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<p>The early Eocene (Ypresian) stage is marked by one of the hottest climatic events of the Cenozoic Era, which peaked during the Early Eocene Climatic Optimum (EECO; ca. 53 to 49&#xa0;Ma). In the north–central Tunisia, the sedimentary deposits from this period correspond to the Bou Dabbous Formation. Previous studies poorly documented the detailed stratigraphic geochemistry of the Bou Dabbous Formation in Tunisia during the EECO. In this study, we investigated samples recovered from the Bou Dabbous Formation at Oued El Hammem locality (OH), north-central Tunisia. Our aim is to reconstruct the depositional evolution and assess patterns of organic matter (OM) accumulation in this Formation within the framework of the EECO global warming. We assign the EECO to the interval extending from the base (ca. 53&#xa0;Ma) to the uppermost part of the Bou Dabbous Formation (ca. 49&#xa0;Ma). The lithostratigraphic and geochemical data exhibit rapid fluctuations in carbonate production, detrital influx, and OM contents across the EECO, influenced by sea–level fluctuations, climate, paleoproductivity, and redox conditions. Distinct phases of sea–level changes and enhanced carbonate production during the EECO were revealed by the fluctuations in Sr, Ca, Sr/Ca, Rb/Sr, and the F index. Variations in detrital input (Si, Zr, Ti and Rb), further, highlight periods of acceleration of the hydrological cycle, intense weathering, and fluvial and/or aeolian continental influx during fluctuating hot–dry and hot–humid climatic regimes. The OM preservation in the Bou Dabbous Formation was related to changes in primary productivity, paleoredox conditions, and terrigenous inputs. P/Ti, Zn/Ti and Cu proxies revealed periods of high phytoplankton productivity and wind–driven intensified upwelling patterns during the deposition of the Bou Dabbous Formation. Fluctuations in redox–sensitive trace elements (S, V, Cr, Mo, Cd, Mo, and U) indicate shifts between suboxic/anoxic and more euxinic bottom–water conditions, likely controlled by water–column stratification (halocline/thermocline) and restricted estuarine and bottom–water circulation throughout this depositional setting. Our study suggests that the Bou Dabbous Formation recorded both global climatic forcing—particularly the EECO—and regional tectono–sedimentary processes along the southern Tethyan margin. These findings contribute to our understanding of the interactions between climate, oceanography, and sedimentation during the EECO in the Southern Tethys.</p>

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Geochemical and climatic patterns during the early eocene climatic optimum (EECO) inferred from the Ypresian Bou Dabbous formation in the Oued El Hammem (OH) section, Northern Tunisia

  • 期刊论文

  • 发表日期：

    2026年2月16日

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  • Aida Affouri,
  • Raouf Ghribi,
  • Khawla Zerai,
  • Asma Bouallagui,
  • Hassene Affouri

摘要

The early Eocene (Ypresian) stage is marked by one of the hottest climatic events of the Cenozoic Era, which peaked during the Early Eocene Climatic Optimum (EECO; ca. 53 to 49 Ma). In the north–central Tunisia, the sedimentary deposits from this period correspond to the Bou Dabbous Formation. Previous studies poorly documented the detailed stratigraphic geochemistry of the Bou Dabbous Formation in Tunisia during the EECO. In this study, we investigated samples recovered from the Bou Dabbous Formation at Oued El Hammem locality (OH), north-central Tunisia. Our aim is to reconstruct the depositional evolution and assess patterns of organic matter (OM) accumulation in this Formation within the framework of the EECO global warming. We assign the EECO to the interval extending from the base (ca. 53 Ma) to the uppermost part of the Bou Dabbous Formation (ca. 49 Ma). The lithostratigraphic and geochemical data exhibit rapid fluctuations in carbonate production, detrital influx, and OM contents across the EECO, influenced by sea–level fluctuations, climate, paleoproductivity, and redox conditions. Distinct phases of sea–level changes and enhanced carbonate production during the EECO were revealed by the fluctuations in Sr, Ca, Sr/Ca, Rb/Sr, and the F index. Variations in detrital input (Si, Zr, Ti and Rb), further, highlight periods of acceleration of the hydrological cycle, intense weathering, and fluvial and/or aeolian continental influx during fluctuating hot–dry and hot–humid climatic regimes. The OM preservation in the Bou Dabbous Formation was related to changes in primary productivity, paleoredox conditions, and terrigenous inputs. P/Ti, Zn/Ti and Cu proxies revealed periods of high phytoplankton productivity and wind–driven intensified upwelling patterns during the deposition of the Bou Dabbous Formation. Fluctuations in redox–sensitive trace elements (S, V, Cr, Mo, Cd, Mo, and U) indicate shifts between suboxic/anoxic and more euxinic bottom–water conditions, likely controlled by water–column stratification (halocline/thermocline) and restricted estuarine and bottom–water circulation throughout this depositional setting. Our study suggests that the Bou Dabbous Formation recorded both global climatic forcing—particularly the EECO—and regional tectono–sedimentary processes along the southern Tethyan margin. These findings contribute to our understanding of the interactions between climate, oceanography, and sedimentation during the EECO in the Southern Tethys.