Structural style of the NW Zagros Mountains and the role of basement thrusting for its Mountain Front Flexure, Kurdistan Region of Iraq

Zebari, Mjahid; Balling, Philipp; Grützner, Christoph; Navabpour, Payman; Witte, Jan; Ustaszewski, Kamil

doi:10.1016/j.jsg.2020.104206

Cited by 13 publications

(13 citation statements)

References 58 publications

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“…Such a broad structural high mandates basement involved deformation and duplexing in the internal portions of the fold and thrust belt. A similar magnitude of structural relief (2.6 km) has also been estimated for the NW Zagros fold‐thrust belt in the study area based on surface geological data (Zebari et al, 2020).…”

Section: Balanced Cross Sectionssupporting

confidence: 83%

“…However, others invoke a hybrid thin‐ and thick‐skinned style of shortening (Allen et al, 2013; Leturmy et al, 2010; Mouthereau et al, 2006; Mouthereau, Lacombe, et al, 2007; Mouthereau, Tensi, et al, 2007; Oveisi et al, 2009; Sherkati et al, 2006), involving either in‐sequence (Saura et al, 2015; Vergés, Goodarzi, et al, 2011) or out‐of‐sequence deformation (Blanc et al, 2003; Molinaro, Leturmy, et al, 2005). In the Kurdistan region of Iraq, regional cross sections of the fold‐thrust belt and adjacent foreland variably show thin‐skinned (Hinsch & Bretis, 2015) or hybrid thin‐ and thick‐skinned geometries (de Vera et al, 2009; Le Garzic et al, 2019; Tozer et al, 2019; Zebari et al, 2020). Whereas others solely focused on the uppermost sedimentary cover with no interpretation of structures below Jurassic strata (e.g., Frehner et al, 2012; Reif et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Late Miocene Deformation Kinematics Along the NW Zagros Fold‐Thrust Belt, Kurdistan Region of Iraq: Constraints From Apatite (U‐Th)/He Thermochronometry and Balanced Cross Sections

et al. 2020

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Apatite (U-Th)/He (AHe) thermochronometric results are integrated with geologic cross sections, structural relationships, and stratigraphic data to reconstruct the growth of the NW Zagros orogenic belt in the Kurdistan region of Iraq. Prolonged exhumation is documented across the belt with deformation advances and retreats from~14 Ma onward. After in-sequence propagation of deformation during middle to late Miocene times, preserved growth strata and AHe data show a deformation retreat by latest Miocene time (~5 Ma). In the NW Zagros, the Phanerozoic succession contains two principal décollements in Lower Triassic and middle Miocene units. The Triassic strata are interpreted as the main décollement for a thinskinned system that was dominant during most of the Cenozoic. By~8-5 Ma, the fold-thrust belt shifted to basement-involved deformation in association with growth of the mountain front flexure and reactivation of frontal structures. The shift from thinskinned to a hybrid thin-and thickskinned mode of shortening may reflect variations in the mechanical behavior of the upper crust and the presence of inherited basement discontinuities. On the basis of two NE-SW balanced cross sections spanning the NW Zagros, the estimated total minimum horizontal shortening is~18.2 km (6%) in the central and~16 km (7%) in the southern sectors of the Kurdistan region of Iraq. These findings suggest that the evolution of the NW Zagros orogenic belt was likely driven by the mechanical stratigraphy of the sedimentary cover, inherited basement discontinuities, and the dynamic and thermomechanical effects of potential slab breakoff and lithospheric mantle delamination events.

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Section: Balanced Cross Sectionssupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Late Miocene Deformation Kinematics Along the NW Zagros Fold‐Thrust Belt, Kurdistan Region of Iraq: Constraints From Apatite (U‐Th)/He Thermochronometry and Balanced Cross Sections

et al. 2020

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“…The amount of shortening along the entire transect of Figure 3 is c. 7.8 km. This is less than in the surrounding transects (34, 18.2, 19, and 24.8 km by Le Garzic et al., 2019; Koshnaw et al., 2020; Tozer et al., 2019; Zebari et al., 2020, respectively). Along our transect the shortening is likely a minimum estimate due to underestimations of the amount of displacement on the Main Zagros Fault, which has been displaced more foreland‐ward than in the surrounding areas (Figure 1).…”

Section: Regional Cross‐sectionmentioning

confidence: 65%

“…Structurally, this segment of the Zagros Fold-Thrust Belt is dominated by NW-SE trending fault-related folds. West of the Greater Zab River, the fold trend changes to nearly E-W (Figure 2a; Csontos et al, 2012;Le Garzic et al, 2019;Tozer et al, 2019;Zebari et al, 2020). The folds are usually S-verging and the related faults emerge at the surface within both the Imbricated Zone and the High Folded Zone, while they remain blind within the Foothill Zone.…”

Section: Geological Backgroundmentioning

confidence: 99%

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Late Pleistocene‐Holocene Slip Rates in the Northwestern Zagros Mountains (Kurdistan Region of Iraq) Derived From Luminescence Dating of River Terraces and Structural Modeling

Zebari

Preusser

Grützner³

et al. 2021

Tectonics

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A significant amount of the ongoing shortening between the Eurasian and Arabian plates is accommodated within the Zagros Fold‐Thrust Belt. However, the spatial and temporal distribution of active shortening within the belt, especially in its NW part, is not yet well constrained. We determined depositional ages of uplifted river terraces crossing the belt along the Greater Zab River using luminescence dating. Kinematic modeling of the fault‐related fold belt was then used to calculate long‐term slip rates during the Late Pleistocene to Holocene. Our results provide new insight into the rates of active faulting and folding in the area. The Zagros Mountain Front Fault accommodates about 1.46 ± 0.60 mm a−1 of slip, while a more external basement fault further to the SW accommodates less than 0.41 ± 0.16 mm a−1. Horizontal slip rates related to detachment folding of two anticlines within the Zagros Foothills are 0.40 ± 0.10 and 1.24 ± 0.36 mm a−1. Basement thrusting and thickening of the crust are restricted to the NE part of the Zagros belt. This is also reflected in the regional topography and in the distribution of uplifted terraces. In the southwestern part, the deformation is limited mainly to folding and thrusting of the sedimentary cover above a Triassic basal detachment. In the NE, deformation is associated with slip on basement thrusts. Our study sheds light on the distribution of shortening in the Zagros Mountains and helps to understand the regional tectonic system. Our results may be the foundation for a better seismic hazard assessment of the entire area.

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The role of long-term preparatory factors in mass rock creep deforming slopes: insights from the Zagros Mts. belt (Iran)

Delchiaro,

Della Seta,

Martino

et al. 2024

Landslides

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The long-term evolution of slopes affected by Mass Rock Creep deformations is controlled by both time-invariant predisposing factors, such as the geo-structural inheritance, and time-dependent preparatory conditions, including regional uplift and landscape evolution rates. However, the relationship among Deep-seated Gravitational Slope Deformations, drainage network evolution, and tectonics remains poorly defined. Here, we focused on an undocumented Deep-seated Gravitational Slope Deformation affecting an area of about 8 km2 in the SE tip termination of the Siah Kuh anticline in the Lorestan arc (Zagros Mts., Iran), upstream to the Mountain Front Fault. To assess the evolution processes which involved the slope up to the present, we integrated quantitative geomorphic analysis, optically stimulated luminescence dating of geomorphic markers, and SAR interferometry techniques. In detail, we semi-automatically extracted the river terrace treads to which we associated an elevation above the thalweg based on the Relative Elevation Model allowing the order definition. The plano-altimetric distribution of the treads and the OSL ages of two levels of strath terraces sampled in the field have been correlated along the river longitudinal profile, allowing the estimation of an uplift rate of 2.8 ± 0.2 mm year−1 and 0.42 ± 0.03 mm year−1, respectively upstream and downstream of the Mountain Front Fault. SAR interferometry was used to spot present-day shallow ground displacements associated with the ongoing slope deformation, by processing 279 satellite Sentinel-1 (A and B) radar images of the ascending and descending orbit spanning from 06 October 2014 to 31 March 2019. Different landslide mechanisms were distinguished across the fold axis, rototranslative to lateral spreading interpreted as two different evolutionary stages of the same process transposed spatially through the fold axis. Indeed, the rototranslative mechanism represents an advanced stage of the strain evolution while the lateral spreading is an earlier one. Finally, we infer that the variability in the spatial distribution of the slope deformation styles and patterns in the Lorestan arc is strictly related to the coupled evolution of the drainage system and tectonics. Involved volumes (from 0.6 up to 44 km3), local relief (from 400 up to 2000 m), incision rates (from 0.8 to 2.8 ± 0.2 mm year−1), and persistence time (from 104 to 105 years) represent the most important preparatory conditions and are predisposed by a moderately dipping downslope (from 8 to 25°) sedimentary sequence characterised by units with significantly different rheological behaviour.

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Structural style of the NW Zagros Mountains and the role of basement thrusting for its Mountain Front Flexure, Kurdistan Region of Iraq

Cited by 13 publications

References 58 publications

Late Miocene Deformation Kinematics Along the NW Zagros Fold‐Thrust Belt, Kurdistan Region of Iraq: Constraints From Apatite (U‐Th)/He Thermochronometry and Balanced Cross Sections

Late Miocene Deformation Kinematics Along the NW Zagros Fold‐Thrust Belt, Kurdistan Region of Iraq: Constraints From Apatite (U‐Th)/He Thermochronometry and Balanced Cross Sections

Late Pleistocene‐Holocene Slip Rates in the Northwestern Zagros Mountains (Kurdistan Region of Iraq) Derived From Luminescence Dating of River Terraces and Structural Modeling

The role of long-term preparatory factors in mass rock creep deforming slopes: insights from the Zagros Mts. belt (Iran)

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