Paleo-oceanographic follow-up of a Younger Dryas contourite in the North and South of the Gulf of Cadiz

Abstract:
How much paleoceanographic information can a single contourite unit comprise is a matter for debate. Focusing on two contourite units sitting in the North and South of the Gulf of Cadiz, on the Iberian (GC-01A) and the Moroccan (TG-2) margins, we examine their synchronous sedimentological evolution during the Younger Dryas (YD). We apply a detailed multi-proxy analysis, which includes physical properties, sediment composition, O and C stable isotopes in foraminifera, and both planktonic and benthic foraminifera species and ecological assemblages. We seek to bound the ecological and environmental conditions playing during the YD´ formation of these specific contouritic sediments by relating geochemistry, biology and water dynamics in order to define a pattern of deposition. In the end, we trace in common water masses involved in the formation of the YD contourites in either sides of the Gulf of Cadiz. While the northern branch of the Mediterranean Outflow Water (MOW) is widely assumed to be responsible for the thick contourite depositional systems found along the Iberian margin, the currents originating the contouritic drifts found in the Moroccan margin are less established. A conceptual model of the detailed characterization of a single contourite is proposed here, contributing to interpret contourite depositional systems.

摘要：关于单一轮廓岩单元能够包含多少古海洋学信息的议题尚存争议。本研究聚焦于加迪斯湾南北两侧的两大轮廓岩单元，即伊比利亚（GC-01A）和摩洛哥（TG-2）边缘的轮廓岩单元，探讨了它们在全新世大冰期（YD）期间的同步沉积演化。本研究采用详细的多代理分析，包括物理性质、沉积物组成、有孔虫中的氧和碳稳定同位素，以及浮游和底栖有孔虫物种及其生态群。通过将地球化学、生物学和水动力学联系起来，旨在界定YD时期这些特定轮廓岩沉积物形成的生态环境，从而定义沉积模式。最终，本研究追踪了参与加迪斯湾两侧YD轮廓岩形成的共同水团。尽管广泛认为地中海出水水流（MOW）的北部分支是伊比利亚边缘发现厚层轮廓岩沉积系统的成因，但摩洛哥边缘轮廓岩漂移的起源尚不明确。本文提出了单一轮廓岩的详细表征概念模型，有助于解释轮廓岩沉积系统。