Chemostratigraphy and Correlation of a Chalk Petroleum Reservoir – Case of the Campanian-basal Maastrichtian Abiod Formation in Tunisia

Mabrouk, Amina; Jarvis, Ian; Moody, Richard; Belayouni, Habib; Brahim, A. Ben; Cabrera, Sandra de

doi:10.3997/2214-4609-pdb.8.s048

Cited by 6 publications

(2 citation statements)

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“…The published isotopic data support these changes in palaeoecological conditions, as a number of studies on the C-M interval demonstrated δ 18 O and δ 13 C values changes in benthic foraminifera coinciding with the C/M boundary. In fact, the record of these changes is widespread and provides clues about global climate and organic matter productivity changes at that time (Jarvis et al, 2002;Mabrouk, 2003;Friedrich et al, 2006;Thibault et al, 2012aThibault et al, , 2012b. The geochemical proxies support a "greenhouse" period characterising most of the Late Cretaceous and especially the Campanian stage.…”

Section: Discussionmentioning

confidence: 99%

“…Subsequent chemostratigraphic studies of the Upper Cretaceous chalky Abiod Formation highlighted chemical events that correlate with zones of planktonic foraminifera (Jarvis et al, 2002;Mabrouk, 2003). These studies revealed a paired negative excursion in stable isotope (δ 18 O and δ 13 C) curves close to the assigned C/M boundary within the Gansserina gansseri Zone, correlating with the interval of the Ncham member (uppermost part of the Abiod Formation).…”

Section: Introductionmentioning

confidence: 94%

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

Bejaoui¹,

Saïdi²,

Zaghbib-Turki³

2019

Turkish J Earth Sci

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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.

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