Relative timing of uplift along the Zagros Mountain Front Flexure (Kurdistan Region of Iraq): Constrained by geomorphic indices and landscape evolution modeling

Abstract

Abstract. The Mountain Front Flexure marks a dominant topographic step in the frontal part of the Zagros Fold–Thrust Belt. It is characterized by numerous active anticlines atop of a basement fault. So far, little is known about the relative activity of the anticlines, about their evolution, or about how crustal deformation migrates over time. We assessed the relative landscape maturity of three along-strike anticlines (from SE to NW: Harir, Perat, and Akre) located on the hanging wall of the Mountain Front Flexure in the Kurdistan Region of Iraq to identify the most active structures and to gain insights into the evolution of the fold–thrust belt. Landscape maturity was evaluated using geomorphic indices such as hypsometric curves, hypsometric integral, surface roughness, and surface index. Subsequently, numerical landscape evolution models were run to estimate the relative time difference between the onset of growth of the anticlines, using the present-day topography of the Harir Anticline as a base model. A stream power equation was used to introduce fluvial erosion, and a hillslope diffusion equation was applied to account for colluvial sediment transport. For different time steps of model evolution, we calculated the geomorphic indices generated from the base model. While Akre Anticline shows deeply incised valleys and advanced erosion, Harir and Perat anticlines have relatively smoother surfaces and are supposedly younger than the Akre Anticline. The landscape maturity level decreases from NW to SE. A comparison of the geomorphic indices of the model output to those of the present-day topography of Perat and Akre anticlines revealed that it would take the Harir Anticline about 80–100 and 160–200 kyr to reach the maturity level of the Perat and Akre anticlines, respectively, assuming erosion under constant conditions and constant rock uplift rates along the three anticlines. Since the factors controlling geomorphology (lithology, structural setting, and climate) are similar for all three anticlines, and under the assumption of constant growth and erosion conditions, we infer that uplift of the Akre Anticline started 160–200 kyr before that of the Harir Anticline, with the Perat Anticline showing an intermediate age. A NW-ward propagation of the Harir Anticline itself implies that the uplift has been independent within different segments. Our method of estimating the relative age difference can be applied to many other anticlines in the Mountain Front Flexure region to construct a model of temporal evolution of this belt.

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

“…(b) Schematic cross section that shows the structural setting of the Dinarta syncline, where the growth strata of the Bai‐Hasan formation is preserved. The cross section is based on Zebari and Burberry (2015) and Zebari et al (2019). (c) Geologic map of the Dinarta syncline that shows a major and a minor reverse fault, and locations of filed photographs.…”

Evaluation of active tectonics using geomorphic indices in a mountainous basin of Iran

“…Geologically, the study region in the Zagros FTB mainly consists of limestone and sandstone rocks aged from the late Cretaceous to the Palaeocene. The Zagros FTB is located along a section of the Arabian and Eurasian plates (Talebian & Jackson 2004) and is characterised by numerous active anticlines atop of a basement fault (Zebari et al 2019). The structurally complex joints, folds, slips, faults, and fractures reflect the dynamic nature of the regional tectonics.…”

“…2018), and the Zagros mountains in northern Iraq (Obaid & Allen 2017; Obaid & Allen 2019; Zebari et al . 2019). For instance, Yıldırım (2014) has noted that the geomorphic indices are compatible with the general relief of the mountain front and differential uplift along the fault zone of central Anatolia.…”

Seismotectonics and Seismic Source Parameters of the Mid-Eastern Iraq - Western Iran Using Moment Tensor Inversion Technique

“…In recently active tectonic areas, the topography of the land surface is an accurate reflection of the underlying structure and its interaction with surface processes [11]. [6]); [7,8]. The black rectangle represents the study area plotted in Figure-3, and the magnitude of the 102 earthquakes is indicated by the diameter of the colored circles.…”