Iraqi Geological

Abstract


Introduction
Geomorphologic indicators can be used to identify places that have suffered extensive tectonic alteration. Each of these indicators assesses the strength of active tectonics in a relative manner. When it comes to a given location, employing many indicators rather than just one yields more useful results (Keller and Pinter, 2002). Rivers play a major part throughout many landscapes, and landscapes in tectonically active locations are the result of a mix of the impacts of lateral and vertical motion of earth's crust blocks, and also surface characteristics erosion or deposition (Burbank and Anderson, 2001). Drainage basins could be a significant indication of tectonic activity in tectonically active areas, such as the Iraqi Kurdistan Location, especially when the region is close to the borderline of plate tectonics. Geographic information systems' rapid advancement, and also continual improvements in (DEM) resolution and availability, providing important and effective techniques for processing, calculating, and evaluating geomorphic indices throughout environments and scales (Fatah et al., 2020;Arrowsmith and Zielke, 2009;Mzuri et al., 2021;Gasparini and Whipple, 2014). The study focused on the Rawanduz basin, which is about 110 kilometers northeast of Erbil city and is among the two main gorges of Al-Sakheqin "Khrand and Kali Khalh wash" (Abdullah et al., 2020). This study proposes a method for identifying moderately active tectonics by applying geomorphic indices important in structure and topographical analysis.Some of the indices considered are the longitudinal River profile, the Hypsometric curve Factor (HF), the Hypsometric Integral (HI), the Sinuosity of River index (S), the Stream length-gradient index (SL), the Asymmetry Factor (AF), the Transverse Topographic Symmetry Factor (TT), and the ratio of valley-floor width to valley height (VF).

The Study Area
The study area is about 110 kilometers northeast of Erbil, situated among the two major gorges of Al-Sakheqin "Khrand and Kali Khalh wash" (Abdullah et al., 2020). The basin lies between longitude 44°30'E and 45°00'E and latitude 36°20'N and 36°50'N. The main river in the study region, which flowing from the northeast to the southwest and also has a length of around 65 km (Jirjees et Al., 2022). The total area covered by the basin is 977.68 km 2 (Fig. 1 (Jirjees et al., 2022).

Materials and Methods
Geomorphic indices are also crucial to estimate the amount of tectonically in a particular region and to characterize structures. To produce natural variability in morphometric features, geographic information system (GIS) and remotely sensed technologies are used. ASTER Global Digital Elevation Model (AGDEM) which is 12.5 m resolusion as well as some other useful data like as topographic scale 1:25000 were also used to delineate the basin drainage system, and also some geomorphic indices were evolved as essential recon method to detect areas facing rapid tectonic displacements. Geomorphic indices are extremely effective in tectonic investigations even though they could be used to evaluate vast areas quickly, and the data required is most often directly available from base map and satellite data (Keller and Pinter, 2002). Some indices elements are also very useful in investigations of active tectonics. The research methodology and style of work involved the flow chart and table Fig. 2    Habibi and Gharibreza, 2015

Longitudinal River Profile
Longitudinal river profile data provide critical information on the geological background, morphology, and geological deformations of a region (Singh and Awasthi, 2010). Rivers with a concave longitudinal profile form when they are not tectonically active. Variations from the ideal smooth shape of the river gradient may signify differences in the riverbed's lithology or tectonic processes. A longitudinal river profile is a figure that relates a river's length to its height. It displays the slope of the river's course from its headwaters to its outlet Fig. 3. Rough surface decreases as more streams and tributaries enter the river, discharge and velocity increase, and the erosional power of bed load decreases (Hack, 1973). As a result, the gradient of the river will cause reduced, resulting in a concave long profile and shows a steep slope at the beginning, which gradually flattens out so that the stream erodes towards the bottom deposition will intensify this effect.

River Profile Shape
River transverse views provide a cross-section of a river's course and valley at a particular location along its path. A river's lengthy profile is divided into three segments. These are the top, mid, and bottom levels of the course. Everything has its own set of channel cross-profile characteristics. The upper course (source) of a river valley has incredibly steep slopes, getting it the term "V-Shaped Valley." The valley expands in the middle course because of more chemical degradation, however its deep remains constant despite the fact that vertical erosion has decreased. The floodplain of a river is the area on each side of the valley's course. In the lower course (mouth), the valley seems to be quite wide, and the floodplain has increased substantially in size (Fig. 4).

Hypsometric curve shape
It is defined as a graph that displays the ratio of surface area that exists at various heights by plotting relative area (a/A) vs relative height (h/H) (Strahler, 1964). Basin evaluation phases are grouped into three classes dependent on the shape and form of the curve: youth, mature, and old (Dehbozorgi et al., 2010). Convex forms indicate the young stage, S curves show the mature stage, while concave shapes indicate the old stage. The hypsometric curve and various geomorphic stages from the hypsometric curve of the examined region are shown in Fig. 5 and Table 2, which suggests that mature stage of the study basin of geomorphic development since it has an S-shaped hypsometric curve.

Hypsometric Integral (HI)
The HI value gives information about the basin's erosional stage, as well as the tectonic, climatic, and lithological conditions (Singh et al., 2008). (Markose and Jayappa, 2011) recently proposed that the hypsometric integral regulates that form of a hypsometric curve and thus gives indications the geomorphic development of drainage network of the basins. (Strahler, 1964) divided the HI into three groups based on value: 1) the old stage HI ≤ 0.35, 2) mature stage 0.35 ≤ HI ≤ 0.60, where the progress of the basin has reached a stable state form, and (3) youth stage HI ≥ 0.60, in which the extremely susceptible of the basin to degradation and which in the process of development. A value of HI is 0.5, which indicates that the area is matured, severely eroded, has high topographical, and has severely slit rivers which is indicating that the region is being tectonically controlled.

Sinuosity of River index (SRI)
(SRI) Explains the channel pattern It is the proportion of length of the curvilinear channel to the length of the valley centerline (Platts et al., 1983). In overall, low sinuosity clearly shows a sharp channel gradient, consistent cross sections, and insufficient ponds. A high sinuosity score is linked with flat slopes, asymmetrical cross sections, overhanging banks, and ponds on the outer bend of meandering. As a result, according to (Morisawa, 1985) classification, the river in the study area is in the Braided-Meander class (Table 3). Table. 3. Classification of Sinuosity Index Channel Pattern in the study region according to (Morisawa, 1985).

Stream Length-Gradient Index (SL)
The SL index is being used to analyze variations in river gradient affected with lithology or area tectonic activity. Higher levels could be seen were rivers flow through impervious strata, demonstrating tectonic rising. Small value imply weaker, lesser impervious strata, or circumstances in which streams may meander over strike slip faults (Keller and Pinter, 2002;Troiani and Della Seta, 2008).The result of SL value is nearly about 645, which is representing the study area tectonically in Moderately to Active depending on (El-Hamdouni et al., 2008) classification ( Fig. 6 and Table 4).

Asymmetry Factor (AF)
The asymmetric factor (Af) is used in evaluating the existence of tectonics at a drainage basin scale.Inside an active region, the steep portion of a mountain is formed by the displacement of two ends of a fault, and so this movement induces the basin to tilt, usually causes the river to move and float away from the basin's middle line. As a result, structural management of bedded direction may have an effect on the formation of basin asymmetry, and bedding tilting allows for suggested river movement on the down side, resulting in an asymmetric valley (El Hamdouni et al., 2008). For the region under analysis, the asymmetry factor is obtained and the result is shown in Table 6 with its class and degree for the basin within the study field. The basin has a low AF factor grade that is less than 50 (Fig. 7), indicating low regression intensity inside the area of the basin, suggesting that the major tributaries or drainage systems become less susceptible to tectonic circumference (convexity), as represented in the tributary extents per each edge of the basin's main stream. This leads to the fact that, relative to the right side, the growth of tributaries to the basin left side is narrower, which shows the asymmetry.   (Keller and Pinter, 2002)

Transverse Topographic Symmetry Factor (TT)
This factor represents river movement in vertical orientation to the axis of the drainage basin (Cox 1994). The midline of a basin is calculated using ArcGIS' polygon centerline tool, Fig. 8. T = 0 for a completely symmetrical basin. As asymmetry increases, this variable rises and approaching one (Cox, 1994), due to causing the main stream to be displaced in the way of the underground fracture. The numbers of T are taken from several stream order and demonstrate that streams perpendicular to the drainage basin axis move preferentially. According to (Burbank &Anderson, 2001) the results of index (TT) was put within three categories (classes and degree) according to the ranges of (TT) values, Table  7. For the area under study, the basin is dividing in to three parts as (lower, middle and upper) for calculation the TT factor and the result is shown in the Table. 8 and Fig. 8 with their classes and degree. The TT value results are; 0.6, 0.3 and 0.15 for the upstream, middle and downstream, separately. All of these numbers, together with the mean value of TT= 0.35, which is represent moderate stage and indicating that even this basin is asymmetric.

Valley Floor Width to Valley Height Ratio (VF)
It is also another specific index for identifying tectonic uplifting appearance the broad or narrow valley floors (V or U-shaped valley profiles) (Keller and Pinter, 2002). It represents a river valley's maturity and also assists in evaluating the relative rate of tectonic uplifting of the mountain face (Kale and Shejwalkar, 2008;El Hamdouni et al., 2008). The main classification to represent classes and shapes of valleys is giving as: Class one VF ≤ 0.5 indicate (Valleys in V-shape) with active stream incision, which is frequently related with highly uplifting; Class two 0.5 ≤ VF <1.0 indicate (U closed to Vshaped valleys) with moderately active tectonics; and Class three VF ≥ 1 indicate (valleys in U-shaped) with primary lateral degradation (Bull and McFadden, 2020;Keller and Pinter, 2002;El-Hamdouni et al., 2008). As a result, VF values vary depending on the basin size, river flow, and rock type involved (El Hamdouni et al., 2008). Moreover, by separating the study basin for three main parts, the lower (mouth of river) representing highly eroded basin and Valleys in U-shaped, while the middle part indicating eroded basin and valleys in U-shaped close to V-shaped and the upper (source of river) part shows less eroded basin and Valleys in V-shaped. Overall, the basin indicating highly eroded basin and valleys in U-shaped Table 9 and Fig. 9&10. Table. 9. Valley floor width to height ratio calculation in the study area (Keller and Pinter, 2002;El-Hamdouni et al., 2008).  9. Vf was calculated using a DEM with superimposed transverse section lines to across main Rawanduz river and its tributaries in the study area.

The Final Rating of the Indicators of Tectonic
Final rating of the indicators of tectonic is the final classification of the collection of the results and categories of geomorphological indices for all previously equations produced from digital elevation models (DEM) have used GIS. This classification provides a comprehensive overview of all the parameters impacted by geomorphological tectonic action in the research region. For the purpose of assessing the final classification of the extent of the research region impacted by tectonic activity, the classifying of (El-Hamdouni et al., 2008) is used, as indicated in Table 10. To describe the influence of tectonic activity for every index of the following indicators separately, results for all indicators are combined in one table Table 11. The tectonic indicator values in the study area is 2.33, which shows Class 3; indicating Moderate tectonic action and representing the basin is situated tectonically inside three main tectonic zones as (High Folded Zone, Imbricated Zone, and Zagros Suture Zone). Therefore, it has already been influenced by the same tectonic processes in the past geological time, including the last orogenic processes, which are still active now (Fouad, 2012). Table. 10. The Categories of IAT Classification after (Eynoddin, 2017;El-Hamdouni et al., 2008). Table. 11. The Iat Classes of Tectonic Activity in the Study Area.

Conclusions
Three transverse profiles have already been generated to better comprehend the characteristics of the valley as well as its width of the Rawanduz River's source towards its outlet. The valley extends in the middle course and gets extremely broad in the lower course. Longitudinal river profile data provide critical information on the geological setting, morphology, and tectonic deformations of a region. The longitudinal profile shows a steep slope at the beginning, which gradually flattens out so that the stream erodes towards to the bottom. The examined area's hypsometric curve and several geomorphic processes show that the basin is in the maturity phase of geomorphic progression since it also has an S-shaped hypsometric curve. A value of 0.5 for the hypsometric integral shows that such area is matured, extensively degraded, has high altitude, and high relief rivers, indicating that the area is tectonically managed. The stream length -gradient index (SL) is being used to identify current tectonic activity by detecting anomalously high index values on certain soft rock formations in a region with high SL indices. High rate was obtained wherever rivers flowed over resistant rocks, showing tectonic rising. The basin has a small AF factor rating that is less than (50), showed low regression frequency inside the area of the basin, suggesting that its major tributaries or drainage systems are less susceptible to tectonic circumference (convexity), as represented in the tributary lengths on every edge of the basin's main stream. As a result, the development of tributaries to the basin's left is smaller in comparison to the right side, demonstrating the asymmetry. The basin exhibits modest movement or displacement (average = from generated cross sections using DEM and GIS, with its basin located in class ordering no.3 on mean. This denotes severely degraded basins and valleys with U-shaped forms. The final rating of the indicators of tectonic is the last categorization of the combination of geomorphological indices findings and classes. The tectonic indicator value estimated in the study region are 2.33, which indicating Class 3 (Moderate tectonic activity) and which means that the basin is geologically located within the High Folded Zone, Imbricated Zone, and Zagros Suture Zone, as well as being influenced by the same tectonic forces in the past geological time, including the most recent orogenic forces.