1) The document discusses the tectonic evolution of part of the Zagros foreland basin in northern Iraq from the Early Cretaceous to Early Eocene periods. 2) During the Cretaceous, there was a shift from a passive margin to a foreland basin phase as the Arabian-Nubian Plate advanced, imposing a tectonic load and forming a flexural wave. This led to the deposition of different formations in foredeep, forbulge, and back-bulge depozones. 3) By the late Cretaceous, the zagros foreland basin was characterized by three depositional realms - a lower carbonate unit, pelagic

1. University of Mosul
College of Sciences
Early Cretaceous – Early Eocene Tectonic Evolution
of a Part of Zagros Foreland Basin
Northern Iraq
A PH.D. Thesis
by
Rabeea Khalaf Hasan Znad
Msc. 1992
Supervised by
Dr. Kamal Haji Karim Dr. Ibrahim Saad Al Jumaily
Professor Ass. Professor
A.H3414 2013 A.D
rabeeazinad@yahoo.com

2. ABSTRACT
The Early Cretaceous –Early Eocene tectonic evolution of a part of
zagros foreland basin of high folded zone has been studied at northern Iraq.
The stratigraphic sequence of studied area includes the Formations of
Qamchuca, Bekhme, Shiranish, Aqra, Tanjero and Kolosh.
It has been shown from this study that, during the cretaceous (Albian –
Cenomanian) there was a geodynamic shift from the passive margin phase to
the foreland basin phase. The shift, however, took place on the north-
northeastern margin of Arabian- Nubian Plate (ANP), the advance of
continental margin of ANP toward subduction zone imposed a tectonic load
leading to the formation of a flexural wave. The consequences of the last
tectonic event were reflected by continuous deposition of carbonate
Balambo formation in a foredeep depozone, concomitant with a flexural
emergence of the continental shelf further to the west forming a forbulge
depozone which was represented by deposition of reefal Qamchuqa
formation. The configuration of wave can be traced through the formation of
a back-bulge depozone leading to the deposition of Jawan and Sarmored
formations according to their own tectonic setting
The Megasequence boundary between AP8and AP9 is considered to be
the representative of that geodynamic changes. The last sequence of the
passive margin is Qamchuqa Fn. Which is called Later the Pre-orogenic
Carbonate Platform, and separated from Bekhme Fn. by regional
unconformity. The Last one is represented by the Lower Sequence of the
foreland basin, which is called later the syn-orogenic carbonate platform.
The Rheological properties of the Arabian Lithosphere and the
structural properties of the inherited structures have led to inhomogeneity of
created the forebulge (Qamchuqa Fn.). These represent the height and
extension parallel with (along Strike) the front of orogeny during the
approaching of the Plates convergence. Other effects are on the sequence
stratigraphy in the study area, as well as the effect of geographical
distribution of the contact between Ap8/Ap9 (forebulge unconformity)
from the southern east (Sulaimania District) toward the northern west,
parallel to the front of orogen, where the stratgraphic gap between
Qamchuqa Fn. and other youngest Fns. are getting successively larger.

3. During the middle Campanian, the zagros foreland basin started with the
underfilled stage, and it was entirely clear by the end of Cretaceous
comprising a broad threefold subdivision of depositional realms that
translated into three stratigraphic units known as- trinity underfilled units- of
foreland basin. The lower carbonate unit represented by Bekhme
formation,the pelagic and hemipelagic unit are represented by Shiranish
formation, while the upper flysch clastic unit is represented by Tanjero
formation. All these units were superimposed during basin migration and
they tend to get younger in the direction opposite to the advancing orogenic
wedge toward Arabian craton.
In Rawandoz, Bekhme and Shaqlawa areas, the contact between
Shiranish and Bekhme formations has been studied from the fossiliferous
point of view. Calcareous nanofossiliferous assemblages have been used to
verify that the base of the Shiranish Fn. is in the lower part of the Late
Campanian, and in the Middle Campanian for the zones of Bekhme,
Shaqlawa and Rawandoz Successively.
The older age of the base of the Shiranish Fn. in Rawanduz area is
attributed to early drowning (flexing downward) of the Arabian platform
under the effect of progressive advancing tectonic load of the orogenic
wedge toward Arabian craton.
According to the aforementioned discussion evidence, the progressive
velocity of the orogenic wedge during the estimated period was (12.10 -
11.02, ±3mm/year), and the paleodrowning line, was generally trending
north-south.
Interpretation of the Isopach map of kolosh fn. revealed the tectonic
effect on the aerial spreading of this formation such a distribution is
characterized by non-deposition on the forebulge depozone (the present
Amadiya, Gara and Aqra anticlines) which were exposed at that time, while
this Formation was deposited in the foredeep and back-bulge depozone. This
forebulge was also hindering the spreading Tanjero formation southwest the
line joined between Gara, Aqra and Harir Anticlines.
Two of parallel main depocenters of kolosh Fn. which extends
northwest- southeast, have been identified. The First is called Kand-Dohuk
basin with its axis deviated by (35) degrees clockwise from the current axis
of Bekhair anticline, and more than (80) degrees from the axes of Matin and
Gara anticlines.

4. The second, which extends northwest-southeast, is called Shaqlawa
basin, it represents an extension of the deposition Kolosh formation in
foredeep basin.The hight of forebulge zone could not be an obstacle to the
transportation of sediments, especially after the sedimentation of upper part
of Kolosh formation during the filling stage of foredeep. This basin
deviates (15) degree clockwise from the current axis of Safin anticline and
extended southeast out of the Study Area.
The anticlockwise rotation of Arabian Plate and its oblique collision with
the Eurasian Plate as well as the reactivation of the basement faults during
the paroxysmal phase of orogeny in Pliocene produced structures which
differently oriented than the orientation of the existing basin during the Late
Cretaceous –Paleocene.
The link between tectonic lithosphere proposed in the Model and the facts
of the sedimentary –stratigraphy situations in the study area, demonstrate
that the Zagros Foreland Basin belong to(Broken Foreland Basin).