Depositional systems accumulating under the combined influence of along-slope currents and downslope sediment-gravity flows are frequent in several continental margins. Despite being well-documented in terms of how these opposing depositional processes shape the margin architecture, many aspects related to their interaction and distinctive characters of resulting sediment accumulations remain elusive. Here we focus on the Gela Basin, the foredeep of the Maghrebian fold-and-thrust belt in the Strait of Sicily, where the Levantine Intermediate Water (LIW) and the Modified Atlantic Water (MAW) are confined by margin morphology, which amplify their velocities. Two sediment cores located on the upper and lower slope of the Gela Basin document the overlapping of along- and downslope processes since the very last phase of the Last Glacial Maximum (LGM). Detailed analysis of several proxies including sedimentary structures, sortable silt, geochemical elemental composition, oxygen and carbon isotopes, ichnofacies and foraminifera assemblages helped to disentangle the sedimentary imprints of contourites (including variations in bottom-current velocity through time) and downslope gravity-driven processes (turbidity currents and mass-transport processes).

The slope experienced exceptionally high sedimentation rates up to 1300 cm kyr⁻¹ during the last phase of LGM and early phase of Heinrich Stadial 1 (HS1), which rapidly decreased before Heinrich Event 1 (< 100 cm kyr⁻¹). The high accumulation rates were driven by a combination of sediment input from the inner and mid shelf and lateral advection promoted by strong bottom-currents under the action of the LIW. An abrupt and brief intensification (+ 7.8 cm⁻¹) of the MAW speed during the early phase of HS1 affected the stability of the sediment drifts, which were growing since the previous interglacial and contributed to the emplacement of mass-transport deposits around 17 kyr BP. During the post-glacial sea-level rise pulses, before and during the Heinrich Event 1, the two sediment cores registered contrasting bottom-current velocities, suggesting a progressive shoaling of the LIW and modifications at the interface between the LIW and the MAW, in response to the increased fresh water discharge from the Atlantic. Our findings suggest that sea-level fluctuations can change the thickness and core-depth of the Central Mediterranean water masses, leading to intervals of enhanced bottom-current erosion and margin instability along the outer shelf and upper slope.

在沿坡流和下坡沉积重力流的共同影响下堆积的沉积系统在几个大陆边缘频繁发生。尽管在这些相反的沉积过程如何塑造边缘结构方面有充分的记录，但与它们的相互作用和由此产生的沉积物堆积的独特特征相关的许多方面仍然难以捉摸。在这里，我们关注 Gela 盆地，即西西里海峡马格里布褶皱冲断带的前渊，其中黎凡特中间水 (LIW) 和修改后的大西洋水 (MAW) 受边缘形态的限制，这放大了它们的速度。位于格拉盆地上坡和下坡的两个沉积岩芯记录了自末次盛冰期 (LGM) 的最后阶段以来沿坡和下坡过程的重叠。

在 LGM 的最后阶段和 Heinrich Stadial 1 (HS1) 的早期阶段，斜坡经历了高达 1300 cm kyr ^{-1 的}异常高的沉降速率，在 Heinrich Event 1 (< 100 cm kyr ^-1 )之前迅速下降。高积累率是由内陆架和中陆架的沉积物输入和LIW作用下强烈底流促进的侧向平流共同驱动的。突然而短暂的强化（+ 7.8 cm ^-1) HS1 早期阶段的 MAW 速度影响了沉积物漂移的稳定性，沉积物漂移自上次间冰期以来一直在增长，并有助于在 17 kyr BP 附近就位质量输送沉积物。在海因里希事件 1 之前和期间的冰川后海平面上升脉冲期间，两个沉积物核心记录了对比的底流速度，表明 LIW 的逐渐成浅滩和 LIW 和 MAW 之间的界面处的修改，在对大西洋淡水排放增加的反应。我们的研究结果表明，海平面波动可以改变地中海中部水团的厚度和核心深度，导致沿外陆架和上坡的底流侵蚀和边缘不稳定的间隔增强。