http://hdl.handle.net/2122/4116 2013-06-19T08:19:08Z 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. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8267 Title: Searching for single domain magnetite in the “pseudo-single-domain” sedimentary haystack: Implications of biogenic magnetite preservation for sediment magnetism and relative paleointensity determinations Authors: Roberts, A. P.; National Oceanography Centre, University of Southampton, Southampton, UK.; Chang, L.; National Oceanography Centre, University of Southampton, Southampton, UK.; Heslop, D.; Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia.; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Larrasoaña, J. C.; Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia. Abstract: Magnetic hysteresis measurements of sediments have resulted in widespread reporting of “pseudo-single-domain”-like magnetic properties. In contrast, the ideal single domain (SD) properties that would be expected to be responsible for high quality paleomagnetic records are rare. Determining whether SD particles are rare or common in sediments requires application of techniques that enable discrimination among different magnetic components in a sediment. We apply a range of such techniques and find that SD particles are much more common than has been reported in the literature and that magnetite magnetofossils (the inorganic remains of magnetotactic bacteria) are widely preserved at depth in a range of sediment types, including biogenic pelagic carbonates, lacustrine and marine clays, and possibly even in glaci-marine sediments. Thus, instead of being rarely preserved in the geological record, we find that magnetofossils are widespread. This observation has important implications for our understanding of how sediments become magnetized and highlights the need to develop a more robust basis for understanding how biogenic magnetite contributes to the magnetization of sediments. Magnetofossils also have grain sizes that are substantially smaller than the 1–15 mm size range for which there is reasonable empirical support for relative paleointensity studies. The different magnetic response of coexisting fine biogenic and coarser lithogenic particles is likely to complicate relative paleointensity studies. This issue needs much closer attention. Despite the fact that sediments have been subjected to paleomagnetic investigation for over 60 years, much remains to be understood about how they become magnetized. 2012-08-21T22:00:00Z http://hdl.handle.net/2122/8007 Title: On the magnetic characterization and quantification of the superparamagnetic fraction of traffic-related urban airborne PM in Rome, Italy Authors: Sagnotti, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Winkler, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: The magnetic properties of traffic-related airborne particulate matter (PM) in the city of Rome, Italy, have been previously analyzed and interpreted as suitable proxies to discriminate between different vehicular sources. In this study, we carried out a new set of measurements and analyses specifically devoted to the identification and evaluation of the contribution of ultrafine superparamagnetic (SP) particles to the overall magnetic assemblage of traffic-related PM in Rome. In particular, the presence and the concentration of SP particles have been estimated on powders collected from disk brakes and gasoline exhaust pipes of circulating vehicles and from Quercus ilex leaves grown along high-traffic roads, measuring their hysteresis parameters in a range of temperatures from 293 K to 10 K and measuring the time decay of their saturation remanent magnetization (MRS) at room temperature. The SP fraction contributes for the 10-15% to the overall room temperature MRS and causes the observed changes in the hysteresis properties measured upon cooling down to 10 K. In all the analyzed samples the SP fraction is associated to a generally prevailing population of larger ferrimagnetic multidomain (MD) particles and we suppose that in traffic-related PM the SP fraction mainly occurs as coating of MD particles and originated by localized stress in the oxidized outer shell surrounding the unoxidized core of magnetite-like grains. Under this hypothesis, the estimate of SP content in traffic-related PM cannot be considered a robust proxy to estimate the overall concentration of nanometric particles. 2012-10-31T23:00:00Z http://hdl.handle.net/2122/7557 Title: Orbitally forced paleoenvironmental and paleoclimate changes in the late postevaporitic Messinian of the central Mediterranean Basin Authors: Cosentino, D.; Dipartimento di Scienze Geologiche, Università degli Studi Roma Tre, Largo San Leonardo Murialdo, 1-00146 Rome, Italy; Bertini, A.; Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via G. La Pira, 4-50121 Firenze, Italy; Cipollari, P.; Dipartimento di Scienze Geologiche, Università degli Studi Roma Tre, Largo San Leonardo Murialdo, 1-00146 Rome, Italy; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Gliozzi, E.; Dipartimento di Scienze Geologiche, Università degli Studi Roma Tre, Largo San Leonardo Murialdo, 1-00146 Rome, Italy; Grossi, F.; Dipartimento di Scienze Geologiche, Università degli Studi Roma Tre, Largo San Leonardo Murialdo, 1-00146 Rome, Italy; Lo Mastro, S.; Dipartimento di Scienze Geologiche, Università degli Studi Roma Tre, Largo San Leonardo Murialdo, 1-00146 Rome, Italy; Sprovieri, M.; Istituto per l’Ambiente Marino Costiero, Consiglio Nazionale delle Ricerche, Via del Mare 3, 91021 Torretta Granitola, Mazara (TP), Italy Abstract: Paleoenvironmental and paleoclimate changes that occurred during the late postevaporitic stage of the Mediterranean Basin in the Messinian foreland domain of the Adriatic region offer a new perspective on the relationship between orbital forcing and climate response. The magnetic susceptibility record of the Fonte dei Pulcini A section (Maiella Mountains, Italy) allows us to orbitally tune the record between 5.394 and 5.336 Ma and to temporally constrain the paleoenvironmental and paleoclimate changes evidenced by quantitative paleontological (palynomorphs, ostracods, and calcareous nannofossils), stable isotope (δ18O and δ13C), and X-ray diffraction (XRD) analyses. The base of the Fonte dei Pulcini A section is characterized by Paratethyan ostracods and dinocysts, which point to the late Messinian Lago-Mare biofacies (Loxocorniculina djafarovi zone) of the Mediterranean Messinian stratigraphy. From paleontological and geochemical (δ18O) analyses, there is no evidence of a marine incursion in the Fonte dei Pulcini A section. The major changes in terms of paleodepth, paleosalinity, evaporation versus precipitation, aridity versus humidity, and reworking processes occurred in the upper part of the Fonte dei Pulcini A section, during the last Messinian insolation cycle (i-cycle 511/512), which is characterized by high-amplitude oscillations. In contrast, the lower part of the Fonte dei Pulcini A section, which was deposited during relatively low-amplitude insolation cycles, is characterized by more stable environmental conditions. Comparing summer insolation with the paleoenvironmental changes at the Fonte dei Pulcini A section, we identify delays of several thousands of years between orbital forcing and climate response. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/7519 Title: Fault-trapped waves depict continuity of the fault system responsible for the 6 April 2009 MW 6.3 L’Aquila earthquake, central Italy Authors: Calderoni, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Di Giovambattista, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Vannoli, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Pucillo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Rovelli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Abstract: We investigate fault-trapped waves observed at a permanent broad-band station (FAGN) installed on the San Demetrio Fault, about 20 km southeast of L'Aquila. This fault has the same strike of the Paganica Fault which was responsible for the MW 6.3, 6 April 2009 earthquake. The two faults display an en-echelon pattern with a few km offset. We have found that events causing efficient trapped waves are clustered at the northwestern and southeastern bottom ends of the ruptured Paganica fault plane. The efficiency of trapped waves at FAGN, which is located about 5 km far from the ruptured fault plane, indicates that the two faults are linked at depth. This suggests that fault segments in the study area can be part of a longer and continuous fault system which controls the seismic hazard of the region. Moreover, we have found that the two earthquake clusters generating the most efficient trapped waves occur in portions of the fault system with the highest fluid pressure. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/7234 Title: ENVIRONMENTAL MAGNETISM: APPLICATIONS TO PALEOCLIMATIC RECONSTRUCTIONS AND AIR POLLUTION MONITORING Authors: Sagnotti, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: This short course will be focused on environmental magnetism. In the first part I will present a general overview of the relevant rock magnetic techniques and parameters, briefly discussing laboratory measurements and basic data analysis. Following this general introduction, I will address the application of rock magnetic techniques to two main lines of research. 2011-11-22T23:00:00Z http://hdl.handle.net/2122/7209 Title: The Role of Geomagnetic Cues in Green Turtle Open Sea Navigation Authors: Benhamou, S.; CEFE, CNRS, Montpellier, France; Sudre, J.; LEGOS, CNRS, Toulouse, France; Bourjea, J.; IFREMER, La Re´union, France; Ciccione, S.; Ke´ lonia, La Re´union, France; De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Luschi, P.; Dipartimento di Biologia, Universita` di Pisa, Italy Abstract: Background: Laboratory and field experiments have provided evidence that sea turtles use geomagnetic cues to navigate in the open sea. For instance, green turtles (Chelonia mydas) displaced 100 km away from their nesting site were impaired in returning home when carrying a strong magnet glued on the head. However, the actual role of geomagnetic cues remains unclear, since magnetically treated green turtles can perform large scale (.2000 km) post-nesting migrations no differently from controls. Methodology/Principal Findings: In the present homing experiment, 24 green turtles were displaced 200 km away from their nesting site on an oceanic island, and tracked, for the first time in this type of experiment, with Global Positioning System (GPS), which is able to provide much more frequent and accurate locations than previously used tracking methods. Eight turtles were magnetically treated for 24–48 h on the nesting beach prior to displacement, and another eight turtles had a magnet glued on the head at the release site. The last eight turtles were used as controls. Detailed analyses of water masses-related (i.e., current-corrected) homing paths showed that magnetically treated turtles were able to navigate toward their nesting site as efficiently as controls, but those carrying magnets were significantly impaired once they arrived within 50 km of home. Conclusions/Significance: While green turtles do not seem to need geomagnetic cues to navigate far from the goal, these cues become necessary when turtles get closer to home. As the very last part of the homing trip (within a few kilometers of home) likely depends on non-magnetic cues, our results suggest that magnetic cues play a key role in sea turtle navigation at an intermediate scale by bridging the gap between large and small scale navigational processes, which both appear to depend on non-magnetic cues. 2011-10-25T22:00:00Z http://hdl.handle.net/2122/7170 Title: Sequence stratigraphy of the ANDRILL AND-2A drillcore, Antarctica: A long-term, ice-proximal record of Early to Mid-Miocene climate, sea-level and glacial dynamism Authors: Fielding, C. R.; Department of Earth & Atmospheric Sciences, 214 Bessey Hall, University of Nebraska-Lincoln, NE 68588-0340, USA; Browne, G. H.; GNS Science, P.O. Box 30368, Lower Hutt, New Zealand; Field, B.; GNS Science, P.O. Box 30368, Lower Hutt, New Zealand; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Harwood, D. M.; Department of Earth & Atmospheric Sciences, 214 Bessey Hall, University of Nebraska-Lincoln, NE 68588-0340, USA; Krissek, L. A.; School of Earth Sciences, Ohio State University, 125 South Oval Mall, Columbus, OH 43210, USA; Levy, R. H.; GNS Science, P.O. Box 30368, Lower Hutt, New Zealand; Panter, K. S.; Department of Geology, Bowling Green State University, Bowling Green, OH 43403, USA; Passchier, S.; Department of Earth & Environmental Sciences, Montclair State University, 252 Mallory Hall, 1 Normal Avenue, Montclair, NJ 07043, USA; Pekar, S. F.; School of Earth & Environmental Sciences, Queen's College, 65-30 Kissena Blvd., Flushing, NY 11367, USA Abstract: Present understanding of Antarctic climate change during the Early to Mid-Miocene, including major cycles of glacial expansion and contraction, relies in large part on stable isotope proxies from deep sea core drilling. Here, we summarize the lithostratigraphy of the ANDRILL Southern McMurdo Sound Project drillcore AND- 2A. This core offers a hitherto unavailable ice-proximal stratigraphic archive from a high-accommodation continental margin setting, and provides clear evidence of repeated fluctuations in climate, ice expansion/ contraction and attendant sea-level change over the period c. 20.2–14.2 Ma, with a more fragmentary record of Late Miocene and Pliocene time. The core is divided into seventy-four high-frequency (fourth- or fifthorder) glacimarine sequences recording repeated advances and retreats of glaciers into and out of the Victoria Land Basin. The section can be resolved into thirteen longer-term, composite (third-order) sequences, which comprise packages of higher frequency sequences that show a consistent stratigraphic stacking pattern (Stratigraphic Motif). The distribution of the six recognized motifs indicates intervals of less and more iceproximal, and temperate to subpolar/polar climate, through the Miocene period. The core demonstrates a dynamic climate regime throughout the Early to Mid-Miocene that may be correlated to some previouslyrecognized events such as the Mid-Miocene Climatic Optimum, and provides a detailed reference point from which to evaluate stable isotope proxy records from the deep-sea. 2011-05-14T22:00:00Z http://hdl.handle.net/2122/7169 Title: Magnetotactic bacterial abundance in pelagic marine environments is limited by organic carbon flux and availability of dissolved iron Authors: Roberts, A. P.; National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, UK; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Villa, G.; Dipartimento Scienze della Terra, Università di Parma, Viale Usberti 157A, 43100 Parma, Italy; Chang, L.; National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, UK; Jovane, L.; National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, UK; Bohaty, S. M.; National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, UK; Larrasoaña, J. C.; Área de Cambio Global, IGME, Oficina de Proyectos de Zaragoza, Manuel Lasala 44 9B, Zaragoza 50006, Spain; Heslop, D.; Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia; Fitz Gerald, J. D.; Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia Abstract: Magnetotactic bacteria intracellularly biomineralize magnetite of an ideal grain size for recording palaeomagnetic signals. However, bacterial magnetite has only been reported in a few pre-Quaternary records because progressive burial into anoxic diagenetic environments causes its dissolution. Deep-sea carbonate sequences provide optimal environments for preserving bacterial magnetite due to low rates of organic carbon burial and expanded pore-water redox zonations. Such sequences often do not become anoxic for tens to hundreds of metres below the seafloor. Nevertheless, the biogeochemical factors that control magnetotactic bacterial populations in such settings are not well known. We document the preservation of bacterial magnetite, which dominates the palaeomagnetic signal throughout Eocene pelagic carbonates from the southern Kerguelen Plateau, Southern Ocean. We provide evidence that iron fertilization, associated with increased aeolian dust flux, resulted in surface water eutrophication in the late Eocene that controlled bacterial magnetite abundance via export of organic carbon to the seafloor. Increased flux of aeolian ironbearing phases also delivered iron to the seafloor, some of which became bioavailable through iron reduction. Our results suggest that magnetotactic bacterial populations in pelagic settings depend crucially on particulate iron and organic carbon delivery to the seafloor. 2011-10-14T22:00:00Z http://hdl.handle.net/2122/7156 Title: First Field Magnetometer Investigation at the Phoenician Island of Mozia (Trapani), Northwestern Sicily: Preliminary Results Authors: Di Mauro, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Alfonsi, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Sapia, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Nigro, L.; Univ. Sapienza; Marchetti, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: The island of Mozia represents a unique location for geophysical investigations applied to archaeological research. The presence of exposed structures and ongoing studies, run by the University ‘La Sapienza’ of Rome, allows a direct comparison of geophysical exploration data with the excavations results, giving an immediate control on the accuracy and robustness of the geophysical survey conducted. Four areas around the Kothon, a Phoenician artificial basin, have been investigated by means of magnetic methods; the purpose was to trace a semi-circular wall surrounding the structure of the basin. The geophysical results confirmed the presence of the wall, as postulated by the archaeological study, and indicated magnetic anomalies associated with previously unknown structures. Subsequent archaeological excavation confirmed these latter data. The magnetic signature of the topsoils and remains characterizing the area surveyed,was undoubtedly weak, even though the resulting anomalies maps were adequately clear and allowed the characterization of the archaeological structures in the area. Field and laboratory magnetic susceptibility measurements allowed better understanding of the data. The study confirmed that geomagnetic investigations can be used in weakly magnetic susceptibility environments, as in Mozia, and are productive if conducted in accordance with an archaeological agenda. Copyright © 2011 John Wiley & Sons, Ltd. 2011-07-27T22:00:00Z