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

Chapter Four
Depositional Environmenment and Paleoecology
species became extinct below the (K/P) boundary while l0 species survived
well into the Danian sediments at El Kef (GSSP) in Tunisia, a phenomena
which indicate in their opinion that the extinction is unrelated to an impact event.
In the present study the available data show both gradual and sudden
catastrophic extinction pattern for partially or halve number in planktonic
foraminiferal species before the (K/T) boundary and complete species
extinction at or near the (K/T) boundary which indicate no Cretaceous
planktonic foraminiferal survivorship into the Danian except of (G. cretacea)
and (H. monmothensis) in the lower most Danian.
In contrast, benthonic foraminifera were not affected by major global
extinction at the Cretaceous/Tertiary boundary, and as fact that could not
differentiate between the Danian and Maastrichtian in the point of benthonic
foraminiferal assemblage point of view (Alegret et al., 2003). In the studied
area, the same document was observed and recorded, in general benthonic
foraminifera were little affected during the K/T mass extinction which was
distinguished by reducing the number of benthonic species at Smaquli from 12-
11 species at Plummerita hantkeninoides Zone (CF1) to 7 species in
Guembelitria cretacea zone (P0) , then increased again upward to 11 species in
Parvularugoglobigerina eugubina zone (Pá) becomes 20 species in (P1a) and
lately 18 species in Subbotina triloculinoides – Praemurica inconstans Zone
(P1b) (Fig. 3.8)
In Qulka section (Dokan area), the number of species remains stable 12
species at the end of Plummerita hantkeninoides Zone (CF1) through Late
Maastrichtian to (P0 & Pá) Earliest Danian, then increased upward to 18
species in (P1a) Parvularugoglobigerina eugubina - Subbotina triloculinoides
Zone. and decreased to 12 species in Subbotina triloculinoides- Praemurica
inconstans Zone (P1b) (Fig. 3.6)
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