1,721,221 research outputs found
MAGNETIC FABRIC OF WEAKLY DEFORMED CLAY SEDIMENTS IN THE ITALIAN PENINSULA: RELATIONSHIP WITH COMPRESSIONAL AND EXTENSIONAL TECTONICS
No full text
Risultati di un'indagine interdisciplinare (analisi di facies, biostratigrafia, magnetostratigrafia) svolta su due sezioni della Val di Fine (Toscana, Pisa) di età compresa tra il Miocene superiore ed il Pliocene inferiore
No full textPALEOMAGNETIC CONSTRAINTS FOR THE RECONSTRUCTION OF THE GEODYNAMIC EVOLUTION OF THE APENNINES DURING THE MIDDLE MIOCENE - PLEISTOCENE
No full textThe Apennines are a mountain belt developed during the Neogene along the western margin of the Adria microplate. This paper presents an updated review of paleomagnetic research aimed at the reconstruction of the geodynamic evolution of the Italian Peninsula and Sicily. Paleomagnetic data collected in the Apennines since the 1970s support the view that the Italian peninsula consists of an articulated system, with vertical-axis rotations distributed over distinct geodynamical provinces and geological times. Vertical-axis rotations are generally counterclockwise in the Apennines and clockwise in the Sicilian Maghrebides. These rotations were mostly linked to the transport and bending of allochthonous units along multiple thrusts. The most recent paleomagnetic data indicate that large and variable vertical-axis rotations characterized the development of various individual arcuate thrust fronts. Some of these rotations may have occurred at very rapid rates. The detailed understanding of these local rotations and the refinement of high-resolution age models for the various phases of vertical-axis rotations are the new frontier and challenge for future paleomagnetic studies in Italy.Submittedope
Paleomagnetic evidence for no tectonic rotation of the Central Italy Tyrrhenian margin since Upper Pliocene
No full textContributi del Paleomagnetismo alla Stratigrafia del Pleistocene Medio-Superiore (Brunhes Chron)
No full textThe contribute of paleomagnetism to the stratigraphy of the middle-late Pleistocene (Brunhes Chron).
This manuscript presents an updated summary on the contribute brought by paleomagnetism to the definition of a high-resolution
magnetic stratigraphy for the middle-late Pleistocene. The middle-late Pleistocene spans a time intervals during which the Earth
magnetic field held predominantly a stable normal polarity and includes the whole normal polarity Brunhes Chron. In absence of full
reversals of the geomagnetic field, magnetic stratigraphy is based upon (a) the record of geomagnetic paleosecular variations (PSV), as
documented in archaeological or volcanic material and in lacustrine and marine sedimentary sequences for the last few ka,(b) the variation of geomagnetic paleointensity and (c) the occurrence of geomagnetic excursions. With regards to Europe, archeomagnetic PSV curves were reconstructed back to 8 ka (i.e., ca. 6000 BC), whereas continuous PSV records based on paleomagnetism of sediments extend back to the last 10-12 ka. The variation in intensity of the earth magnetic field has been reconstructed in the detail at a global scale for the last 800 ka. Relative paleointensity curves reconstructed in sedimentary sequences provide original correlation and dating tools and are particularly valuable to establish high-resolution age models in sequences that may lack other valuable stratigraphic proxies, such as those deposited in the
carbonate-corrosive waters of peri-Antarctic margins. Finally, the recognition and the dating of geomagnetic excursions, defined as sharp, short-lived and wide geomagnetic variations, during which the earth magnetic field has departed from its usual near-axial configuration but did not give rise to complete reversals, is providing the basis for the establishment of a Geomagnetic Instability Time Scale (GITS) that extends back to the last 2.2 Ma.Published69-742.2. Laboratorio di paleomagnetismoN/A or not JCRreserve
Iron Sulfides
No full textIron sulfides are generally quoted as minor magnetic minerals and the interest of paleomagnetists for this family of minerals progressively developed only during the last 10 – 15 years. This was due partly to the fact that their occurrence was originally believed to be restricted to peculiar geological environments (i.e. sulfidic ores, anoxic sulfate-reducing sedimentary environments) and partly to their metastability with respect to pyrite (FeS2), which is paramagnetic. Magnetic iron sulfides were therefore not expected to carry a stable remanent magnetisation and to survive over long periods of geological time in sedimentary environments. However, their occurrence as main carriers of a remanent magnetisation stable through geological times has been increasingly reported in recent years from a large variety of rock types, primarily as a result of more frequent application of magnetic methods to characterize the magnetic mineralogy in paleomagnetic samples. The recognition of the widespread occurrence of magnetic iron sulfides as stable carriers of natural remanent magnetisations in rocks propelled specific researches on their fundamental magnetic properties.Published454-4592.2. Laboratorio di paleomagnetismoope
Iron Sulfides
No full textIron sulfides are generally quoted as minor magnetic minerals and the interest of paleomagnetists for this family of minerals progressively developed only during the last 10 – 15 years. This was due partly to the fact that their occurrence was originally believed to be restricted to peculiar geological environments (i.e. sulfidic ores, anoxic sulfate-reducing sedimentary environments) and partly to their metastability with respect to pyrite (FeS2), which is paramagnetic. Magnetic iron sulfides were therefore not expected to carry a stable remanent magnetisation and to survive over long periods of geological time in sedimentary environments. However, their occurrence as main carriers of a remanent magnetisation stable through geological times has been increasingly reported in recent years from a large variety of rock types, primarily as a result of more frequent application of magnetic methods to characterize the magnetic mineralogy in paleomagnetic samples. The recognition of the widespread occurrence of magnetic iron sulfides as stable carriers of natural remanent magnetisations in rocks propelled specific researches on their fundamental magnetic properties.Published454-4592.2. Laboratorio di paleomagnetismoope
ENVIRONMENTAL MAGNETISM: APPLICATIONS TO PALEOCLIMATIC RECONSTRUCTIONS AND AIR POLLUTION MONITORING
No full textThis 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.PublishedTandil, Argentina3.8. Geofisica per l'ambienteope
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