Oxygen isotope composition of surface, thermocline and mid-depth western South Atlantic during Termination I and II

After glacial terminations, large amounts of heat and salt were transferred from low to high latitudes, which is a crucial phenomenon for the reestablishment of the Atlantic Meridional Overturning Circulation (AMOC). However, how different glacial terminations evolved in the (sub)tropics is still poorly documented. Here we use foraminifera oxygen (d18O) and carbon (d13C) stable isotopes to show that the North Atlantic heat piracy, following the AMOC resumption at the early Last Interglacial, affected the thermocline d18O levels of the subtropical western South Atlantic. Because of the cooling imposed by this process, glacial d18O persisted in the thermocline for ~7 kyr after the onset of the Last Interglacial, dampening the effect of sea level rise usually imprinted on foraminifera d18O during terminations. Faunal composition and d13C also suggest the existence of a colder and thicker South Atlantic Central Water coeval with the AMOC recovery. […]

在冰川消退之后，大量热量和盐分从低纬度地区转移至高纬度地区，这一现象对于大西洋经向翻转环流（AMOC）的重建至关重要。然而，不同冰川消退在（亚）热带地区的演变过程仍然记载不足。本研究利用有孔虫氧（d18O）和碳（d13C）稳定同位素，揭示了在末次间冰期早期大西洋经向翻转环流恢复之后，北大西洋的热量盗用现象影响了亚热带西部南大西洋的温跃层d18O水平。由于这一过程带来的冷却作用，末次间冰期开始后，冰川d18O在温跃层中持续了约7千年，削弱了通常在冰川消退期间海平面上升对有孔虫d18O的影响。动物群组成和d13C也暗示了与AMOC恢复同期存在一个较冷且较厚的南大西洋中央水。