Climate variability during MIS 20–18 as recorded by alkenone-SST and calcareous plankton in the Ionian Basin (central Mediterranean)

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

Data for: Surface and deep water variability in the Western Mediterranean (ODP Site 975) during insolation cycle 74: high resolution calcareous plankton, biomarker and organic geochemical signals

Surface and deep water variability in the Western Mediterranean (ODP Site 975) during insolation cycle 74: high resolution calcareous plankton, biomarker and organic geochemical signal

Data for: Surface and deep water variability in the Western Mediterranean (ODP Site 975) during insolation cycle 74: high resolution calcareous plankton, biomarker and organic geochemical signals

Surface and deep water variability in the Western Mediterranean (ODP Site 975) during insolation cycle 74: high resolution calcareous plankton, biomarker and organic geochemical signal

THE Montalbano Jonico section (South Italy) as a reference for the Early/Middle Pleistocene boundary

The most recent data obtained at the Montalbano Jonico succession (MJS), in the interval including the Marine Isotope Stage (MIS) 19, document the occurrence of numerous chronostratigraphic constraints and paleoenvironmental events contributing to the knowledge of a crucial time through the Lower-Middle Pleistocene transition, characterised by major modifications of the Earth’s climate system. Marine and terrestrial biologic data-sets (pollen, ostracods, benthic and planktonic foraminifera, coccolithophores, teleostean fishes, mollusks) are compared with the high resolution astronomically-tuned benthic oxygen isotope curve in order to provide accurate paleonvironmental reconstruction and acquire additional climatostratigraphic and biostratigraphic constraints within a chronostratigraphic framework which also includes the 40Ar/39Ar ages of three volcaniclastic layers. Environmental and climatic events (e.g. Termination IX, substages 19.3, 19.2, and 19.1, maximum flooding and climate optimum, maximum depth) highlight a succession of clear paleoenvironmental changes close to MIS 19, showing a remarkable correspondence between the response of marine and terrestrial proxies. Such changes have stratigraphic implication and high potential of correlation as they evidence wide scale climate changes, stressing the tight interconnection between the Mediterranean region and North Atlantic Ocean. Based on these results the MJS reveals to be an excellent candidate for the Lower-Middle Pleistocene Subseries boundary. In fact, at present the MJS fully meets the requirements indicated by Remane et al. (1996) for a GSSP selection with the sole exception that a paleomagnetic signal is missing. 10Be analyses are in progress and should enhance the already rich documentation of several independent age-significant elements, contributing to the recent critical discussion on the significance of the magnetic signal at the Matuyama-Brunhes boundary as well as its role as a primary marker for the Middle Pleistocene GSSP definition