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

Chapter Four
Depositional Environmenment and Paleoecology
Paleocene planktonic foraminifera (Liu & Olsson 1992 and Olsson et al., 2000)
consequently the biotic parameters or factors which play an important role on
the environmental output based on quantitative analysis of planktonic
foraminiferal assemblages is of little values when it is compared with qualitative
investigation in the base of Paleocene age.
1-The Early Paleocene episode characterized by low Planktonic
foraminiferal species richness 18 in Pá decreased to 12 species in P1b, P/B
ratios are 65 in Pá and 40 in P1b, Aggl./Calc. percent ranged between 40-25-
in Gali section.
2- In Qulka section species richness is 14 in P1a decreased to 11 species in
P1b, P/B ratios are 45 in P1a and 50 in P1b, Aggl. /Calc. percent ranged
between 30-20- .
3-Species richness is 17 in P1a decreased to 15 species in P1b, P/B ratios
are 50 and Aggl. /Calc. percent is 35 in P1a and 25 in P1b in Sirwan section.
The planktonic assemblages of the lower Danian in (P0) in Smaquli, and (P0
& Pá) from Dokan and Sirwan valley are characterized by no recording of
planktonic foraminiferal assemblage except for (Hedbergella monmothensis &
Guembelitria cretacea), in the last 25cm of (P0) at Smaquli section. Little
increase in Agglutinated percent at Smaquli and Sirwan valley refers to the
shallowing episode around 10-50m. (Olsson & Nyong, 1984 in Samir, 2002),
(Keller, 1988; Li and Keller, 1998c: Keller and others, 2002b in Keller, 2004),
(Abramovich. and Keller, 2002). Afterward the planktonic foraminiferal species
richness was recognized from Smaquli, Sirwan and Dokan are 18, 17, and 14
species respectively from (Pá, P1a), it decreased to 11, 15 and 12 in (P1b).
P/B ratios shows normal percent varied between 40 to 50% during the total
interval low Agglutinated percentages around 20 to 25. These environmental
parameters and general benthonic morphotypes of Upper Cretaceous/Early
Paleocene Paleodepth indicators reveal shallow water bathymetry of innermiddle
neritic around 50 - 70m depth. (Keller, 1988; Li and Keller, 1998c: Keller
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