
    Abstract [en]

    Recent basaltic-andesite lavas from Merapi volcano contain abundant and varied igneous inclusions suggesting a complex sub-volcanic magmatic system for Merapi volcano. In order to better understand the processes occurring beneath Merapi, we have studied this suite of inclusions by petrography, geochemistry and geobarometric calculations. The inclusions may be classified into four main suites: (1) highly crystalline basaltic-andesite inclusions, (2) co-magmatic enclaves, (3) plutonic crystalline inclusions and (4) amphibole megacrysts. Highly crystalline basaltic-andesite inclusions and co-magmatic enclaves typically display liquid–liquid relationships with their host rocks, indicating mixing and mingling of distinct magmas. Co-magmatic enclaves are basaltic in composition and occasionally display chilled margins, whereas highly crystalline basaltic-andesite inclusions usually lack chilling. Plutonic inclusions have variable grain sizes and occasionally possess crystal layering with a spectrum of compositions spanning from gabbro to diorite. Plagioclase, pyroxene and amphibole are the dominant phases present in both the inclusions and the host lavas. Mineral compositions of the inclusions largely overlap with compositions of minerals in recent and historic basaltic-andesites and the enclaves they contain, indicating a cognate or ‘antelithic’ nature for most of the plutonic inclusions. Many of the plutonic inclusions plot together with the host basaltic-andesites along fractional crystallisation trends from parental basalt to andesite compositions. Results for mineral geobarometry on the inclusions suggest a crystallisation history for the plutonic inclusions and the recent and historic Merapi magmas that spans the full depth of the crust, indicating a multi-chamber magma system with high amounts of semi-molten crystalline mush. There, crystallisation, crystal accumulation, magma mixing and mafic recharge take place. Comparison of the barometric results with whole rock Sr, Nd, and Pb isotope data for the inclusions suggests input of crustal material as magma ascends from depth, with a significant late addition of sedimentary material from the uppermost crust. The type of multi-chamber plumbing system envisaged contains large portions of crystal mush and provides ample opportunity to recycle the magmatic crystalline roots as well as interact with the surrounding host lithologies.

  • 134. Chew, D.
    et al.
    Ganerd, M.
    Troll, V.R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Corfu, F.
    Meade, F.
    U-Pb TIMS zircon age constraints on the Tardree Rhyolite zircon fission track standard. OnTrack2008Report (Other (popular science, discussion, etc.))
  • 135.
    Choudhury, Debraj
    et al.
    Solid State and Structural Chemistry Unit, and Department of Physics, at Indian Institute of Science, Bangalore, Indien.
    Mukherjee, S
    Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, Indien.
    Mandal, P
    Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Indien.
    Sundaresan, A
    Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Indien.
    Waghamare, U V
    Theoretical Science Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Indien.
    Bhattacharjee, Satadeep
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lazor, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sharma, Ajay
    Department of Physics, Indian Institute of Science, Bangalore, Indien.
    Bhat, S V
    Department of Physics, Indian Institute of Science, Bangalore, Indien.
    Karis, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Sarma, Dipankar Das
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Tuning of dielectric properties and magnetism of SrTiO3 by site-specific doping of Mn2011In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, no 12, p. 125124-Article in journal (Refereed)
    Abstract [en]

    Combining experiments with first-principles calculations, we show that site-specific doping of Mn into SrTiO(3) has a decisive influence on the dielectric properties of these doped systems. We find that phonon contributions to the dielectric constant invariably decrease sharply on doping at any site. However, a sizable, random dipolar contribution only for Mn at the Sr site arises from a strong off-centric displacement of Mn in spite of Mn being in a non-d(0) state; this leads to a large dielectric constant at higher temperatures and gives rise to a relaxor ferroelectric behavior at lower temperatures. We also investigate magnetic properties in detail and critically reevaluate the possibility of a true multiglass state in such systems.

  • 136. Chukanov, Nikita V.
    et al.
    Pekov, Igor V.
    Jonsson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Zubkova, Natalia V.
    Filinchuk, Yaroslav E.
    Belakovskiy, Dmitriy I.
    Pushcharovsky, Dmitry Yu
    Långbanshyttanite, a new low-temperature arsenate mineral with a novel structure from Långban, Sweden2011In: European journal of mineralogy, ISSN 0935-1221, E-ISSN 1617-4011, Vol. 23, no 4, p. 675-681Article in journal (Refereed)
    Abstract [en]

    The new mineral långbanshyttanite was discovered in a specimen from the Långban mine (59.86 degrees N, 14.27 degrees E), Filipstad district, Varmland County, Bergslagen ore province, Sweden. Associated minerals are calcite, Mn-bearing phlogopite, spinels of the jacobsite-magnetite series, antigorite and trigonite. The mineral is named after the old name of the mine, smelter and mining village: Långbanshyttan. Långbanshyttanite is transparent, colourless. It occurs in late-stage fractures or corroded pockets, forming soft, radial and random aggregates (up to 1 mm) of acicular crystals up to 5 x 20 x 400 mu m. D(calc) is 3.951 g/cm(3). The new mineral is biaxial (+), alpha = 1.700(5), beta = 1.741(5), gamma = 1.792(5), 2V (meas.) approximate to 90 degrees, 2V (calc.) = 86 degrees. Dispersion is strong, r < v. The IR spectrum is given. The chemical composition is (electron microprobe, mean of five analyses, wt%): PbO 44.71, MgO 3.79, MnO 13.34, FeO 1.89, P(2)O(5) 0.65, As(2)O(5) 22.90, H(2)O (determined by gas chromatographic analysis of the products of ignition at 1200 degrees C) 14.4; total 101.68. The empirical formula based on 18 O atoms is: Pb(1.97)Mn(1.85)Mg(0.93)Fe(0.26)(AsO(4))(1.96)(PO(4))(0.09)(OH)(3.87)cen ter dot 5.93H(2)O. The simplified formula is: Pb(2)Mn(2)Mg(AsO(4))(2)(OH)(4)center dot 6H(2)O. Single-crystal diffraction data obtained using synchrotron radiation indicate that långbanshyttanite is triclinic, P<(1)over bar>, a = 5.0528(10), b = 5.7671(6), c = 14.617(3) angstrom, alpha = 85.656(14), beta = 82.029(17), gamma = 88.728(13)degrees, V = 420.6(2) angstrom(3), Z = 1, and is a representative of a new structure type. In the structure, edge-sharing MnO(2)(OH)(4) octahedra form zig-zag columns that are linked by isolated AsO(4) tetrahedra. Pb cations having six-fold coordination are located between the AsO(4) tetrahedra. Isolated Mg(H(2)O)(6) octahedra are located in the inter-block space. The strongest lines of the powder diffraction pattern [d, angstrom (I,%) (hkl)] are: 14.48 (100) (001), 7.21 (43) (002), 4.969 (34) (100, 101), 4.798 (28) (003), 3.571 (54) (112, 1-1-1, 01-3, 11-1), 2.857 (45) (020, 021, 114), 2.800 (34) (11-3). Parts of the holotype specimen are deposited in the Fersman Mineralogical Museum of Russian Academy of Sciences, Moscow, Russia, with the registration number 4032/1 and in the collections of the Swedish Museum of Natural History, Stockholm, Sweden, under catalogue number NRM 20100076.

  • 137. Clarke, H.
    et al.
    Troll, V. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Carracedo, J.C.
    Phreatomagmatic to strombolian eruptive activity of basaltic cinder cones: Montana Los Erales, Tenerife, Canary Islands2009In: Journal of Volcanology and Geothermal Research, ISSN 0377-0273, E-ISSN 1872-6097, Vol. 180, p. 225-245Article in journal (Refereed)
  • 138. Cosgrove, John W.
    et al.
    Talbot, Christopher J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Aftabi, Pedram
    A train of kink folds in the surficial salt of Qom Kuh, Central Iran2009In: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 31, no 10, p. 1212-1222Article in journal (Refereed)
    Abstract [en]

    The many subaerial extrusions of salt current in Iran are smaller and   faster versions of steady state extrusions of metamorphic rocks from   crustal channels in mountain chains. The extruded salt develops a   variety of internal folds as the salt accumulates ductile displacements   that can reach metres a year. Weather-induced elastic strains de-stress   the outer layers of salt extrusions to a brittle carapace of broken   dilated salt. Qom Kuh, situated in Central Iran, is a comparatively   small and slow example of a viscous salt fountain and, as a result, its   brittle elastic carapace may be thicker than most This may account for   Qom Kuh being the only salt fountain known to have a train of 10 m   scale kink folds in its surficial salt. We attribute these folds to   lateral shortening and back-shear of a surface-parallel planar   mechanical anisotropy in the surficial salt induced by gravitationally   driven ductile flow of the underlying salt. When it is dry, the elastic   carapace is relatively strong and acts as a stiff corset impeding   gravity spreading of the underlying confined salt. However, the   carapace weakens and kinks on wetting, allowing the underlying salt to   gravity spread. These folds illustrate how the weather can affect   gravity spreading of surficial salt masses and how complex the   interplay of tectonic and climatic signals can be in "steady state"   mountains.

  • 139. Cotton, James
    et al.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Modeling of thrust fronts above ductile and frictional detachments: Application to structures in the Salt Range and Potwar Plateau, Pakistan2000In: Geological Society of America Bulletin, ISSN 0016-7592, Vol. 112, no 3, p. 351-363Article in journal (Refereed)
    Abstract [en]

    Series of scaled sandbox models are used to simulate the development of thin-skinned simultaneous shortening above adjacent ductile and frictional substrates, These models simulate the evolution of the Potwar Plateau and Salt Range in Pakistan, where Pale

  • 140. Cruden, Alexander
    et al.
    Sjöström, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Aaro, Sven
    Structure and geophysics of the Gåsborn Granite, central Sweden: an example of fracture-fed asymmetric magma emplacement1999In: Geological Society of London, Special Publications: Understanding granites: Integrating new and classical techniques, no 168, p. 141-160Article in journal (Refereed)
  • 141.
    Cruden, A.R.
    et al.
    Department of Geology, University of Toronto, Erindale College, Mississauga, Ont.,Canada.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Schmeling, H.
    Bayerisches Geoinstitut, Universität Bayreuth, Germany.
    Diapiric basal entrainment of mafic into felsic magma.1995In: Earth and Planetary Science Letters, ISSN 0012-821X, Vol. 131, no 3-4, p. 321-340Article in journal (Refereed)
    Abstract [en]

    One consequence of partial melting of the lower crust by heat transfer from a mantle-derived underplate is that the resultant buoyant, felsic magma layer (density ϱ2, viscosity μ2, thickness h2) will overllie a denser mafic layer (density ϱ3, viscosity μ3, thickness h3, which can be fully liquid to completely solid, depending on its thermal history. Laboratory experiments and finite-difference numerical models have been used to determine the conditions that favour the entrainment of the mafic layer into the overlying felsic magma as it ascends diapirically. Large amounts of entrainment occur when (where ϱ1 is the density of the crust), , and . When these conditions occur, the buoyancy and viscous effects acting to maintain the stability of the felsic-mafic layer interface are minimized. The role of m is much more important in the diapiric entrainment phenomenon than in the comparable problem of axial withdrawal from a density- and viscosity-stratified magma chamber with rigid walls.

    Favourable conditions for entrainment are likely to occur during the evolution of many lower crustal felsic magma source regions with a mafic underplate. Low amounts of entrainment result in minimal interaction (i.e., mixing) between the felsic host and entrained mafic material. If a large amount of entrainment occurs, our models combined with other studies show that mafic magma can remain in the centre of the conduit (low to high Reynolds number (Re), m ≈ 1), become fully mixed with the felsic host (high Re, low m), or become encapsulated by the felsic magma (low Re, m < 0.6). Such mechanical processes may account for the textural and compositional complexity shown by some plutons.

  • 142.
    Dahlin, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Lithogeochemistry and alteration of a Palaeoproterozoic metavolcanic succession in the Dannemora area, Bergslagen region, central SwedenManuscript (preprint) (Other academic)
    Abstract [en]

    The rocks in the Dannemora area constitute the Dannemora Formation, which can be divided into eight different sections, A-H, on the basis of stratigraphy and geochemistry. The great thickness and alteration pattern of the deposit indicate deposition in a caldera environment, related to both intensive and waning volcanic stages and hydrothermal processes. The partly strong alteration is shown by the sericite dominated matrix and the completely sericite replaced plagioclase and volcaniclastic clasts. The northern part of the Dannemora area in general shows a lower degree of alteration than the central part in comparable stratigraphic levels, which implies that these parts were located in different positions to hydrothermal cells.

    A lapilli-bearing ash layer is present between the massive pyroclastic beds in section A and C that have distinctly different alteration patterns suggesting that the strong alteration in section A occurred before deposition of section C. During the waning volcanic stage, the calmer environment allowed stromatolitic limestone interlayered with thin horizons of ash-siltstone to deposit. During subsequent dolomitisation of the limestone the interlayered ash-siltstone was affected by great enrichment of CaO and depletion of MgO. Despite this strong alteration this section is classified as least altered by alteration index, which most likely reflect a two stage alteration with initial alkali enrichment, followed by CaO enrichment that “reset” the alteration index. The great enrichment of Ba in the upper member is supported by the occurrence of hyalophane. On the basis of lithogeochemical signature of immobile element ratios together with the reoccurrence of an accretionary lapilli-bed the position of a previously inferred anticline has been established.

  • 143.
    Dahlin, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Palaeoproterozoic metavolcanic and metasedimentary succession hostingthe Dannemora iron ore deposits, Bergslagen region, Sweden2012In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 134, no 2, p. 71-85Article in journal (Refereed)
    Abstract [en]

    The Dannemora supracrustal inlier is located in the north-eastern part of the Bergslagen regionin south-central Sweden and hosts the second largest iron ore deposit in the region. The metasupracrustalsuccession of the inlier consists of c. 1.9 Ga Palaeoproterozoic rocks that are mainly sub-alkaline, rhyoliticto dacitic, pyroclastic deposits, reworked pyroclastic deposits and metalimestone. It is c. 700–800-m thickand termed the Dannemora Formation. The formation is divided into lower and upper members and theformer is in turn subdivided into subunits 1 and 2. The great thickness of individual pyroclastic depositsindicates deposition within a caldera. The rocks show characteristics of a pyroclastic origin by containingabundant pumice, cuspate and Y-shaped former glass shards, and fragmented crystals of quartz andsubordinate feldspars. Scattered spherulites and lack of welding-compacted fiamme suggest that the lowermember was slightly welded, where as the upper member contains sericite-replaced glass shards withpreserved primary shapes indicating no welding. Undisturbed layers of ash-siltstone with normal gradingand fluid–escape structures are attributed to subaqueous deposition below storm wave base in the easternpart of the inlier, where as erosion channels and cross-bedding in some of the volcaniclastic deposits implydeposition and reworking above wave base in the central part of the inlier. Epidote spots, previouslyinterpreted as altered limestone fragments and an indicator for subaquatic deposition, are here reinterpretedas the result of selective alteration related to the intrusion of mafic dykes and to Ca release duringdolomitisation of limestone.

  • 144.
    Dahlin, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Stratigraphy and Geochemistry of the Palaeoproterozoic Dannemora inlier, north-eastern Bergslagen region, central Sweden.2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Palaeoproterozoic Dannemora inlier is situated in the north-eastern Bergslagen region. The inlier consists of primary and reworked volcanic deposits, stromatolitic limestone and skarn that have been subjected to upper greenschist facies metamorphism. Thicknesses of the different volcanic deposits indicate deposition within a caldera, where syn-volcanic alkali alteration was strong. The deposition was submarine and below wave base in the eastern part of the inlier, but above wave base in the central part where erosion channels together with cross-bedding occurs frequently.

    The Dannemora Formation is the volcanosedimentary succession of the inlier. Two borehole profiles, a northern and a southern, cover the whole Formation and show different alteration patterns. A strong depletion of Na2O and enrichment of K2O dominate in the southern profile, whereas this pattern is not as evident in the northern profile. The uppermost section of the totally eight constituting the Formation, is intercalated with ore-bearing dolomitic limestone and skarn, and has experienced at least two episodes of alteration. An anticline has been established lithogeochemically from immobile element ratios and the reoccurrence of an accretionary lapilli bed.

    Numerous altered sub-alkaline, calc-alkaline and basaltic dykes have been recorded in the Dannemora inlier. They are the result of mixing and fractionation of at least three magmatic sources and carry a mixed signature of subduction zone and within-plate volcanic tectonic setting.

    A seismic profile across the Dannemora inlier images a strong reflector package that dips c. 50° E to the east of the inlier. This package coincides with the polyphase, E-up reverse, brittle-ductile Österbybruk deformation zone (ÖDZ). Yet another steep reflector in the Dannemora ore-field extends to a depth of more than two kilometres. This reflector might represent either a deep-seated iron deposit or a fluid-bearing fault zone.

    List of papers
    1. Palaeoproterozoic metavolcanic and metasedimentary succession hostingthe Dannemora iron ore deposits, Bergslagen region, Sweden
    Open this publication in new window or tab >>Palaeoproterozoic metavolcanic and metasedimentary succession hostingthe Dannemora iron ore deposits, Bergslagen region, Sweden
    2012 (English)In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 134, no 2, p. 71-85Article in journal (Refereed) Published
    Abstract [en]

    The Dannemora supracrustal inlier is located in the north-eastern part of the Bergslagen regionin south-central Sweden and hosts the second largest iron ore deposit in the region. The metasupracrustalsuccession of the inlier consists of c. 1.9 Ga Palaeoproterozoic rocks that are mainly sub-alkaline, rhyoliticto dacitic, pyroclastic deposits, reworked pyroclastic deposits and metalimestone. It is c. 700–800-m thickand termed the Dannemora Formation. The formation is divided into lower and upper members and theformer is in turn subdivided into subunits 1 and 2. The great thickness of individual pyroclastic depositsindicates deposition within a caldera. The rocks show characteristics of a pyroclastic origin by containingabundant pumice, cuspate and Y-shaped former glass shards, and fragmented crystals of quartz andsubordinate feldspars. Scattered spherulites and lack of welding-compacted fiamme suggest that the lowermember was slightly welded, where as the upper member contains sericite-replaced glass shards withpreserved primary shapes indicating no welding. Undisturbed layers of ash-siltstone with normal gradingand fluid–escape structures are attributed to subaqueous deposition below storm wave base in the easternpart of the inlier, where as erosion channels and cross-bedding in some of the volcaniclastic deposits implydeposition and reworking above wave base in the central part of the inlier. Epidote spots, previouslyinterpreted as altered limestone fragments and an indicator for subaquatic deposition, are here reinterpretedas the result of selective alteration related to the intrusion of mafic dykes and to Ca release duringdolomitisation of limestone.

    Place, publisher, year, edition, pages
    Taylor & Francis, 2012
    Keywords
    Bergslagen; Dannemora; Palaeoproterozoic; pyroclastic rocks; volcanic textures; ignimbrites
    National Category
    Geology
    Identifiers
    urn:nbn:se:uu:diva-182809 (URN)10.1080/11035897.2012.674551 (DOI)
    Available from: 2012-10-15 Created: 2012-10-15 Last updated: 2017-12-07Bibliographically approved
    2. Source character, mixing, fractionation and alkali metasomatismin in Palaeoproterozoic greenstone dykes, Dannemora area, NE Bergslagen region, Sweden
    Open this publication in new window or tab >>Source character, mixing, fractionation and alkali metasomatismin in Palaeoproterozoic greenstone dykes, Dannemora area, NE Bergslagen region, Sweden
    2013 (English)In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 151, no 04, p. 573-590Article in journal (Refereed) Published
    Abstract [en]

    The geochemical and isotopic characteristics of metamorphosed Svecofennian maficdykes from the Dannemora area in the NE part of the Bergslagen region in central Sweden wereinvestigated and compared to mafic intrusive rocks in their vicinity. The dykes, with an inferred ageof c. 1860–1870 Ma, are calc-alkaline, sub-alkaline and basaltic in composition and have a mixedsubduction and within-plate geochemical affinity. They are the result of mixing of at least three mantlesource components with similar basaltic major element composition, but different concentrations ofincompatible trace elements. Magma M1 is strongly enriched both in Rare Earth Elements (REE)and High-Field-Strength Elements (HFSE); magma M2 is highly enriched in Large-Ion LithophileElements (LILE, except Sr) with only moderate enrichment in HFSE and REE (particularly low inHeavy Rare Earth Elements); and magma M3 is enriched in Sr and has a flat REE profile. MagmaM3 also has a somewhat more positive (depleted) initial εNd value of +1.8, compared to +0.4 to +0.5 for magmas M1 and M2. The magma evolution was controlled by a mixture of fractionation (mainlyaffecting the compatible elements) and mixing, best seen in the incompatible element concentrationsand the Nd isotope data. The basaltic overall composition indicates little or no wholesale contaminationby upper continental crust, but the dykes have undergone later metasomatic changes mainly affectingthe alkali elements.

    Place, publisher, year, edition, pages
    Cambridge Academic, 2013
    Keywords
    Svecofennian, Bergslagen region, Dannemora, greenstone dykes, alkali metasomatism
    National Category
    Geology
    Research subject
    Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
    Identifiers
    urn:nbn:se:uu:diva-214689 (URN)10.1017/S0016756813000551 (DOI)000337751000001 ()
    Available from: 2014-01-09 Created: 2014-01-09 Last updated: 2017-12-06Bibliographically approved
    3. Reflection seismic investigations in the Dannemora area, central Sweden: Insights into the geometry of polyphasedeformation zones and magnetite‐skarn deposits
    Open this publication in new window or tab >>Reflection seismic investigations in the Dannemora area, central Sweden: Insights into the geometry of polyphasedeformation zones and magnetite‐skarn deposits
    Show others...
    2011 (English)In: Journal of Geophysical Research - Solid Earth, ISSN 2169-9313, E-ISSN 2169-9356, Vol. 116, p. B11307-Article in journal (Refereed) Published
    Abstract [en]

    The Bergslagen region is one of the most ore prospective districts in Sweden. Presented here are results from two nearly 25 km long reflection seismic profiles crossing this region in the Dannemora mining area. The interpretations are constrained by seismic wave velocity measurements on a series of rock samples, cross-dip analysis, prestack time migration, and swath 3-D imaging, as well as by other available geophysical and geological observations. A series of major fault zones is imaged by the seismic data, as is a large mafic intrusion. However, the most prominent feature is a package of east-dipping reflectors found east of the Dannemora area that extend down to at least 3 km depth. This package is associated with a polyphase, ductile-brittle deformation zone with the latest ductile movement showing east-side-up or reverse kinematics. Its total vertical displacement is estimated to be in the order of 2.5 km. Also clearly imaged in the seismic data is a steeply dipping reflector near the Dannemora mine that extends down to a depth of at least 2.2 km. The geological nature of this reflector is not known, but it could represent either a fluid-bearing fault zone or a deep-seated iron deposit, making it an important target for further detailed geophysical and geological investigations.

    National Category
    Geology
    Identifiers
    urn:nbn:se:uu:diva-166692 (URN)10.1029/2011JB008643 (DOI)000297675200001 ()
    Available from: 2012-01-12 Created: 2012-01-12 Last updated: 2017-12-08Bibliographically approved
    4. Lithogeochemistry and alteration of a Palaeoproterozoic metavolcanic succession in the Dannemora area, Bergslagen region, central Sweden
    Open this publication in new window or tab >>Lithogeochemistry and alteration of a Palaeoproterozoic metavolcanic succession in the Dannemora area, Bergslagen region, central Sweden
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The rocks in the Dannemora area constitute the Dannemora Formation, which can be divided into eight different sections, A-H, on the basis of stratigraphy and geochemistry. The great thickness and alteration pattern of the deposit indicate deposition in a caldera environment, related to both intensive and waning volcanic stages and hydrothermal processes. The partly strong alteration is shown by the sericite dominated matrix and the completely sericite replaced plagioclase and volcaniclastic clasts. The northern part of the Dannemora area in general shows a lower degree of alteration than the central part in comparable stratigraphic levels, which implies that these parts were located in different positions to hydrothermal cells.

    A lapilli-bearing ash layer is present between the massive pyroclastic beds in section A and C that have distinctly different alteration patterns suggesting that the strong alteration in section A occurred before deposition of section C. During the waning volcanic stage, the calmer environment allowed stromatolitic limestone interlayered with thin horizons of ash-siltstone to deposit. During subsequent dolomitisation of the limestone the interlayered ash-siltstone was affected by great enrichment of CaO and depletion of MgO. Despite this strong alteration this section is classified as least altered by alteration index, which most likely reflect a two stage alteration with initial alkali enrichment, followed by CaO enrichment that “reset” the alteration index. The great enrichment of Ba in the upper member is supported by the occurrence of hyalophane. On the basis of lithogeochemical signature of immobile element ratios together with the reoccurrence of an accretionary lapilli-bed the position of a previously inferred anticline has been established.

    National Category
    Geology
    Identifiers
    urn:nbn:se:uu:diva-236878 (URN)