GEOMORPHOLOGY AND MORPHOMETRY OF SEGMENTED KIRKUK ALLUVIAL FAN, NORTHERN IRAQ

Abstract

The Khas'sa Soo River is one of the main tributaries of the Adhaim River. The Khas'sa Soo River runs in the central part of Iraq, It is a perennial stream, running almost in straight line, especially in its middle and upper parts of its course. The width of the Khas'sa Soo River ranges from 0.1 to 1.1 Km, whereas its length is about 90 Km. It is filled by valley fill sediments, indicating prevailance of very active fluvial climate; during the Pleistocene and the Holocene.The catchment area of the Khas'sa Soo River consists of mainly fine clastics derived from Injana and Mukdadiyah formations and coarse clastics from Bai Hassan Formation. Along its course, the stream crosses many anticlines perpendicularly, some of these crossings have gorge forms with water gaps. A main alluvial fan is developed in the outlet of the Khas'sa Soo River from Kani Dommilan Mountain, which forms part of Kirkuk oil field. The length and width of the fan is 42 Km and 20 Km respectively. The main constituent of the fan is sandy silt, underlain by gravels of different sizes. The shape of the fan has almost disappeared, due to human activities, but it is still clear on the topographic maps of scale 1: 100 000. The morphology of a segmented alluvial fan can be used as an indicator for active tectonics. The fan form may reflect different rates of tectonic processes, such as faulting, uplifting, tilting, and folding along and adjacent to the mountain front.This study of the fans in Khas'sa Soo River found that tilting had produced segmented fan. Alluvial fan on the valley is shifted to the east as illustrated by remnant terraces (two levels for Early and Late Pleistocene age), consequently the location of the fan deposits is moved down-fan. Therefore, fanhead incision has occurred, and younger fan segments are located far away from the mountain front and fan apex, which represents the tectonic activity in the area.In this study, topographic profiles and fan contours are used to identify the position of the fan apex, identify relic mountain fronts, and calculate the tectonic tilt. Modeling of alluvial-fan morphology is used in evaluating the amount of uplift, which the fan apex has experienced.