Climatic patterns revealed by pollen and oxygen isotope records across the Matuyama–Brunhes Boundary in the central Mediterranean (southern Italy)
Published:January 01, 2005
L. Capraro, A. Asioli, J. Backman, R. Bertoldi, J. E. T. Channell, F. Massari, D. Rio, 2005. "Climatic patterns revealed by pollen and oxygen isotope records across the Matuyama–Brunhes Boundary in the central Mediterranean (southern Italy)", Early–Middle Pleistocene Transitions: The Land–Ocean Evidence, M.J. Head, P.L. Gibbard
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A c. 50 m thick section located in the Crotone Basin (southern Italy) was investigated using oxygen isotopes, pollen and planktonic foraminifera. The section records two complete transgressive-regressive cycles mainly driven by glacio-eustasy. Biostratigraphy and oxygen isotope chronology indicate that the section spans from Marine Isotope Stage (MIS) 22 (c. 0.87 Ma) to MIS 18.3 (c. 0.73 Ma), thus straddling the Matuyama-Brunhes (M-B) boundary which occurs in the middle of MIS 19. The rich pollen assemblages provide a unique record of the vegetation in the central Mediterranean during the Early-Middle Pleistocene climatic transition. Interglacials are characterized by a mesothermic vegetation similar to the present day, whereas a rain-demanding conifer forest dominates the glacials of MIS 20 and MIS 18. This is unexpected because it is generally considered that during the Pleistocene, glacials in central Mediterranean were characterized by steppe (arid) conditions. By contrast, arid conditions occur during the deglaciations. These results are inconsistent with the widespread practice of linking glacials with arid conditions in the central Mediterranean during Pliocene and Early Pleistocene times. This study emphasizes the need to establish more accurate land-sea correlation.
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Early–Middle Pleistocene Transitions: The Land–Ocean Evidence
The Early–Middle Pleistocene transition (around 1.2 to 0.5 Ma) marks a profound shift in Earth’s climate state. Low-amplitude 41 ka climate cycles, dominating the earlier part of the Pleistocene, gave way progressively to a 100 ka rhythm of increased amplitude that characterizes our present glacial—interglacial world. This volume assesses the biotic and physical response to this transition both on land and in the oceans: indeed it examines the very nature of Quaternary climate change. Milankovitch theory, palaeoceanography using isotopes and microfossils, marine organic geochemistry, tephrochronology, the record of loess and soil deposition, terrestrial vegetationa! change, and the migration and evolution of hominins as well as other large and small mammals, are all considered. These themes combine to explore the very origins of our present biota.