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  • 1
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    Changes in Neogene Himalayan erosion regime: Input of Pb and Nd isotopes into the Indian Ocean (2011)
    In:  [Talk] In: Goldschmidt Conference 2011, 14.-19.08.2011, Prague, Czech Republic .
    Details
    Publication Date: 2012-02-23
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Talk
  • 2
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    Persistence and origin of the lunar core dynamo [Earth, Atmospheric, and Planetary Sciences] (2013)
    National Academy of Sciences
    Details
    Publication Date: 2013-05-22
    Description: The lifetime of the ancient lunar core dynamo has implications for its power source and the mechanism of field generation. Here, we report analyses of two 3.56-Gy-old mare basalts demonstrating that they were magnetized in a stable and surprisingly intense dynamo magnetic field of at least ∼13 μT. These data...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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    PAPER CURRENT
  • 3
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    The Cenozoic palaeoenvironment of the Arctic Ocean (2006)
    Nature Publishing Group
    In:  Nature, 441 . pp. 601-605.
    Details
    Publication Date: 2019-07-03
    Description: The history of the Arctic Ocean during the Cenozoic era (0–65 million years ago) is largely unknown from direct evidence. Here we present a Cenozoic palaeoceanographic record constructed from 〉400 m of sediment core from a recent drilling expedition to the Lomonosov ridge in the Arctic Ocean. Our record shows a palaeoenvironmental transition from a warm 'greenhouse' world, during the late Palaeocene and early Eocene epochs, to a colder 'icehouse' world influenced by sea ice and icebergs from the middle Eocene epoch to the present. For the most recent approx14 Myr, we find sedimentation rates of 1–2 cm per thousand years, in stark contrast to the substantially lower rates proposed in earlier studies; this record of the Neogene reveals cooling of the Arctic that was synchronous with the expansion of Greenland ice (approx3.2 Myr ago) and East Antarctic ice (approx14 Myr ago). We find evidence for the first occurrence of ice-rafted debris in the middle Eocene epoch (approx45 Myr ago), some 35 Myr earlier than previously thought; fresh surface waters were present at approx49 Myr ago, before the onset of ice-rafted debris. Also, the temperatures of surface waters during the Palaeocene/Eocene thermal maximum (approx55 Myr ago) appear to have been substantially warmer than previously estimated. The revised timing of the earliest Arctic cooling events coincides with those from Antarctica, supporting arguments for bipolar symmetry in climate change.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1038/nature04800
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Constraining the terrestrial age of micrometeorites using their record of the Earth's magnetic field polarity (2011)
    Geological Society of America (GSA)
    Details
    Publication Date: 2011-02-01
    Description: We propose a new nondestructive method that uses the paleomagnetic record of micrometeorites in Earth's polar regions to constrain the age of their fall. During atmospheric entry, melted micrometeorites acquire a thermal remanent magnetization and record the polar subvertical geomagnetic field. When the fall vector can be determined, due to the location of bubbles, iron-nickel droplets, or grain-size gradients, it is possible to ascribe the fall to a normal or reverse polarity interval of the geomagnetic field. We tested this concept on a set of eight melted micrometeorites from the Transantarctic Mountains (Antarctica). Two micrometeorites have magnetization directions consistent with a normal polarity of the Earth's magnetic field, whereas four others have recorded a reverse polarity, and therefore fell to Earth at least 0.78 m.y. ago. One micrometeorite has a magnetization that is seemingly unrelated to the inferred entry direction. The fall direction could not be determined with certainty for one micrometeorite. These results provide new evidence suggesting that the Transantarctic Mountains micrometeorite traps are 1-2 m.y. old, and confirm that they contain the oldest non-fossil micrometeorites available.
    Print ISSN: 0091-7613
    Electronic ISSN: 1943-2682
    Topics: Geosciences
    Published by Geological Society of America (GSA)
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  • 5
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    Magnetic evidence for a partially differentiated carbonaceous chondrite parent body [Geophysics] (2011)
    National Academy of Sciences
    Details
    Publication Date: 2011-04-20
    Description: The textures of chondritic meteorites demonstrate that they are not the products of planetary melting processes. This has long been interpreted as evidence that chondrite parent bodies never experienced large-scale melting. As a result, the paleomagnetism of the CV carbonaceous chondrite Allende, most of which was acquired after accretion of the parent body, has been a long-standing mystery. The possibility of a core dynamo like that known for achondrite parent bodies has been discounted because chondrite parent bodies are assumed to be undifferentiated. Resolution of this conundrum requires a determination of the age and timescale over which Allende acquired its magnetization. Here, we report that Allende’s magnetization was acquired over several million years (Ma) during metasomatism on the parent planetesimal in a 〉 ∼ 20 μT field up to approximately 9—10 Ma after solar system formation. This field was present too recently and directionally stable for too long to have been generated by the protoplanetary disk or young Sun. The field intensity is in the range expected for planetesimal core dynamos, suggesting that CV chondrites are derived from the outer, unmelted layer of a partially differentiated body with a convecting metallic core.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 6
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    Magnetic classification of stony meteorites: 3. Achondrites (2009)
    The Meteoritical Society
    Details
    Publication Date: 2021-06-07
    Description: A database of magnetic susceptibility measurements of stony achondrites (acapulcoitelodranite clan, winonaites, ureilites, angrites, aubrites, brachinites, howardite-eucrite-diogenite (HED) clan, and Martian meteorites, except lunar meteorites) is presented and compared to our previous work on chondrites. This database provides an exhaustive study of the amount of iron-nickel magnetic phases (essentially metal and more rarely pyrrhotite and titanomagnetite) in these meteorites. Except for ureilites, achondrites appear much more heterogeneous than chondrites in metal content, both at the meteorite scale and at the parent body scale. We propose a model to explain the lack of or inefficient metal segregation in a low gravity context. The relationship between grain density and magnetic susceptibility is discussed. Saturation remanence appears quite weak in most metal-bearing achondrites(HED and aubrites)compared to Martian meteorites. Ureilites are a notable exception and can carry a strong remanence, similar to most chondrites.
    Description: Published
    Description: 405 - 427
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: meteorites ; magnetic susceptibility ; rock magnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
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    Magnetic classification of stony meteorites: 2. Non-ordinary chondrites (2008)
    The Meteoritical Society
    Details
    Publication Date: 2021-06-07
    Description: A database of magnetic susceptibility (χ) measurements on different non-ordinary chondrites (C, E, R, and ungrouped) populations is presented and compared to our previous similar work on ordinary chondrites. It provides an exhaustive study of the amount of iron-nickel magnetic phases (essentially metal and magnetite) in these meteorites. In contrast with all the other classes, CM and CV show a wide range of magnetic mineral content, with a two orders of magnitude variation of χ. Whether this is due to primary parent body differences, metamorphism or alteration, remains unclear. C3–4 and C2 yield similar χ values to the ones shown by CK and CM, respectively. By order of increasing χ, the classes with well-grouped χ are: R 〈〈 CO 〈 CK ≈ CI 〈 Kak 〈 CR 〈 E ≈ CH 〈 CB. Based on magnetism, EH and EL classes have indistinguishable metal content. Outliers that we suggest may need to have their classifications reconsidered are Acfer 202 (CO), Elephant Moraine (EET) 96026 (C4–5), Meteorite Hills (MET) 01149, and Northwest Africa (NWA) 521 (CK), Asuka (A)-88198, LaPaz Icefield (LAP) 031156, and Sahara 98248 (R). χ values can also be used to define affinities of ungrouped chondrites, and propose pairing, particularly in the case of CM and CV meteorites.
    Description: Published
    Description: 959-980
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: meteorites ; chondrites ; magnetic susceptibility ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    Paleomagnetic constraints for the tectonic evolution of the southern Apennines belt (Italy) (2007)
    Società Geologica Italiana
    Details
    Publication Date: 2021-06-07
    Description: The southern Apennine belt is formed by nappes that have undergone large (i. e. hundreds of kms) horizontal displacements. In such tectonic scenario, orogenic rotations of nappes are clearly expected, and paleomagnetism may represent a key tool to constrain displacements and understand the pre-orogenic paleogeography. Recent paleomagnetic data have shown that the Apenninic carbonate platform, on top of the nappe pile, has rotated ~80° counterclockwise (CCW) after Langhian times. A similar rotation may be inferred for the Lagonegro basinal unit. Numerous data from the Plio-Pleistocene sediments unconformably overlying these two units reveal a 0°-40° (20° on average) CCW rotation since early Pliocene. Data from the exposed Apulian swell, and from other parts of the Adriatic plate, suggest that the buried Apulian platform has not undergone a significant rotation. Therefore the overall paleomagnetic/ geological data suggest that during mid-late Miocene the Apenninic platform and Lagonegro unit were detached from basement, underwent internal imbrication associated with a 60° CCW rotation. During early-mid Pliocene, this wedge was carried over the Apulian carbonates (which were in turn internally stacked in late Plioceneearly Pleistocene times), and underwent a final 20° CCW rotation. The paleomagnetic data also prove that the southeastward drift of Calabrian block (and synchronous spreading of the southern Tyrrhenian Sea) induced oroclinal deformation of the southern Apennines and Sicily, which underwent similar-magnitude (but opposite in sign) orogenic rotations. Relying on such rotational pattern, we propose a paleogeographic reconstruction for late Langhian (and older) times characterized by the presence of a NNE-oriented narrow carbonate platform corridor separating the Ionian and Liguro- Piedmont oceans.
    Description: Published
    Description: 39-46
    Description: 3.4. Geomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Paleomagnetism ; orogenic rotations southern Apennines ; southern Tyrrhenian Sea ; paleogeography ; 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
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    The Cenozoic palaeoenvironment of the Arctic Ocean (2006)
    In:  EPIC3Nature, 441, pp. 601-605
    Details
    Publication Date: 2019-07-16
    Description: The Cenozoic history (0 to 65 million years, Myr, ago) of the Arctic Ocean is largely unknown from direct evidence. Here we present the first Cenozoic palaeoceanographic record constructed from 〉 400 m of core from a recent drilling expedition to the Lomonosov Ridge. Our record shows a palaeoenvironmental transition from a warm greenhouse world, of the latest Palaeocene and early Eocene, to an icehouse world influenced by sea ice and icebergs from the middle Eocene to the present. We show: 1-2 cm per thousand years (ka) sedimentation rates occurred from the middle Miocene - Holocene (~18-0 Myr) in stark contrast to rates proposed in earlier studies; the first occurrence of ice-rafted debris (IRD) is in the middle Eocene (~45 Myr), ~35 Myr earlier than previously thought; prior to the IRD, fresh surface waters were present at ~49 Myr; and warm surface waters, ~10° warmer than previous estimates, occurred during the Palaeocene Eocene Thermal Maximum (PETM). The revised timing of Arctic cooling events coincides with those from Antarctica, supporting arguments for bi-polar symmetry in climate change.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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