This study explores the paleoenvironmental changes of the Acholla coast over the last 2000 years by means of subsurface sediment analyses of lagoonal deposits via a multiproxy approach. A sequence of 5 steps is shown to have shaped the coastal development at Acholla and includes (i) the settlement of an open marine embayment during the Upper Pleistocene (substage 5e) in response to a transgressive event as evidenced by the deposition of carbonate sandstones rich in mollusc associations and marine elemental ratios Sr/Al, Ca/Al, Cl/Al, and S/Al; (ii) a sea-level rise towards183 AD, after a long period of emergence of the coast, leading to transgressive deposits of poorly sorted fine sands that are rich in diversified mollusc and ostracod taxa; (iii) a high-energy event (towards 417AD) with a peculiar biofacies characterized by coarse bioclastic mollusc-rich sands, charcoal particles, Tyrrhenian lithoclasts, and high values of marine elemental ratios Cl/Al, S/Al, and Ca/Al; (iv) a progradation of coastal habitats (between 417 and 1577 AD), favored by a period of flooding/detrital input and longshore current drifts, resulting in the development of an extensive sandspit and the formation of the Acholla lagoon. The construction of a Roman pier, originally constructed to protect the Acholla harbor from sedimentation, was counterproductive and favored the expansion of coastal swash bars and extension of the sandspit, ultimately resulting in the abandonment of the Acholla harbor; (v) the closure of the lagoon (from 1577 AD onward) and the built-up of well-sorted silt deposits are marked by the decrease of detrital elemental ratios (Ti/Al, Si/Al, and K/Al) and by reduced ostracod species richness values. The inferred scenario for the evolution at Acholla coast matches those for Sfax and Skhira coast in the Gulf of Gabes (Tunisia). Unlike Sfax and Skhira, however, the Acholla coast has been subjected to uplift by active faults, resulting in a time shift of depositional patterns.

本研究通过多代理方法对泻湖沉积物的地下沉积物分析，探索了过去 2000 年 Acholla 海岸的古环境变化。显示出 5 个步骤的序列塑造了 Acholla 的沿海发展，包括 (i) 在上更新世（子阶段 5e）期间开放的海洋海湾的沉降，以响应海侵事件，如富含碳酸盐砂岩的沉积所证明的在软体动物协会和海洋元素比率 Sr/Al、Ca/Al、Cl/Al 和 S/Al 中；(ii) 到公元 183 年，海平面上升，在海岸长期出现之后，导致富含多样化软体动物和介形类群的分类不良的细砂的海侵沉积物；(iii) 一个高能事件（到公元 417 年），具有特殊的生物相，其特征是富含粗生物碎屑软体动物的砂、木炭颗粒、第勒尼安碎石，以及高值的海洋元素比 Cl/Al、S/Al 和 Ca/Al ; (iv) 沿海栖息地的退化（公元 417 年至 1577 年之间），受洪水/碎屑输入和沿岸洋流漂移时期的青睐，导致广泛的沙坑发展和 Acholla 泻湖的形成。罗马码头的建造最初是为了保护阿霍拉港免遭沉积，结果适得其反，有利于沿海斜杠的扩建和沙坑的延伸，最终导致阿霍拉港被废弃；(v) 泻湖的关闭（从公元 1577 年开始）和分选良好的淤泥沉积物的形成以碎屑元素比（Ti/Al、Si/Al 和 K/Al）的降低为标志，并且降低介形类物种丰富度值。Acholla 海岸演化的推断情景与 Gabes 湾（突尼斯）的 Sfax 和 Skhira 海岸的演化情景相匹配。然而，与 Sfax 和 Skhira 不同的是，Acholla 海岸受到活动断层的抬升，导致沉积模式的时间偏移。