Palaeontological and sedimentological studies of dated cores from the coast of Thyna (Sfax, Gulf of Gabes, Tunisia): multiproxy evidence for a high-energy extreme event and palaeoenvironmental reconstructions

Autor: Kamoun, Mohamed, Zaïbi, Chahira, Khalifa, Khawla Ben, da Conceição Freitas, Maria, Langer, Martin R., Costa, Ana Maria, Costa, Pedro J. M., Andrade, César, Tian, Skye Yunshu, Bahrouni, Najib, Kamoun, Fekri
Zdroj: Euro-Mediterranean Journal for Environmental Integration; 20240101, Issue: Preprints p1-28, 28p
Abstrakt: In this paper, sedimentological, geochemical, palaeontological and radiocarbon dating results from Holocene cores are presented to infer the palaeoenvironmental evolution of the Thyna coast in the Gulf of Gabes (Tunisia). Based on detailed faunal, sedimentological and geochemical analyses, the evolution of the coastline and the impact of a high-energy event around 365 CE which led to the destruction of parts of the historic city of Thyna are reconstructed. The scenario developed here is based on the analysis of four drill cores and shows an evolution from a shallow marine palaeoenvironment to a gradually enclosed lagoon. The core record includes the following. (i) Evidence of the first Holocene transgression at around 6234–5733 cal year BCE (8184–7683 cal yr BP), characterised by the first appearance of foraminifera and molluscs. The transgressive sediments of the first transgression overlie the Upper Pleistocene–Greenlandian terrigenous clays. (ii) Deposits of a high-energy event that formed in the fourth century after the Crete earthquake (365 AD). The bioclastic deposits are characterised by an erosive base and are rich in rip-up clasts, charcoal particles, wood and pottery fragments, and abundant shell debris. This deposit comprises a blend of remains from coastal and lagoonal molluscs, along with brackish foraminifera originating from the more internal regions of a confined lagoon. (iii) After the high-energy event, there is evidence of a partially open lagoon off the coast, which was protected from the open sea by a sand barrier. (iv) Evidence of increased marine influence and further opening of the lagoon in the nineteenth and twentieth centuries, suggesting that the coastal area of Thyna is affected not only by the current sea level rise but probably also by subsidence. The scenario developed and the events identified here are compared with those already known.
Databáze: Supplemental Index
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