Thrust fault in the maastrichtian sequences of Mawat area, Ne Iraq

الملخص EN

Stratigraphic studies of Maastrichtian Tanjero and Aqra formations and compression of microtectonic faults in Khewata – Dolbeshk valley constrains new geological setting of the Mawat area northeast Iraq.

During Middle – Late Maastrichtian a carbonate-siliciclastic succession deposited in front of the subducted ophiolite and accretionary prism.

These successions are well developed in the area.

This study concentrates on the overthrust sequence and identifies the geometry of the thrust fault.

The reefal limestone/ shallow clays succession are thrusted over reefal limestone/ marl-sandstone succession.

This thrust fault illustrates (1) these two successions were initially deposited laterally beside each other during the Maastrichtian and (2) the limestone/ clay sequences belong to the Tanjero/ Aqra formations and not to the Red bed Suwais.

The fault initiated during the last stages of collision, formed duplexes-imbricated thrusting fault and it brought the shallow facies over the deeper one.

The thrusting can also be identified on Google Earth image manifested by vertical repetition of Aqra Formation and it changes to reverse fault when it laterally meet the thicker and massive limestone of Aqra Formation.

The displacement of the thrust fault is accommodated by a fault-propagation folds in its southeastern tip.

In addition to the studied thrust fault, the valley contains many well developed relatively smaller compression faults which might form in a relation to the main thrust fault.