uu.seUppsala University Publications
Change search
Refine search result
1234 101 - 150 of 169
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 101.
    Koyi, Hemin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Talbot, Christopher J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Tørudbakken, Björn O.
    Saga Petroleum a.s. Sandvika, Norway .
    Salt tectonics in the north-eastern Nordkapp Basin, south-western Barents Sea.1995In: American Association of Petroleum Geologists Bulletin Memoir, Vol. 65, p. 437-447Article in journal (Refereed)
    Abstract [en]

    Salt structures in the northeastern Nordkapp subbasin are interpreted on reflection seismic profiles. Thickness variations indicate localized accumulation of the mother salt in Late Carboniferous-Early Permian time. Rapid sedimentation in the Early Triassic accompanied rise of salt into asymmetric salt pillows during regional extension. These pillows domed the prekinematic Permian sediments and became diapiric during the late Early-Middle Triassic, perhaps as a result of thin-skinned normal faulting decoupled by the salt from old basement faults reactivated by thick-skinned regional (northwest-southeast) extension.

    Variations in size, maturity, and evolution history of individual salt structures can be attributed to local differences in thickness of the initial salt layer and its burial history. Salt structures form three rows concentric to the basin margins and cover ~ 20% of the basin area. Some salt stocks appear to overlie basement faults. Asymmetric primary, secondary, and in places tertiary, peripheral sinks indicate that salt was withdrawn mainly from the basin side of most diapirs throughout Triassic downbuilding.

    The ratio of net salt rise rate to net aggradation rate (/) increased slowly from <1 to >1 during Middle Triassic time and increased markedly during slow sedimentation in the Late Triassic and Jurassic. By Jurassic time, more than 18 enormous salt fountains extruded downslope and spread a partial salt canopy in the central and northern parts of the northeastern subbasin. Larger and more widely spaced salt extrusions in the northeastern subbasin spread significantly farther than their equivalents in the southwestern subbasin, where Triassic subsidence or downbuilding was slower. Salt extrusion (and perhaps dissolution) ceased during Cretaceous burial but probably resumed locally in the late Tertiary. Salt loss during Cretaceous-Tertiary reactivation of salt rise reduced the area of the salt canopy. Surviving remnants of the salt canopy may still trap any pre-Jurassic hydrocarbons despite hydrocarbon venting throughout the Arctic during Tertiary uplift.

  • 102.
    Koyi, Hemin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology. Berggrundsgeologi.
    Talbot, Christopher J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Tørudbakken, B.O.
    Saga Petroleum, Sandviken, Norway.
    Salt diapirs of the southwest Nordkapp Basin: analogue modelling1993In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 228, no 3-4, p. 167-187Article in journal (Refereed)
    Abstract [en]

    The geometry and evolution of the salt diapirs in the southwestern segment of the Nordkapp Basin (SW NKB) were interpreted on reflection seismic data. Reflection seismic profiles were used to build a dynamically scaled model analogue to study salt tectonics of the basin. The model was prepared using lengths, densities, and sedimentary histories obtained from seismic and well data. Model results suggest that the salt structures in the SW NKB were influenced by basement faults that horizontally stretched and faulted their overburden and induced salt flow by differential loading. Model diapirs rose only where the overburden was faulted.          The salt structures are aligned in two NE-SW rows that parallel the major basement faults that outline the basin. Carboniferous salt in the SW NKB formed conformable pillows in the Early Triassic (Scythian), which became diapiric during the late Early and Middle Triassic. The salt diapirs spread to form asymmetric broad overhangs at superficial levels during slow sedimentation in Late Triassic and/or Jurassic. Diapir overhangs were later reactivated because of burial by Cretaceous and Tertiary sediments. Basement faults were mapped by comparing thickness of the sediments and/or level of the reflectors on either side of the diapirs that had relatively narrow overhangs. Depth conversion and restoration of velocity pull-up of reflectors beneath salt diapirs suggest that the salt diapirs of the SW NKB have broad overhangs above narrow stems.

  • 103.
    Koyi, Hemin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Vendeville, B.C
    bBureau of Economic Geology, University of Texas at Austin, USA.
    The effect of décollement dip on geometry and kinematics of model accretionary wedges.2003In: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 25, no 9, p. 1445-1450Article in journal (Refereed)
    Abstract [en]

    We conducted a series of sand-box models shortened asymmetrically above a frictional-plastic de´collement to study the influence ofamount and sense of the de´collement dip on the geometry and kinematics of accretionary wedges. Model results illustrate that the amount anddirection of de´collement dip strongly influence the geometry and mode of deformation of the resulting wedge. In general, for models havingsimilar de´collement frictional parameters, the resulting wedge is steeper, grows higher and is shorter when shortened above a de´collementthat dips toward the hinterland. At 42% bulk shortening, the length/height ratio of wedges formed above a 58-dipping de´collement was equalto 2.4 whereas this ratio was equal to 3 for wedges shortened above a horizontal de´collement. Moreover, models with a hinterland dippingde´collement undergo larger amounts of layer parallel compaction (LPC) and area loss than models shortened above a non-dippingde´collement. The effect of de´collement dip on wedge deformation is most pronounced when basal friction is relatively high (mb ¼ 0.55),whereas its effect is less significant in models where the basal de´collement has a lower friction (mb ¼ 0.37). Model results also show thatincreasing basal slope has a similar effect to that of increasing basal friction; the wedge grows taller and its critical taper steepens.

  • 104. Krzywiec, P
    et al.
    Gutowski, J
    Popadyuk, I
    Koyi, H.A
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Gliniak, P
    Gubych, I
    Madej, K
    Matyjasik, I
    Olszewska, B
    Syrota, T
    Urbaniec, A
    Wróbel, G
    Jurassic to Miocene evolution of the Polish and Ukrainian Carpathian foreland based on geological and geophysical data and analogue modelling2005In: American Association of Petroleum Geologists (AAPG) International Conference, Abstract Volume AAPG 2005, 9, 2005Conference paper (Other (popular science, discussion, etc.))
  • 105. Lawa, F.
    et al.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Ibrahim, A.
    Tectono-stratigraphic evolution of the NW segment of the Zagros fold-thrust belt, Kurdistan, NE Iraq2013In: Journal of Petroleum Geology, ISSN 0141-6421, E-ISSN 1747-5457, Vol. 36, no 1, p. 75-96Article in journal (Refereed)
    Abstract [en]

    The Kurdistan (NW) segment of the Zagros fold-thrust belt, located in the Kurdistan Region of NE Iraq, forms the external part of the Zagros orogen and is bounded by the Zagros suture to the NE. To the SW is the Arabian Plate into which the deformation front has migrated progressively, beginning in the Late Cretaceous and culminating in the Tertiary. Regional compression resulted in obduction of the Mawat ophiolites and emplacement of the Avroman and Qulqula nappes onto the continental margin, and the formation of the Kurdistan foreland basin. In this paper, structural, stratigraphic and palaeontological data together with new field observations are used to investigate the tectono-stratigraphic evolution of this basin, and to study the propagation of the deformation front from the Zagros Imbricate Zone in the NE towards the Mesopotamian foredeep in the SW. Six unconformities within the Kurdistan foreland basin succession are recognized: Turonian (base-AP9; 92 Ma); Danian (base-AP10; 65 Ma); Paleocene–Eocene (intra-AP10; 55 Ma); late Eocene (top-AP10; 34 Ma); middle-upper Miocene (a local unconformity; intra-AP11; 12 Ma); and Pleistocene. These unconformities can be divided into two groups; obduction-related (Turonian, Danian, and Paleocene-Eocene); and collision-related (late Eocene, middle-upper Miocene, and Pleistocene).

    The geographical position of the unconformities is used to determine the rate of propagation of the deformation front, which is estimated at ca. 3 mm/yr. This is in agreement with previous studies which suggested a NW-ward decrease in the propagation rate. The rate was most rapid (2.95 mm/yr) in the Low Zagros Fold-Thrust Zone and slower (2.06 mm/yr) in the High Zagros Fold-Thrust Zone. The more rapid propagation rate in the former area may be attributed to the presence there of the Miocene Lower Fars Formation which acted as a shallow décollement surface.

    Within the Zagros fold-thrust belt, the intensity of deformation decreases towards the foreland (SW). Deformation in the High Zagros Fold-Thrust Zone is characterized by thrust imbricates and high amplitude fault-propagation folds at the surface separated by narrow synclines. However, the Low Zagros Fold-Thrust Zone (Simply Folded Belt) is characterised by detachments and low amplitude fault propagation folds separated by broad synclines. In the foredeep area, folds are confined to the subsurface. Deeply buried Jurassic units, together with Upper Cretaceous – Paleocene siliciclastics, and the evaporite-dominated Lower Fars Formation may have acted as décollement surfaces in the NW segment of the Zagros fold-thrust belt, and controlled the structural geometry and evolution of the area.

  • 106.
    Liu, Zhina
    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.
    Analogue modeling of the collapse of non-homogeneous granular slopes along weak horizons2014In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 632, p. 76-95Article in journal (Refereed)
    Abstract [en]

    In this study, we use results of analogue models to investigate the effect of the orientation, location and thickness of a weak horizon on the stability/failure, kinematics and internal deformation of a granular slope. The models are systematically designed to simulate the collapse of non-homogeneous granular slopes by focusing on the spatial and temporal distribution of their internal deformation. Model results show that the presence of a weak horizon embedded within the granular slope has a significant influence on the granular failure which is accommodated through different generation pulses that successively decrease in volume. However, the dip and stratigraphic location of the weak horizon dictate whether the weak horizon plays a role during the failure or not. When the main failure surface is contained within a weak horizon, the dip and thickness of the weak horizon have a positive effect on the displacement of the failure mass, whereas a shallow-located weak horizon causes larger displacement of the failure mass during the collapse of granular slopes. In addition, the collapse of granular slopes results in formation of different-generation normal faults and shortening structures (folds and thrusts) within the failure mass. The first-generation normal faults with a steep dip (about 60º) cut across the entire stratigraphy of the slope, whereas the later-generation normal faults with a gentle dip (about 40º) cut across the shallow units. The distribution of these internal structures within the failure mass is affected significantly by the orientation, location and thickness of the weak horizon. 

  • 107.
    Liu, Zhina
    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.
    Kinematics and internal deformation of granular slopes: insights from discrete element modeling2013In: Landslides: Journal of the International Consortium on Landslides, ISSN 1612-510X, E-ISSN 1612-5118, Vol. 10, no 2, p. 139-160Article in journal (Refereed)
    Abstract [en]

    The kinematics and internal deformation of a failure mass during the flow-like moving off a slope were monitored and quantified with the particle flow method in this study. Two kinds of cases were investigated, noncohesive and cohesive granular slopes. Three different internal friction angles and cohesive strengths were considered to systematically investigate their effect on the kinematics and internal deformation of the failure mass. We analyzed the movement within the failure mass and concluded that the mass moves downwards in an undulating pattern. The slope surface topography changes from a straight line to curved lines with slope breaks in a convex geometry. In addition, dilatation within the failure mass, which deforms internally and heterogeneously, is strongly dependent on its mechanical properties. A larger mass moves downslope, and the mass moves faster and further in the model with lower internal friction and cohesion. The internal friction and cohesion have a positive impact on porosity and two-dimensional (or volumetric in 3D) strain within the failure mass.

  • 108.
    Liu, Zhina
    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.
    Monitoring internal deformation of unstable cohesionless slopes: insights from DEM modeling2011Conference paper (Refereed)
  • 109.
    Liu, Zhina
    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.
    The impact of a weak horizon on kinematics and internal deformation of a failure mass using discrete element method2013In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 586, p. 95-111Article in journal (Refereed)
    Abstract [en]

    Weak horizons within slopes may induce and/or accelerate failure of slopes. In this study, we focus on the effect of orientation, location and dimension of a weak horizon on the mode and kinematics of downslope movement of a failure mass using discrete element method. Two kinds of cases with weak horizons were studied, one unstable homogeneous slope with low shear strength (c = 50 kPa, μ = 0.57) and two stable homogeneous slopes with high shear strength (c = 60 kPa, μ = 0.57 or c = 50 kPa, μ = 0.7). In the three set of slope models, there was a weak horizon with a finite thickness embedded within the slope. In each set of slope models, two different thicknesses and locations for the weak horizons were considered to systematically investigate the effect of these parameters on the mass movement. In addition, the dip of the weak horizon was changed where in some models, it was parallel to the slope and in others it was dipping either steeper or gentler than the slope. We analyzed both kinematics and internal deformation of the failure mass in all models and conclude that the presence and geometry (i.e., thickness, location and dip) of a weak horizon changes the mode and kinematics of mass movement and governs the location of the failure surface.

  • 110.
    Liu, Zhina
    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.
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Kinematics and internal deformation within 3-D granular slopes: insights from analogue mdoels and natural slopes2013Conference paper (Refereed)
  • 111.
    Liu, Zhina
    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.
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Swantesson, J.
    Internal deformation within an unstable granular slope: insights from physical modeling2012Conference paper (Refereed)
  • 112.
    Liu, Zhina
    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.
    Swantesson, Jan
    Department of Ecophilosophy, Karlstad University.
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Reshetyuk, Yuri
    Department of Industrial Development, IT and Land Management, University of Gävle.
    Kinematics and 3-D internal deformation of granular slopes: analogue models and natural landslides2013In: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 53, p. 27-42Article in journal (Refereed)
    Abstract [en]

    This study uses results from a series of analogue models, and field observations, scanned data and sections of natural landslides to investigate the kinematics and internal deformation during the failure of an unstable slope. The models simulate collapse of granular slopes and focus on the spatial and temporal distribution of their internal structures. Using a series of systematically designed models, we have studied the effect of friction and deformability of the runout base on internal deformation within a granular slope. The results of these different models show that the collapse of granular slopes resulted in different-generation extensional faults at the back of the slope, and contractional structures (overturned folds, sheath folds and thrusts) at the toe of the slope. The failure surfaces and the volume of the failure mass changed both spatially and temporally. Younger failure surfaces formed in the back of the older ones by incorporating additional new material from the head of the slope. Our model results also show that the nature of the runout base has a significant influence on the runout distance, topography and internal deformation of a granular slope. Model results are compared with natural landslides where local profiles were dug in order to decipher the internal structures of the failure mass. The natural cases show similar structural distribution at the head and toe of the failure mass. As in model results, our field observations indicate the presence of at least two generations of failure surfaces where the older ones are steeper.

  • 113. Lundström, Ingmar
    et al.
    Koyi, H.A
    Vulkanön som blev fritidsparadis – några glimtar från Utös allra tidigaste historia2003In: Geologiskt Forum, Vol. 37, p. 4-15Article in journal (Other (popular science, discussion, etc.))
  • 114.
    Ma, Delong
    et al.
    PetroChina, Res Inst Petr Explorat & Dev Northwest, Lanzhou 730020, Gansu, Peoples R China;PetroChina, Key Lab Reservoir Descript, Lanzhou 730020, Gansu, Peoples R China.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Yuan, Jianying
    PetroChina, Res Inst Petr Explorat & Dev Northwest, Lanzhou 730020, Gansu, Peoples R China;PetroChina, Key Lab Reservoir Descript, Lanzhou 730020, Gansu, Peoples R China.
    He, Dengfa
    China Univ Geosci, Sch Energy Resources, Beijing 100083, Peoples R China.
    Zhang, Huquan
    PetroChina, Res Inst Petr Explorat & Dev Northwest, Lanzhou 730020, Gansu, Peoples R China.
    Wang, Hongbin
    PetroChina, Res Inst Petr Explorat & Dev Northwest, Lanzhou 730020, Gansu, Peoples R China;PetroChina, Key Lab Reservoir Descript, Lanzhou 730020, Gansu, Peoples R China.
    Wang, Yanjun
    PetroChina, Res Inst Petr Explorat & Dev Northwest, Lanzhou 730020, Gansu, Peoples R China;PetroChina, Key Lab Reservoir Descript, Lanzhou 730020, Gansu, Peoples R China;Nanjing Univ, Dept Earth Sci, Nanjing 210093, Jiangsu, Peoples R China.
    Cui, Jian
    Nanjing Univ, Dept Earth Sci, Nanjing 210093, Jiangsu, Peoples R China.
    The role of deep-seated half-grabens in the evolution of Huoerguosi-Manasi-Tugulu fold-and-thrust belt, northern Tian Shan, China2019In: Journal of Geodynamics, ISSN 0264-3707, E-ISSN 1879-1670, Vol. 131, article id 101647Article in journal (Refereed)
    Abstract [en]

    The Huoerguosi-Manasi-Tugulu fold-and-thrust belt, which is located in the southern Junggar Basin, has formed in response to contraction during Late Cenozoic. However, the tectonic environment for its formation before Late Cenozoic is still controversial. In this paper, we use surface data, recently collected and processed subsurface seismic refection data, isopach map of Lower Jurassic and balanced sections to propose pre-existing half-graben system developed in the Lower Jurassic with this fold-and-thrust belt. We also use results of a series of scaled sandbox analogue models, where industrial CT apparatus was used to monitor deformation, to simulate the evolution of this fold-and-thrust belt. We suggest that the segmented shape of the Huoerguosi-Manasi-Tugulu fold-and-thrust belt is a response to the presence of thrust ramps, which were formed during Early Jurassic. During Late Cenozoic shortening, the Lower Jurassic syn-rift sediments served as major detachment horizon, making a pre-existing normal fault act as a stress concentration zone leading to steeping of a thrust-ramp over the normal fault and cover detachment overstep the underlying half-grabens. Modeling results reveal that the presented structural framework has close resemblance with paleostructures especially in the intracontinental environment, which underwent a complex multicycle evolution process, and provide a new prospective for the interpretation of natural examples.

  • 115. Maillot, Bertrand
    et al.
    Koyi, Hemin
    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.
    Thrust dips and refraction in fault-bend faults: analogue experiments and theoretical predictions2006In: Journal of Structural Geology, Vol. 28, p. 36-49Article in journal (Refereed)
  • 116. Masrouhi, A.
    et al.
    Bellier, O.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Geometry and structural evolution of Lorbeus diapir, northwestern Tunisia: polyphase diapirism of the North African inverted passive margin2014In: International journal of earth sciences, ISSN 1437-3254, E-ISSN 1437-3262, Vol. 103, no 3, p. 881-900Article in journal (Refereed)
    Abstract [en]

    Detailed geologic mapping, structural analysis, field cross-sections, new dating based on planktonic foraminifera, in addition to gravity signature of Lorbeus diapir, are used to characterize polyphase salt diapirism. This study highlights the role of inherited faulting, which controls and influences the piercement efficiency and the style and geometry of the diapir; and also the localization of evaporite early ascent displaying diapiric growth during extension. Salt was extruded along the graben axis developed within extensional regional early Cretaceous tectonic associated with the North African passive margin evolution. Geologic data highlight reactive diapirism during Albian time (most extreme extension period) and passive diapirism during the late Cretaceous post-rift stage. Northeastern Maghreb salt province gives evidences that contractional deformations are not associated with significant diapirism. During shortening, the initial major graben deforms as complex anticlines where diapirs are squeezed and pinched from their feeding.

  • 117. Masrouhi, A.
    et al.
    Koyi, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Submarine ‘salt glacier’ of Northern Tunisia, a case of Triassic salt mobility in North African Cretaceous passive margin2012In: Geological Society of London, Special Publications, Vol. 363, p. 579-593Article in journal (Refereed)
    Abstract [en]

    Stratigraphical, sedimentological and structural data and a Bouguer gravity map of Medjez-El-Bab (MEB) in Northern Tunisia are used to illustrate a Cretaceous example of salt extrusion on a passive continental margin. Located just south of the Teboursouk thrust front (a preferential décollement surface used by the continuous Tertiary shortening in this area), the MEB structure is a simple N40°E box anticline. Removing the two Tertiary foldings (Eocene and Miocene) leads to the exposure of the original feature of a simple submarine ‘salt glacier’. The Triassic salt rocks appear as an Albian interstratified body between two Cretaceous series with stratigraphic normal polarity, suggesting a bedding parallel extrusion (at the sediment–water interface) of the Triassic salt in Cretaceous times. The formation of such salt extrusions are associated with extensional faulting (probably both in the cover and basement), the presence of a slope and basinwards salt flow. This scenario is similar to the allochthonous salt described in other salt provinces, characterizing passive margins.

  • 118. Masrouhi, Amara
    et al.
    Bellier, Olivier
    Ben Youssef, Mohamed
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Submarine allochthonous salt sheets: Gravity-driven deformation of North African Cretaceous passive margin in Tunisia - Bled Dogra case study and nearby salt structures2014In: Journal of African Earth Sciences, ISSN 1464-343X, Vol. 97, p. 125-142Article in journal (Refereed)
    Abstract [en]

    We used structural, stratigraphic and sedimentologic data, together with a comparison of nearby structures and a Bouguer gravity map, to evaluate the evolution of the Bled Dogra salt structure (northern Tunisia) during the Cretaceous. Triassic salt sheets are recognized in the northwestern region of the Tunisian Atlas. These salt sheets are the result of Cretaceous thick and/or thin-skinned extension along the south Tethyan margin. The Bled Dogra salt structure is one of these submarine allochthonous salt sheets, which was emplaced during the Early Cretaceous. The geologic framework, during this period, produces conditions for a predominantly gravity-driven deformation: extension has produced space for the salt to rise; vigorous differential sedimentation created differential loading that resulted in the emplacement and extrusion of a large volume of Triassic salt and formation of large submarine salt sheets. Geologic field data suggest an interlayered Triassic salt sheet within Albian sequences. Salt was extruded at the sea floor during the Early-Middle Albian and was initially buried by Middle-Late Albian strata. The Coniacian corresponds to a second transgressive cover onto the salt sheet after the gliding of the first salt cover (Late Albian-Turonian). In addition, this northwest Tunisian area exposes evidences for salt flow and abundant slump features at the base of a northward facing submarine slope, which was probably dominant from the Early Cretaceous to Santonian. Two gravity deformation processes are recognized: gravity gliding and gravity spreading. Acting concurrently, these two processes appear indistinguishable in this geologic context. Like the present-day salt-involved passive margins - such as the northern Gulf of Mexico, the Atlantic margin of Morocco, the Brazilian Santos basin, the Angola margin, Cadiz in western Iberia, and the Red Sea - the North African Cretaceous passive margin in Tunisia provides evidences that deformation in a passive-margin salt basin is predominantly gravity-driven deformation.

  • 119. Masrouhi, Amara
    et al.
    Bellier, Olivier
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Vila, Jean-Marie
    Ghanmi, Mohamed
    The evolution of the Lansarine-Baouala salt canopy in the North African Cretaceous passive margin in Tunisia2013In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 150, no 5, p. 835-861Article in journal (Refereed)
    Abstract [en]

    Detailed geological mapping, dating, and gravimetric and seismic data are used to interpret the Lansarine-Baouala salt structure (North Tunisia) as a salt canopy emplaced during the Cretaceous Period. The extensional tectonic regime related to the Cretaceous continental margin offered at least two factors that encouraged buried Triassic salt to extrude onto the sea floor and flow downslope: (i) extension induced normal faults that provided routes to the surface, and led to the formation of submarine slopes along which salt could flow; (ii) this structural setting led to differential sedimentation and consequently differential loading as a mechanism for salt movement. The present 40-km-long Lansarine-Baouala salt structure with its unique mass of allochthonous Triassic salt at surface was fed from at least four stems. The salt structure is recognized as one of the few examples worldwide of a subaerial salt canopy due to the coalescence of submarine sheets of Triassic salt extruded in Cretaceous times.

  • 120.
    Massoli, D
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Koyi, H.A
    Barchi, M
    Rogledi, S
    Analogue modelling of Po Basin: Structural evolution of a fold-thrust beltgenerated by multiple decollement2002In: Bullettino di Geofisica Teorica ed Applicata, Vol. 42, p. 64-66Article in journal (Refereed)
  • 121.
    Massoli, Donatella
    et al.
    Department of Earth Sciences, University of Perugia, Italy.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Barchi, Massimilliano
    Department of Earth Sciences, University of Perugia, Italy.
    Structural evolution of a fold and thrust belt generated by multiple décollements: analogue models and natural examples from the Northern Apennines2006In: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 28, p. 185-199Article in journal (Refereed)
    Abstract [en]

    This study analyses the role played by the mechanical proprieties of the rocks involved in a thrust system, focusing on the problem of multiple décollements and of related compressional structures. Integration of geophysical (seismic reflection profiles) and geological data and scaled sandbox models are used to study the deformation style of two areas of the Northern Apennines (Italy): the Po Plain and the Umbria-Marche Apennines. Both areas are characterised by a complex stratigraphy, consisting of décollements located at different depths that influence the geometry and kinematics of the thrust system. The main characteristic of the models presented here is the presence of two décollement horizons, situated at the base and in an intermediate level of the models. During deformation of the models, these two décollement horizons generate two sets of structures, with different geometrical characteristics and significance. Through the joint analysis of geophysical and geological data and model results, wavelengths of the compressional structures analysed show that the structural style of the two analysed areas is almost similar. Moreover, model results prove that the final configuration of the thrust system follows the general rules of evolution of a wedge deformed above a weak décollement and is largely governed by the larger, deep seated structures.

  • 122. Mukherjee, S.
    et al.
    Koyi, Hemin A
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Higher Himalayan Shear Zone, Zanskar Indian Himalaya: microstructural studies and extrusion mechanism by a combination of simple shear and channel flow2010In: International journal of earth sciences, ISSN 1437-3254, E-ISSN 1437-3262, Vol. 99, no 5, p. 1083-1110Article in journal (Refereed)
    Abstract [en]

    Thin-section studies of the Zanskar Shear Zone (ZSZ) rocks reveal a top-to-SW and subsequent primary and secondary top-to-NE ductile shearing; brittle-ductile and brittle extensions; top-to-SW brittle shear, steep normal faulting and fracturing. In the proposed two-phase model of ductile extrusion of the Higher Himalayan Shear Zone (HHSZ), a top-to-SW simple shearing during 22-18 Ma was followed by a combination of top-to-SW simple shear and channel flow at 18-16 Ma. The second phase simulates a thin ZSZ characterized by a top-to-NE shearing. The channel flow component ceased around 16 Ma, the extruding HHSZ entered the brittle regime but the top-to-SW shearing continued until perturbed by faults and fractures. Variation in the extrusion parameters led to variable thickness of the ZSZ. Shear strain after the extrusion is presumably maximum at the boundaries of the HHSZ and falls towards the base of the ZSZ, which crudely matches with the existing data. The other predictions: (1) spatially uniform shear strain after the first stage, (2) fastest extrusion rate at the base of the ZSZ, and (3) a lack of continuation of the ZSZ along the Himalayan trend are not possible to validate due to paucity of suitable data. Non-parabolic shear fabrics of the ZSZ indicate their heterogeneous deformation.

  • 123. Mukherjee, S.
    et al.
    Talbot, Christopher J.
    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.
    Double detachments and secondary thrusting inside the higher Himalayan shear zone: intrinsic to extrusive flow patterns and independent to climate: insights from analogue models2008In: Bollettino di Geofisica Teorica ed Applicata, ISSN 0006-6729, Vol. 49, p. 257-261Article in journal (Refereed)
  • 124. Mukherjee, S.
    et al.
    Talbot, Christopher J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Koyi, Hemin A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Viscosity estimates of salt in the Hormuz and Namakdan salt diapirs, Persian Gulf2010In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 147, no 4, p. 497-507Article in journal (Refereed)
    Abstract [en]

    The parabolic surface profiles of the Hormuz and Namakdan salt diapirs in the Persian Gulf suggest that they have been extruding with Newtonian viscous rheologies for the last 104 years. We derive velocity profiles for these diapirs, neglecting gravitational spreading and erosion/dissolution while assuming incompressible Newtonian rheology of the salt. Fitting known rates of extrusion at specific points in its elliptical cross-section, the dynamic viscosity of the salt of the Hormuz diapir is found to range between 1018 and 1021 Pa s. Approximating its sub-circular cross-section to a perfect circle, the range of viscosity of the salt of the Namakdan diapir is obtained as 1017–1021 Pa s. These calculated viscosities fall within the range for naturally flowing salts elsewhere and for other salt diapirs but are broader than those for salts with Newtonian rheology deforming at room temperatures. The salts of the Hormuz and Namakdan diapirs are expected to exhibit a broader range of grain size, which matches the limited existing data.

  • 125.
    Mukherjee, Soumyajit
    et al.
    Department of Earth Sciences, Indian Institute of Technology Roorkee, Uttarakhand, India.
    Koyi, Hemin A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Microflanking Structures & Their Rheological Significance2007In: Annual Transactions - The Nordic Rheology Society, ISSN 1601-4057, Vol. 15, p. 243-245Article in journal (Refereed)
    Abstract [en]

    We report flanking structures from micro-scales from sheared rocks in the Himalaya, and designate them as ‘microflanking structures’. Cleavages and grain boundaries of host minerals act as shear plains and also impart anisotropy during shearing event. Rheological possibilities, other than a weaker host within a stronger matrix, have been encountered.

  • 126. Mukherjee, Soumyajit
    et al.
    Koyi, Hemin A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Talbot, Christopher J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Implications of channel flow analogue models for extrusion of the Higher Himalayan Shear Zone with special reference to the out-of-sequence thrusting2012In: International journal of earth sciences, ISSN 1437-3254, E-ISSN 1437-3262, Vol. 101, no 1, p. 253-272Article in journal (Refereed)
    Abstract [en]

    The Higher Himalayan Shear Zone (HHSZ) contains a ductile top-to-N/NE shear zone-the South Tibetan detachment system-lower (STDS(L)) and an out-of-sequence thrust (OOST) as well as a top-to-N/NE normal shear at its northern boundary and ubiquitously distributed compressional top-to-S/SW shear throughout the shear zone. The OOST that was active between 22 Ma and the Holocene, varies in thickness from 50 m to 6 km and in throw from 1.4 to 20 km. Channel flow analogue models of this structural geology were performed in this work. A Newtonian viscous polymer (PDMS) was pushed through a horizontal channel leading to an inclined channel with parallel and upward-diverging boundaries analogous to the HHSZ and allowed to extrude to the free surface. A top-to-N/NE shear zone equivalent to the STDS(U) developed spontaneously. This also indirectly connotes an independent flow confined to the southern part of the HHSZ gave rise to the STDS(L). The PDMS originally inside the horizontal channel extruded at a faster rate through the upper part of the inclined channel. The lower boundary of this faster PDMS defined the OOST. The model OOST originated at the corner and reached the vent at positions similar to the natural prototype some time after the channel flow began. The genesis of the OOST seems to be unrelated to any rheologic contrast or climatic effects. Profound variations in the flow parameters along the HHSZ and the extrusive force probably resulted in variations in the timing, location, thickness and slip parameters of the OOST. Variation in pressure gradient within the model horizontal channel, however, could not be matched with the natural prototype. Channel flow alone presumably did not result in southward propagation of deformation in the Himalaya.

  • 127. Mukherjee, Soumyajit
    et al.
    Koyi, Hemin A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Talbot, Christopher J.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Secondary Thrusting and Concomitant Extrusion of the Higher Himalayan Shear Zone Intrinsic to Flow Pattern and Independent to Climate- Insights from Analogue Models2008In: Himalayan geology, ISSN 0971-8966, Vol. 29, no 3, p. 53-53Article in journal (Refereed)
  • 128.
    Mukherjee, Soumyajit
    et al.
    Indian Institute of Technology Roorkee, Uttarakhand, India.
    Talbot, Christopher J.
    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.
    Estimation of salt Viscosity in the Hormuz- & the Namakdan Salt Diapirs, Persian Gulf2007In: Annual Transactions - The Nordic Rheology Society, ISSN 1601-4057, Vol. 15, p. 189-196Article in journal (Refereed)
    Abstract [en]

    The Hormuz- and the Namakdan salt diapirs extrude as parabolic profiles in the last 10 4  years. Velocity profiles of salts extruding through these diapirs are derived assuming Newtonian viscous flow of salts. Viscosity of salt in these diapirs are calculated to be 10 18-10 21 Pa s and10 17-10 21 Pa s, respectively.

  • 129.
    Mulugeta, G.
    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.
    Episodic accretion and strain partitioning in a model sand wedge1992In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 202, no 2-4, p. 319-333Article in journal (Refereed)
    Abstract [en]

    We model led thrust wedge accretion and deformation partitioning in a passively layered sand, detached and shortened above a smooth rigid decollement. The thrust wedge accretes in piggyback style during forward advance of a rear wall. The passively layered sand accommodates the shortening penetratively, by kinking/ramp folding, and by imbrication. In single layers, the style of compression changes with time and/or stratigraphic position within the sand prism. Initial penetrative layer shortening, above a slipped zone of decollement is succeeded by formation of monoclinal or conjugate shear bands at temporary terminations of decollement. The shear bands subsequently narrow down and lock as thrust ramps. The model sand wedge accrets episodically rather than steadily. Episodicity is controlled by the stick/slip mode of decollement propagation, and by volume loss and compaction of the wedge material in response to convergence. This results in formation of a wedge with a convex-upwards cross-sectional topography

  • 130.
    Mulugeta, Genene
    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.
    Three-dimensional geometry of piggyback thrusting1987In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 15, no 11, p. 1052-1056Article in journal (Refereed)
    Abstract [en]

    The three-dimensional geometry and kinematics of piggyback stacks of imbricate thrust sheets are illustrated and discussed using a single model shortened in a squeeze box. Strike-parallel geometric elements simulated include lateral ramps, eyed sheath folds, splays, and thrust/thrust interference. Fine details of these structures were exposed by eroding a shortened wedge of sand using a newly developed vacuum-eroding technique. A kinematic analysis of the model shows a stepwise increase in imbricate thrust spacing and/or a decrease in rate of nucleation of imbricate thrusts in the direction of thrust transport. Despite the steady forward advance of a rear wall, the piggyback wedge accreted episodically, recording different strain domains in longitudinal cross sections. Strain partitioning in single layers by bed-length balancing showed an increase in layer shortening with volume loss and a corresponding decrease in imbricate thrusting and ramp folding with depth.

  • 131.
    Nikkila, K.
    et al.
    Univ Helsinki, Inst Seismol, FI-00014 Helsinki, Finland..
    Korja, A.
    Univ Helsinki, Inst Seismol, FI-00014 Helsinki, Finland..
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Eklund, O.
    Abo Akad Univ, Geol & Mineral, FI-20500 Turku, Finland..
    Analog modeling of one-way gravitational spreading of hot orogens - A case study from the Svecofennian orogen, Fennoscandian Shield2015In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 268, p. 135-152Article in journal (Refereed)
    Abstract [en]

    Geodynamic models offer insight into deformation styles of syn- and post-collisional extensional processes. Such models often ignore the effect of lateral viscosity contrast between accreted terranes and inherited tectonic boundaries. This paper presents a set of crustal-scale analog experiments of one-way post-collisional gravitational spreading testing the effect of crustal heterogeneity by using two mechanically contrasting blocks, pre-existing cuts with varying dips, and three layers with contrasting rheologies. Two blocks represent strong, mature, and weak, juvenile crustal parts. Both blocks have three horizontal crustal layers: brittle upper, weak partially molten middle and dry strong lower layer. Cuts represent pre-existing crustal-scale shear zones and tectonic boundaries. The experiments indicated that tectonic boundaries may facilitate exhumation and increase extensional strain, when the boundaries dip opposite to the flow direction. The tectonic boundaries may also split and divide the crust into separate blocks with independent deformation signatures: shortening, elongation or rotation. The tectonic boundaries rotated along vertical axes toward the flow direction. The modeling results suggest that in areas with inherited tectonic boundaries and compositional differences the amount of extension is unevenly distributed between the different parts during the widespread unilateral gravitational spreading and that the flow has different effects on the contrasting crustal units, in both lateral and vertical directions. To validate the modeling, the results are compared to geophysical and geological data from the Paleo-proterozoic Svecofennian orogen in the Fennoscandian Shield. The comparison suggests that the orogen underwent 50% extension and was thinned by maximum of 20% via westward gravitational spreading. This spreading rotated the crustal-scale blocks, shear zones and tectonic contacts. It also brought exhumed, high grade middle crustal blocks into contact with subsided, low grade, upper crustal blocks. We suggest that results of the analog models can be used as proxies in both ancient and modern hot accreted orogens, which have undergone post-convergence continental mid-crustal weakening and have comprised of juxtaposed terranes with varying rheological compositions.

  • 132.
    Nilforoushan, Faramarz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Koyi, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Displacement fields and finite strains in a sandbox model simulating a fold-thrust-belt2007In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 169, no 3, p. 1341-1355Article in journal (Refereed)
    Abstract [en]

    A sandbox model consisting of two adjacent mechanically different decollements (frictional and viscous) loosely simulated the southeastern part of the Zagros fold-thrust-belt. Digital images of the model surface are used to coordinate passive markers on the surface and quantify displacement fields and estimate 2-D finite strains. These analyses show that, mapped in a fixed coordinate system, the deformation front propagates at different rates above the two decollements. Strain analysis of the model surface at different stages of deformation also shows that cumulative strain is more heterogeneous above the viscous decollement where strain domains are separated by fault zones. Maps of displacement fields, finite strain ellipses and dilatation also differ in character above the two decollements. Displacements above a viscous decollement decrease gradually towards the foreland, whereas they decrease sharply in front of the frontal thrust above the frictional decollement. Our analyses also show that the estimated finite strain depends not only on the density of the marker points chosen for the analysis, but also their initial distribution relative to the structures. This comparison shows that marker density limits measuring the actual strains in a heterogeneously deforming fold-thrust-belt and marker density and distribution have a strong impact on the strain analysed in nature. The similarity of our model with nature is examined with recent GPS study in the Zagros fold-thrust-belt (SW Iran) and shows, similar to the model results, that a weak salt decollement causes divergent movement in the sedimentary cover in SE Zagros.

  • 133.
    Nilforoushan, Faramarz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Swantesson, Jan O. H.
    Talbot, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Effect of basal friction on surface and volumetric strain in models of convergent settings measured by laser scanner2008In: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 30, no 3, p. 366-379Article in journal (Refereed)
    Abstract [en]

    This paper uses measurements by a high-accuracy laser scanner to investigate the role of basal friction on surface and volumetric strains in sandbox models simulating fold-thrust belts and accretionary wedges. We monitor progressive deformation, wedge growth, and strain distribution in three models with similar initial boundary conditions but with different basal frictions. Our analyses show that, in addition to influencing the kinematics and geometry of model wedges, basal friction also governs both the surface and volumetric strains of the wedge. After 16.3% bulk shortening, the volume decreased 5 +/- 0.5%, 9.5 +/- 0.5% and 12.5 +/- 0.5% in the models shortened above low, intermediate and high friction decollements, respectively. Applied to nature, our model results suggest that more compaction and penetrative strain is expected in convergent settings with a high-friction decollement than those shortened above a low-friction decollement or a weak basal bed (like the salt formation under parts of the Zagros fold-thrust belt). This volume decrease probably reduces the porosity in the deformed lithologies.

  • 134.
    Nilfouroushan, Faramarz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Pysklywec, Russell
    Cruden, Alexander
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Numerical modeling of salt-based mountain belts with pre-existing basement faults: application to the Zagros fold- and thrust belt, southwest Iran2013Conference paper (Refereed)
    Abstract [en]

    Two-dimensional thermal-mechanical models of thick-skinned, salt-based fold- and thrust belts, such as the Zagros,SW Iran, are used to address: 1) the degree of deformation and decoupling between cover and basement rocks dueto the presence of a weak salt detachment; 2) the reactivation potential of pre-existing basement normal faults dueto brittle or ductile behavior of the lower crust (as related to cold or hot geothermal gradients); and 3) variations indeformation style and strain distribution. The geometry and kinematics of the orogenic wedge and the activity ofpre-existing basement faults are strongly influenced by the geothermal gradient (defined by the Moho temperature,MT) and basement rheology. We infer that the MT plays a major role in how the lower and upper crust transferdeformation towards the foreland. In relatively hot geotherm models (MT = 600C at 36 km depth), the lowermostbasement deforms in a ductile fashion while the uppermost basement underlying the sedimentary cover deformsby folding, thrusting, and displacements along pre-existing basement faults. In these models cover units abovethe salt detachment are less deformed in the hinterland. In relatively cold geotherm models (MT = 400C at 36km depth), deformation is mainly restricted to the hinterland of the models where basement imbricates form.Detachment folding, thrusting and gravity gliding occur within cover sediments above uplifted basement blocks.Gravity gliding contributes to a larger amount of shortening in the cover compared to the basement.

  • 135.
    Nilfouroushan, Faramarz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Pysklywec, Russell
    Cruden, Alexander
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Thermal-mechanical modeling of salt-based mountain belts with pre-existing basement faults: application to the Zagros fold and thrust belt, southwest Iran2013In: Tectonics, ISSN 0278-7407, E-ISSN 1944-9194, Vol. 32, no 5, p. 1212-1226Article in journal (Refereed)
    Abstract [en]

    Two-dimensional thermal-mechanical models of thick-skinned, salt-based fold and thrust belts,  such as the Zagros, SW Iran, are used to address: 1) the degree of deformation and decoupling between cover and basement rocks due to the presence of a weak salt detachment; 2) the reactivation potential of pre-existing basement normal faults due to brittle or ductile behavior of the lower crust (as related to cold or hot geothermal gradients); and 3) variations in deformation style and strain distribution. The geometry and kinematics of the orogenic wedge and the activity of pre-existing basement faults are strongly influenced by the geothermal gradient (defined by the Moho temperature, MT) and basement rheology. We infer that the MT plays a major role in how the lower and upper crust transfer deformation towards the foreland. In relatively hot geotherm models (MT = 600°C at 36 km depth), the lowermost basement deforms in a ductile fashion while the uppermost basement underlying the sedimentary cover deforms by folding, thrusting, and displacements along pre-existing basement faults. In these models, cover units above the salt detachment occur within a less deformed, wide plateau in the hinterland. In relatively cold geotherm models (MT = 400°C at 36 km depth), deformation is mainly restricted to basement imbricate thrusts that form within the orogenic hinterland. Detachment folding, thrusting and gravity gliding occur within cover sediments above uplifted basement blocks. Gravity gliding contributes to a larger amount of shortening in the cover compared to the basement.

  • 136.
    Nilfouroushan, Faramarz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Pysklywec, Russell
    Cruden, A.R.
    Koyi, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Role of Basement Faults on the Crustal Wedge Deformation of the Zagros fold-thrust belt, New Insights from 2-D Thermo-mechanical Numerical Models2010Conference paper (Refereed)
  • 137.
    Nilfouroushan, Faramarz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Talbot, C.J.Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.Hodacs, PeterUppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.Koyi, HeminUppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.Sjöberg, LarsRoyal Institute of Technology (KTH), Stockholm, Sweden.
    Geodetic horizontal velocity and strain rate fields around Lake Vänern (SW Sweden) derived from GPS measurements between 1997 and 20112012Conference proceedings (editor) (Refereed)
    Abstract [en]

    In 1989, the Värmland GPS network consisting of 8 stations spaced an average of 60 km apart was setup to monitor the ongoing deformation in and around Lake Vänern due to tectonic and mainly Glacial Isostatic Adjustment (GIA) processes in Fennoscandia. This network covers an area of about 10000 km2, straddles the Protogine and the Mylonite zones and includes one of the most active seismic zones of Sweden. We use GAMIT-GLOBK software to process the past GPS data, collected in October 1997, the only campaign that was measured with choke ring antenna, and the new GPS measurements in October 2010 and 2011 to estimate station velocities. We also integrate our local network with the SWEPOS (Swedish Permanent GPS network) and IGS (International GNSS Service) stations to better constrain the velocity fields in ITRF2008 and Eurasia-fixed reference frames. Since the rates of horizontal movements are very slow (less than 1 mm/year), our measurements in longer time spans (at least in 13 years, between 1997 to 2010, 2011 and planned 2012) better resolve the tectonic signal from the noise. Preliminary results obtained from campaign-mode measurements in 1997, 2010 and 2011 agree well with those reported in the latest study by Lidberg et al. (2010) who used the data from permanent GPS stations of the BIFROST (Baseline Inferences for Fennoscandian Rebound Observations Sea Level and Tectonics) project. Strain-rate analysis resulting from the obtained velocities illustrates the overall extensional component trending NW-SE with local variations. Adding more campaigns in 2012 and 2013 will surely increase the reliability of our analysis. The velocity field obtained from this research will add more details to the tectonic picture generated by BIFROST. The results are also relevant to GIA modeling, geodetic vs. seismic strain accumulation, waste isolation and seismic hazards.

  • 138.
    Oskooi, B.
    et al.
    Institute of Geophysics, University of Tehran, Tehran, Iran.
    Mansoori, I
    Institute of Geophysics, University of Tehran, Tehran, Iran.
    Pedersen, Laust B.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    A Magnetotelluric Survey on Ophiolites in Neyriz area of southwestern Iran2015In: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 172, p. 491-502Article in journal (Refereed)
    Abstract [en]

    A wide band magnetotelluric study of the ophiolitic zone of the Zagros orogenic belt was conducted in the Neyriz area of southwestern Iran. The purpose of the study was to image subsurface structures electrically and relocate the main Zagros thrust fault in the region. The thrust fault has a complex structure with obscure behavior and is believed to be located within a zone of ongoing continental plate convergence. The fault zone with a NW–SE geological trend is parallel to the Zagros orogenic belt and separates the Neyriz ophiolite assemblage from the adjacent Sanandaj-Sirjan metamorphic zone. Magnetotelluric data were collected along a SW–NE profile across the geologic strike; the study included 18 stations and modeling was performed using a 2-D inversion scheme. Analysis of both modes of magnetotelluric data (TE and TM) clarifies the signatures of large resistivity variation in the study area. Due to the presence of a high contrast in resistivity between the ophiolites and neighboring rocks, we are able to discern two sharp boundaries as faulting planes and borders of the ophiolite–radiolarite zone in the north-eastern and southwestern parts of the 2-D resistivity models, respectively.

  • 139. Oskooi, B.
    et al.
    Mansoori, I.
    Pedersen, Laust Börsting
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Koyi, Hemin A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    A Magnetotelluric Survey of Ophiolites in the Neyriz area of southwestern Iran2015In: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 172, no 2, p. 491-502Article in journal (Refereed)
    Abstract [en]

    A wide band magnetotelluric study of the ophiolitic zone of the Zagros orogenic belt was conducted in the Neyriz area of southwestern Iran. The purpose of the study was to image subsurface structures electrically and relocate the main Zagros thrust fault in the region. The thrust fault has a complex structure with obscure behavior and is believed to be located within a zone of ongoing continental plate convergence. The fault zone with a NW-SE geological trend is parallel to the Zagros orogenic belt and separates the Neyriz ophiolite assemblage from the adjacent Sanandaj-Sirjan metamorphic zone. Magnetotelluric data were collected along a SW-NE profile across the geologic strike; the study included 18 stations and modeling was performed using a 2-D inversion scheme. Analysis of both modes of magnetotelluric data (TE and TM) clarifies the signatures of large resistivity variation in the study area. Due to the presence of a high contrast in resistivity between the ophiolites and neighboring rocks, we are able to discern two sharp boundaries as faulting planes and borders of the ophiolite-radiolarite zone in the north-eastern and southwestern parts of the 2-D resistivity models, respectively.

  • 140. Oskooi, B.
    et al.
    Pedersen, Laust Börsting
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Koyi, Hemin A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Magnetotelluric signature for the Zagros collision2014In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 196, no 3, p. 1299-1310Article in journal (Refereed)
    Abstract [en]

    Zagros is a relatively young and active fold-thrust belt, which has formed due to convergence between the Eurasian and Arabian plates. Magnetotelluric (MT) soundings along a transect were carried out to determine the crustal structure in the collision zone of the two Palaeocontinents. MT data were analysed and modelled using 2-D inversion schemes. The models show clear conductive and resistive domains along the MT profile consistent to a great extent with documented tectonic features and surface geology. The models obtained from the joint inversion of transverse electric and transverse magnetic modes as well as the inversion of the determinant data show similar features along the profile. The new MT results reveal that the transition between two continents at the surface coincides with the western boundary of Sanandaj-Sirjan Zone (SSZ) at the Main Zagros Thrust (MZT). Along the profile towards northeast the conductors at top indicate massive Neogene sediments of the central domain (CD) while the very thick, shallow-located, resistive body (5-25 km thick and 100 km long) beneath is unlikely to be of oceanic affinity, but continental. Another main feature along the profile is the main resistive and conductive parts of the Arabian Plate, which coincide with the tectonic events of High Zagros Fault and Mountain Front Fault. Two highly conductive thick zones are recognized at the southwest part and in the middle of the profile apparently extending to a depth of about 50 km, possibly related to a downward smearing effect due to the presence of thick sedimentary columns in the upper crust. Along the profile, conductive features are recognized at the metamorphic SSZ and Urumieh-Dokhtar Magmatic Assemblage units as well as at CD. Below site 31 along the surface trace of the MZT, the transition between the two continents is distinguished by a complex sequence of conductive and resistive zones both varying laterally as well as vertically. The main difference between the two domains is that the Eurasian Plate seems to be more resistive than the Arabian Plate, although some part of the difference can be related to the thick sequence of conductive sedimentary rocks on the Arabian Plate.

  • 141.
    Rahmati-Ilkhchi, Mahmoud
    et al.
    Institute of Petrology and Structural Geology, Charles University in Prague, Czech Republic.
    Jeřábek, Petr
    Geological Survey of Iran, Meraj, Tehran, Iran.
    Faryad, Shah Wali
    Institute of Petrology and Structural Geology, Charles University in Prague, Czech Republic.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Mid-Cimmerian, Early Alpine and Late Cenozoic orogenic events in the Shotur Kuh metamorphic complex, Great Kavir block, NE Iran2010In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 494, no 1-2, p. 101-117Article in journal (Refereed)
    Abstract [en]

    The Shotur Kuh complex, exposed in the NE part of the Great Kavir block, is composed of amphibolite facies metaigneous rocks and micaschist, and of lower-grade Permian–Miocene cover sequences that experienced four main deformation phases and at least two metamorphic events. The D1 deformation phase is associated with a prograde metamorphism that in the basement reached amphibolite facies conditions. This Barrovian-type metamorphism with field gradient of 20–22 °C/km was related to collision-induced crustal thickening. The D2 event corresponds to post-collisional exhumational upflow of middle crust, resulting in updoming of the basement core and its top-to-the-Northwest unroofing along a low-angle detachment shear zone at the basement/cover boundary. The D1 and D2 events are considered as Mid-Cimmerian in age because they also affected the Upper Triassic–Lower Jurassic Shemshak Formation and are sealed by the Middle Jurassic conglomerates. The D3 folding event, characterised by NE–SW shortening, also affected the Cretaceous limestones, and it is sealed by Paleocene conglomerates. Considering the Late Cretaceous age of this deformation, it is related to the Late Cimmerian–Early Alpine orogeny that resulted from the Cenozoic closure of the Neo-Tethys oceanic tract(s) and convergence between the Arabian and Eurasian plates. The D4 folding event, characterised by NW–SE shortening, also affected the Miocene conglomerates, suggesting its Miocene or post-Miocene age. This deformation event is associated with Late Cenozoic convergence between Arabia and Eurasia, and it could be combined with a left-lateral activity along the Great Kavir fault-bounding system.

  • 142. Roca, Eduard
    et al.
    Sans, Maura
    Koyi, Hemin
    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.
    Polyphase deformation of diapiric areas in models and in the Eastern Prebetics (Spain)2006In: American Association of Petroleum Geologists Bulletin, Vol. 90, p. 115-136Article in journal (Refereed)
  • 143.
    Rojo, Luis Alberto
    et al.
    Deparment of Energy Resources, University of Stavanger, 4036 Stavanger, Norway.
    Cardozo, Nestor
    Deparment of Energy Resources, University of Stavanger, 4036 Stavanger, Norway.
    Escalona, Alejandro
    Deparment of Energy Resources, University of Stavanger, 4036 Stavanger, Norway.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Structural style and evolution of the Nordkapp Basin, Norwegian Barents Sea2019In: American Association of Petroleum Geologists Bulletin, ISSN 0149-1423, E-ISSN 1558-9153, Vol. 103, no 9, p. 2177-2217Article in journal (Refereed)
    Abstract [en]

    After three decades of research and hydrocarbon exploration in the Nordkapp Basin (Norwegian Barents Sea), the dynamics of Mesozoic salt mobilization is still poorly understood. Both, progradational loading and basement-involved extension have been proposed as triggers of salt mobilization, where the latter is most accepted. This study combines 2D and 3D seismic reflection data, borehole data, isochore maps and structural restorations to: (1) provide a tectonostratigraphic evolution of the Nordkapp Basin, (2) indicate which triggering mechanisms fit the observed structural styles, and (3) determine the geological controls that influenced the along-strike distribution of salt structures in the basin. Our results indicate that a combination of Early–Middle Triassic thick-skinned extension and sediment loading induced the differential loading and mobilization of the underlying salt, generating a series of NW-shifting minibasins bounded by salt walls, ridges and stocks. Sediment loading and the distribution of salt structures were strongly conditioned by rheology variations within the salt layer and subsalt fault activity which: (1) created tectonically-induced depressions that became preferential areas of infill and differential loading; (2) caused faulting and extension of the overburden, allowing the preferential growth of reactive diapirs which later on evolved into passive diapirs; and (3) acted as effective barriers of salt expulsion, enhancing salt inflation and growth of salt above the subsalt faults. Early Triassic differential loading occurred diachronically along strike, causing early passive diapirism, salt welding, and salt depletion in the eastern and central subbasins due to the diachronous subsalt activity and the closer proximity of these basins respect to the sediment source, the Uralides. Although most of the salt was depleted by the end of the Middle Triassic, the ongoing extension created across-fault thickness variations and sagging of some of the WNW-ESE salt walls in the central subbasin. The rest of the structures in the Nordkapp Basin continued growing until the end of the Mesozoic by minor evacuation of the remaining salt and thin-skinned gliding and subsequent shortening triggered by subsalt fault activity. Finally, salt structures were rejuvenated and eroded during Cenozoic contraction and uplift. These results have implications for the 4D understanding of the Nordkapp Basin and its petroleum system, and they can be used as an analogue to decipher other confined salt bearing-basins alike.

  • 144.
    Rönnlund, p.
    et al.
    Berggrundsgeologi.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Fry spacing of deformed and undeformed modelled and natural salt domes1988In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 16, no 5, p. 465-468Article in journal (Refereed)
    Abstract [en]

    Fry's center-point spacing strain analysis is applied to experiments of gravity-driven overturn of horizontal fluid layers on scales of centimetres or decimetres, and to natural salt diapirs on scales of kilometres to tens of kilometres. Laboratory experiments in which about 100 diapirs formed from initially plane horizontal layers resulted in laterally isotropic spacing and yielded an open circle on a Fry plot with a radius equal to the wavelength (W). Lateral deformation and initial departures from horizontal layers with uniform properties may influence W. Sample experiments of diapirism with and without lateral deformation are compared to natural equivalents.

    The spacing of post-Late Triassic diapirs in the Zechstein salt of Germany and of post-Jurassic diapirs in the Hormuz salt of Arabia yields circles on Fry plots which indicate that these gravity structures developed without additional lateral forces. Fry plots of the spacing of salt diapirs in the Zagros Mountains define a strain ellipse with the long axis (= W in Arabia) parallel and the short axis perpendicular to post-Miocene regional fold axes. The ratio of the Zagros strain ellipse is about 1.7, which suggests a northeast-southwest shortening of 41%, rather than 10%-21% as estimated from folding alone. This mismatch may be a result of unquantified shortening due to thrusts and/or layer-parallel shortening. Center-point spacing of post-Late Triassic domes of Zechstein salt in the central North Sea also gives an ellipse. Here, the long axis coincides with the direction of Middle Jurassic to Cretaceous extension. The axial ratio of the North Sea strain ellipse is about 2.8, compared to estimates of about 1.5-2.0 by Sclater and Christie, and 1.8 by Wood and Barton.

  • 145. Sans, Maura
    et al.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Modeling the role of erosion in diapir development in contractional settings2001In: Tectonic Modeling: A Volume in Honor of Hans Ramberg / [ed] Hemin Koyi, Neil S. Mancktelow, Geological Society of America , 2001, p. 111-122Chapter in book (Refereed)
  • 146.
    Sattar, Nauman
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Juhlin, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics. ¨.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Ahmad, Nadeem
    United Energy Pakistan, Karachi, Pakistan..
    Seismic stratigraphy and hydrocarbon prospectivity of the Lower, Cretaceous Knurr Sandstone lobes along the southern margin of Loppa High, Hammerfest Basin, Barents Sea2017In: Marine and Petroleum Geology, ISSN 0264-8172, E-ISSN 1873-4073, Vol. 85, p. 54-69Article, review/survey (Refereed)
    Abstract [en]

    The Lower Cretaceous Knurr Sandstone deposited along the southern slope of Loppa High and overlain by the Kolje and Kolmule seals forms an attractive play in the Hammerfest Basin of the Barents Sea. Late Jurassic organic-rich Hekkingen shale directly underlies the Knurr Sandstone and acts as a source to provide effective charge. Three wells, 7120/2-2, 7122/2-1 and 7120/1-2, have proven the Knurr-Kolje play in structural traps, with an oil discovery in 7120/1-2. Prospectivity related to stratigraphic traps is, however, highly under-explored. In order to document and map the reservoir distribution and stratigraphic-trap fairway, the Lower Cretaceous sedimentary package containing the Knurr Sandstone is divided into a number of depositional sequences and systems tracts using key regional seismic profiles calibrated with logs. Mapping of the key surfaces bounding the Knurr sandstone has been carried out using all the seismic vintages available from Norwegian Petroleum Directorate (NPD).The thick massive nature of the sandstone (123 m in well 7122/2-1), sedimentary features characteristic of gravity flow deposits, high-resolution internal seismic reflections and stratal geometries (truncations and lapout patterns), and sequence stratigraphic position of the Knurr Sandstone on seismic profiles confirm that the lobes identified on the seismic section are gravity driven base of the slope lobes. These Knurr lobes and slope aprons were formed as a result of uplift of the Loppa paleo-high in the Late Jurassic to Early Cretaceous times which caused subaerial exposure and incision. The characteristic mounded, lobate geometry evident on the seismic can be mapped along the toe-of-slope and records multiple stacked lobes fed by multiple feeder canyons. Lateral partitioning and separation of the lobes along the toe-of-slope could potentially create strati graphic traps. The existing 2D seismic coverage is, however, not sufficient to capture lateral stratigraphic heterogeneity to identify stratigraphic traps. 3D seismic coverage with optimum acquisition parameters (high spatial and vertical resolution, appropriate seismic frequency and fold, long offsets and original amplitudes preserved) can allow for the reconstruction of 3D geomorphologic elements to de-risk potential stratigraphic traps prior to exploratory drilling.

  • 147. Schreurs, G.
    et al.
    Buiter, S.
    Burberry, C.
    Callot, Jean-Paul
    Cavozzi, C.
    Cerca, M.
    Cristallini, E.
    Cruden, A.
    Chen, J.H.
    Cruz, L.
    Daniel, J.M.
    Garcia, V.H.
    Gomes, C.
    Grall, C.
    Guzmán, C.
    Nur Hidayah, T.
    Hilley, G.
    Lu, C.Y.
    Klinkmüller, M.
    Koyi, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Macauley, J.
    Maillot, B.
    Meriaux, C.
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Pan, C.C.
    Pillot, D.
    Portillo, R.
    Rosenau, M.
    Schellart, W.P.
    Schlische, R.
    Take, A.
    Vendeville, B.
    Vettori, M.
    Vergnaud, M.
    Wang, S.H.
    Withjack, M.
    Yagupsky, D.
    Yamada, Y.
    Quantitative comparisons of analogue models of brittle wedge2010Conference paper (Refereed)
  • 148. Schreurs, G.
    et al.
    Buiter, SJH
    Boutelier, D.
    Corti, G.
    Costa, E
    Cruden, AR
    Daniel, J.M.
    Hoth, S
    Koyi, H
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Kukowski, N
    Lohrmann, J
    Ravaglia, A
    Schlishe, RW
    Withjack, MO
    Yamada, Y.
    Cavozzi, C
    Delventisette, C
    Elder Brady, JA
    Hoffmann-Rothe, A
    Mengus, J-M
    Montanari, D
    Nilforoushan, F.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Analogue benchmarks of shortening and extension experiments2006In:  Analogue and Numerical Modeling of Crustal-Scale Processes,, Geological Society of London, 2006, 253, p. 1-27Chapter in book (Refereed)
    Abstract [en]

    We report a direct comparison of scaled analogue experiments to test thereproducibility of model results among ten different experimental modelling laboratories.We present results for two experiments: a brittle thrust wedge experiment and a brittleviscousextension experiment. The experimental set-up, the model construction technique,the viscous material and the base and wall properties were prescribed. However, each laboratoryused its own frictional analogue material and experimental apparatus. Comparisonof results for the shortening experiment highlights large differences in model evolutionthat may have resulted from (1) differences in boundary conditions (indenter or basal-pullmodels), (2) differences in model widths, (3) location of observation (for example, sidewallversus centre of model), (4) material properties, (5) base and sidewall frictional properties,and (6) differences in set-up technique of individual experimenters. Six laboratories carriedout the shortening experiment with a mobile wall. The overall evolution of their models isbroadly similar, with the development of a thrust wedge characterized by forward thrustpropagation and by back thrusting. However, significant variations are observed inspacing between thrusts, their dip angles, number of forward thrusts and back thrusts, andsurface slopes. The structural evolution of the brittle-viscous extension experiments issimilar to a high degree. Faulting initiates in the brittle layers above the viscous layer in close vicinity to the basal velocity discontinuity. Measurements of fault dip angles and faultspacing vary among laboratories. Comparison of experimental results indicates an encouragingoverall agreement in model evolution, but also highlights important variations in thegeometry and evolution of the resulting structures that may be induced by differences inmodelling materials, model dimensions, experimental set-ups and observation location

  • 149. Schreurs, Guido
    et al.
    Buiter, Susanne
    Corti, Giacomo
    Costa, Elisabetta
    Lohrmann, Jo
    Boutelier, David
    Koyi, Hemin
    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.
    Cavozzi, Cristian
    Analogue benchmarks of shortening and extension experiments2006In: Geological Society. London, Special Publication, Vol. 253, p. 1-27Article in journal (Refereed)
  • 150.
    Schreurs, Guido
    et al.
    Univ Bern, Inst Geol Sci, Baltzerstr 1 & 3, CH-3012 Bern, Switzerland..
    Buiter, Susanne J. H.
    Geol Survey Norway, Geodynam Team, N-7491 Trondheim, Norway.;Univ Oslo, Ctr Earth Evolut & Dynam, POB 1048, N-0316 Oslo, Norway..
    Boutelier, Jennifer
    Univ Toronto, Dept Geol, 22 Russell St, Toronto, ON M5S 3B1, Canada..
    Burberry, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Univ Nebraska Lincoln, Dept Earth & Atmospher Sci, 214 Bessey Hall,POB 880340, Lincoln, NE 68588 USA..
    Callot, Jean-Paul
    IFP Energies Nouvelles, 1 & 4 Ave Bois Preau, F-92500 Rueil Malmaison, France.;Univ Pau & Pays Adour, Lab Fluides Complexes & Leurs Reservoirs, UMR5150, BP 1155, F-64012 Pau, France..
    Cavozzi, Cristian
    Univ Parma, Dept Phys & Earth Sci Macedonio Melloni, NEXT Nat & Expt Tecton Res Grp, Via G Usberti 157-A, I-43100 Parma, Italy..
    Cerca, Mariano
    Univ Nacl Autonoma Mexico, Ctr Geociencias, Blvd Juriquilla 3001, Juriquilla 76230, Queretaro, Mexico..
    Chen, Jian-Hong
    Natl Taiwan Univ, Dept Geosci, 1 Roosevelt Rd Sect 4, Taipei 106, Taiwan..
    Cristallini, Ernesto
    Univ Buenos Aires, Dept Ciencias Geol, Pabellon 2,Ciudad Univ,C1428EHA, Buenos Aires, DF, Argentina..
    Cruden, Alexander R.
    Univ Toronto, Dept Geol, 22 Russell St, Toronto, ON M5S 3B1, Canada.;Monash Univ, Sch Earth Atmosphere & Environm, Melbourne, Vic 3800, Australia..
    Cruz, Leonardo
    Stanford Univ, Dept Geol & Environm Sci, Braun Hall 215, Stanford, CA 94305 USA..
    Daniel, Jean -Marc
    IFP Energies Nouvelles, 1 & 4 Ave Bois Preau, F-92500 Rueil Malmaison, France.;IFREMER, Dept Phys Resources & Deep Sea Ecosyst PDG REM, Ctr Bretagne, ZI Pointe Diable, CS 10070, F-29280 Plouzane, France..
    Da Poian, Gabriela
    Univ Buenos Aires, Dept Ciencias Geol, Pabellon 2,Ciudad Univ,C1428EHA, Buenos Aires, DF, Argentina.;Univ Nacl Rio Negro, Inst Invest Paleobiol & Geol, Isidro Lobo 516, RA-8332 Gen Roca, Rio Negro, Argentina..
    Garcia, Victor H.
    Univ Buenos Aires, Dept Ciencias Geol, Pabellon 2,Ciudad Univ,C1428EHA, Buenos Aires, DF, Argentina.;Univ Nacl Rio Negro, Inst Invest Paleobiol & Geol, Isidro Lobo 516, RA-8332 Gen Roca, Rio Negro, Argentina..
    Gomes, Caroline J. S.
    Univ Fed Ouro Preto, Dept Geol, Morro Cruzeiro S-N 35, BR-400000 Ouro Preto, MG, Brazil..
    Grall, Celine
    IFP Energies Nouvelles, 1 & 4 Ave Bois Preau, F-92500 Rueil Malmaison, France.;Columbia Univ, Marine Geol & Geophys, Lamont Doherty Earth Observ, Palisades, NY 10964 USA..
    Guillot, Yannick
    Univ Lille Nord France, Lab Geosyst, FRE CNRS 3298, F-59655 Villeneuve Dascq, France..
    Guzman, Cecilia
    Univ Buenos Aires, Dept Ciencias Geol, Pabellon 2,Ciudad Univ,C1428EHA, Buenos Aires, DF, Argentina..
    Hidayah, Triyani Nur
    Rutgers State Univ, Dept Earth & Planetary Sci, 610 Taylor Rd, Piscataway, NJ 08854 USA..
    Hilley, George
    Stanford Univ, Dept Geol & Environm Sci, Braun Hall 233, Stanford, CA 94305 USA..
    Klinkmuller, Matthias
    Univ Bern, Inst Geol Sci, Baltzerstr 1 & 3, CH-3012 Bern, Switzerland..
    Koyi, Hemin A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Lu, Chia-Yu
    Natl Taiwan Univ, Dept Geosci, 1 Roosevelt Rd, Taipei 106, Taiwan..
    Maillot, Bertrand
    Univ Cergy Pontoise, Lab Geosci & Environm Cergy, 5 Mail Gay Lussac, F-95031 Neuville Sur Oise, Cergy Pontoise, France..
    Meriaux, Catherine
    Univ Lisbon, Dept Engn Geog Geofis & Energia, P-1749016 Lisbon, Portugal..
    Nilfouroushan, Faramarz
    Univ Gavle, Dept Ind Dev IT & Land Management, Gavle, Sweden..
    Pan, Chang-Chih
    Natl Taiwan Univ, Dept Geosci, 1 Roosevelt Rd Sect 4, Taipei 106, Taiwan..
    Pillot, Daniel
    IFP Energies Nouvelles, 1 & 4 Ave Bois Preau, F-92500 Rueil Malmaison, France..
    Portillo, Rodrigo
    Univ Nacl Autonoma Mexico, Ctr Geociencias, Blvd Juriquilla 3001, Juriquilla 76230, Queretaro, Mexico..
    Rosenau, Matthias
    Helmholtz Ctr Potsdam, GFZ German Res Ctr Geosci, D-14473 Potsdam, Germany..
    Schellart, Wouter P.
    Monash Univ, Sch Earth Atmosphere & Environm, Melbourne, Vic 3800, Australia..
    Schlische, Roy W.
    Rutgers State Univ, Dept Earth & Planetary Sci, 610 Taylor Rd, Piscataway, NJ 08854 USA..
    Take, Andy
    Queens Univ, Dept Civil Engn, Kingston, ON K7L 3N6, Canada..
    Vendeville, Bruno
    Univ Lille, UMR 8187, LOG, F-59000 Lille, France..
    Vergnaud, Marine
    IFP Energies Nouvelles, 1 & 4 Ave Bois Preau, F-92500 Rueil Malmaison, France..
    Vettori, Matteo
    Univ Parma, Dept Phys & Earth Sci Macedonio Melloni, NEXT Nat & Expt Tecton Res Grp, Via G Usberti 157-A, I-43100 Parma, Italy.;E FEM Srl, CAE Struct Anal & Composite Design, CTO Area, Parma, Italy..
    Wang, Shih-Hsien
    Natl Taiwan Univ, Dept Geosci, 1 Roosevelt Rd Sect 4, Taipei 106, Taiwan..
    Withjack, Martha O.
    Rutgers State Univ, Dept Earth & Planetary Sci, 610 Taylor Rd, Piscataway, NJ 08854 USA..
    Yagupsky, Daniel
    Univ Buenos Aires, Dept Ciencias Geol, Pabellon 2,Ciudad Univ,C1428EHA, Buenos Aires, DF, Argentina..
    Yamada, Yasuhiro
    Kyoto Univ, Dept Civil & Earth Resources Engn, Kyoto 6158540, Japan..
    Benchmarking analogue models of brittle thrust wedges2016In: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 92, p. 116-139Article in journal (Refereed)
    Abstract [en]

    We performed a quantitative comparison of brittle thrust wedge experiments to evaluate the variability among analogue models and to appraise the reproducibility and limits of model interpretation. Fifteen analogue modeling laboratories participated in this benchmark initiative. Each laboratory received a shipment of the same type of quartz and corundum sand and all laboratories adhered to a stringent model building protocol and used the same type of foil to cover base and sidewalls of the sandbox. Sieve structure, sifting height, filling rate, and details on off-scraping of excess sand followed prescribed procedures. Our analogue benchmark shows that even for simple plane-strain experiments with prescribed stringent model construction techniques, quantitative model results show variability, most notably for surface slope, thrust spacing and number of forward and backthrusts. One of the sources of the variability in model results is related to slight variations in how sand is deposited in the sandbox. Small changes in sifting height, sifting rate, and scraping will result in slightly heterogeneous material bulk densities, which will affect the mechanical properties of the sand, and will result in lateral and vertical differences in peak and boundary friction angles, as well as cohesion values once the model is constructed. Initial variations in basal friction are inferred to play the most important role in causing model variability. Our comparison shows that the human factor plays a decisive role, and even when one modeler repeats the same experiment, quantitative model results still show variability. Our observations highlight the limits of up-scaling quantitative analogue model results to nature or for making comparisons with numerical models. The frictional behavior of sand is highly sensitive to small variations in material state or experimental set-up, and hence, it will remain difficult to scale quantitative results such as number of thrusts, thrust spacing, and pop-up width from model to nature.

1234 101 - 150 of 169
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf