The Mesopotamian Structure & Tectonics researches..

  Article

Tectonics Settings of Iraq

Abdul-Mutalib H. Al-Marsoumi*
College of Science, Basrah University, Basrah-Iraq
 

       Iraq lies in the border area between the Nubio- Arabian platform and the Asian branches of the Alpine Geosyncline.  Based on the geophysical investigations  the depth of  basement complex rocks is about 12 km, the ancient platform was subjected to fragmentation during Proterzoic and and Pre-Cambrian movements; Hajaz an Najid causing the longitudinal and transverse regional faults which in turn divide the basement into many blocks of various shape. 

   From tectonic point of view Iraqi territories have been subdivided into two main subdivisions;

I-Tripartite; This subdivision depends upon the shape of basement blocks, so Iraqi territories subdivided into the following zones from NE to SW; Major overthrust, folded, and unfolded zone.

II- Bipatite; This subdivision based on the block movements, initial structures within the sedimentary cover in addition to the block shapes. Thereafter, the geophysical investigations led to subdivide the geosyncline and the Nubio-Arabian platform as follows;

Geosyncline: this part cover narrow belt of north and northeastern part of Iraq, it has divided into; Eugeosycline, Ridge and Miogeosyncline.

Nubio-Arabian Platform; This part has been subdivided into;

A-Unstable shelf or folded zone which comprises the high folded zone, low folded zone and Foothill zone.

B- Mesopotamia plain; characterize by its thick sedimentary cover and simple topographic surface.

C- Stable shelf or unfolded zone; characterize the horizontality of bed rocks and thin sedimentary cover with many breaks.

   It is believed that Alpine Orogeny (Late Pliocene) play an important role in the architecture of Iraqi Earth Surface.

 The overall evaluation of tectonic movement that left their prints in Iraqi tectonic settings could summarize as follow;

    1- Hujaz-Najid tectonic movements (Pre-Cambrian) affected the basement rocks and initiated the N-S transverse fault (Abu-Jir Fault).

     2- Alpine Orogeny (Late Pliocene) reactivate the faults and fractures within the basement and affected the sedimentary cover up to Jurassic beds.

     3- Austrian Orogeny and other local movements which represent a phase of Alpine Orogeny took place  as a result of Sinjar block movement causing the strike slip faults with a genera trend of NE-SW.

      4- Tertiary movements reactivated the pre-existing fault and fractures with a general trend of NE- SW.

 * Phd: Abdul – Mutalib Hasson Mohammed Al-Marsoumi

     E-mail: abdmars@yahoo.com