Plastered drifts are a complex type of contouritic drift, very common along continental slopes, although their precise sedimentary stacking pattern and long-term evolution are not well understood. In this work we used 3D and 2D multichannel reflection seismic and well datasets to characterize a Paleogene plastered drift along the Uruguayan continental margin. A large buried drift running parallel to the middle and lower slope was identified, comprising five main seismic units (SU1-SU5) and a number of subunits subdivided by internal widespread erosive discontinuities. An extensive contourite terrace is developed on the landward top of the drift, while smaller-scale bottom current features (channels and bedforms) denote a hierarchy of features related to water mass circulation and interfaces, as well as associated oceanographic processes. Four long-term evolutionary stages were decoded in the plastered drift formation: I) Onset Stage (66 Ma – 56 Ma), whose basal surface represents a prominent erosional surface marking the onset of drift, after which extensive sheeted deposits develop; II) Growth Stage (Eocene ~ 56 – ~38 Ma) with a prominent backstepping sedimentary stacking pattern; III) Maintained Stage (~38 Ma – ~20 Ma) of limited growth of the drift, characterised by aggradational sheeted deposits and extensive erosion; and IV) Burial Stage (<20 Ma), which determines a major change in the margin evolution —the main depocenter shifts to deeper domains, leading to the final burial of the drift. The plastered drift formation is attributed to the influence of a deeper and weak water mass and a shallower but more vigorous water mass, as well as their interface. The aforementioned evolutionary stages and the greatest changes in the drift depositional style would be a consequence of spatial and vertical changes in these water masses over millions of years, the Growth Stage being related to the expansion and intensification of deep-water circulation that modulated the formation of the proximal terrace at its top and resulted in the backstepping stacking pattern. The smaller lateral and vertical changes in the seismic units and subunits along the drift are linked to local bottom current processes and their interaction with the slope morphology, the slope gradient playing a key role in the lateral bottom current behavior. This study shows the complex lateral and temporal sedimentary stacking pattern and evolution of a contouritic drift, and decodes the dominant oceanographic and depositional processes in its long-term formation. In doing so, we demonstrate the requirement of extensive 2D and 3D seismic datasets for accurate characterisations. Still, similar research in other continental margins is needed to better understand how and when (in geological time) large contouritic drifts are generated, in light of their implications for basin analysis, paleoceanographic reconstructions, and energy geosciences.

灰泥漂移是一种复杂的等高漂移，在大陆斜坡上非常常见，尽管其精确的沉积堆积模式和长期演化尚不清楚。在这项工作中，我们使用 3D 和 2D 多道反射地震和井数据集来表征沿乌拉圭大陆边缘的古近系灰泥漂移。发现了一个平行于中下斜坡的大型埋藏漂移，包括五个主要地震单元（SU1-SU5）和由内部广泛的侵蚀不连续性细分的多个子单元。在漂移的陆地顶部开发了一个广泛的等高线阶地，而较小尺度的底部流特征（通道和床形）表示与水团循环和界面以及相关海洋过程相关的特征层次。起始阶段（66 Ma - 56 Ma），其基面代表一个突出的侵蚀面，标志着漂移的开始，之后形成广泛的片状沉积物；II)生长阶段（始新世 ~  56 – ~38 Ma），具有显着的后退沉积堆积模式；III)漂移有限增长的维持阶段（~38 Ma – ~20 Ma），其特征是加积片状沉积物和广泛的侵蚀；和 IV)埋藏阶段 (<20 Ma)，这决定了边缘演化的重大变化——主要沉积中心转移到更深的领域，导致漂移的最终掩埋。灰泥漂流的形成归因于较深和较弱的水团和较浅但更有活力的水团以及它们的界面的影响。上述演化阶段和漂移沉积类型的最大变化是这些水团在数百万年间空间和垂直变化的结果，生长阶段与调节地层的深水环流的扩大和加强有关。在其顶部的近端露台，导致后退堆叠模式。沿漂移的地震单元和子单元中较小的横向和垂直变化与局部底流过程及其与斜坡形态的相互作用有关，斜坡梯度在横向底流行为中起关键作用。这项研究显示了等高线漂移的复杂的横向和时间沉积堆积模式和演化，并解码了其长期形成中的主要海洋学和沉积过程。在此过程中，我们证明了准确表征需要大量 2D 和 3D 地震数据集。尽管如此，鉴于它们对盆地分析、古海洋学重建、