(Table 2) Radiocarbon dates and age calibration

The high-energy, low-accumulation NW Iberian shelf features three confined Holocene mud depocentres. Here, we show that the evolution of such depocentres follows successive steps. The flooding of inner shelf zones and river catchment areas by the late deglacial sea-level rise provided the precondition for shelf mud deposition. Following this, the Holocene deceleration of the sea-level rise caused a rapid refill of the accommodation space within river valleys. Subsequently, the export of major amounts of fines was initiated. The initial onset and loci of shelf mud deposition were related to deposition-favouring conditions in mid-shelf position or to the presence of morphological highs, which act as sediment traps by providing protection against stronger hydrodynamic energy. The detailed reconstruction of the Holocene depocentre evolution shows for the first time that the expansion of such shelf mud deposits cannot only occur by linear growth off the associated sediment source. Rather, they might develop around centres that are fully disconnected from the source of original sediment supply, and expand later into specific directions. Based on these differences and on the connection of the individual mud depocentres to the material source we propose a conceptual subdivision of the group "mid-shelf mud depocentres".

高能量、低堆积速率的伊比利亚西北陆架发育三处受局限的全新世泥质沉积中心（mud depocentres）。在此，我们揭示了此类沉积中心的演化遵循一系列连续阶段：晚冰消期海平面上升淹没了陆架内侧区域与河流汇水区，这为陆架泥质沉积的形成提供了先决条件；随后，全新世时期海平面上升速率减缓，导致河谷内的沉积可容空间（accommodation space）快速得到充填，进而启动了大量细粒沉积物的向外搬运过程。陆架泥质沉积的初始发育时机与沉积位点，既与陆架中部的有利沉积环境相关，也与地形高地的存在密切相关——此类地形高地可通过削弱强水动力作用，充当沉积物捕集区。本次研究对全新世沉积中心演化的精细重建首次揭示：此类陆架泥质沉积体的扩张并非仅能通过围绕物源区的线性增生实现，相反，它们也可在与原始沉积物供给完全隔绝的沉积中心周边形成，并随后向特定方向延展扩张。基于上述演化差异，以及各单个泥质沉积中心与物源区的连通关系，我们提出了"陆架中部泥质沉积中心（mid-shelf mud depocentres）"类群的概念性划分方案。