1,721,111 research outputs found

    UBSU e cartografia geologica: problemi e potenzialità dell’utilizzo delle UBSU per l’interpretazione e la rappresentazione cartografica dei depositi quaternari vulcanici. L’esempio dei fogli n.451 “Melfi” e n. 452 “Rionero in Vulture”

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    C. Principe & P. Giannandrea, Ubsu inside geological mapping: the use of the unconformity bounded stratigraphic units in the chartography of the quaternary volcanic deposits - the exemples of melfi (n. 451) and rionero (n.452) areas. By means of the use of the Unconformity Bounded Stratigraphic Units the sedimentary and volcanic stratigraphic successions outcropping in the area of Mount Vulture volcano (n.451 “Melfi” and n.452 “Rionero in Vulture”) has been subdivided in synthematic units. Unconformity use hallowed to define two Supersynthems and five Synthems. The synthematic subdivision over passed the limits of the chartographed area and make possible the correlations of deposits on a wider area. The clear and objective criteria on witch Sybthematic units are based resulted in an improvement of geological significance and in the volcanological detail of the chartographed areas

    Comment on: Carbonatites in a subduction system: the Pleistocene alvikites from Mount Vulture (Southern Italy)by d'Orazio et al., (2007)

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    [D'Orazio, M., Innocenti, F., Tonarini, S., Doglioni, C., 2007. Carbonatites in a subduction system: the Pleistocene alvikites from Mt. Vulture (southern Italy). Lithos 98, 313–334] describe a new finding of alvikite Ca-carbonatite at Vulture. They stress its importance as being the first carbonatite to be discovered in a subduction environment. They suggest that this rock is different from the other Italian carbonatites, considered as ‘rocks sharing a carbonatitic affinity’, which are radiogenic and chemically diluted by addition of sedimentary limestone. They note that Vulture ‘alvikite’ is not diluted and is very unradiogenic with respect to other Italian carbonatites. However, they maintain that Vulture ‘alvikite’ carbonate is derived from subducted limestones. We present an account of the field relationships relating to the above-mentioned rocks, setting the geological and petrographic records straight and describing pyroclastic rocks. We did not find that these rocks are formed from alvikite dykes or lava, but instead recognised them to be a continuous blanket of ‘flaggy’, welded tuff. We found that the rocks consist of physically separated melilitite and carbonatite juvenile lapilli settled into a carbonatite ash matrix form the rock. We disagree with the geochemical interpretation of the rock by [D'Orazio, M., Innocenti, F., Tonarini, S., Doglioni, C., 2007. Carbonatites in a subduction system: the Pleistocene alvikites from Mt. Vulture (southern Italy). Lithos 98, 313–334], and are particularly concerned by their conclusion of its carbonate origin. We remark on the rock's geodynamic assignment in the frame of an extensional tectonic setting, also referring to the other Italian carbonatite occurrences. We reject any ad hoc modified subduction as a direct source of Vulture and Italian carbonatites. © 2007 Elsevier B.V. All rights reserved

    Comments on: Carbonatites in a subduction system: The Pleistocene alvikites from Mt. Vulture (southern Italy) by d'Orazio et al., (2007)

    No full text
    [D'Orazio, M., Innocenti, F., Tonarini, S., Doglioni, C., 2007. Carbonatites in a subduction system: the Pleistocene alvikites from Mt. Vulture (southern Italy). Lithos 98, 313–334] describe a new finding of alvikite Ca-carbonatite at Vulture. They stress its importance as being the first carbonatite to be discovered in a subduction environment. They suggest that this rock is different from the other Italian carbonatites, considered as ‘rocks sharing a carbonatitic affinity’, which are radiogenic and chemically diluted by addition of sedimentary limestone. They note that Vulture ‘alvikite’ is not diluted and is very unradiogenic with respect to other Italian carbonatites. However, they maintain that Vulture ‘alvikite’ carbonate is derived from subducted limestones. We present an account of the field relationships relating to the above-mentioned rocks, setting the geological and petrographic records straight and describing pyroclastic rocks. We did not find that these rocks are formed from alvikite dykes or lava, but instead recognised them to be a continuous blanket of ‘flaggy’, welded tuff. We found that the rocks consist of physically separated melilitite and carbonatite juvenile lapilli settled into a carbonatite ash matrix form the rock. We disagree with the geochemical interpretation of the rock by [D'Orazio, M., Innocenti, F., Tonarini, S., Doglioni, C., 2007. Carbonatites in a subduction system: the Pleistocene alvikites from Mt. Vulture (southern Italy). Lithos 98, 313–334], and are particularly concerned by their conclusion of its carbonate origin. We remark on the rock's geodynamic assignment in the frame of an extensional tectonic setting, also referring to the other Italian carbonatite occurrences. We reject any ad hoc modified subduction as a direct source of Vulture and Italian carbonatites
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