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<p>A detailed study of benthic foraminiferal assemblages from the pre-evaporitic Messinian deposits of the Moroccan Mediterranean basins (Boudinar and Melilla-Nador) has provided new insights into the main paleoenvironmental changes that occurred prior to the Messinian Salinity Crisis. The analysis of three basin sections reveals that the paleoenvironment evolved in two distinct phases, based on detailed statistical analysis and the ecological preferences of various benthic foraminiferal species. During the first phase (7.24&#xa0;Ma to 6.52&#xa0;Ma), foraminiferal assemblages spanning a broad depth range indicate lower to upper bathyal conditions in both the Boudinar and Melilla-Nador basins. The marine environment was open and moderately oxygenated, with occasional episodes of oxygen depletion, as evidenced by the presence of stress-tolerant species such as <i>Bolivina spathulata</i> and <i>Bulimina aculeata</i>. The second phase (6.52&#xa0;Ma to 6.08&#xa0;Ma) is characterized by a gradual decline in species diversity, reflecting increasingly restricted environmental conditions in the Melilla-Nador basin. The strong dominance of dysoxic, stress-tolerant taxa such as <i>Bolivina spathulata</i>, <i>Bulimina aculeata</i>, <i>Hopkinsina bononiensis</i>, and <i>Rectuvigerina cylindrica</i>, together with the disappearance of oxyphilic species, indicates a deterioration of bottom-water conditions and a shift toward circalittoral depths just before the onset of the Messinian Salinity Crisis. This two-step environmental deterioration parallels restriction trends documented in other Mediterranean basins, including Chélif, Sicily, and Sorbas. Overall, this study refines our understanding of pre-evaporitic Messinian geological, paleoceanographic, and paleoclimatic evolution by documenting how progressive basin restriction, reduced deep-water ventilation, and bathymetric shoaling unfolded in the southwestern Mediterranean prior to the Messinian Salinity Crisis. </p>

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Paleoenvironmental reconstructions of the pre-evaporitic Messinian in northeastern Morocco (Boudinar and Melilla-Nador basins) based on benthic foraminifera

  • 期刊论文

  • 发表日期：

    2025年12月26日

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  • Jihad Rahmouna,
  • Naima Berry,
  • Nadia Barhoun,
  • Ahmed Rachid,
  • Hanane Bahaj,
  • Soukaina Targhi

摘要

A detailed study of benthic foraminiferal assemblages from the pre-evaporitic Messinian deposits of the Moroccan Mediterranean basins (Boudinar and Melilla-Nador) has provided new insights into the main paleoenvironmental changes that occurred prior to the Messinian Salinity Crisis. The analysis of three basin sections reveals that the paleoenvironment evolved in two distinct phases, based on detailed statistical analysis and the ecological preferences of various benthic foraminiferal species. During the first phase (7.24 Ma to 6.52 Ma), foraminiferal assemblages spanning a broad depth range indicate lower to upper bathyal conditions in both the Boudinar and Melilla-Nador basins. The marine environment was open and moderately oxygenated, with occasional episodes of oxygen depletion, as evidenced by the presence of stress-tolerant species such as Bolivina spathulata and Bulimina aculeata. The second phase (6.52 Ma to 6.08 Ma) is characterized by a gradual decline in species diversity, reflecting increasingly restricted environmental conditions in the Melilla-Nador basin. The strong dominance of dysoxic, stress-tolerant taxa such as Bolivina spathulata, Bulimina aculeata, Hopkinsina bononiensis, and Rectuvigerina cylindrica, together with the disappearance of oxyphilic species, indicates a deterioration of bottom-water conditions and a shift toward circalittoral depths just before the onset of the Messinian Salinity Crisis. This two-step environmental deterioration parallels restriction trends documented in other Mediterranean basins, including Chélif, Sicily, and Sorbas. Overall, this study refines our understanding of pre-evaporitic Messinian geological, paleoceanographic, and paleoclimatic evolution by documenting how progressive basin restriction, reduced deep-water ventilation, and bathymetric shoaling unfolded in the southwestern Mediterranean prior to the Messinian Salinity Crisis.