--> Abstract: Paleomagnetic Study of Upper Cretaceous-Lower Tertiary Rocks in Northeastern Iraq, by Basim R.A. Hijab, Ezadin Baban, and Emad H. Al Kharssan; #90077 (2008)

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Paleomagnetic Study of Upper Cretaceous-Lower Tertiary Rocks in Northeastern Iraq

Basim R.A. Hijab1*, Ezadin Baban2, and Emad H. Al Kharssan3
1Baghdad University, Iraq
2Sulaimaniya University, Iraq
3Basrah University, Iraq
*[email protected]

The following rock units in northeastern Iraq were sampled for a paleomagnetic study: (1) Paleocene-Lower Eocene Naoprdan Limestone Formation at Chwarta and Zainal, (2) Maastrichtian Aqra Limestone Formation at Maukaba and Zardabe, (3) Valanginian-Turonian Balambo Limestone Formation at Azmar locality and igneous gabbros intrusions at Kanaroe and Waraz. Twelve hand samples and 200 oriented drilled cores were collected from these localities. The remnant magnetization (NRM) was measured using a spinner magnetometer (Baghdad University) and the cryogenic magnetometer (Oklahoma University, USA). The remnant magnetization in the Aqra Formation is of a depositional origin and carried by a detrital magnetite grains. In other localities (Chwarta, Zainal, Azmar, Kanaroe and Waraz), secondary haematite or maghemite is dominant. The rocks of the Chwarta, Zainal, Azmar, Kanaroe and Waraz localities are not good indicators for the paleomagnetic direction. Results from Maukaba and Zardabe rocks (Aqra Limestone) provided reliable paleomagnetic results. These rocks showed reverse paleomagnetic directions. All computed virtual geomagnetic poles (VGP) correspond to a reverse polarity, and the overall mean VGPs position of the Maukaba locality is paleo-latitude (Plat) of 44.4° S and paleo-longitude (Plong) of 279°, and for Zardabe locality (Plat = 57.1° S, Plong = 235°) with co-latitude (-14°) and (-13.9°). Accordingly, the paleo-latitude of the Maastrichtian Aqra Limestone basin was between 13.9° and 14° N. This suggests that the Neo-Tethys Ocean was located to the north and northeast of northeastern Iraq during the Maastrichtian time. The closure of this ocean occurred between the Maastrichtian and Early Tertiary. The paleo-position of the Aqra Limestone basin clearly suggests that the northern part of Iraq was still in warm environmental conditions during Maastrichtian times. This means that the oil accumulation can be found in rocks of ages for Maastrichtian and older than Maastrichtian.


AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain