Shift from lamproite-like to leucititic rocks: Sr–Nd–Pb isotope data from the Monte Cimino volcanic complex vs. the Vico stratovolcano, Central Italy.
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| Title: | Shift from lamproite-like to leucititic rocks: Sr–Nd–Pb isotope data from the Monte Cimino volcanic complex vs. the Vico stratovolcano, Central Italy. |
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| Authors: | Conticelli, Sandro1,2 sandro.conticelli@unifi.it, Avanzinelli, Riccardo1, Poli, Giampiero3, Braschi, Eleonora2, Giordano, Guido4 |
| Source: | Chemical Geology. Aug2013, Vol. 353, p246-266. 21p. |
| Subjects: | Lamproite, Petrology, Geochemistry, Isotope geology, Magmas, Pleistocene stratigraphic geology, Volcanology |
| Geographic Terms: | Central Italy |
| Abstract: | Abstract: In the Italian peninsula leucite-free and -bearing ultrapotassic rocks occur intimately associated but well separated in time. Silica-saturated ultrapotassic and associated shoshonitic magmas erupted during the Pliocene to Lower Pleistocene. Silica under-saturated leucite-bearing ultrapotassic rocks, mainly leucitites, were emplaced sometime later, during the Middle–Upper Pleistocene. The transition from leucite-free to -bearing rocks is diachronous and in some cases is complicated by the occurrence of crustal-derived magmas coeval with early leucite-free magma. The Monte Cimino–Vico area is a key locality for studying the transition from leucite-free to -bearing ultrapotassic rocks. There a volcanic complex is overlain by some 500ka younger leucite-bearing rocks of Vico stratovolcano. Most of the potassic and ultrapotassic rocks of the Monte Cimino volcanic complex are characterised by high Mg-# (66.4–77.8), and compatible element abundances in spite of their high silica contents (52.9–58.0wt.%). Ultrapotassic leucite-free rocks transitional to lamproites are olivine-bearing orthopyroxene- and plagioclase-free latites and K-rich basaltic trachyandesite and they are confined in the final mafic activity of the Monte Cimino volcanic complex. Two-pyroxene parageneses are observed in the early Monte Cimino volcanic complex giving equilibration temperature as high as 1050°C and suggesting a sub-crustal derivation of their parental magmas. A two-pyroxene high-K calc-alkaline magma is then inferred for the genesis of the early Monte Cimino activity (e.g. dome complex and silicic lava flows and ignimbrites), which was modelled through crystal-fractionation from a high-K basaltic andesitic magma plus mixing with crustal anatectic rhyolitic magma. Final mafic lavas fill the isotopic and chemical gap between shoshonite-like and lamproite-like rocks, and each lava flow could be considered as a mantle-derived term from a heterogeneous sub-continental lithospheric mantle. Final mafic lavas are high-silica and -MgO ultrapotassic rocks due to crystallisation of primitive magmas generated by partial melting of a vein metasomatised network within a lithospheric upper mantle source, at low pressure and high PH2O. The shift to the younger Vico volcano, in which leucite-bearing magmas prevail, is thought to be due to the arrival in the mantle source of newly formed metasomatic agent from the undergoing slab characterised by the increasing of a sedimentary carbonate recycled component. This new component appears in the Middle Pleistocene and it is responsible for the composition of the magmatism of the Roman region. The recycling of carbonate-bearing pelitic sediments within the mantle wedge produces a carbonate-rich metasomatic agent. The latter is responsible for stabilisation of phlogopite-bearing wehrlitic veins within the mantle wedge. Partial melting of this newly formed vein network under high XCO2 generated silica under-saturated, and then leucite-bearing, ultrapotassic primary melts. A further shift is observed among the Vico post-caldera magmas, in which the appearance of a deep asthenospheric component is argued to be channelled late through slab-tears. [Copyright &y& Elsevier] |
| Copyright of Chemical Geology is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
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| Items | – Name: Title Label: Title Group: Ti Data: Shift from lamproite-like to leucititic rocks: Sr–Nd–Pb isotope data from the Monte Cimino volcanic complex vs. the Vico stratovolcano, Central Italy. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Conticelli%2C+Sandro%22">Conticelli, Sandro</searchLink><relatesTo>1,2</relatesTo><i> sandro.conticelli@unifi.it</i><br /><searchLink fieldCode="AR" term="%22Avanzinelli%2C+Riccardo%22">Avanzinelli, Riccardo</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Poli%2C+Giampiero%22">Poli, Giampiero</searchLink><relatesTo>3</relatesTo><br /><searchLink fieldCode="AR" term="%22Braschi%2C+Eleonora%22">Braschi, Eleonora</searchLink><relatesTo>2</relatesTo><br /><searchLink fieldCode="AR" term="%22Giordano%2C+Guido%22">Giordano, Guido</searchLink><relatesTo>4</relatesTo> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Chemical+Geology%22">Chemical Geology</searchLink>. Aug2013, Vol. 353, p246-266. 21p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Lamproite%22">Lamproite</searchLink><br /><searchLink fieldCode="DE" term="%22Petrology%22">Petrology</searchLink><br /><searchLink fieldCode="DE" term="%22Geochemistry%22">Geochemistry</searchLink><br /><searchLink fieldCode="DE" term="%22Isotope+geology%22">Isotope geology</searchLink><br /><searchLink fieldCode="DE" term="%22Magmas%22">Magmas</searchLink><br /><searchLink fieldCode="DE" term="%22Pleistocene+stratigraphic+geology%22">Pleistocene stratigraphic geology</searchLink><br /><searchLink fieldCode="DE" term="%22Volcanology%22">Volcanology</searchLink> – Name: SubjectGeographic Label: Geographic Terms Group: Su Data: <searchLink fieldCode="DE" term="%22Central+Italy%22">Central Italy</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Abstract: In the Italian peninsula leucite-free and -bearing ultrapotassic rocks occur intimately associated but well separated in time. Silica-saturated ultrapotassic and associated shoshonitic magmas erupted during the Pliocene to Lower Pleistocene. Silica under-saturated leucite-bearing ultrapotassic rocks, mainly leucitites, were emplaced sometime later, during the Middle–Upper Pleistocene. The transition from leucite-free to -bearing rocks is diachronous and in some cases is complicated by the occurrence of crustal-derived magmas coeval with early leucite-free magma. The Monte Cimino–Vico area is a key locality for studying the transition from leucite-free to -bearing ultrapotassic rocks. There a volcanic complex is overlain by some 500ka younger leucite-bearing rocks of Vico stratovolcano. Most of the potassic and ultrapotassic rocks of the Monte Cimino volcanic complex are characterised by high Mg-# (66.4–77.8), and compatible element abundances in spite of their high silica contents (52.9–58.0wt.%). Ultrapotassic leucite-free rocks transitional to lamproites are olivine-bearing orthopyroxene- and plagioclase-free latites and K-rich basaltic trachyandesite and they are confined in the final mafic activity of the Monte Cimino volcanic complex. Two-pyroxene parageneses are observed in the early Monte Cimino volcanic complex giving equilibration temperature as high as 1050°C and suggesting a sub-crustal derivation of their parental magmas. A two-pyroxene high-K calc-alkaline magma is then inferred for the genesis of the early Monte Cimino activity (e.g. dome complex and silicic lava flows and ignimbrites), which was modelled through crystal-fractionation from a high-K basaltic andesitic magma plus mixing with crustal anatectic rhyolitic magma. Final mafic lavas fill the isotopic and chemical gap between shoshonite-like and lamproite-like rocks, and each lava flow could be considered as a mantle-derived term from a heterogeneous sub-continental lithospheric mantle. Final mafic lavas are high-silica and -MgO ultrapotassic rocks due to crystallisation of primitive magmas generated by partial melting of a vein metasomatised network within a lithospheric upper mantle source, at low pressure and high PH2O. The shift to the younger Vico volcano, in which leucite-bearing magmas prevail, is thought to be due to the arrival in the mantle source of newly formed metasomatic agent from the undergoing slab characterised by the increasing of a sedimentary carbonate recycled component. This new component appears in the Middle Pleistocene and it is responsible for the composition of the magmatism of the Roman region. The recycling of carbonate-bearing pelitic sediments within the mantle wedge produces a carbonate-rich metasomatic agent. The latter is responsible for stabilisation of phlogopite-bearing wehrlitic veins within the mantle wedge. Partial melting of this newly formed vein network under high XCO2 generated silica under-saturated, and then leucite-bearing, ultrapotassic primary melts. A further shift is observed among the Vico post-caldera magmas, in which the appearance of a deep asthenospheric component is argued to be channelled late through slab-tears. [Copyright &y& Elsevier] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Chemical Geology is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/j.chemgeo.2012.10.018 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 21 StartPage: 246 Subjects: – SubjectFull: Lamproite Type: general – SubjectFull: Petrology Type: general – SubjectFull: Geochemistry Type: general – SubjectFull: Isotope geology Type: general – SubjectFull: Magmas Type: general – SubjectFull: Pleistocene stratigraphic geology Type: general – SubjectFull: Volcanology Type: general – SubjectFull: Central Italy Type: general Titles: – TitleFull: Shift from lamproite-like to leucititic rocks: Sr–Nd–Pb isotope data from the Monte Cimino volcanic complex vs. the Vico stratovolcano, Central Italy. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Conticelli, Sandro – PersonEntity: Name: NameFull: Avanzinelli, Riccardo – PersonEntity: Name: NameFull: Poli, Giampiero – PersonEntity: Name: NameFull: Braschi, Eleonora – PersonEntity: Name: NameFull: Giordano, Guido IsPartOfRelationships: – BibEntity: Dates: – D: 30 M: 08 Text: Aug2013 Type: published Y: 2013 Identifiers: – Type: issn-print Value: 00092541 Numbering: – Type: volume Value: 353 Titles: – TitleFull: Chemical Geology Type: main |
| ResultId | 1 |
