Evidence for short-lived oscillations in the biological records from the sediments of Lago Albano (Central Italy) spanning the period ca. 28 to 17 k yr BP |
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| Authors: | Piero Guilizzoni Aldo Marchetto Andrea Lami Frank Oldfield Marina Manca Claudio A Belis Anna M Nocentini Patrizia Comoli Vivienne J Jones Steve Juggins Christina Chondrogianni Daniel Ariztegui John J Lowe David B Ryves Richard W Battarbee Tim C Rolph Julieta Massaferro |
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| Institution: | (1) C.N.R. Institute Italiano di Idrobiologia, I-28922 Verbania Pallanza, Italy;(2) C.N.R. Institute Italiano di Idrobiologia, I-28922 Verbania Pallanza, Italy;(3) IGBP PAGES International Project Office, Bärenplatz 2, 3011 Bern, Switzerland;(4) Environmental Change Research Centre, Department of Geography, University College, London, 26 Bedford Way, London, WC1H 0AP, UK;(5) Department of Geography, University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK;(6) ETH-Zentrum, Geological Institute, Sonneggstrasse 5, 8092 Zürich, Switzerland;(7) Centre for Quaternary Research, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, UK;(8) Department of Geology, University of Newcastle, Callaghan, 2308, NSW, Australia;(9) PROGEBA-CONICET, Apartado postal 47, 8400 Bariloche, Argentina |
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| Abstract: | We report the results of analyses of pigments (derived from algae and photosynthetic bacteria), diatoms and invertebrate fossil remains (ostracods, cladocerans, chironomids) in two late Pleistocene sediment cores from Lago Albano, a crater lake in Central Italy. The record contains evidence for oscillations in lake biota throughout the period ca. 28 to 17 k yr BP. The earliest of these are contained in the basal 3.5 m of light olive-gray and yellowish-gray spotted muds sampled in core PALB 94-1E from 70 m water depth. The later oscillations are best represented in the more extended sediment sequence recovered from a second core site, PALB 94-6B, in 30 m water depth. The sediments at site 1E, containing the earlier oscillations (ca. 28-24 k yr BP), predate any sedimentation at the shallower site, from which we infer an initially low lake level rising to permit sediment accumulation at site 6B from ca. 24 k yr onwards. At site 6B, massive silts rich in moss remains are interbedded with laminated silts and carbonates. These sediments span the period ca. 24 to 17 k yr and are interpreted as representing, respectively, times of shallow water alternating with higher lake stands, when the lake was stratified and bottom water was stagnant. A range of mutually independent chronological constraints on the frequency and duration of the oscillations recorded in the lake biota indicate that they were aperiodic and occurred on millennial to century timescales. We interpret them as responses to climate forcing through its impact on lake levels and changing aquatic productivity. The time span they occupy, their frequency and their duration suggest that at least some of these changes may parallel both the Dansgaard-Oeschger events recorded in Greenland Ice Cores and the contemporary oscillations in North Atlantic circulation documented in marine sediment cores. |
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| Keywords: | crater lake late Pleistocene pigments diatoms ostracods Cladocera chironomids climatic oscillation Italy |
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