Academic Journal
K-feldspar hygrochronology
| Title: | K-feldspar hygrochronology |
|---|---|
| Authors: | VILLA, IGOR MARIA, Hanchar, JM |
| Contributors: | Villa, I, Hanchar, J |
| Publisher Information: | Elsevier US |
| Publication Year: | 2013 |
| Collection: | Università degli Studi di Milano-Bicocca: BOA (Bicocca Open Archive) |
| Subject Terms: | systematic analysi, alkali feldspar, swiss alp, geochronology, isotope, ar39-ar40, Settore GEOS-01/C - Geochimica e vulcanologia |
| Description: | The significance of the multi-isotopic record preserved in K-feldspars is assessed on samples from the Aar metagranite, Central Alps, Switzerland having very tight independent geological constraints. Stepwise leaching reveals that two diachronically grown K-feldspar generations coexist: Kfs-1 (>= 35 Ma old, Ca-poor, Rb-Cl-rich, with low Sr-87/Sr-86 and high Pb-206/Pb-204) and Kfs-2 (<= 10 Ma old, antithetic isotopic signatures deriving from external fluids). Microtextures imaged by cathodoluminescence, backscattered electrons, and electron probe microanalysis are patchy and chemically heterogeneous, with pronounced enrichments in Ba in the retrogressed regions. This confirms the simultaneous presence of fluid-dominated retrogression and recrystallization and isotopic inheritance. The staircase-shaped Ar-40/Ar-39 age spectrum correlates with the Ca/K and Cl/K signatures. This reflects a mixture of heterochemical K-feldspar generations, and not an intracrystalline Ar gradient caused by diffusion. The shape of the age spectrum and the in vacuo release kinetics proceed from entirely different physical and geological phenomena. What K-feldspars can be effectively used for is to constrain the timing of the fluids that interacted with them by multi-isotopic analyses, rather than to model a "cooling history" from Ar-39 release alone. The identification of multiple mineral generations by imaging combined with multi-isotopic analysis enables the accurate dating of the events of a multistage evolution after the initial crystallization of the rock in which the minerals occur. |
| Document Type: | article in journal/newspaper |
| File Description: | STAMPA |
| Language: | English |
| Relation: | info:eu-repo/semantics/altIdentifier/wos/WOS:000312854900003; volume:101; firstpage:24; lastpage:33; numberofpages:10; journal:GEOCHIMICA ET COSMOCHIMICA ACTA; https://hdl.handle.net/10281/45140 |
| DOI: | 10.1016/j.gca.2012.09.047 |
| Availability: | https://hdl.handle.net/10281/45140 https://doi.org/10.1016/j.gca.2012.09.047 |
| Accession Number: | edsbas.C03E3D70 |
| Database: | BASE |
| FullText | Text: Availability: 0 CustomLinks: – Url: https://hdl.handle.net/10281/45140# Name: EDS - BASE (ns324271) Category: fullText Text: View record from BASE |
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| Items | – Name: Title Label: Title Group: Ti Data: K-feldspar hygrochronology – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22VILLA%2C+IGOR+MARIA%22">VILLA, IGOR MARIA</searchLink><br /><searchLink fieldCode="AR" term="%22Hanchar%2C+JM%22">Hanchar, JM</searchLink> – Name: Author Label: Contributors Group: Au Data: Villa, I<br />Hanchar, J – Name: Publisher Label: Publisher Information Group: PubInfo Data: Elsevier<br />US – Name: DatePubCY Label: Publication Year Group: Date Data: 2013 – Name: Subset Label: Collection Group: HoldingsInfo Data: Università degli Studi di Milano-Bicocca: BOA (Bicocca Open Archive) – Name: Subject Label: Subject Terms Group: Su Data: <searchLink fieldCode="DE" term="%22systematic+analysi%22">systematic analysi</searchLink><br /><searchLink fieldCode="DE" term="%22alkali+feldspar%22">alkali feldspar</searchLink><br /><searchLink fieldCode="DE" term="%22swiss+alp%22">swiss alp</searchLink><br /><searchLink fieldCode="DE" term="%22geochronology%22">geochronology</searchLink><br /><searchLink fieldCode="DE" term="%22isotope%22">isotope</searchLink><br /><searchLink fieldCode="DE" term="%22ar39-ar40%22">ar39-ar40</searchLink><br /><searchLink fieldCode="DE" term="%22Settore+GEOS-01%2FC+-+Geochimica+e+vulcanologia%22">Settore GEOS-01/C - Geochimica e vulcanologia</searchLink> – Name: Abstract Label: Description Group: Ab Data: The significance of the multi-isotopic record preserved in K-feldspars is assessed on samples from the Aar metagranite, Central Alps, Switzerland having very tight independent geological constraints. Stepwise leaching reveals that two diachronically grown K-feldspar generations coexist: Kfs-1 (>= 35 Ma old, Ca-poor, Rb-Cl-rich, with low Sr-87/Sr-86 and high Pb-206/Pb-204) and Kfs-2 (<= 10 Ma old, antithetic isotopic signatures deriving from external fluids). Microtextures imaged by cathodoluminescence, backscattered electrons, and electron probe microanalysis are patchy and chemically heterogeneous, with pronounced enrichments in Ba in the retrogressed regions. This confirms the simultaneous presence of fluid-dominated retrogression and recrystallization and isotopic inheritance. The staircase-shaped Ar-40/Ar-39 age spectrum correlates with the Ca/K and Cl/K signatures. This reflects a mixture of heterochemical K-feldspar generations, and not an intracrystalline Ar gradient caused by diffusion. The shape of the age spectrum and the in vacuo release kinetics proceed from entirely different physical and geological phenomena. What K-feldspars can be effectively used for is to constrain the timing of the fluids that interacted with them by multi-isotopic analyses, rather than to model a "cooling history" from Ar-39 release alone. The identification of multiple mineral generations by imaging combined with multi-isotopic analysis enables the accurate dating of the events of a multistage evolution after the initial crystallization of the rock in which the minerals occur. – Name: TypeDocument Label: Document Type Group: TypDoc Data: article in journal/newspaper – Name: Format Label: File Description Group: SrcInfo Data: STAMPA – Name: Language Label: Language Group: Lang Data: English – Name: NoteTitleSource Label: Relation Group: SrcInfo Data: info:eu-repo/semantics/altIdentifier/wos/WOS:000312854900003; volume:101; firstpage:24; lastpage:33; numberofpages:10; journal:GEOCHIMICA ET COSMOCHIMICA ACTA; https://hdl.handle.net/10281/45140 – Name: DOI Label: DOI Group: ID Data: 10.1016/j.gca.2012.09.047 – Name: URL Label: Availability Group: URL Data: https://hdl.handle.net/10281/45140<br />https://doi.org/10.1016/j.gca.2012.09.047 – Name: AN Label: Accession Number Group: ID Data: edsbas.C03E3D70 |
| PLink | https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=edsbas&AN=edsbas.C03E3D70 |
| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/j.gca.2012.09.047 Languages: – Text: English Subjects: – SubjectFull: systematic analysi Type: general – SubjectFull: alkali feldspar Type: general – SubjectFull: swiss alp Type: general – SubjectFull: geochronology Type: general – SubjectFull: isotope Type: general – SubjectFull: ar39-ar40 Type: general – SubjectFull: Settore GEOS-01/C - Geochimica e vulcanologia Type: general Titles: – TitleFull: K-feldspar hygrochronology Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: VILLA, IGOR MARIA – PersonEntity: Name: NameFull: Hanchar, JM – PersonEntity: Name: NameFull: Villa, I – PersonEntity: Name: NameFull: Hanchar, J IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 01 Type: published Y: 2013 Identifiers: – Type: issn-locals Value: edsbas |
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