The depositional record of carbonate slopes provides a valuable archive of past environmental and climatic changes. Modern carbonate slopes reveal morphological variabilities (for example, gullies and canyons) shaped by episodic slope collapses and turbidity currents. Furthermore, climate-induced fluctuations in sea level regulate sediment availability and delivery to the deep-sea. Morphological and climatic controls on calciclastic sediment transfer are often complex to decipher. The aim of this study is to link seafloor morphology and depositional processes in an active carbonate submarine channel (Exuma Valley, the Bahamas) over the last 40 kyr. The dataset includes multibeam and seismic surveys, and two sediment cores retrieved from the valley axis. A series of abrupt slope-breaks, called knickpoints, occurs along Exuma Valley, and plays a key role in sediment transport and accumulation. Initiation processes proposed for knickpoint formation include bank-collapse, side gully erosion and loss of confinement. Slope collapses detected on the bathymetry prevail in the upstream muddy section of the submarine valley, as attested to by a planktic-rich debrite–turbidite couplet in the first core. In contrast, the second core collected downstream of the knickpoints train, includes 32 bioclastic sandy event-beds (i.e. turbidites). Hydrodynamic sorting generates grain segregation (for example, Halimeda-rich base versus planktic-rich top) and geochemical contrasts (Sr/Ca) in turbidites. Turbidite frequency and grain composition within beds reflect the variation of carbonate sources during glacial–interglacial periods. This research allows to link slope morphology with deposits of a modern large-scale carbonate factory, and to deduce sea-level changes over that last 40 kyr in the Bahamas. These results can provide new perspectives on the understanding of ‘source to sink’ mechanisms in carbonate systems.

中文翻译：

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将碳酸盐沉积物转移与海底形态联系起来：来自巴哈马埃克苏马山谷的见解

碳酸盐岩斜坡的沉积记录提供了过去环境和气候变化的宝贵档案。现代碳酸盐岩斜坡揭示了由偶发斜坡崩塌和浊流形成的形态变化（例如，沟壑和峡谷）。此外，气候引起的海平面波动调节了沉积物的可用性和向深海的输送。对碎屑沉积物迁移的形态和气候控制通常很难破译。本研究的目的是将过去 40 kyr 活动碳酸盐海底通道（Exuma Valley，巴哈马）的海底形态和沉积过程联系起来。该数据集包括多波束和地震调查，以及从山谷轴检索到的两个沉积岩心。沿着埃克苏马山谷发生了一系列突然的斜坡断裂，称为拐点，并在泥沙输送和堆积中起关键作用。为形成裂缝而提出的引发过程包括堤岸坍塌、侧沟侵蚀和失去约束。在海底河谷的上游泥泞部分，测深仪检测到的斜坡坍塌盛行，第一个岩心中富含浮游生物的碎屑-浊积岩对就证明了这一点。相比之下，第二个岩心收集到的断点列下游，包括 32 个生物碎屑砂质事件床（即浊积岩）。水动力分选在浊积岩中产生颗粒分离（例如，富含 Halimeda 的底部与富含浮游生物的顶部）和地球化学对比（Sr/Ca）。床内浊积岩频率和颗粒组成反映了冰期-间冰期碳酸盐来源的变化。这项研究允许将斜坡形态与现代大型碳酸盐工厂的沉积物联系起来，并推断巴哈马过去 40 基尔的海平面变化。这些结果可以为理解碳酸盐系统中的“源汇”机制提供新的视角。