Keywords : Foreland

Paleo and Neo-Tectonics of the Mosul Fault and its Impact on the Tectonics of the Foreland Area of Iraq

Nabeel K. Al-Azzawi

Iraqi National Journal of Earth Sciences, 2013, Volume 13, Issue 1, Pages 59-74

Interpretation of Paleofacies maps was used as a tool to prove that Mosul fault was active since Middle Jurassic or even earlier. This fault extends from the Turkish border to the Lower Zab tributary of the Tigris River dividing the region into Mosul and Sinjar blocks. The sedimentary facies were used as indicators for the fault extension and its vertical displacements. They showed that Sinjar block was uplifted until Cretaceous when the two blocks were at almost a same elevation. Such a situation was remained until Middle Eocene.
During this epoch, the collision between Arabian and Eurassian plates resulted in a relative uplift of the Mosul block and the deposition of the continental Gercus Fm. In the mean time, a thick deposition of the basinal Jaddala Fm. was dominating the subsided Sinjar block. The Mosul block persisted the extremely uplifting until end of the Oligocene. The Early Miocene was characterized by the up- and downward movements of Sinjar block. This was also manifested by the facies alternations of both basinal and lagoonal types although in general the Sinjar block was relatively uplifted. During the Middle Miocene, the deposition of the Jeribe Fm. on the Sinjar block side may indicate that the Mosul block was in a higher position. In Late Miocene the Injana Fm. covered both blocks revealing that their elevation might be on the same level. However, later and according to the presence of the Bakhtiari Fm. the Sinjar Block seemed to be slightly in a higher position.
The paleostress analysis showed that the Mosul fault might be sinistral strike-slip at the extension phase of the Alpine orogeny (Triassic- Upper Cretaceous) then later it was becoming dextral strike-slip during the compression phase from Upper Cretaceous till now. As a result the present day may expose the risk of the fault displacement. Some fractures of such displacement were recorded on the
Al-Shohada' Bridge (the 3rd bridge over the Tigris River) of the Mosul city, which are indicating the existence of the dextral strike-slip neotectonics within the city of Mosul. So it is highly recommended to take such a risk into consideration, particularly when constructing large projects in future.

Paleocurrent Analysis of Upper Cretaceous Zagros Foreland Basin:A Case Study for Tanjero Formation in Sulaimaniya Area NE-Iraq

Ali M. Surdashy; Kamal H. Karim

Iraqi National Journal of Earth Sciences, 2005, Volume 5, Issue 1, Pages 30-44

Tanjero Formation is an Upper Cretaceous (Campanian-Maastrichtian) unit, which crops out within the Imbricated and High Folded Zones in Northeastern Iraq. Its outcrop stretches as narrow northwest-southeast belt near and parallel to the Iranian border. The formation mainly consists of alternation of clastic rocks of sandstone, marl and calcareous shale with occurrence of very thick conglomerate and biogenic limestones.
In this study many sedimentary structures are found in the Tanjero Formation, which have paleocurrent importance. These structures are cross bedding interference ripple marks, imbricated pebbles, elongate rudist and belemnite, plant debris, sole marks, valleys and channels. Most of these structures are found in the lower part. The paleocurrent analyses, as revealed by these structures, are presented in rose and stereonet diagrams, which show south and southwest directions.