THE MONTALBANO JONICO SECTION (SOUTH ITALY) AS A REFERENCE FOR THE EARLY/MIDDLE PLEISTOCENE BOUNDARY

Abstract

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.