biostratigraphy and paleoecology of cretaceous/tertiary boundary in ...

Chapter one
Introduction
area north of Koy Sinjaq town by about 25 Km. This area is represented
geomorphologically by mountain series and narrow or wide subsequent (strike)
valleys trending northwest—southeast. The Mountains and valleys are
dissected by, at least, two large consequent valleys and tens of smaller ones.
The large valleys are those in which the Little Zab and Diala Rivers. The
outcrops of the studied sections consist mainly of alternation of thick beds of
flysch type marl, shale, marly limestone, claystone and sandstone of Tanjero-
Kolosh Formations, ridge forming massive pale grey tough recrystalized
occasionally dolomitized, siliclastic limestone of interfingering Aqra Formation
and thick beds of red claystone, sandstone and conglomerate molasses type
of Red Bed Series.
1.3- Geological Setting
The studied area is located at the southern boundary (in front) of the Zagros
Thrust Belt, which is developed from the basin fill of the Neo-Tethys and
colliding of the Iranian and Arabian plates (Buday 1980). Structurally, the
studied area is located within two different zones. The outcrops of Qishlagh
section ( Qala Cholan area), Kato section (Barzinja area) and Sirwan valley
section (Halabja area) are located in the Imbricated Zone while that of Dokan
section ( Dokan area) and Gali section (Smaquli area) are located exactly on
the high folded Zone, as divided by Buday and Jassim (1987) (Fig.1.1 and
1.2).
Because of intense imbrications, the studied area in Qishlagh, Kato and
Sirwan valley is characterized by obscured anticlines and synclines which
have been stacked together as very thick and tight packages which were
overturned toward southwest (Karim 2004). These imbrications include
Qulqula, Balambo, Aqra, and other units such as Kometan, Shiranish, Tanjero,
Kolosh Formations and the Red Bed Series.
3