Borisov Dmitrii G, Frey Dmitry I, Ivanova Elena V, Dmitrevskiy Nikolay N, Levchenko Oleg V, Fomin Vladimir V, Ligi Marco
Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia.
Moscow Institute of Physics and Technology, Dolgoprudny, Russia.
Sci Rep. 2023 Aug 24;13(1):13834. doi: 10.1038/s41598-023-40401-4.
A combination of a high sediment input and intense bottom currents often leads to the formation of contourites (sediments deposited or significantly reworked by bottom currents). Both of these components are present in the Vema Fracture Zone valley which is the most important passageway for the distribution of the Antarctic Bottom Water from the West to the North-East of the Atlantic. However, no contourite drifts, moats or contourite channels have been found in this region in more than half a century of research. The prevailing sedimentation paradigm postulates that turbidity currents have predominantly governed sedimentation in this region during the Pleistocene. This work describes the first example of contourite depositional system identified in the Vema Fracture Zone. The discovery was made through detailed high-resolution sub-bottom profiling, as well as numerical modeling and direct measurements of bottom current velocities. Such systems are exceptionally uncommon in fracture zones. This study highlights the importance of further research of contourites along the Vema Fracture Zone based on modern concepts of contourite and mixed depositional systems. The work also emphasizes the need to reevaluate the impact of bottom currents on sedimentation in this region, and particularly in the narrow segments of the fracture zone valley.
高沉积物输入和强烈底流相结合，常常会导致等深流沉积（由底流沉积或显著改造的沉积物）的形成。这两个因素在韦马断裂带峡谷中都存在，该峡谷是南极底层水从大西洋西部向东北部扩散的最重要通道。然而，在半个多世纪的研究中，该区域尚未发现等深流沉积漂移体、凹槽或等深流通道。普遍的沉积模式假定，在更新世期间，浊流在该区域的沉积过程中起主要作用。本文描述了在韦马断裂带发现的首个等深流沉积体系实例。这一发现是通过详细的高分辨率浅地层剖面测量以及底流速度的数值模拟和直接测量得出的。此类体系在断裂带极为罕见。本研究强调了基于现代等深流和混合沉积体系概念，对韦马断裂带沿线等深流进行进一步研究的重要性。这项工作还强调了重新评估底流对该区域沉积作用的影响的必要性，尤其是在断裂带峡谷的狭窄地段。
