Geochemical study and climatic signal within the saline system of Mhabeul (Southwestern Mediterranean Sea): spectral and statistical analysis

Cyclostratigraphy is considered as the study of the cyclicality recorded in sedimentary series, based especially on mathematical methods. High resolution proxy derived from sebkhas provide significant insights into climatic condition fluctuations. In this context, this work aims to study the cyclicality of the grey scale (GS), the chemical parameters, the sand-fraction percentages and the carbonate percentages along a 91.5-cm core (Mh 2) from the sebkha of Mhabeul. According to the GS results, there is a total of six climatic stages. In fact, the bottom and the top of the Warming Present are marked by high GS (up to 75) indicating dry climatic conditions. The Late Little Ice Age is characterized by intermediate to high GS values indicating a moderate climate. The Early Little Ice Age is manifested by high GS (up to 79) and low sand-fraction percentages (2%), indicating a wet climate. The Medieval Climatic Anomaly (MCA) is marked by an intense decrease of the GS (up to 65), indicating wet climate. The Dark Age is manifested by an increase in the GS values (up to 75). The Roman Warm Period (RWP) is subdivided into two sub-stages: (1) marked by low GS intensity (up to 63) indicating wet climate and (2) marked by high GS intensity (till 86) indicating stable climatic conditions. In fact, the spectral analysis of the studied parameters visualized eight cycles: 2000 years, 1500 years, 865–800 yearsr, 600 yearsr, 560–544 years, 453 years, 346–360 years and 293 years. Those cycles are related to sun activity, oceanographic mechanisms and atmospheric factors.