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<p>The present study aims to identify the foraminiferal assemblages and recognize the biostratigraphic units as well as the depositional environments of the exposed shaly successions assigned to Al Hilal Formation in the southern part of Marsa Al Hilal embayment, in northeastern Libya. The foraminiferal assemblages are dominated by well preserved, quite abundant and highly diversified planktonic and benthic foraminifera species. The foraminiferal association suggests an age ranging from late Albian to late Cenomanian for the studied section. Based on the stratigraphical range of the recognized species, three planktonic and three benthic foraminiferal zones have been established. The planktonic foraminiferal zones comprise the <i>Thalmanninella appenninica</i> Zone (late Albian), the <i>Thalmanninella globotruncanoides</i> Zone (early Cenomanian) and the <i>Rotalipora cushmani</i> Zone (middle-late Cenomanian). The benthic foraminiferal zones include <i>Mesorbitolina subconcava</i> Zone (late Albian), <i>Gavelinella baltica</i> Zone (early Cenomanian) and <i>Lenticulina muensteri</i> Zone (middle-late Cenomanian). The foraminiferal zones are discussed and correlated with the standard zones from the southern and northern margins of the Tethys Ocean. The Albian-Cenomanian transition is also considered depending on the lowest (LO) and highest occurrences (HO) of the index species <i>Thalmanninella globotruncanoides</i>,<i> Rotalipora cushmani</i>,<i> Pseudothalmanninella ticinensis</i>,<i> Pseudothalmanninella tehamensis</i> and <i>Planomalina praebuxtorfi</i> among planktonic foraminifera. The semiquantitative analysis of the planktonic and benthic foraminifera used to distinguish the depositional environment of the shale deposits in Al Hilal Formation.</p>

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Foraminiferal biostratigraphy and depositional environment of the late Albian–Cenomanian Al Hilal formation in northeastern Libya

  • 期刊论文

  • 发表日期：

    2025年1月14日

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  • Ibrahim M. Abd El-Gaied,
  • Yasser F. Salama,
  • Mansour H. Al-Hashim,
  • Michael M. Grammer,
  • Sayed M. Abd El-Aziz

摘要

The present study aims to identify the foraminiferal assemblages and recognize the biostratigraphic units as well as the depositional environments of the exposed shaly successions assigned to Al Hilal Formation in the southern part of Marsa Al Hilal embayment, in northeastern Libya. The foraminiferal assemblages are dominated by well preserved, quite abundant and highly diversified planktonic and benthic foraminifera species. The foraminiferal association suggests an age ranging from late Albian to late Cenomanian for the studied section. Based on the stratigraphical range of the recognized species, three planktonic and three benthic foraminiferal zones have been established. The planktonic foraminiferal zones comprise the Thalmanninella appenninica Zone (late Albian), the Thalmanninella globotruncanoides Zone (early Cenomanian) and the Rotalipora cushmani Zone (middle-late Cenomanian). The benthic foraminiferal zones include Mesorbitolina subconcava Zone (late Albian), Gavelinella baltica Zone (early Cenomanian) and Lenticulina muensteri Zone (middle-late Cenomanian). The foraminiferal zones are discussed and correlated with the standard zones from the southern and northern margins of the Tethys Ocean. The Albian-Cenomanian transition is also considered depending on the lowest (LO) and highest occurrences (HO) of the index species Thalmanninella globotruncanoides, Rotalipora cushmani, Pseudothalmanninella ticinensis, Pseudothalmanninella tehamensis and Planomalina praebuxtorfi among planktonic foraminifera. The semiquantitative analysis of the planktonic and benthic foraminifera used to distinguish the depositional environment of the shale deposits in Al Hilal Formation.