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

Chapter one
Introduction
The Shiranish Formation in the studied area overlies Kometan Formation
conformably. This evidence was studied in the recent years and during
fieldwork, new observations are recorded in many different localities that show,
distinct character in opposite to previous studies, like gradational contact
between the Kometan and Shiranish Formations. The gradation contact can
be seen as the regular alternating of beds of white limestone and bluish white
marl. Fig (1.4) (Karim et al., 2007).
In the studied area the Shiranish Formation overerlain by Tanjero
Formation graditionally and the contact is marked by the first appearance of
gray sandstone or siltstone beds at the top of Shiranish Formation (bluish
white marl and marly limestone) and starting of olive green lithology of Tanjero
Formation.
Fig. (1.4) A: Modification of the time expanded stratigraphic column of Bellen et al (1959)
showing the gradational contact between Kometan and Shiranish Formations.
B: Original column of the above authors without modification. (After Karim et al., 2007)
1.4.1.2- Tanjero Formation
According to Bellen et al. (1959), Tanjero Formation is first defined and
described under the name of Tanjero Formation by Dunnington (1952). From
the selected type section at Sirwan valley, 2 km to the south of Kani
Karweshkan village, near Halabja town (Fig 1.1 ) and at the right bank of
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