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<p>To characterize the paleoenvironments of the Cenomanian in northeastern Algeria, 74 samples from the Ras El mers section (Aurès Mountains) were quantitatively analyzed. Based on planktic foraminifera and ammonites, substages of the Cenomanian were identified. The lower Cenomanian age was indicated by the <i>Thalmanninella globotruncanoides</i> Zone, supported by <i>Mantelliceras</i> ammonites. The <i>Thalmanninella greenhornensis</i> Zone ending with the FO of <i>Whiteinella baltica</i>, indicates a middle Cenomanian age, confirmed by the ammonite <i>Acanthoceras rhotomagense</i>. Although the <i>Rotalipora cushmani</i> Zone is missing, <i>Dicarinella hagni</i> and related species suggested an upper Cenomanian age for the top part of the section. Non-Metric Multidimensional Scaling (NMDS) and Permutational MANOVA (PERMANOVA) tests indicated a significant difference between the lower and the middle Cenomanian association, while middle and upper Cenomanian associations are non-significantly different. The biotic attributes of the benthic foraminifera indicated that during early Cenomanian, stable, deeper marine conditions prevailed. The middle Cenomanian saw a shift to a shallower setting, characterized by slightly higher water energy and harder substrates, indicating moderate stress levels (more epifauna and lower diversity). By the late Cenomanian, the environment transitioned to shallower, low-energy conditions dominated by soft substrates, with moderate stress persisting. This progression reflects gradual tectonic-influenced shallowing trend and growing environmental variability throughout the Cenomanian. The muddy and pelagic nature of the sediments, the dominance of infaunal echinoids and planktic foraminifera indicates deep, soft substrates, outer ramp setting, and the general lower diversity values of all associations point to environmental stress associated with eutrophic dysoxic/poikiloaerobic regime. The diversity patterns and key biotic indices provide valuable insights for identifying depositional sequences and complementing stratigraphic interpretation.</p>

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Cenomanian foraminifera in the Aurès Mountains of northeastern Algeria: Biostratigraphy and palaeoecology

  • 期刊论文

  • 发表日期：

    2026年4月10日

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  • Nabila Maandi,
  • Fatiha Kechid-Benkherouf,
  • Lynda Tayeb Cherif,
  • Orabi Orabi,
  • Ali Hussain,
  • Ahmed Awad Abdelhady

摘要

To characterize the paleoenvironments of the Cenomanian in northeastern Algeria, 74 samples from the Ras El mers section (Aurès Mountains) were quantitatively analyzed. Based on planktic foraminifera and ammonites, substages of the Cenomanian were identified. The lower Cenomanian age was indicated by the Thalmanninella globotruncanoides Zone, supported by Mantelliceras ammonites. The Thalmanninella greenhornensis Zone ending with the FO of Whiteinella baltica, indicates a middle Cenomanian age, confirmed by the ammonite Acanthoceras rhotomagense. Although the Rotalipora cushmani Zone is missing, Dicarinella hagni and related species suggested an upper Cenomanian age for the top part of the section. Non-Metric Multidimensional Scaling (NMDS) and Permutational MANOVA (PERMANOVA) tests indicated a significant difference between the lower and the middle Cenomanian association, while middle and upper Cenomanian associations are non-significantly different. The biotic attributes of the benthic foraminifera indicated that during early Cenomanian, stable, deeper marine conditions prevailed. The middle Cenomanian saw a shift to a shallower setting, characterized by slightly higher water energy and harder substrates, indicating moderate stress levels (more epifauna and lower diversity). By the late Cenomanian, the environment transitioned to shallower, low-energy conditions dominated by soft substrates, with moderate stress persisting. This progression reflects gradual tectonic-influenced shallowing trend and growing environmental variability throughout the Cenomanian. The muddy and pelagic nature of the sediments, the dominance of infaunal echinoids and planktic foraminifera indicates deep, soft substrates, outer ramp setting, and the general lower diversity values of all associations point to environmental stress associated with eutrophic dysoxic/poikiloaerobic regime. The diversity patterns and key biotic indices provide valuable insights for identifying depositional sequences and complementing stratigraphic interpretation.