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Climate variability during MIS 20–18 as recorded by alkenone-SST and calcareous plankton in the Ionian Basin (central Mediterranean)
Palaeogeography, Palaeoclimatology, Palaeoecology ( IF 3 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.palaeo.2020.110027
Maria Marino , Angela Girone , Salvatore Gallicchio , Timothy Herbert , Marina Addante , Pietro Bazzicalupo , Ornella Quivelli , Franck Bassinot , Adele Bertini , Sebastien Nomade , Neri Ciaranfi , Patrizia Maiorano

Abstract This study shows the first Mediterranean high-resolution record of alkenone-derived sea surface temperature (SST) in the marine sediments outcropping at the Ideale section (IS) (southern Italy, central Mediterranean) from late marine isotope stage (MIS) 20 - through early MIS 18. The SST pattern evidences glacial-interglacial up to submillennial-scale temperature variation, with lower values (~13 °C) in late MIS 20 and substage 19b, and higher values (up to 21 °C) in MIS 19c and in the interstadials of MIS 19a. The SST data are combined with the new calcareous plankton analysis and the available, chronologically well-constrained carbon and oxygen isotope records in the IS. The multi-proxy approach, together with the location of the IS near the Italian coasts, the lower circalittoral-upper bathyal depositional setting, and high sedimentation rate allow to document long-and short-term paleoenvironmental modifications (sea level, rainfall, inorganic/organic/fresh water input to the basin), as a response to regional and global climate changes. The combined proxies reveal the occurrence of a terminal stadial event in late MIS 20 (here Med-HTIX), and warm-cold episodes (here Med-BATIX and Med-YDTIX) during Termination IX (TIX), which recall those that occurred through the last termination (TI). During these periods and the following ghost sapropel layer (insolation cycle 74, 784 ka) in the early MIS 19, high frequency internal changes are synchronously recorded by all proxies. The substage MIS 19c is warm but quite unstable, with several episodes of paleoenvironmental changes, associated with fluctuating tropical-subtropical water inflow through the Gibraltar Strait, variations of the cyclonic regime in the Ionian basin, and the southward shift of westerly winds and winter precipitation over southern Europe and Mediterranean basin. Three high-amplitude millennial-scale oscillations in the patterns of SST and calcareous plankton key taxa during MIS 19a are interpreted as linked to changes in temperature as well as in salinity due to periodical water column stratification and mixing. The main processes involved in the climate variability include changes in oceanographic exchanges through the Gibraltar Strait during modulations of Atlantic meridional overturning circulation and/or variations in atmospheric dynamics related to the influence of westerly and polar winds acting in the paleo-Ionian basin. A strong climate teleconnection between the North Atlantic and Mediterranean is discussed, and a prominent role of atmospheric processes in the central Mediterranean is evidenced by comparing data sets at the IS with Italian and extra-Mediterranean marine and terrestrial records.

中文翻译:

由烯酮-SST 和爱奥尼亚盆地(地中海中部)的钙质浮游生物记录的 MIS 20-18 期间的气候变化

摘要 本研究显示了海洋同位素阶段晚期 (MIS) 20 - 理想剖面 (IS)(意大利南部、地中海中部)出露的海洋沉积物中烯酮衍生海面温度 (SST) 的首次地中海高分辨率记录。通过早期的 MIS 18。 SST 模式证明了冰期 - 间冰期直至千禧年尺度的温度变化,MIS 20 晚期和亚阶段 19b 的值较低(~13 °C),MIS 19c 的值较高(高达 21 °C)并在 MIS 19a 的间隙中。SST 数据与新的钙质浮游生物分析和 IS 中可用的、按时间顺序严格约束的碳和氧同位素记录相结合。多代理方法,连同 IS 靠近意大利海岸的位置,较低的环流-上深海沉积环境,高沉积率允许记录长期和短期的古环境变化(海平面、降雨、流入盆地的无机/有机/淡水),作为对区域和全球气候变化的响应。组合代理揭示了 MIS 20 晚期(此处为 Med-HTIX)中的终末期事件的发生,以及 Termination IX (TIX) 期间的暖冷发作(此处为 Med-BATIX 和 Med-YDTIX),这些事件回顾了那些通过最后一个终止 (TI)。在这些时期和早期 MIS 19 中的后续鬼腐泥层(日照周期 74, 784 ka)期间,所有代理都同步记录了高频内部变化。MIS 19c 亚级温暖但相当不稳定,有几次古环境变化,与通过直布罗陀海峡波动的热带-亚热带水流入有关,爱奥尼亚盆地气旋体系的变化,以及欧洲南部和地中海盆地的西风和冬季降水的南移。MIS 19a 期间 SST 和钙质浮游生物关键分类群模式中的三个高振幅千年尺度振荡被解释为与由于周期性水柱分层和混合引起的温度和盐度变化有关。气候变率所涉及的主要过程包括大西洋经向翻转环流调制期间通过直布罗陀海峡的海洋交换的变化和/或与作用于古爱奥尼亚盆地的西风和极地风的影响相关的大气动力学变化。讨论了北大西洋和地中海之间强烈的气候遥相关,
更新日期:2020-12-01
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