Small benthic foraminiferal biostratigraphy and palaeoecology during the Campanian-Maastrichtian transition in north-western Tunisia

Abdellatif BEJAOUI; Ezzedine SAÏDI; Dalila ZAGHBIB-TURKI

Article Details

Small benthic foraminiferal biostratigraphy and palaeoecology during the Campanian-Maastrichtian transition in north-western Tunisia

Authors:

Abdellatif BEJAOUI | Ezzedine SAÏDI | Dalila ZAGHBIB-TURKI

Publisher:

TUBITAK

Journal:

Turkish Journal of Earth Sciences 2019 Vol.28 Issue 4, pp.500-530

Document Type:

Article

Publication Date:

7/2019

Document Language:

English

Document ID (Org No.):

2000730993

Frequency:

Bimonthly

eISSN:

1303-619X

pISSN:

1300-0985

Abstract:

 

Campanian-Maastrichtian (C-M) sediments in the Kalâat Senan area (north-western Tunisia) include rich microfauna. Small  benthic foraminifera (SBF) analysis at the Wadi Necham (ON) section reveals significant biostratigraphic and palaeoecological changes  during the C-M transition. A progressive evolutionary trend within the Bolivinoides lineage allowed us to establish the late Campanian  B. decoratus Interval Range Zone (IRZ) and two successive zones in the early Maastrichtian, namely the B. miliaris IRZ and the B. draco  Total Range Zone (TRZ), which span the standard planktonic foraminifera Gansserina gansseri IRZ. Foraminiferal semiquantitative  data from the C-M transition interval at the studied section yield high values of planktonic/benthic (P/B) ratios (92%-98%) suggesting  an upper to middle bathyal depositional palaeoenvironment. Assemblages of such a deep environment comprise diversified epibenthic  and endobenthic taxa indicating major changes across and above the C-M transition. During the late Campanian (Bolivinoides  decoratus Zone) endobenthic morphogroups dominate (71%) the assemblages as compared to epibenthic morphogroups, which reach  29%. In contrast, the abundance of epibenthic morphogroups increases to 40% just above the C/M boundary (Bolivinoides miliaris  Zone) and suggests cooler and more oxygenated conditions on the sea floor. Epibenthic and endobenthic abundances fluctuate in  opposite trends (40%-60%) throughout the early Maastrichtian (B. draco TRZ). These variations are interpreted to reflect mesotrophic  conditions intermittently interrupted by eutrophic shifts associated with the early Maastrichtian cooling event. The relative proportion  of endobenthics increased (60%-80%) again towards the late Maastrichtian (upper part of the B. draco TRZ), showing a particular  increase in EnA morphogroups prevailing in the SBF assemblages. Moreover, test morphology analyses of SBF assemblages allowed  us to distinguish six epibenthic (M1 to M6) and seven endobenthic (M7 to M13) morphogroups based on their mode of coiling.  This classification reveals the flourishing of EpC M4 and M5 morphogroups during the early Maastrichtian due to more oxygenated  conditions on the sea floor.

Article Details

Small benthic foraminiferal biostratigraphy and palaeoecology during the Campanian-Maastrichtian transition in north-western Tunisia

Authors: Abdellatif BEJAOUI | Ezzedine SAÏDI | Dalila ZAGHBIB-TURKI

Publisher: TUBITAK

Journal: Turkish Journal of Earth Sciences 2019 Vol.28 Issue 4, pp.500-530

Document Type: Article

Publication Date: 7/2019

Document Language: English

Document ID (Org No.): 2000730993

Frequency: Bimonthly

eISSN: 1303-619X

pISSN: 1300-0985

Issues

Authors:

Abdellatif BEJAOUI | Ezzedine SAÏDI | Dalila ZAGHBIB-TURKI

Publisher:

TUBITAK

Journal:

Turkish Journal of Earth Sciences 2019 Vol.28 Issue 4, pp.500-530

Document Type:

Article

Publication Date:

7/2019

Document Language:

English

Document ID (Org No.):

2000730993

Frequency:

Bimonthly

eISSN:

1303-619X

pISSN:

1300-0985