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

Chapter one
Introduction
Lawa et al. (1998) argued the interfingering carbonate layers in the upper
part of the Tanjero Formation at Chwarta-Mawat area and concluded that
these layers belong to Aqra Formation with Late Maastrichtian age according
to existence of Abathomphalus mayaroensis Subzone.
Sharbazheri (2007) estimated the age of unconformity within Tanjero
Formation, by about (1.23 my) duration through thick succession of 500m
conglomerate and red claystone layers at the lower part of Tanjero Formation
at Chwarta area, depending on describing the following planktonic
foraminiferal biostratigraphic zones from the base upward: Globotruncana
aegyptiaca Interval Zone (CF8), Gansserina gansseri Interval Zone (CF7)
Racemiguembelina fructicosa Interval Zone (CF4), Pseudoguembelina
hariaensis Interval Zone (CF3) with missing zones of Contusotruncana
contusa Interval zone (CF6) and Pseudotextularia intermedia Interval zone
(CF5).
1.6 – Review on the Upper Cretaceous- Lower Tertiary Contact in Iraq.
The Upper Cretaceous and Lower Tertiary sedimentary rocks in Iraq have
been the subject of numerous stratigraphic and paleontological investigations.
Such sediments are well developed in both surface and subsurface exactly the
exposed part at north and northeastern territory
The Upper Cretaceous and Lower Tertiary boundary is marked by one of
the most dramatic extinction of different groups of organism; especially the
planktonic foraminifera, the recognition of the major paleoclimatic change
during the late Maastrichtian has focused new attention on global climate
changes and their effect on marine organism.
In particular the last half million years of the Maastrichtian is increasingly
recognized as a time of rapid and extreme climatic changes characterized by
maximum cooling at about 65, 5 Ma, followed by (3-4 0 ) C greenhouse warming
and major Deccan volcanic activity between 65.4 and 65.2 Ma. (Li & Keller,
1998a) (Keller 2001) (Barrera, 1994; Courtillot et al., 1996, Hoffman et al.,
2000, in Keller, 2004)
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