Abstract

Sinjar Mountain is the most conspicuous outstanding geomorphic feature in the central northwestern part of Iraq; it is surrounded from north and south by gently inclined plains. The highest peak attains 1462 m, whereas the elevation of the surrounding plains ranges in height between (407 – 432) m. The mountain forms asymmetrical anticline, almost with E – W trend that has steeper northern limb (45 – 80)° and gentler southern limb (15 – 25)°, its length is about 80 Km, whilst the width is about 20 Km. The oldest exposed rocks belong to Shiranish Formation (Late Cretaceous), which is the main source for development of the alluvial fans, beside many other formations.A well developed set of alluvial fans can be observed along the northern limb of Sinjar anticline; they extend northwards to (20 – 22) Km, partly out of the Iraqi territory, inside Syria. Generally, four stages of alluvial fans are developed, the fourth being in Syria. Locally, the fans of the first stage overlap laterally forming "Bajada". The first stage alluvial fans; genetically are of Type I being still active, whereas the fans of the remaining three stages are of Type II; being partly dormant. The formers are of very coarse size sediments, deposited in low water/ sediments ratio with typical fan shape. On contrary the remaining fans have longitudinal shape, mainly of fine size materials, being deposited in high water/ sediments ratio. The age of the first stage alluvial fans is Early Pleistocene, whereas, the fans of the other three stages are of Pleistocene – Holocene age. No pavement and/ or desert varnish were observed in the alluvial fans. The main reason for the development of the fans is the neotectonic movement of the Sinjar Basin, besides the exposures of Shiranish Formation, which are overlain by hard and massive limestone of Sinjar Formation.

The article was added to IASJ on 2012-10-23

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