Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK.
Sci Rep. 2021 Oct 13;11(1):20291. doi: 10.1038/s41598-021-99730-x.
Contourite features are increasingly identified in seismic data, but the mechanisms controlling their evolution remain poorly understood. Using 2D multichannel reflection seismic and well data, this study describes large Oligocene- to middle Miocene-aged sedimentary bodies that show prominent lateral migration along the base of the Argentine slope. These form part of a contourite depositional system with four morphological elements: a plastered drift, a contourite channel, an asymmetric mounded drift, and an erosive surface. The features appear within four seismic units (SU1-SU4) bounded by discontinuities. Their sedimentary stacking patterns indicate three evolutionary stages: an onset stage (I) (~ 34-25 Ma), a growth stage (II) (~ 25-14 Ma), and (III) a burial stage (< 14 Ma). The system reveals that lateral migration of large sedimentary bodies is not only confined to shallow or littoral marine environments and demonstrates how bottom currents and secondary oceanographic processes influence contourite morphologies. Two cores of a single water mass, in this case, the Antarctic Bottom Water and its upper interface, may drive upslope migration of asymmetric mounded drifts. Seismic images also show evidence of recirculating bottom currents which have modulated the system's evolution. Elucidation of these novel processes will enhance basin analysis and palaeoceanographic reconstructions.
等深流特征在地震数据中越来越多地被识别出来，但控制其演化的机制仍了解甚少。本研究利用二维多道反射地震和测井资料，描述了大型始新世至中新世时期的沉积体，这些沉积体沿阿根廷斜坡底部表现出明显的侧向迁移。这些沉积体构成了一个等深流沉积体系的一部分，具有四个形态要素：泥质漂移、等深流通道、不对称堆积漂移和侵蚀面。这些特征出现在四个地震单元（SU1-SU4）之间的不连续面内。它们的沉积堆积模式表明经历了三个演化阶段：起始阶段（I）（34-25 百万年前）、生长阶段（II）（25-14 百万年前）和（III）埋藏阶段（<14 百万年前）。该体系表明，大型沉积体的侧向迁移不仅局限于浅海或滨海海洋环境，并展示了底流和二次海洋过程如何影响等深流形态。在这种情况下，单一水体的两个核心，即南极底层水及其上界面，可能驱动不对称堆积漂移向上坡迁移。地震图像还显示出回流底层流的证据，这些回流底层流调制了该体系的演化。阐明这些新过程将增强盆地分析和古海洋重建。
