Distribution of Miocene dinoflagellate cysts in the paralic basins of Tunisia: Paleogeographic and paleoecological reconstruction and eustatic movements

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology Pub Date : 2025-01-19 DOI:10.1016/j.marmicro.2025.102443

Nadia Ben Moktar , Amel Mahjoubi-Ghanmi , Beya Mannai-Tayech

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Abstract

The Miocene deposits of northeastern and central-eastern Tunisia are primarily of clastic, deltaic-type. These deposits are organized into complex sedimentary sequences shaped by tectonic activity, eustatic fluctuations, and changes in climatic conditions. This study presents the evolution of dinoflagellate cysts associations extracted from Miocene-age deposits. These deposits ranged from 16 million to 5.3 million years ago. They are taken from three boreholes and three sections in northeastern and central Tunisia. Dinocysts serve as valuable indicators of climatic variations and sea-level fluctuations. Their study supports the results obtained from the analysis of pollen grains. It sheds light on paleoecology, paleogeography, and eustatic conditions during that period.

Various associations (oceanic, neritic, climatic, etc.) were established based on the ecological preferences of these marine microorganisms. Oceanic conditions are characterized by the presence of Impagidinium. Shallow marine environments are defined by the presence of Cordosphaeridium inodes minimus. Meanwhile, Nematosphaeropis and Tectatodinium indicate a neritic to oceanic environment. It is confirmed by the abundance of Lejeunecysta, Operculodinium, israelianum, Polysphardium zoharyi, Homotryblium, Spiniferites, Cleistosphaeridium, and Lingulodinium machaerophorum. These results align with lithological and biostratigraphic data related to paleobathymetry and paleogeography.

Changes in dinocyst taxa relative abundances helped track the shoreline's evolution during the Miocene. Variations in the relative abundance of Impagidinium and Cordosphaeridium inodes minimus, or their absence, indicate environmental shifts. This shift reflects a transition from a neritic environment (Aïn Grab Formation) to an oceanic one (Mahmoud Formation). The Saouaf Formation is marked by a eustatic drop at its base (Unit I). However, Units II and III are defined by eustatic rises in pulsations. The Somaa sands were deposited in a neritic and/or epicontinental environment, followed by a return to an oceanic setting (Melquart Formation).

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来源期刊

Marine Micropaleontology 地学-古生物学

CiteScore

3.70

自引率

15.80%

发文量

审稿时长

26.7 weeks

期刊介绍： Marine Micropaleontology is an international journal publishing original, innovative and significant scientific papers in all fields related to marine microfossils, including ecology and paleoecology, biology and paleobiology, paleoceanography and paleoclimatology, environmental monitoring, taphonomy, evolution and molecular phylogeny. The journal strongly encourages the publication of articles in which marine microfossils and/or their chemical composition are used to solve fundamental geological, environmental and biological problems. However, it does not publish purely stratigraphic or taxonomic papers. In Marine Micropaleontology, a special section is dedicated to short papers on new methods and protocols using marine microfossils. We solicit special issues on hot topics in marine micropaleontology and review articles on timely subjects.