Environmental evolution of the Acholla coast (Gulf of Gabes, Tunisia) during the past 2000 years as inferred from palaeontological and sedimentological proxies
Abstract:A multi-proxy approach to infer the environmental evolution and coastal dynamics was conducted on four sediment cores with the aim to decipher forcing factors shaping the coastline of Acholla (Tunisia) over the last 2000 years. The data recorded from palaeontological and sedimentological
studies combined with 14C dating suggest a progression of four successive phases: (1) the first Holocene marine transgression (183 A. D.), overlying Upper Pleistocene marine sandstones, resulted in a brackish shallow-water co… Show more
“…Further southeast in the Gulf of Gabes and the Libyan border, Holocene marine terraces show a minimum 1.9 ± 0.10 m emergence above present-day sea level since about 6000 years ago 26 . These active phenomena are either correlated with a phase of stripping and erosion of soils on the slopes, or the coastal elevation as the result of the shoreline emergence of post-glacial hydro-isostatic effects 22 , 27 . The relatively low topography made of marine and alluvial terraces ranging between about 1.9 m and 32 m high (above sea level) favour sea wave inundations along east Tunisia.…”
Section: Introductionmentioning
confidence: 99%
“…The relatively low topography made of marine and alluvial terraces ranging between about 1.9 m and 32 m high (above sea level) favour sea wave inundations along east Tunisia. In addition, at the end of antiquity, coastal east Tunisia recorded phenomena of silted-up land and siltation that imply a severe sudden marine inundation 27 – 29 . Figure 2 ( A ) The site at Henchir El Mejdoul (landscape photo; see location in Fig.…”
New field investigations along the East Tunisian coastline reveal sedimentary deposits and damaged localities that may account for a catastrophic event during the late Holocene. North of Sfax city, ~ 3.4 m high cliff coastal marine and alluvial terraces show 20 to 50-cm-thick chaotic layer with sandy coarse gravels mixed with reworked pebbles, broken shells of gastropods and molluscs, organic matter and Roman pottery. The chaotic layer truncates sandy-silty paleosol, covers Roman settlements and is overlain by fire remains, a thin sandy-silty aeolian unit and ~ 1-m-thick alluvial deposits. Charcoal samples collected at 10 cm below and 4 cm above the catastrophic deposits provide radiocarbon dating that brackets the catastrophic unit between 286 and 370 CE. Other historical investigations on the Roman sites of Neapolis (Nabeul), Hadrumete (Sousse), Thyna (Sfax), Meninx in Girba (Djerba), Wadi Ennouili (Gulf of Gabes), and Sabratha (in Libya) evidenced major damage and abandonment of sites in the fourth century (16, 41, 42, 43, 44). The new identification of catastrophic deposits, offshore-onshore correlations with turbidites and modelling of tsunami waves suggest the relationship with the 21 July 365 tsunamigenic earthquake (Mw ~ 8) of west Crete (Greece) and call for a better estimate of tsunami risk on the Mediterranean coastlines.
“…Further southeast in the Gulf of Gabes and the Libyan border, Holocene marine terraces show a minimum 1.9 ± 0.10 m emergence above present-day sea level since about 6000 years ago 26 . These active phenomena are either correlated with a phase of stripping and erosion of soils on the slopes, or the coastal elevation as the result of the shoreline emergence of post-glacial hydro-isostatic effects 22 , 27 . The relatively low topography made of marine and alluvial terraces ranging between about 1.9 m and 32 m high (above sea level) favour sea wave inundations along east Tunisia.…”
Section: Introductionmentioning
confidence: 99%
“…The relatively low topography made of marine and alluvial terraces ranging between about 1.9 m and 32 m high (above sea level) favour sea wave inundations along east Tunisia. In addition, at the end of antiquity, coastal east Tunisia recorded phenomena of silted-up land and siltation that imply a severe sudden marine inundation 27 – 29 . Figure 2 ( A ) The site at Henchir El Mejdoul (landscape photo; see location in Fig.…”
New field investigations along the East Tunisian coastline reveal sedimentary deposits and damaged localities that may account for a catastrophic event during the late Holocene. North of Sfax city, ~ 3.4 m high cliff coastal marine and alluvial terraces show 20 to 50-cm-thick chaotic layer with sandy coarse gravels mixed with reworked pebbles, broken shells of gastropods and molluscs, organic matter and Roman pottery. The chaotic layer truncates sandy-silty paleosol, covers Roman settlements and is overlain by fire remains, a thin sandy-silty aeolian unit and ~ 1-m-thick alluvial deposits. Charcoal samples collected at 10 cm below and 4 cm above the catastrophic deposits provide radiocarbon dating that brackets the catastrophic unit between 286 and 370 CE. Other historical investigations on the Roman sites of Neapolis (Nabeul), Hadrumete (Sousse), Thyna (Sfax), Meninx in Girba (Djerba), Wadi Ennouili (Gulf of Gabes), and Sabratha (in Libya) evidenced major damage and abandonment of sites in the fourth century (16, 41, 42, 43, 44). The new identification of catastrophic deposits, offshore-onshore correlations with turbidites and modelling of tsunami waves suggest the relationship with the 21 July 365 tsunamigenic earthquake (Mw ~ 8) of west Crete (Greece) and call for a better estimate of tsunami risk on the Mediterranean coastlines.
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