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  • 1. Bayer, R
    et al.
    Chery, J
    Tatar, M
    Vernant, Ph
    Abbassi, M
    Masson, F
    Nilforoushan, F
    Doerflinger, E
    Regard, V
    Bellier, O
    Active deformation in Zagros-Makran transition zone inferred from GPS measurements2006In: Geophysical Journal International, Vol. 165, no 1, p. 373-381Article in journal (Refereed)
    Abstract [en]

    The Bandar Abbas-Strait of Hormuz zone is considered as a transition between the Zagros collision and the Makran oceanic subduction. We used GPS network measurements collected in 2000 and 2002 to better understand the distribution of the deformation between the collision zone and the Makran subduction. Analysing the GPS velocities, we show that transfer of the deformation is mainly accommodated along the NNW–SSE-trending reverse right-lateral Zendan–Minab–Palami (ZMP) fault system. The rate is estimated to 10 ± 3 mm yr−1 near the faults. Assuming that the ZMP fault system transfers the motion between the Makran–Lut Block and the Arabian plate, we estimate to 15 mm yr−1 and 6 mm yr−1, respectively, the dextral strike-slip and shortening components of the long-term transpressive displacement. Our geodetic measurements suggest also a 10–15 km locking depth for the ZMP fault system. The radial velocity pattern and the orientation of compressive strain axes around the straight of Hormuz is probably the consequence of the subducting Musandam promontory. The N–S Jiroft–Sabzevaran (JS) fault system prolongates southwards the dextral shear motion of the Nayband–Gowk (NG) fault system at an apparent rate of 3.1 ± 2.5 mm yr−1. The change from strong to weak coupling for underthrusting the Arabian plate beneath the Zagros (strong) and the Makran (weak) may explain the dextral motion along the ZMP, JS/NG and Neh–Zahedan fault systems which transfer the convergence from a broad zone in the western Iran (Zagros, Tabriz fault system, Alborz, Caucasus and Caspian sea surroundings) to Makran subduction.

  • 2. Buiter, S.
    et al.
    Schreurs, G.
    Albertz, M.
    Beaumont, C.
    Burberry, C.
    Callot, Jean-Paul
    Cavozzi, C.
    Cerca, M.
    Chen, J.H.
    Cristallini, E.
    Cruden, A.
    Cruz, L.
    Cooke, M.
    Daniel, J.M.
    Egholm, D.
    Ellis, S.
    Gerya, T.
    Hodkinson, L.
    Hofmann, F.
    Garcia, V.H.
    Gomes, C.
    Grall, C.
    Guillou, H.
    Guzmán, C.
    Nur Hidayah, T.
    Hilley, G.
    Kaus, B.
    Klinkmüller, M.
    Koyi, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Lazor, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Lu, C.Y.
    Macauley, J.
    Maillot, B.
    Meriaux, C.
    Mishin, Y.
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Pan, C.C.
    Pascal, C.
    Pillot, D.
    Portillo, R.
    Rosenau, R.
    Schellart, W.P.
    Schlische, R.
    Soulomiac, P.
    Take, A.
    Vendeville, B.
    Vettori, M.
    Vergnaud, M.
    Wang, S.H.
    Withjack, M.
    Yagupsky, D.
    Yamada, Y.
    Benchmarking the Sandbox: Quantitative Comparisons of Numerical and Analogue Models of Brittle Wedge Dynamics2010Conference paper (Refereed)
  • 3.
    Carrillo, Emilio
    et al.
    Univ Barcelona, Dept Geoquim Petr & Prospeccio Geol, C Marti & Franques S-N, E-08028 Barcelona, Spain.;Yachay Tech Univ, Sch Geol Sci & Engn, Hacienda San Jose S-N, San Miguel De Urcuqui, Ecuador..
    Koyi, Hemin A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Nilforoushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Univ Gavle, Dept Ind Dev IT & Land Management, Gavle, Sweden.;Lantmateriet, Gavle, Sweden..
    Structural significance of an evaporite formation with lateral stratigraphic heterogeneities (Southeastern Pyrenean Basin, NE Spain)2017In: Marine and Petroleum Geology, ISSN 0264-8172, E-ISSN 1873-4073, Vol. 86, p. 1310-1326Article in journal (Refereed)
    Abstract [en]

    We run a series of analogue models to study the effect of stratigraphic heterogeneities of an evaporite formation on thin-skinned deformation of the Southeastern Pyrenean Basin (SPB; NE Spain). This basin is characterized by the existence of evaporites, deposited during the Early-Middle Eocene with lateral variations in thickness and lithological composition. These evaporites are distributed in three lithostratigraphic units, known as Serrat Evaporites, Vallfogona and Beuda Gypsum formations and acted as decollement levels, during compressional deformation in the Lutetian. In addition to analogue modeling, we have used field data, detailed geological mapping and key cross-sections supported by seismic and well data to build a new structural interpretation for the SPB. In this interpretation, it is recognized that the basal and upper parts of the Serrat Evaporites acted as the main decollement levels of the so-called Cadi thrust sheet and Serrat unit. A balanced restoration of the basin indicates that thrust faults nucleated at the stratigraphic transition of the Serrat Evaporites (zone with lateral variations of thickness and lithological composition), characterized by a wedge of anhydrite and shale. The analogue models were setup based on information extracted from cross-sections, built in two sectors with different lithology and stratigraphy of the evaporites, and the restored section of the SPB. In these models, deformation preferentially concentrated in areas where thickness change, defined by wedges of the ductile materials, was inbuilt. Based on the structural interpretation and model results, a kinematic evolution of the SPB is proposed. The kinematic model is characterized by the generation of out-of-sequence structures developed due to lateral stratigraphic variations of the Serrat Evaporites. The present work shows a good example of the role of stratigraphic heterogeneities of an evaporite formation which acts as decollement level on structural deformation in a fold-thrust belt. The results of this work have implications for hydrocarbon exploration and are relevant for studying structural geometry and mechanics in shortened evaporite basins. (C) 2017 Elsevier Ltd. All rights reserved.

  • 4.
    Deng, Hongling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Superimposed folding and thrusting by two phases of mutually orthogonal or oblique shortening in analogue models2016In: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 83, p. 28-45Article in journal (Refereed)
    Abstract [en]

    Orogens may suffer more than one phase shortening resulting in superposition of structures of different generations. Superimposition of orthogonal or oblique shortening is studied using sandbox and centrifuge modelling. Results of sand models show that in orthogonal superimposition, the two resulting structural trends are approximately orthogonal to each other. In oblique superimposition, structures trend obliquely to each other in the relatively thin areas of the model (foreland), and mutually orthogonal in areas where the model is thickened during the first phase of shortening (i.e. the hinterland). Thrusts formed during the first shortening phase may be reactivated during the later shortening phase. Spacing of the later phase structures is not as wide as expected, considering they across the pre-existing thickened wedge. Superposition of structures results in formation of type 1 fold interference pattern. Bedding is curved outwards both in the dome and basin structures. Folded layers are dipping and plunging outwards in a dome, while they are dipping and plunging inwards in a basin. In the areas between two adjacent domes or basins (i.e. where an anticline is superimposed by a syncline or a syncline is superimposed by an anticline), bedding is curved inwards, and the anticlines plunge inwards and the synclines outwards. The latter feature could be helpful to determine the age relationship for type 2 fold interference pattern. In tectonic regions where multiple phases of shortening have occurred, the orogenic-scale dome-and-basin and arrowhead-shaped interference patterns are commonly formed, as in the models. However, in some areas, the fold interference pattern might be modified by a later phase of thrusting. Similar to models results, superimposition of two and/or even more deformation phases may not be recorded by structures all over the tectonic area.

  • 5.
    Farzipour-Saein, Ali
    et al.
    Department of Geology, University of Isfahan, Iran.
    Nilfouroushan, Faramarz
    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 effect of basement step/topography on the geometry of the Zagros fold and thrust belt (SW Iran): an analogue modeling approach2013In: International journal of earth sciences, ISSN 1437-3254, E-ISSN 1437-3262, Vol. 102, no 8, p. 2117-2135Article in journal (Refereed)
    Abstract [en]

    Systematic analogue models are run to study the variation in deformation across basement steps in the Zagros Fold-Thrust Belt. Our model results demonstrate that basement configuration/topography influences the sedimentation thickness and, hence, the kinematics and geometric evolution of the fold and thrust belt. The greater the difference in thickness between the adjacent cover units across a basement step, the sharper and clearer will be the offset the deformation front. Based on model results, we conclude that in a fold-thrust belt, where basement step/topography is covered by a layer of ductile salt acting as a decollement, the effect of the salt decollement on the evolution of the belt is far greater than the effect of thickness variation of the cover units.

  • 6.
    Hessami, Khaled
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Nilforoushan, Faramarz
    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.
    Active deformation within the Zagros Mountains deduced from GPS measurements2006In: Journal of the Geological Society, ISSN 0016-7649, E-ISSN 2041-479X, Journal of the Geological Society, London, Vol. 163, no 1, p. 143-148Article in journal (Refereed)
    Abstract [en]

    We present and interpret the results of Global Positioning System (GPS) measurements at 35 stations in and beside the Zagros Mountain belt, SW Iran, for three campaigns ending March 1998, December 1999 and June 2001. Preliminary motion estimates show clearly the change in character along the strike of the belt. Stations to the SE move at 13–22 ± 3 mm a–1 towards N 7 ± 5°E with respect to Eurasia. Most of the shortening indicated by the GPS velocities seems to occur in the SE Zagros along two major seismic zones and along the Zagros front. To the NW, stations move oblique to the trend of the belt towards N 12 ± 8°W, at 14–19 ± 3 mm a–1. Most of the shortening in the NW Zagros seems to occur along the Mountain Front Fault with its major earthquakes as well as along the Zagros front. The change in direction and magnitude of the velocity vectors across the north–south-trending Kazerun and Karebas faults involves extension of up to 4 mm a–1 along the strike of the Zagros belt.

  • 7.
    Joudaki, Masoud
    et al.
    Univ Isfahan, Dept Geol, PO Code 81746-73441, Esfahan, Iran.
    Farzipour-Saein, Ali
    Univ Isfahan, Dept Geol, PO Code 81746-73441, Esfahan, Iran.
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Kinematics and surface fracture pattern of the Anaran basement fault zone in NW of the Zagros Fold-Thrust Belt2016In: International journal of earth sciences, ISSN 1437-3254, E-ISSN 1437-3262, Vol. 105, no 3, p. 869-883Article in journal (Refereed)
    Abstract [en]

    The preexisting north-south trending basement faults and their reactivation played an important role during the evolution of the Zagros fold-thrust belt. The Anaran basement fault in the Lurestan region, NW of the Zagros, has been considered as a N-S trending basement lineament, although its surface structural expression is still debated. In this study, we use satellite images and field observations to identify and analyze the fractures in the sedimentary cover above the Anaran basement fault. Fracture analysis demonstrates that approaching the Anaran basement fault, the fracture pattern changes. The fractures association with reactivation of the deep-seated preexisting Anaran basement fault can be categorized in 4 sets based on their directions. The mean direction for maximum compressional stress is different between the fault- and fold-related fractures within and around the ABF shear zone. We estimated an orientation of N30±5° for the fault-related fractures and N45±5° for the fold-related fracture sets outside of the ABF shear zone. This difference suggests that the fold-related and fault-related fracture sets have been formed in different two stages of deformation throughout the area. The axial traces of some folds, especially the Anaran anticline, demonstrate a right-lateral offset along the ABF, such that, in central part of the Anaran anticline, the fold axis of this anticline is changed from its original NW–SE trend to approximately north-south trend of the ABF.

  • 8.
    Koyi, Hemin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Univ Gavle, Dept Ind Dev IT & Land Management, Gavle, Sweden.
    Hessami, Khaled
    IIEES, Tehran, Iran.
    Modelling role of basement block rotation and strike-slip faulting on structural pattern in cover units of fold-and-thrust belts2016In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 153, no 5-6, p. 827-844Article in journal (Refereed)
    Abstract [en]

    A series of scaled analogue models are used to study (de)coupling between basement and cover deformation. Rigid basal blocks were rotated about a vertical axis in a bookshelf' fashion, which caused strike-slip faulting along the blocks and in the overlying cover units of loose sand. Three different combinations of cover-basement deformations are modelled: (i) cover shortening before basement fault movement; (ii) basement fault movement before cover shortening; and (iii) simultaneous cover shortening with basement fault movement. Results show that the effect of the basement faults depends on the timing of their reactivation. Pre- and syn-orogenic basement fault movements have a significant impact on the structural pattern of the cover units, whereas post-orogenic basement fault movement has less influence on the thickened hinterland of the overlying belt. The interaction of basement faulting and cover shortening results in the formation of rhombic structures. In models with pre- and syn-orogenic basement strike-slip faults, rhombic blocks develop as a result of shortening of the overlying cover during basement faulting. These rhombic blocks are similar in appearance to flower structures, but are different in kinematics, genesis and structural extent. We compare these model results to both the Zagros fold-and-thrust belt in southwestern Iran and the Alborz Mountains in northern Iran. Based on the model results, we conclude that the traces of basement faults in cover units rotate and migrate towards the foreland during regional shortening. As such, these traces do not necessarily indicate the actual location or orientation of the basement faults which created them.

  • 9.
    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)
  • 10.
    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)
  • 11.
    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.

  • 12. Mousavi, Z.
    et al.
    Walpersdorf, A.
    Walker, R.T.
    Tavakoli, F.
    Pathier, E.
    Nankali, H.
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Djamour, Y.
    Global Positioning System constraints on the active tectonics of NE Iran and the South Caspian region2013In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 377-378, p. 287-298Article in journal (Refereed)
    Abstract [en]

    We present a velocity field compiled from a network of 27 permanent and 20 campaign GPS stations  across NE Iran. This new GPS velocity field helps to investigate how Arabia-Eurasia collision deformation is accommodated at the northern boundary of the deforming zone. The present-day northward motion decreases eastward from 11 mm/yr at Tehran (~52°E) to 1.5 mm/yr at Mashhad  (~60°E). N-S shortening across the Kopeh Dagh, Binalud and Kuh-e-Surkh ranges sums to 4.5±0.5 mm/yr at longitude 59°E. The available GPS velocities allow us to describe the rigid-body rotation of the South Caspian about an Euler pole that is located further away than previously thought. We suggest that two new stations (MAVT and MAR2), which are sited far from the block boundaries, are most  likely to indicate the full motion of the South Caspian basin. These stations suggest that NW motion is accommodated by right-lateral slip on the Ashkabad fault (at a rate of up to 7 mm/yr) and by up to 4-6 mm/yr of summed left-lateral slip across the Shahroud left-lateral strike-slip system. Our new GPS results are important for assessing seismic hazard in NE Iran, which contains numerous large population centers and possesses an abundant historical earthquake record. Our results suggest that the fault zones along the eastern Alborz and western Kopeh Dagh may accommodate slip at much faster rates than previously thought. Fully assessing the role of these faults, and the hazard that they represent, requires independent verification of their slip-rates through additional GPS measurements and geological fieldwork.

  • 13.
    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.

  • 14.
    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.

  • 15.
    Nilforoushan, Faramarz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Masson, F.
    Laboratoire Dynamique de la Lithosphere, Université Montpellier, France.
    Vernant, P.
    Laboratoire Dynamique de la Lithosphere, Université Montpellier, France.
    Vigny, C.
    Laboratoire de Geologie, Ecole Normale Supérieure – CNRS, Paris, France.
    Martinod, J.
    Laboratoire de Geophysique Interne et Tectonophysique, Universite´ Joseph Fourrier Grenoble, France.
    Abbasi, M.
    International Institute of Earthquake Engineering and Seismology, Tehran, Iran.
    Nankali, H.
    Geodynamic Department, National Cartographic Centre ,Tehran, Iran.
    Hatzfeld, D.
    Laboratoire de Geophysique Interne et Tectonophysique, Universite´ Joseph Fourrier Grenoble, France.
    Bayer, R.
    Laboratoire Dynamique de la Lithosphere, Université Montpellier, France.
    Tavakoli, F.
    Geodynamic Department, National Cartographic Centre ,Tehran, Iran.
    Ashtiani, A.
    International Institute of Earthquake Engineering and Seismology, Tehran, Iran.
    Doerflinger, E.
    Laboratoire Dynamique de la Lithosphere, Université Montpellier, France.
    Daignières, M.
    Laboratoire Dynamique de la Lithosphere, Université Montpellier, France.
    Collard, P.
    Laboratoire Dynamique de la Lithosphere, Université Montpellier, France.
    Chéry, J.
    Laboratoire Dynamique de la Lithosphere, Université Montpellier, France.
    GPS network monitors the Arabia-Eurasia collision deformation in Iran2003In: Journal of Geodesy, ISSN 0949-7714, E-ISSN 1432-1394, Vol. 77, p. 411-422Article in journal (Refereed)
    Abstract [en]

    The rate of crustal deformation in Iran due to the Arabia–Eurasia collision is estimated. The results are based on new global positioning system (GPS) data. In order to address the problem of the distribution of the deformation in Iran, Iranian and French research organizations have carried out the first large-scale GPS survey of Iran. A GPS network of 28 sites (25 in Iran, two in Oman and one in Uzbekistan) has been installed and surveyed twice, in September 1999 and October 2001. Each site has been surveyed for a minimum observation of 4 days. GPS data processing has been done using the GAMIT-GLOBK software package. The solution displays horizontal repeatabilities of about 1.2 mm in 1999 and 2001. The resulting velocities allow us to constrain the kinematics of the Iranian tectonic blocks. These velocities are given in ITRF2000 and also relative to Eurasia. This last kinematic model demonstrates that (1) the north–south shortening from Arabia to Eurasia is 2–2.5 cm/year, less than previously estimated, and (2) the transition from subduction (Makran) to collision (Zagros) is very sharp and governs the different styles of deformation observed in Iran. In the eastern part of Iran, most of the shortening is accommodated in the Gulf of Oman, while in the western part the shortening is more distributed from south to north. The large faults surrounding the Lut block accommodate most of the subduction–collision transition.

  • 16.
    Nilforoushan, Faramarz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Talbot, Christopher
    SAR interferometry locates and constrains the kinematics of an active fault along SW Qeshm Island, offshore ZagrosManuscript (Other academic)
  • 17.
    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
    Comparison of analogue and numerical models: Sensitivity of numerical "sandbox" models of fold-thrust belts to material cohesion2010Conference paper (Refereed)
    Abstract [en]

    Scaled analogue and numerical brittle-viscous shortening models are conducted and the effects of uncertainties of the cohesion of brittle materials in the numerical modeling results are investigated. We demonstrate that the numerical models are very sensitive to small cohesion changes; specifically the geometry and number of structures are variable, especially in models with two weak viscous layers.  The results of some of the scaled numerical models can be very similar to analogue models in the usual range of cohesion values (here 0-100 Pa) of brittle materials.

  • 18.
    Nilfouroushan, Faramarz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Pysklywec, Russell
    Department of Geology, University of Toronto, Canada .
    Cruden, Alexander
    Department of Geology, University of Toronto, Canada M5S 3B1 c School of Geosciences, Monash University, Melbourne, Australia.
    Sensitivity analysis of numerical scaled models of fold-and-thrust belts to granular material cohesion variation and comparison with analogue experiments2012In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 526-529, p. 196-206Article in journal (Refereed)
    Abstract [en]

    Scaled analog and numerical brittle–viscous shortening models are employed to evaluate how fold–thrust structures evolve with changes in the cohesion of brittle materials, a rather poorly constrained physical parameter at this scale of experiment. The shortening models are characterized by various styles of shear zones and features resembling pop-up structures. The kinematics, geometry, and number of these structures are controlled by the viscous detachment layers in the models; the finite deformation of the model wedges is fundamentally different in model sets with one or two viscous layers. We demonstrate that the structural evolution of the numerical models is very sensitive to small changes in cohesion value. This is especially pronounced in the experiments that incorporate two weak viscous layers. The overall deformation of the numerical models is most similar to analog models when cohesion values are 70–80 Pa.

  • 19.
    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.

  • 20.
    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.

  • 21.
    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)
  • 22.
    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.

  • 23. 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)
  • 24. 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, R.
    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 thrusting2010Conference paper (Refereed)
  • 25. 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

  • 26. Shahpasandzadeh, M.
    et al.
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Koyi, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Kinematics of structures and active tectonics of an active orogenic belt, Alborz Mountains, northern Iran: New insights from scaled analogue modeling2010Conference paper (Refereed)
  • 27.
    Shahpasandzadeh, Majid
    et al.
    Grad Univ Adv Technol, Dept Earth Sci, Kerman, Iran.
    Koyi, Hemin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Nilfouroushan, Faramarz
    Univ Gavle, Dept Ind Dev IT & Land Management, Gavle, Sweden.
    The significance of switch in convergence direction in the Alborz Mountains, northern Iran: Insights from scaled analogue modeling2017In: Interpretation, ISSN 2324-8858, E-ISSN 2324-8866, Vol. 5, no 1, p. SD81-SD98Article in journal (Refereed)
    Abstract [en]

    The switch in direction of convergence between Central Iran and the Eurasian Plate is believed to have a significant impact on the structural style in the Alborz Mountains, in the north of Iran. To understand the deformation pattern and investigate the influence of the South Caspian Basin kinematics since the middle Miocene on the structural styles and active tectonics of the Alborz Mountains, a series of scaled analogue models were prepared, in which passively layered loose sand simulating the sedimentary units were subjected to orthogonal and subsequently oblique shortening by a rigid indenter. Model results indicate that during the shortening, an arcuate-shaped foreland-vergent imbricate stack forms in front of the indenter. The orthogonal shortening is characterized by a prevailing right-lateral and left-lateral oblique-slip motion in the east and west of the model, respectively. This shift in kinematics contradicts the proposed preneotectonic (orthogonal) model of the Alborz. However, during oblique shortening, model results show that deformation is mainly accommodated by leftlateral transpression within the sand wedge and internal deformation. Oblique shortening is consistently accommodated by continued left-lateral motion on the west-northwest-trending oblique thrusts, whereas the east-westtrending thrusts and the preexisting east-northeast-trending right-lateral oblique thrusts reactivate as left-lateral oblique faults. Precise monitoring of the model surface also illustrates partitioning of shortening into the forelandvergent left-lateral thrusting in the south and hinterland-vergent back thrusting in the north. These model results are generally consistent with field observations and GPS data of structure and kinematics of the Alborz Mountains.

  • 28. Sorbi, Mohammad Reza
    et al.
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Zamani, Ahmad
    Seismicity patterns associated with the September 10th, 2008 Qeshm earthquake, South Iran2012In: International journal of earth sciences, ISSN 1437-3254, E-ISSN 1437-3262, Vol. 101, no 8, p. 2215-2223Article in journal (Refereed)
    Abstract [en]

    The b value of the Gutenberg-Richter relation and the standard deviate, Z, were calculated to investigate the temporal and spatial variations in seismicity patterns associated with the September 10th, 2008 (Mw=6.1) Qeshm earthquake. The temporal variations of b value illustrate a distinct dramatic drop preceding the Qeshm earthquake and the spatial changes in b value highlight a zone with an abnormally low b value around the epicenter of this event. The Cumulative number and Z value as a function of time shows a precursory seismic quiescence preceding the 2008 Qeshm earthquake that observed for one year in a circle with R=50 km around its epicenter. The spatial distribution map of the standard deviate, Z, also exhibits an obvious precursory seismic quiescence region before the 2008 Qeshm event around the epicenter of this event. Interestingly, the precursory seismic quiescence region is approximately consistent with low b value anomaly region and both have E-W to NE-SW trend. These two precursory anomalies took place in relatively large regions, which were possibly relevant to the preparation zone of the 2008 Qeshm event.

  • 29. Tavakoli, F.
    et al.
    Walpersdorf, A.
    Authemayou, C.
    Nankali, H.R.
    Hatzfeld, D.
    Tatar, M.
    Djamour, Y.
    Nilfouroushan, Faramarz
    Cotte, N.
    Distribution of the right-lateral strike-slip motion from the Main Recent Fault to the Kazerun Fault System (Zagros, Iran): Evidence from present-day GPS velocities2008In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 275, p. 342-375Article in journal (Refereed)
    Abstract [en]

    GPS measurements across the Kazerun Fault System in the Zagros mountain belt provide first instantaneous velocities on the different segments. These results are closely consistent with the geological fault slip rates (over 150 ka), implying stable velocities over a longer period. The present-day strike–slip motion is distributed from the Main Recent Fault to the N-trending Kazerun Fault System along a preferential en-echelon fault zone included in a more distributed fan-shape fault pattern. The Hormuz salt decoupling layer cannot be the only cause of a sedimentary spreading because seismicity attests these faults are rooted in the basement. The Dena fault (3.7 mm/yr) transfers the MRF fault slip mainly to the Kazerun (3.6 mm/yr) and slightly to the High Zagros and Sabz Pushan faults (1.5 mm/yr), and the Kazerun fault further to the Kareh Bas fault (3.4 mm/yr). Total geological horizontal offsets associated with GPS slip rates help inferring precise fault slip onset ages. The successive onsets deduced by this approach imply that the right-lateral strike-slip activity of the MRF has propagated in time southeastward to the Dena segment, and then to the Kazerun segment and to the Kareh Bas fault.

  • 30. Vajedian, Sanaz
    et al.
    Motagh, Mahdi
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Improved multi-temporal InSAR technique for monitoring volcano and tectonic deformation in the center of Alborz, Iran2014In: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292Article in journal (Other academic)
  • 31. Vajedian, Sanaz
    et al.
    Motagh, Mahdi
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Response to Sowter, A.; Cigna, F. On the Use of the ISBAS Acronym in InSAR Applications. Comment on Vajedian, S.; Motagh, M.; Nilfouroushan, F. StaMPS Improvement for Deformation Analysis in Mountainous Regions: Implications for the Damavand Volcano and Mosha Fault in Alborz. Remote Sens. 2015, 7, 8323–83472015In: Remote Sensing, Vol. 7, no 9, p. 11324-11325Article in journal (Refereed)
  • 32. Vajedian, Sanaz
    et al.
    Motagh, Mahdi
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    STaMPS improvement for deformation analysis in mountainous regions: Implications for Damavand volcano and Mosha fault in Alborz2015In: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292, Vol. 7, no 7, p. 8323-8347Article in journal (Refereed)
    Abstract [en]

    Interferometric Synthetic Aperture Radar (InSAR) capability to detect slow deformation over terrain areas is limited by temporal decorrelation, geometric decorrelation and atmospheric artefacts. Multitemporal InSAR methods such as Persistent Scatterer (PS-InSAR) and Small Baseline Subset (SBAS) have been developed to deal with various aspects of decorrelation and atmospheric problems affecting InSAR observations. Nevertheless, the applicability of both PS-InSAR and SBAS in mountainous regions is still challenging. Correct phase unwrapping in both methods is hampered due to geometric decorrelation in particular when using C-band SAR data for deformation analysis. In this paper, we build upon the SBAS method implemented in StaMPS software and improved the technique, here called ISBAS, to assess tectonic and volcanic deformation in the center of the Alborz Mountains in Iran using both Envisat and ALOS SAR data. We modify several aspects within the chain of the processing including: filtering prior to phase unwrapping, topographic correction within three-dimensional phase unwrapping, reducing the atmospheric noise with the help of additional GPS data, and removing the ramp caused by ionosphere turbulence and/or orbit errors to better estimate crustal deformation in this tectonically active region. Topographic correction is done within the three-dimensional unwrapping in order to improve the phase unwrapping process, which is in contrast to previous methods in which DEM error is estimated before/after phase unwrapping. Our experiments show that our improved SBAS approach is able to better characterize the tectonic and volcanic deformation in the center of the Alborz region than the classical SBAS. In particular, Damavand volcano shows an average uplift rate of about 3 mm/year in the year 2003–2010. The Mosha fault illustrates left-lateral motion that could be explained with a fault that is locked up to 17–18 km depths and slips with 2–4 mm/year below that depth.

  • 33. Vernant, P
    et al.
    Nilforoushan, F
    Chéry, J
    Bayer, R
    Djamour, Y
    Masson, F
    Nankali, H
    Ritz, J-F
    Sedighi, M
    Tavakoli, F
    Deciphering oblique shortening of central Alborz in Iran using geodetic data2004In: Earth and Planetary Science Letters, ISSN 0012-821X, Vol. 223, no 1-2, p. 177-185Article in journal (Refereed)
    Abstract [en]

    The Alborz is a narrow (100 km) and elevated (3000 m) mountain belt which accommodates the differential motion between the Sanandaj–Sirjan zone in central Iran and the South Caspian basin. GPS measurements of 12 geodetic sites in Central Alborz between 2000 and 2002 allow to constrain the motion of the belt with respect to western Eurasia. One site velocity on the Caspian shoreline suggests that the South Caspian basin moves northwest at a rate of 6±2 mm/year with respect to western Eurasia. North–South shortening across the Alborz occurs at 5±2 mm/year. To the South, deformation seems to extend beyond the piedmont area, probably due to active thrusting on the Pishva fault. We also observe a left-lateral shear of the overall belt at a rate of 4±2 mm/year, consistent with the geological motion observed along E–W active strike-slip faults inside the belt (e.g., the Mosha fault).

  • 34. Vernant, P
    et al.
    Nilforoushan, F
    Hatzfeld, D
    Abbassi, M.R
    Vigny, C
    Masson, F
    Nankali, H
    Martinod, J
    Ashtiani, A
    Bayer, R
    Tavakoli, F
    Chéry, J
    Present-day crustal deformation and plate kinematics in the Middle East constrained by GPS measurements in Iran and northern Oman2004In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 157, no 1, p. 381-398Article in journal (Refereed)
    Abstract [en]

    A network of 27 GPS sites was implemented in Iran and northern Oman to measure displacements in this part of the Alpine–Himalayan mountain belt. We present and interpret the results of two surveys performed in 1999 September and 2001 October. GPS sites in Oman show northward motion of the Arabian Plate relative to Eurasia slower than the NUVEL-1A estimates (e.g. 22 ± 2 mm yr−1 at N8°± 5°E instead of 30.5 mm yr−1 at N6°E at Bahrain longitude). We define a GPS Arabia–Eurasia Euler vector of 27.9°± 0.5°N, 19.5°± 1.4°E, 0.41°± 0.1° Myr−1. The Arabia–Eurasia convergence is accommodated differently in eastern and western Iran. East of 58°E, most of the shortening is accommodated by the Makran subduction zone (19.5 ± 2 mm yr−1) and less by the Kopet-Dag (6.5 ± 2 mm yr−1). West of 58°E, the deformation is distributed in separate fold and thrust belts. At the longitude of Tehran, the Zagros and the Alborz mountain ranges accommodate 6.5 ± 2 mm yr−1 and 8 ± 2 mm yr−1 respectively. The right-lateral displacement along the Main Recent Fault in the northern Zagros is about 3 ± 2 mm yr−1, smaller than what was generally expected. By contrast, large right-lateral displacement takes place in northwestern Iran (up to 8 ± mm yr−1). The Central Iranian Block is characterized by coherent plate motion (internal deformation <2 mm yr−1). Sites east of 61°E show very low displacements relative to Eurasia. The kinematic contrast between eastern and western Iran is accommodated by strike-slip motions along the Lut Block. To the south, the transition zone between Zagros and Makran is under transpression with right-lateral displacements of 11 ± 2 mm yr−1.

  • 35. Walpersdorf, A
    et al.
    Hatzfeld, D
    Nankali, H
    Tavakoli, F
    Nilforoushan, Faramarz
    Tatar, M
    Vernant, P
    Chery, J
    Masson, F
    Difference in the GPS deformation pattern of North and Central Zagros (Iran)2006In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 167, no 3, p. 1077-1088Article in journal (Refereed)
    Abstract [en]

    Measurements on either side of the Kazerun fault system in the Zagros Mountain Belt, Iran, show that the accommodation of the convergence of the Arabian and Eurasian Plates differs across the region. In northwest Zagros, the deformation is partitioned as 3–6 mm yr−1 of shortening perpendicular to the axis of the mountain belt, and 4–6 mm yr−1 of dextral strike-slip motion on northwest–southeast trending faults. No individual strike-slip fault seems to slip at a rate higher than ∼2 mm yr−1. In southeast Zagros, the deformation is pure shortening of 8 ± 2 mm yr−1 occurring perpendicular to the simple folded belt and restricted to the Persian Gulf shore. The fact that most of the deformation is located in front of the simple folded belt, close to the Persian Gulf, while seismicity is more widely spread across the mountain belt, confirms the decoupling of the surface sedimentary layers from the seismogenic basement. A comparison with the folding and topography corroborates a southwestward propagation of the surface deformation. The difference in deformation between the two regions suggests that right-lateral shear cumulates on the north–south trending Kazerun strike-slip fault system to 6 ± 2 mm yr−1.

  • 36.
    Zarifi, Zoya
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Nilfouroushan, Faramarz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Raeesi, Mohammad
    Department of Earth Science, University of Bergen, Allegaten 41, 5007 Bergen, Norway.
    Crustal stress Map of Iran: Insight from seismic and geodetic computations2014In: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 171, no 17, p. 1219-1236Article in journal (Refereed)
    Abstract [en]

    We used the focal mechanisms of crustal earthquakes (depth <40 km) in the period 1909-2012 and the available GPS velocities, estimated from the data collected between 1999 to 2011, to estimate the magnitude and directions of maximum principal stress and strain rates in Iran. The Pearson product moment correlation was used to find the correlation between the stress field obtained from the focal mechanism stress inversion and that obtained using the seismic and geodetic strain rates. Our assumption is that stresses in a continuum are produced by tectonic forces and the consequent deformation on the crustal scale. Therefore, the direction of the stress and strain (or strain rate) are ideally be the same. Our results show a strong correlation between the directions of the principal components of stress and strain (rate) obtained using the different data/methods.  Using  weighted average analysis, we present a new stress map for Iran.

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