TY - JOUR

T1 - Integrated stratigraphy of the middle-upper Eocene Souar Formation (Tunisian dorsal)

T2 - Implications for the Middle Eocene Climatic Optimum (MECO) in the SW Neo-Tethys

AU - Messaoud, Jihede Haj

AU - Thibault, Nicolas

AU - Bomou, Brahimsamba

AU - Adatte, Thierry

AU - Monkenbusch, Johannes

AU - Spangenberg, Jorge E.

AU - Aljahdali, Mohammed H.

AU - Yaich, Chokri

N1 - Funding Information: Funding for this study was ensured through internal funds from the University of Copenhagen allocated to J.H.M. via the double-degree Ph.D. program. T.A. and N.T. also acknowledge the IGN International Academy program that facilitated collaboration between KU and Lausanne. Publisher Copyright: © 2021 The Authors

PY - 2021/11/1

Y1 - 2021/11/1

N2 - Calcareous nannofossil biostratigraphy and carbon-isotope stratigraphy on bulk organics of the middle-upper Eocene Souar Formation (Tunisia) allow for a refined stratigraphy of this interval in the southwestern Neo-Tethys margin. The Souar Formation represents the deepest sedimentary deposits of the central northern Tunisian Basin and was only dated previously by coarse data on planktonic foraminifera. Together with our new data, a correlation is proposed to previous Tunisian records of the Halk El Menzal carbonate platform to the NE and shallow-water deposits of central Tunisia to the SW, which leads us to the erection of a synthetic stratigraphic chart of the middle-upper Eocene in central and northeastern Tunisia. Our results allow for a review of the accurate position of the Lutetian / Bartonian and the Bartonian / Priabonian stage boundaries in Tunisia relative to calcareous nannofossil biohorizons. We apply Bayesian statistics to build our age-depth model which points to a hiatus in the Lutetian (CNE12 Zone) that we relate to the middle Lutetian regressive sequence leading to the Lu-4 M-cycle. Radiolarian-rich sediments and cherts of the late Lutetian and early Bartonian are interpreted as a response to an increase in productivity, tied to the seasonal upwelling of nutrient-rich waters. Correlation to other sections in Tunisia highlights the strong contrast in facies between the carbonate-rich sequences of the edges of the dorsal and the silica-rich deposition in the Souar Formation. This contrast is particularly pronounced in the interval before and across the Middle Eocene Climatic Optimum (MECO) characterized by a maximum of nummulitic carbonate production on the platform and a minimum of carbonate production in the deep basinal parts of the Tunisian dorsal, rather dominated by silica-rich sediments.

AB - Calcareous nannofossil biostratigraphy and carbon-isotope stratigraphy on bulk organics of the middle-upper Eocene Souar Formation (Tunisia) allow for a refined stratigraphy of this interval in the southwestern Neo-Tethys margin. The Souar Formation represents the deepest sedimentary deposits of the central northern Tunisian Basin and was only dated previously by coarse data on planktonic foraminifera. Together with our new data, a correlation is proposed to previous Tunisian records of the Halk El Menzal carbonate platform to the NE and shallow-water deposits of central Tunisia to the SW, which leads us to the erection of a synthetic stratigraphic chart of the middle-upper Eocene in central and northeastern Tunisia. Our results allow for a review of the accurate position of the Lutetian / Bartonian and the Bartonian / Priabonian stage boundaries in Tunisia relative to calcareous nannofossil biohorizons. We apply Bayesian statistics to build our age-depth model which points to a hiatus in the Lutetian (CNE12 Zone) that we relate to the middle Lutetian regressive sequence leading to the Lu-4 M-cycle. Radiolarian-rich sediments and cherts of the late Lutetian and early Bartonian are interpreted as a response to an increase in productivity, tied to the seasonal upwelling of nutrient-rich waters. Correlation to other sections in Tunisia highlights the strong contrast in facies between the carbonate-rich sequences of the edges of the dorsal and the silica-rich deposition in the Souar Formation. This contrast is particularly pronounced in the interval before and across the Middle Eocene Climatic Optimum (MECO) characterized by a maximum of nummulitic carbonate production on the platform and a minimum of carbonate production in the deep basinal parts of the Tunisian dorsal, rather dominated by silica-rich sediments.

KW - Bayesian modelling

KW - Calcareous nannofossils

KW - Carbon isotope stratigraphy

KW - Global warming

KW - X-ray diffraction

KW - X-ray fluorescence

U2 - 10.1016/j.palaeo.2021.110639

DO - 10.1016/j.palaeo.2021.110639

M3 - Journal article

AN - SCOPUS:85114440523

VL - 581

JO - Palaeogeography, Palaeoclimatology, Palaeoecology - An International Journal for the Geo-Sciences

JF - Palaeogeography, Palaeoclimatology, Palaeoecology - An International Journal for the Geo-Sciences

SN - 0031-0182

M1 - 110639

ER -