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  • 1
    Publication Date: 2017-04-04
    Description: We report a high-resolution record of a Miocene polarity transition (probably the Chron C6r-C6n transition) from glacimarine sediments in McMurdo Sound, Ross Sea, Antarctica, which is the first transition record reported from high southern latitudes. The transition is recorded in two parallel cores through a 10.7 m stratigraphic thickness. The sediments are interpreted as having been deposited in a marine environment under the influence of floating ice or seaward of a glacier terminus from which a large sediment load was delivered to the drill site. The core was recovered using rotary drilling, which precludes azimuthal orientation of the core and determination of a vector record of the field during the transition. However, constraints on transitional field behaviour are provided by the exceptional resolution of this record. Large-scale paleomagnetic inclination fluctuations in the two cores can be independently correlated with each other using magnetic susceptibility data, which suggests that the sediments are reliable recorders of geomagnetic field variations. Agreement between the two parallel transition records provides evidence for highly dynamic field behaviour, as suggested by numerous large-scale inclination changes (∼90◦) throughout the transition. These large-scale changes occur across stratigraphically narrow intervals, which is consistent with the suggestion of rapid field changes during transitions. In one intact portion of the core, where there is no apparent relative core rotation between samples, declinations and inclinations are consistent with the presence of a stable cluster of virtual geomagnetic poles within the transition (although the possibility that this cluster represents a rapid depositional event cannot be precluded). These observations are consistent with those from other high-resolution records and provide a rare detailed view of transitional field behaviour compared to most sedimentary records, which are not as thick and which appear to have been smoothed by sedimentary remanence acquisition processes.
    Description: Published
    Description: 815-824
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Paleomagnetism ; geomagnetic field behaviour ; polarity reversal ; glacial processes ; Antarctica ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: Because of the paucity of exposed rock, the direct physical record of Antarctic Cenozoic glacial history has become known only recently and then largely from offshore shelf basins through seismic surveys and drilling. The number of holes on the continental shelf has been small and largely confined to three areas (McMurdo Sound, Prydz Bay, and Antarctic Peninsula), but even in McMurdo Sound, where Oligocene and early Miocene strata are well cored, the late Cenozoic is poorly known and dated. The latest Antarctic geological drilling program, ANDRILL, successfully cored a 1285-m-long record of climate history spanning the last 13 m.y. from subsea-floor sediment beneath the McMurdo Ice Shelf (MIS), using drilling systems specially developed for operating through ice shelves. The cores provide the most complete Antarctic record to date of ice-sheet and climate fluctuations for this period of Earth’s history. The 〉60 cycles of advance and retreat of the grounded ice margin preserved in the AND-1B record the evolution of the Antarctic ice sheet since a profound global cooling step in deep-sea oxygen isotope records ~14 m.y.a. A feature of particular interest is a ~90-m-thick interval of diatomite deposited during the warm Pliocene and representing an extended period (~200,000 years) of locally open water, high phytoplankton productivity, and retreat of the glaciers on land.
    Description: Published
    Description: Santa Barbara, California
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: 3.8. Geofisica per l'ambiente
    Description: open
    Keywords: ANDRILL ; Late Cenozoic climate history ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 3
    Publication Date: 2017-04-04
    Description: Because of the paucity of exposed rock the direct physical record of Antarctic Cenozoic glacial history has become known only recently and then largely from off-shore shelf basins through seismic surveys and drilling. The number of holes has been small and largely confined to three areas (McMurdo Sound, Prydz Bay and Antarctic Peninsula), but even in McMurdo Sound, where Oligocene and early Miocene strata are well-cored, the Late Cenozoic is poorly known and dated. The latest Antarctic geological drilling program, ANDRILL, successfully cored a 1285m-long record of climate history spanning the last 13 m.y. from sub-sea floor sediment beneath the McMurdo Ice Shelf (MIS), using drilling systems specially developed for operating through ice shelves. The cores provide the most complete Antarctic record to date of ice sheet and climate fluctuations for this period of Earth’s history. The 〉60 cycles of advance and retreat of the grounded ice margin preserved in the AND¬1B record the evolution of the Antarctic ice sheet since a profound global cooling step in deep sea oxygen isotope records ~14 m.y. ago. A feature of particular interest is a ~90m-thick interval of diatomite deposited during the warm Pliocene, and representing an extended period (~200,000 years) of locally open water, high phytoplankton productivity and retreat of the glaciers on land.
    Description: USGS - National Academy
    Description: Published
    Description: Santa Barbara USA
    Description: 3.8. Geofisica per l'ambiente
    Description: open
    Keywords: climate history ; ANDRILL ; 02. Cryosphere::02.01. Permafrost::02.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 4
    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
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    In:  EPIC3IAntarctica : a keystone in a changing world : proceedings of the 10th International Symposium on Antarctic Earth Sciences, Santa Barbara, California, August 26 to September 1, 2007 / edited by Alan K Cooper; National Research Council (U.S.). Polar Resear, pp. 71-82, ISBN: 978-0-309-11854-5
    Publication Date: 2014-04-15
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 6
    Publication Date: 2018-08-10
    Description: The ANDRILL (Antarctic Drilling Project) McMurdo Ice Shelf (MIS) project drilled 1285 m of sediment in Hole AND-1B, representing the past 12 m.y. of glacial history. Downhole geophysical logs were acquired to a depth of 1018 mbsf (meters below seafloor), and are complementary to data acquired from the core. The natural gamma radiation (NGR) and magnetic susceptibility logs are particularly useful for understanding lithological and paleoenvironmental change at ANDRILL McMurdo Ice Shelf Hole AND-1B. NGR logs cover the entire interval from the seafloor to 1018 mbsf, and magnetic susceptibility and other logs covered the open hole intervals between 692 and 1018 and 237–342 mbsf. In the upper part of AND-1B, clear alternations between low and high NGR values distinguish between diatomite (lacking minerals containing naturally radioactive K, U, and Th) and diamictite (containing K-bearing clays, K-feldspar, mica, and heavy minerals). In the lower open hole logged section, NGR and magnetic susceptibility can also distinguish claystones (rich in K-bearing clay minerals, relatively low in magnetite) and diamictites (relatively high in magnetite). Sandstones can be distinguished by their high resistivity values in AND-1B. On the basis of these three downhole logs, diamictite, claystones, and sandstones can be predicted correctly for 74% of the 692–1018 mbsf interval. The logs were then used to predict facies for the 6% of this interval that was unrecovered by coring. Given the understanding of the physical property characteristics of different facies, it is also possible to identify subtle changes in lithology from the physical properties and help refine parts of the lithostratigraphy, for example, the varying terrigenous content of diatomites and the transitions from subice diamictite to open-water diatomite.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 7
    Publication Date: 2022-04-22
    Description: Deep sea geological records indicate that Antarctic ice-sheet growth and decay is strongly influenced by the Earth's astronomical variations (known as Milankovitch cycles), and that the frequency of the glacial-interglacial cycles changes through time. Here we examine the emergence of a strong obliquity (axial tilt) control on Antarctic ice-sheet evolution during the Miocene by correlating the Antarctic margin geological records from 34 to 5 million years ago with a measure of obliquity sensitivity that compares the variance in deep sea sediment core oxygen-isotope data at obliquity timescales with variance of the calculated obliquity forcing. Our analysis reveals distinct phases of ice-sheet evolution and suggests the sensitivity to obliquity forcing increases when ice-sheet margins extend into marine environments. We propose that this occurs because obliquity-driven changes in the meridional temperature gradient affect the position and strength of the circum-Antarctic easterly flow and enhance (or reduce) ocean heat transport across the Antarctic continental margin. The influence of obliquity-driven changes in ocean dynamics is amplified when marine ice sheets are extensive, and sea ice is limited. Our reconstruction of the Antarctic ice-sheet history suggests that if sea-ice cover decreases in the coming decades, ocean-driven melting at the ice-sheet margin will be amplified.
    Description: Published
    Description: 132-137
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: 4A. Oceanografia e clima
    Description: 5A. Ricerche polari e paleoclima
    Description: JCR Journal
    Keywords: :MIDDLE MIOCENE CLIMATE; SEA-LEVEL; ROSS SEA; HEMISPHERE CLIMATE; CONTINENTAL-SHELF; ODP SITE-1165; PRYDZ BAY; SOUTHERN; INTENSIFICATION; HISTORY
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    Publication Date: 2022-06-14
    Description: Stratigraphic drilling from the McMurdo Ice Shelf in the 2006/2007 austral summer recovered a 1284.87 m sedimentary succession from beneath the sea floor. Key age data for the core include magnetic polarity stratigraphy for the entire succession, diatom biostratigraphy for the upper 600 m and 40Ar/39Ar ages for in-situ volcanic deposits as well as reworked volcanic clasts. A vertical seismic profile for the drill hole allows correlation between the drill hole and a regional seismic network and inference of age constraint by correlation with well‐dated regional volcanic events through direct recognition of interlayered volcanic deposits as well as by inference from flexural loading of pre‐existing strata. The combined age model implies relatively rapid (1 m/2–5 ky) accumulation of sediment punctuated by hiatuses, which account for approximately 50% of the record. Three of the longer hiatuses coincide with basin‐wide seismic reflectors and, along with two thick volcanic intervals, they subdivide the succession into seven chronostratigraphic intervals with characteristic facies: 1. The base of the cored succession (1275–1220 mbsf) comprises middle Miocene volcaniclastic sandstone dated at approx 13.5 Ma by several reworked volcanic clasts; 2. A late-Miocene sub-polar orbitally controlled glacial–interglacial succession (1220–760 mbsf) bounded by two unconformities correlated with basin‐wide reflectors associated with early development of the terror rift; 3. A late Miocene volcanigenic succession (760–596 mbsf) terminating with a ~1 my hiatus at 596.35 mbsf which spans the Miocene–Pliocene boundary and is not recognised in regional seismic data; 4. An early Pliocene obliquity-controlled alternating diamictite and diatomite glacial–interglacial succession(590–440 mbsf), separated from; 5. A late Pliocene obliquity-controlled alternating diamictite and diatomite glacial–interglacial succession (440–150 mbsf) by a 750 ky unconformity interpreted to represent a major sequence boundary at other locations; 6. An early Pleistocene interbedded volcanic, diamictite and diatomite succession (150–80 mbsf), and; 7. A late Pleistocene glacigene succession (80–0 mbsf) comprising diamictite dominated sedimentary cycles deposited in a polar environment.
    Description: Published
    Description: 189-203
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Stratigraphic Drilling ; McMurdo Ice Shelf ; Chronostratigraphy ; Neogene ; Tectonics ; Ice Sheet history ; 02. Cryosphere::02.03. Ice cores::02.03.05. Paleoclimate ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 7 (1959), S. 643-646 
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 19 (1966), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Nodule-roots of Myrica cerifera (Southern Wax Myrtle) and Casuarina cunning hamiana (Australian Pine) have a negative geotropic curvature. Studies of their endogenotts auxin content revealed a pattern of correlation: the absence of detectable auxin when the geotropisni was negative. Non-nodulated roots of Myrica exhibited a normal positive geotropic curvature and possessed an auxin content within an anticipated range (10 mg/kg). Root nodules of Alnus species, whose roots exhibit a positive geotropic curvature, contained measurable endogenous auxin (20 mg IAA/kg).The presence of an indoleaectic acid oxidase system in Myrica and Casuarina root nodules has heen described and correlations are drawn between non-detectable endogenous auxin concentrations and high enzymatic activities.It is suggested that the negative geotropic curvature of the nodule-roots of Myrica and Casuarina is due to the presence of a sub-optimal concentration of auxin which in turn results from the activity of an indoleacetic aeid destroying system.
    Type of Medium: Electronic Resource
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