Climate-induced variability in Mediterranean Outflow to the North Atlantic Ocean during the late Pleistocene

Mediterranean Outflow Water (MOW) adds salt and density to open ocean intermediate waters and is therefore an important motor of Atlantic meridional overturning circulation (AMOC) and climate variability. However, the variability in strength and depth of MOW on geological timescales is poorly documented. Here we present new detailed records, with excellent age control, of MOW variability from 416 ka to present from rapidly accumulated marine sediments recovered from the West Iberian Margin during Integrated Ocean Drilling Program (IODP) Expedition 339. Our records of x-ray fluorescence (XRF), physical grain size and palaeocurrent information from the anisotropy of magnetic susceptibility (AMS) indicate (i) a close relationship between the orientation of principle AMS axes and glacial-interglacial cycles and (ii) two distinct regimes of MOW behaviour over the last ~416 kyrs in grain size and AMS variability at orbital (mainly precessional) and suborbital timescales. […]

地中海外流水（MOW）向开阔大洋的次级水体中注入盐分和密度，因而成为大西洋经向翻转环流（AMOC）和气候变率的驱动力之一。然而，在地质时间尺度上，MOW的强度和深度的变化记录并不充分。本研究基于整合海洋钻探计划（IODP）第339次探险在西伊比利亚边缘快速堆积的海洋沉积物中，提供了416千年前至今的MOW变化的详细记录，并具备卓越的年龄控制。我们通过对X射线荧光（XRF）、物理颗粒尺寸以及古地磁各向异性（AMS）信息的研究，发现：（i）主AMS轴的取向与冰期-间冰期旋回之间存在密切联系；（ii）在过去约416千年的MOW行为中，粒度和AMS在轨道（主要是旋回）和亚轨道时间尺度上呈现出两种截然不同的状态。