http://hdl.handle.net/2122/158 Sat, 25 May 2013 14:19:02 GMT 2013-05-25T14:19:02Z http://hdl.handle.net/2122/8469 Title: Orbital variations in planktonic foraminifera assemblages from the Ionian Sea during the Middle Pleistocene Transition Authors: Incarbona, A.; Università degli Studi di Palermo, Dipartimento di Scienze della Terra e del Mare, Via Archirafi 22, 90134 Palermo, Italy; Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Di Stefano, E.; Università degli Studi di Palermo, Dipartimento di Scienze della Terra e del Mare, Via Archirafi 22, 90134 Palermo, Italy; Ippolito, G.; Università degli Studi di Palermo, Dipartimento di Scienze della Terra e del Mare, Via Archirafi 22, 90134 Palermo, Italy; Pelosi, N.; Consiglio Nazionale delle Ricerche, Istituto per l'Ambiente Marino Costiero, Calata Porto di Massa, Interno Porto di Napoli, 80133, Naples, Italy; Sprovieri, R.; Università degli Studi di Palermo, Dipartimento di Scienze della Terra e del Mare, Via Archirafi 22, 90134 Palermo, Italy Abstract: The Middle Pleistocene Transition (1.2-0.7 Ma) is the most recent re-organization of the global climate system which includes variations in the frequency and amplitude of glacial/interglacial cycles, increased ice sheet volume, sea surface temperature cooling and a significant drop in the CO2 atmospheric levels. Here we present high-resolution planktonic foraminifera data (mean sampling resolution of about 780 years) from core LC10 recovered in the Ionian Sea (eastern Mediterranean), between 1.2 and 0.9 Ma. Selected taxa, among them G. ruber, T. quinqueloba and G. bulloides, show significant periodicities that can be associated to orbital cycles, mainly precession and obliquity. The planktonic foraminifera based paleoclimatic curve exhibits a cooling linear trend that can be associated to similar phenomena observed in the North Atlantic. On the other hand, we refer to the influence of the North African Monsoon the occurrence of two peaks of the low-salinity tolerant species G. quadrilobatus that fall in coincidence of sapropel layers. Finally, we discuss the distribution pattern of N. pachyderma sinistral coiling, with peaks up to about 20% between MIS 30 and 28, and compare it to middle-late Quaternary records of the Sicily Channel and western Mediterranean. Mon, 31 Dec 2012 23:00:00 GMT http://hdl.handle.net/2122/8469 2012-12-31T23:00:00Z http://hdl.handle.net/2122/8363 Title: Prismatic magnetite magnetosomes from cultivated Magnetovibrio blakemorei strain MV-1: a magnetic fingerprint in marine sediments? Authors: Jovane, L.; Instituto Oceanográfico, Universidade de São Paulo, São Paulo, Brazil.; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bazylinski, D. A.; School of Life Sciences, University of Nevada at Las Vegas, Las Vegas, Nevada, USA.; Lins, U.; Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. Abstract: The magnetic properties (first-order reversal curves, ferromagnetic resonance and decomposition of saturation remanent magnetization acquisition) of Magnetovibrio blakemorei, a cultivated marine magnetotactic bacterium, differ from those of other magnetotactic species from sediments deposited in lakes and marine habitats previously studied. This finding suggests that magnetite produced by some magnetotactic bacteria retains magnetic properties in relation to the crystallographic structure of the magnetic phase produced and thus might represent a ‘magnetic fingerprint’ for a specific magnetotactic bacterium. The use of this fingerprint is a non-destructive, new technology that might allow for the identification and presence of specific species or types of magnetotactic bacteria in certain environments such as sediments. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8363 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8335 Title: The Palaeocene ‘‘top chron C27n’’ transient greenhouse episode: evidence from marine pelagic Atlantic and peri-Tethyan sections Authors: Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Pujalte, V.; Department of Stratigraphy and Paleontology, Fac. Science and Technology, University of the Basque Country UPV⁄EHU, PO Box 644, Bilbao E-48080, Spain; Stoykova, K.; Department of Paleontology and Stratigraphy, Geological Institute, Bulgarian Academy of Science, Sofia BG-1113, Bulgaria; Baceta, J. I.; Department of Stratigraphy and Paleontology, Fac. Science and Technology, University of the Basque Country UPV⁄EHU, PO Box 644, Bilbao E-48080, Spain; Ivanov, M.; Department of Geology and Paleontology, University of Sofia, Sofia BG-1000, Bulgaria Abstract: The early Cenozoic, which is punctuated by several negative carbon isotope excursions (CIEs), was a time of climatic and oceanographic transition from ’Greenhouse’ to ’Icehouse’ conditions. The occurrence of a 0.5& CIE starting at the top of Chron C27n (TC27N) is reconfirmed with stable isotope data from Zumaia (Spain) and Bjala (Bulgaria) localities. Spectral analysis on respective carbonate ⁄magnetic susceptibility proxy records substantiates the orbital cyclostratigraphy allowing correlation to a high-resolution benthic foraminifera isotope record from ODP Pacific Site 1209, that indicates a coeval 2 C transient warming. The hyperthermal event lasts 200 ka, contrasting with other short-lived events from the Eocene, and displays a relatively rapid onset and a longer tailing back to pre-event values similar to the Palaeocene–Eocene Thermal Maximum (PETM), though lower in amplitude. That a causal trigger for the TC27N event may be the onset of volcanism in the North Atlantic Igneous Province (NAIP) can be inferred from a 200-m-thick lava pile erupted during C27n ⁄ C26r polarity transition in the E Greenland margin. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8335 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8302 Title: Multiproxy record for the last 4500 years from Lake Shkodra (Albania/Montenegro) Authors: Zanchetta, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Van Welden, A.; Geological Survey of Norway (NGU), Trondheim, Norway; Baneschi, I.; IGG-CNR sez. Pisa, Pisa, Italy; Drysdale, R. N.; Department of Resource Management and Geography, University of Melbourne, Victoria, Australia; Sadori, L.; Dipartimento di Biologia Ambientale, Università ‘La Sapienza’, Rome, Italy; Roberts, N.; School of Geography, Earth and Environmental Sciences, University of Plymouth, UK; Giardini, M.; Dipartimento di Biologia Ambientale, Università ‘La Sapienza’, Rome, Italy; Beck, C.; Laboratoire de Géodynamique des Chaînes Alpines, Université de Savoie, Le Bourget du Lac, France; Pascucci, V.; Dipartimento Scienze Botaniche, Ecologiche e Geologiche University of Sassari, Sassari, Italy; Sulpizio, R.; Dipartimento Scienze della Terra e Geoambientali, University of Bari, Bari, Italy Abstract: A multi-proxy record is presented for approximately the last 4500 cal a BP from Lake Shkodra, Albania/Montenegro. Lithological analyses, C/N ratio and δ13C of the organic and inorganic carbon component suggest that organic matter and bulk carbonate are predominantly authigenic. The δ18O record of bulk carbonate indicates the presence of two prominent wet periods: one at ca. 4300 cal a BP and one at ca. 2500–2000 cal a BP. The latter phase is also found in southern Spain and Central Italy, and represents a prominent event in the western and central Mediterranean. In the last 2000 years, four relatively wet intervals occurred between ca. 1800 and 1500 cal a BP (150–450 AD), 1350–1250 (600–700 AD), 1100–800 (850–1150 AD), and at ca. 90 cal a BP (1860 AD). Between ca. 4100 and 2500 cal a BP δ18O values are relatively high, with three prominent peaks indicating drier conditions at ca. 4100–4000 cal a BP, ca. 3500 and at ca. 3300 cal a BP. Four additional drier events are identified at 1850 (ca. 100 AD), 1400 (ca. 550 AD), 1150 (800 AD) and ca.750 cal a BP (1200 AD). The pollen record does not show changes in accordance with these episodes owing to the poor sensitivity of vegetation in this area, which is dominated by an orographic rainfall effect and where changes in altitudinal vegetation belts do not affect the pollen rain in the lake catchment. However, since ca. 900 cal a BP a significant decrease in the percentage arboreal pollen and in pollen concentrations suggest major deforestation produced by human activities. Copyright © 2012 John Wiley & Sons, Ltd. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8302 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8301 Title: Constraining the onset of the Holocene “Neoglacial” over the central Italy using tephra layers Authors: Zanchetta, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Giraudi, C.; ENEA, C.R. Saluggia, 13040 Vercelli, Italy; Sulpizio, R.; CIRISIVU, c/o Dipartimento Geomineralogico, University of Bari, 70125, Bari, Italy; Drysdale, R. N.; Department of Resource Management and Geography, University of Melbourne, Victoria 3010, Australia; Sadori, L.; Dipartimento di Biologia Vegetale, Università “La Sapienza”, 00185 Roma, Italy Abstract: A study of six tephra layers discovered in different deposits between 1600 and 2700 m a.s.l. in the Apennine chain in central Italy allowed precise stratigraphic constraints on environmental and climatic changes between ca. 4.5 and 3.8 cal ka BP. Chemical analyses allowed the correlation of these tephra layers with the eruptions of Agnano Mt Spina (AMST) from Phlegrean Field and Avellino (AVT) from Somma–Vesuvius. Major environmental changes in the high mountains of the Central Apennines occurred just after the deposition of the AMST and predate the deposition of the AVT. At this time, renewed growth of the Calderone Glacier occurred, marking the onset of the Apennine “Neoglacial”. The presence of the AMST and AVT enabled us to make a precise, physical correlation with other archives in central Italy. Synchronization of records between sites showed that the period intervening the deposition of the AMST and AVT layers coincided with environmental changes that were not always exactly in phase. This highlights the fact that stratigraphic correlations using only radiocarbon chronologies (the most common method used for dating archives during the Holocene) could produce erroneous correlation of events, giving rise to oversimplified paleoclimatic reconstructions. Fri, 31 Aug 2012 22:00:00 GMT http://hdl.handle.net/2122/8301 2012-08-31T22:00:00Z http://hdl.handle.net/2122/8296 Title: Stratigraphy, petrography and chronology of speleothem concretion at Tana Che Urla (Lucca, Italy): paleoclimatic implications Authors: Regattieri, E.; Department of Earth Sciences, University of Pisa, Pisa 56100, Italy; Isola, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Zanchetta, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Drysdale, R. N.; Department of Resource Management and Geography, University of Melbourne, Parkville 3010, Victoria, Australia; Hellstrom, J. C.; School of Earth Sciences, University of Melbourne, Parkville 3010, Victoria, Australia; Baneschi, I.; Istituto di Georisorse e Geoscienza-CNR, Pisa 56100, Italy Abstract: In this work we present the results of a stratigraphic and lithologic study of a flowstone from Tana che Urla Cave, Apuan Alps (central Italy) which grew intermittently between ca. 160 and 8 ka. The studied succession consists of an alternation of two different lithofacies (Lf-A, Lf-B): a brown, detrital-rich (Lf-A) and a white, inclusion-poor calcite (Lf-B). Using available growth rate data, the difference between the two lithofacies is thought to be the result of different amounts of meteoric precipitation, with Lf-A related to low growth rates at times of low precipitation during phases of climatic deterioration (stadial or glacial) and a higher flux of clastic material, and Lf-B related to high growth rates due to high infiltration under conditions of higher precipitation during wetter (interstadial/interglacial) periods, with lower clastic flux. Following this interpretation and the available chronology, the flowstone investigated shows a basal portion of Lf- A that was deposited during MIS6. The flowstone then passed from Lf-A to Lf B at the MIS6-5 transition, with Lf-B lasting for the full interglacial of MIS5e. A long growth interruption (hiatus H1) can be correlated with the MIS5d stadial, with resumption of lithofacies Lf-B occurring during the climatic amelioration of interstadial MIS5c. The age profile of the upper part of the flowstone is poorly constrained, and is characterised by several growth interruptions, suggesting that the last glacial was more severe compared to MIS6. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8296 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8257 Title: Precise microsampling of poorly laminated speleothems for U-series dating Authors: Drysdale, R. N.; Department of Resource Management and Geography, University of Melbourne, Parkville 3010, Victoria, Australia; Bence, T. P.; School of Earth Sciences, University of Melbourne, Parkville 3010, Victoria, Australia; Hellstrom, J. C.; School of Earth Sciences, University of Melbourne, Parkville 3010, Victoria, Australia; Couchoud, I.; Department of Resource Management and Geography, University of Melbourne, Parkville 3010, Victoria, Australia; Greig, A.; School of Earth Sciences, University of Melbourne, Parkville 3010, Victoria, Australia; Bajo, P.; Department of Resource Management and Geography, University of Melbourne, Parkville 3010, Victoria, Australia; Zanchetta, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Isola, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Spötl, C.; Institut für Geologie und Paläontologie, Universität Innsbruck, 6020 Innsbruck, Austria; Baneschi, I.; Istituto di Georisorse e Geoscienza-CNR, Pisa 56100, Italy; Regattieri, E.; Department of Earth Sciences, University of Pisa, Pisa 56100, Italy; Woodhead, J. D.; School of Earth Sciences, University of Melbourne, Parkville 3010, Victoria, Australia Abstract: One of the principal reasons why speleothems are recognised as important palaeoclimate archives is their suitability for accurate and precise uranium-series (U-series) age determination. Sampling speleothem sections for U-series dating is straightforward in most cases because visible growth layers are preserved. However, this is not always the case, and here we describe a sampling strategy whereby growth layers are resolved from trace-element images produced by laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We apply this method to a section of an Italian subaqueous speleothem (CD3) that lacks persistent visible growth layering. Trace-element imaging revealed growth layers that are strongly non-planar in their geometry owing to the speleothem's pronounced euhedral crystal terminations. The most prominent trace-element layers were first digitized as x, y vector contours. We then interpolated these in the growth-axis direction to generate a series of contour lines at ∼250-μm increments. The coordinates of these contours were used to guide the sampling via a computerised micromilling lathe. This produced a total of 22 samples for U-series dating by multi-collector ICP-MS. The dating results returned ages in correct stratigraphic order within error. Close inspection of the U-series data and the derived depth–age model suggests that the main source of model-age uncertainty is unrelated to the contour sampling but instead more associated with how closely spaced the model ages are in time, i.e. the model age density. Comparisons between stable oxygen and carbon isotope profiles derived from aliquots of the dating samples and two other stable isotope profiles from CD3 spanning the same time period compare very favourably. Taken together, this suggests that our trace-element contouring method provides a reliable means for extracting samples for dating (and other geochemical analyses), and can be applied to similar speleothems lacking visible growth layering. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8257 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8239 Title: Late Pleistocene to Holocene tephrostratigraphic record from the Northern Ionian Sea Authors: Caron, B.; Laboratoire des Interactions et Dynamique des Environnements de Surface (IDES), UMR 8148, CNRS—Université de Paris-Sud, Orsay Cedex, France; Siani, G.; Laboratoire des Interactions et Dynamique des Environnements de Surface (IDES), UMR 8148, CNRS—Université de Paris-Sud, Orsay Cedex, France; Sulpizio, R.; CIRISIVU, c/o Dipartimento Geomineralogico, Bari, Italy; Zanchetta, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Paterne, M.; Laboratoire des Sciences du Climat et de l'Environnement, Laboratoire Mixte CNRS-CEA-UVSQ, Gif-sur-Yvette Cedex, France; Santacroce, R.; Dipartimento di Scienze della Terra, Pisa, Italy; Tema, E.; Dipartimento di Scienze della Terra, Torino, Italy; Zanella, E.; Dipartimento di Scienze della Terra, Torino, Italy Abstract: A detailed tephrostratigraphic study supported by stable isotope (δ18O) analyses and AMS 14C dating was carried out on a high sedimentation rate deep-sea core recovered in the northern Ionian Sea. Eight tephra layers were recognised, all originated from explosive eruptions of southern Italian volcanoes. These tephra layers are correlated with terrestrial proximal counterparts and with both marine and lacustrine tephra already known in the central Mediterranean area. The oldest tephra (dated at ca. 19.4 ka cal BP) is tentatively correlated to the Monte Guardia eruption from Lipari Island. Two other rhyolitic tephra layers were correlated with the explosive volcanic activity of Lipari Island: Gabellotto-Fiumebianco/E-1 (8.3 ka cal BP) located close to the interruption of Sapropel S1 deposit, and Monte Pilato (ca. AD 1335) in the uppermost part of the core. The Na-phonolitic composition of the other five recognised tephra layers indicates the Somma-Vesuvius as the source. The composition is quite homogeneous among the five tephra layers, and fits that of the Mercato proximal deposits. Beyond the striking chemical similarity with the Mercato eruption, these tephra layers span over ca. 2000 years, preventing correlation with the single well known Plinian eruption of the Somma-Vesuvius. Therefore, at least two of these tephra layers were assigned to an interplinian activity of the Somma-Vesuvius between the eruptions of Mercato and Avellino, even though these eruptions remains poorly constrained in the proximal area. By contrast, the most prominent tephra layer (2 mm white tephra visible at naked eyes) was found within the S1a Sapropel interval. Despite the possible complication for the presence of similar eruption with different ages we argue that Mercato is probably a very good marker for the onset of sapropelic condition in the Ionian Sea and can be used for land-sea correlations for this important climatic event. More in general, these data allow a significant update of the knowledge of the volcanic ash dispersal from Lipari and Somma-Vesuvius volcanoes. Mon, 14 May 2012 22:00:00 GMT http://hdl.handle.net/2122/8239 2012-05-14T22:00:00Z http://hdl.handle.net/2122/8192 Title: Plio-Pliocene high-low latitude climate interplay: a Mediterranean point of view Authors: Colleoni, F.; Centro Euro-Mediterraneo sui Cambiamenti Climatici; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Negri, A.; Universita' Politecnica delle Marche; Marzocchi, A.; Centro Euro-Mediterraneo sui Cambiamenti Climatici Abstract: The high–low latitude climate interplay during the Plio–Pleistocene global cooling is not yet well understood. Insight on the Mediterranean region can provide some clues about past significant climate changes since the basin reflects the climate dynamics of both high-latitude and low-latitude regions, being connected to the North Atlantic and subjected to monsoon influence. Here we shade light on this connection problem by per- forming a spectral analysis on an Eastern Mediterranean stack of planktonic records spanning the last 5 Ma and by further comparing it to North Atlantic and Pacific deep- and surface-water records. Our main conclu- sion is that the Mediterranean detected the main global climate transitions over the last 5 Myr although sapropel depositions indicate that it remained influenced by the African summer monsoon during the whole interval. Our analysis reveals that until 2.2 Ma the Mediterranean planktonic record is driven by re- gional processes dominated by precession. The progressive emergence of the 41-kyr frequency in the Medi- terranean records around 2.8 Ma suggests that, since this date, the Mediterranean was more and more affected by the high-latitude climate dynamics forcing than by the low-latitude one. Moreover, during the ongoing Plio–Pleistocene cooling, the 41-kyr frequency signal in the Mediterranean records anticipated high-latitude deep-water response to the intensification of the Northern Hemisphere Glaciations (NHG) and lagged the signal in tropical latitudes. Finally, toward 1.2 Ma the results suggest that the progressive shift from the 41-kyr to the 100-kyr frequency was led by the northern high latitudes. Overall, our results confirm that the Mediterranean is an ideal site to study the interplay between high and low latitude climates. Tue, 31 Jan 2012 23:00:00 GMT http://hdl.handle.net/2122/8192 2012-01-31T23:00:00Z http://hdl.handle.net/2122/7742 Title: The sensitivity of the Late Saalian (140 ka) and LGM (21 ka) Eurasian ice sheets to sea surface conditions Authors: Colleoni, F.; Centro Euro-Mediterraneo per i Cambiamenti Climatici; Liakka, J.; Department of Meteorology, Stockholm University; Krinner, G.; Laboratoire de Glaciologie et Ge´ophysique de l’Environnement, UJF, CNRS; Jakobsson, M.; Department of Geological Sciences, Stockholm University; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Peyaud, V.; Laboratoire de Glaciologie et Ge´ophysique de l’Environnement, UJF, CNRS Abstract: This work focuses on the Late Saalian (140 ka) Eurasian ice sheets’ surface mass balance (SMB) sensitivity to changes in sea surface temperatures (SST). An Atmospheric General Circulation Model (AGCM), forced with two preexisting Last Glacial Maximum (LGM, 21 ka) SST reconstructions, is used to compute climate at 140 and 21 ka (reference glaciation). Contrary to the LGM, the ablation almost stopped at 140 ka due to the climatic cooling effect from the large ice sheet topography. Late Saalian SST are simulated using an AGCM coupled with a mixed layer ocean. Compared to the LGM, these 140 ka SST show an inter-hemispheric asymmetry caused by the larger ice-albedo feedback, cooling climate. The resulting Late Saalian ice sheet SMB is smaller due to the extensive simulated sea ice reducing the precipitation. In conclusion, SST are important for the stability and growth of the Late Saalian Eurasian ice sheet. Fri, 31 Dec 2010 23:00:00 GMT http://hdl.handle.net/2122/7742 2010-12-31T23:00:00Z