Abstract:
The present study deals with Oligocene-Pliocene planktonic foraminiferal
biostratigraphy of the studied succession at Well-A1-89 in the offshore of Sirt Basin.
One hundred and forty one ditch cutting samples have been used for this study,
covering the interval from 1050’ – 9000’. The examination of the studied samples has
led to the identification of fifty-one species and eleven subspecies belong to twelve
genera. On the basis of the vertical stratigraphic distribution of the planktonic
foraminiferal species, with particular attention to last occurrence (LO) of the marker
species, ten planktonic foraminiferal biozones have been identified through the
studied succession following Bolli and Saunders (1985) and Iaccarino (1985) zonal
schemes, in descending order as follows: Sphaeroidinellopsis seminulina s.l
(Zanclean); Praeorbulina glomerosa (Langhian); Globigerinoides trilobus
(Burdigalian); Catapsydrax dissimlis (Aquitanian-Burdigalian); Globigerinoides
primordius (Aquitanian); Globorotalia kugleri (Chattian); Globigerina ciperoensis
ciperoensis (Chattian); Globorotalia opima opima (Chattian); Globigerina
ampliapertura (Rupelian); Cassigerinella chipolensis/ Pseudohastegrina micra
(Rupelian). The Oligocene–Miocene (O/M) boundary is found to be conformable and
is placed at the top of the Globorotalia kugleri Biozone. However, the
Miocene/Pliocene (M/P) boundary is unconformable and is placed at the top of
Praeorbulina glomerosa Biozone. Additionally, the established biozones have been
regionally correlated with their equivalents in Tunisia and Egypt.
