Laminated sediments as archives of short timescale climate change and palaeoceanography of the Mediterranean. Geologica Ultraiectina (296)

Abstract

Geochemical profiles of laminated sediments from selected periods in Earth history are presented as archives of subdecadal to centennial timescale climate variability in the Mediterranean region. A resin embedding protocol is developed which preserves the redox sensitive components of unconsolidated anoxic laminated sediments from brine-filled basins in the modern Eastern Mediterranean. Major element microanalysis of these embedded sediments by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is used to investigate interdecadal variability in the magnitude and composition of aeolian dust transport to the Mediterranean over the last 140 years, which is linked to summer climate change. Trace element LA-ICP-MS microanalysis of embedded sapropel S1 sediments is then used to investigate centennial scale variability in Mediterranean water column ventilation during the Holocene Climatic Optimum (~10-6 ky BP), which is controlled by winter climate. Finally, decadal timescale summer and winter climate variability in the late Miocene (~6 Ma) are investigated using a combined approach of LA-ICP-MS scanning of laminated evaporites and fully coupled climate model simulations. All investigations reveal persistent decadal to centennial scale climate variability in the Mediterranean region. However, while Mediterranean summer climate appears to be linked to oscillations of high northern latitude climate modes regardless of global background temperatures, winter climate during warmer periods such as the late Miocene is more likely influenced by tropical variability associated with the El Niño Southern Oscillation (ENSO).