Planktonic Foraminiferal Zonation of the Oligocene-Miocene Succession of Well H1-NC41, NW Offshore, Libya

Abstract

Analysis of the planktonic foraminiferal contents of 183 cutting and sidewall core samples from the Oligocene-Miocene sequence of well H1-NC41, NW offshore, Libya enabled the subdivision of the sequence into eleven planktonic foraminiferal zones. They are, in ascending order:

1. The Globigerina ampliapertura Zone.
2. The Globorotalia opima opima Zone.

3. The Globorotalia kugleri Zone

4. The Globoquadrina dehiscens Zone.

5. The Globigerinoides altiapertura Zone.

6. The Globigerinoides bisphericus Zone.

7. The Praeorbulina glomerosa glomerosa Zone.

8. The Orbulina suturalis Zone.

9. The Orbulina universa Zone.

10. The Globorotalia acostaensis Zone.

11. The Globigerinoides extremus Zone.

The Oligocene-Miocene planktonic foraminiferal biosequence of well H1-NC41 has been correlated with P-N Zones, the biostratigraphic events age estimates in million years, and the European stage boundaries.

The absence of Zones P17, P18, P19, and possibly the lower part of Zone P20 may indicate a period of erosion and non-deposition at the Eocene/Oligocene boundary. In the Late Oligocene, Zone P22 and possibly the lowermost Zone N4a are missing, indicating a hiatus at this interval. The missing of Zones N10 (part), N11, N12, N13, N14 (part) may be due to non-deposition (hiatus), change in depositional environment, or both.

The top of Zone N17 is also missing, indicating unconformity at the end of the Miocene.