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<p>The El Djehaf section (DLF) in Northern Tunisia offers a detailed record of palaeoenvironmental and geochemical changes associated with the Oceanic Anoxic Event (OAE)1d during the late Albian. The upper part of this section, including the F3-DLF unit, is characterized by an increase in total organic carbon (TOC) content that is accompanied by an overall positive δ¹³Corg excursion. Geochemical data reveal prevailing anoxic redox conditions during deposition, which, along with evidence of abundant calcispheres and opportunistic r-strategist forms of planktic foraminifera including hedbergellids, suggest high surface productivity driven by enhanced nutrient input. These conditions likely resulted in the formation and the preservation of organic matter in sediments, emphasizing the critical role of nutrient flux and redox dynamics in organic matter sequestration. The δ¹³C<sub>org</sub> excursion observed in the El Djehaf section is coeval with the Breistroffer black shale level and is correlated with global records from Europe and Mexico, providing a robust framework for the occurrence of OAE1d-related black shale deposits. Moreover, the geochemical patterns observed in the El Djehaf section highlight the interplay between local and global factors during OAE1d. Enhanced nutrient input played a crucial role in sustaining elevated productivity, while bottom-water anoxia allowed organic matter to be efficiently preserved. The data emphasise the importance of regional studies in refining our understanding of global oceanic anoxic events, particularly in reconstructing the mechanisms driving carbon cycle perturbations and their impacts on marine ecosystems.</p>

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An integrated study of late Albian OAE1d event in Northern Tunisia: inferred stable carbon isotopes correlation with Europe and Mexico

  • 期刊论文

  • 发表日期：

    2025年9月20日

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  • Salma Soussi,
  • Fares Khemiri,
  • Moez Ben Fadhel,
  • Gonzalo Márquez Martinez,
  • Moncef Saidi,
  • Khaled El Asmi,
  • Amina Mabrouk El Asmi

摘要

The El Djehaf section (DLF) in Northern Tunisia offers a detailed record of palaeoenvironmental and geochemical changes associated with the Oceanic Anoxic Event (OAE)1d during the late Albian. The upper part of this section, including the F3-DLF unit, is characterized by an increase in total organic carbon (TOC) content that is accompanied by an overall positive δ¹³Corg excursion. Geochemical data reveal prevailing anoxic redox conditions during deposition, which, along with evidence of abundant calcispheres and opportunistic r-strategist forms of planktic foraminifera including hedbergellids, suggest high surface productivity driven by enhanced nutrient input. These conditions likely resulted in the formation and the preservation of organic matter in sediments, emphasizing the critical role of nutrient flux and redox dynamics in organic matter sequestration. The δ¹³Corg excursion observed in the El Djehaf section is coeval with the Breistroffer black shale level and is correlated with global records from Europe and Mexico, providing a robust framework for the occurrence of OAE1d-related black shale deposits. Moreover, the geochemical patterns observed in the El Djehaf section highlight the interplay between local and global factors during OAE1d. Enhanced nutrient input played a crucial role in sustaining elevated productivity, while bottom-water anoxia allowed organic matter to be efficiently preserved. The data emphasise the importance of regional studies in refining our understanding of global oceanic anoxic events, particularly in reconstructing the mechanisms driving carbon cycle perturbations and their impacts on marine ecosystems.