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

Chapter Three Biostratigraphy
from predeposited sediment of Tanjero basin to be the transitional time interval
from Cretaceous to Tertiary, the second estimation is that the transitional unit
may represent time interval of latest Maastrichtian or Earliest Danian of
deposition, or the upper most part of Tanjero Formation chronostratigraphically
may extended to the lower Paleocene while the another contradictory
assumption is that the Red Bed Series may began from the upper Maastrichtian.
The most important sedimentological evidence is Tagaran conglomerate
within the upper part of Tanjero formation, shows the same sedimentological
origin of that of transitional unit and conglomerate beds within the lower part of
Red Bed Series. (Karim, 2004 and Al-Barzinjy, 2005), The K/T contact in the
studied areas has been interpreted as conformable contact.
3.2.2- Biostratigraphy of the Early Paleocene Formations:
According to identified planktonic foraminiferal assemblages within Lower
part of Kolosh Formation, in Smaquli, Dokan and Sirwan area, four biozones
recorded in the region. The biostratigraphic zones of the studied area are
described from the bottom to the top as below:
3.2.2.1- P0. Guembelitria cretacea interval Zone.
The contact line between Tanjero and overlying Kolosh Formation in Gali
section placed on the last oily impregnated friable soft and weathered pale
brown fine sandstone beds of 1 meter thickness barren of foraminifera except
for few forms of Guembelitria cretacea Cushman. This fine sandstone bed
overlied by 25cm dark organic papery shale and interlayred by thin beds of dark
grey marl which evidenced by the record of Hedbergella monmothensis (Olsson)
with Guembelitria cretacea. This interval is 1,25 meter thick representing the
Guembelitria cretacea (P0) zone and marks the K/T boundary and defined as
interval between the extinction of Cretaceous planktonic foraminifera, Last
appearance Datum (LAD) of (Globotruncana, Rugoglobigerina,
Globigerinelloides, Heterohelicids) at the base and the first appearance datum
(FAD) of Parvularugoglobigerina eugubina (loterbacher & Premoli Silva) at the
top. (Plate.26, Figs. 17-18) (Fig. 3. 7 part. 2). The Guembelitria cretacea
Biozone is comparatively very well expanded (1, 25 meter) and lithologically
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