Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Behaviour of radiogenic Pb in zircon during ultrahigh‑temperature metamorphism: an ion imaging and ion tomography case study from the Kerala Khondalite Belt,southern India
Swedish Museum of Natural History, Department of Geology. (Nordsim)ORCID iD: 0000-0003-2227-577X
2014 (English)In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 168Article in journal (Refereed) Published
Abstract [en]

Zircon crystals from a locally charnockitizedPaleoproterozoic high-K metagranite from the KeralaKhondalite Belt (KKB) of southern India have been investigatedby high-spatial resolution secondary ion mass spectrometryanalysis of U–Th–Pb and rare earth elements(REE), together with scanning ion imaging and scanningion tomography (depth-profiled ion imaging). The spotanalyses constrain the magmatic crystallization age of themetagranite to ca. 1,850 Ma, with ultrahigh-temperature(UHT) metamorphism occurring at ca. 570 Ma and superimposedcharnockite formation at ca. 520–510 Ma, whilethe ion imaging reveals a patchy distribution of radiogenicPb throughout the zircon cores. Middle- to heavy-REEdepletion in ca. 570 Ma zircon rims suggests that thesegrew in equilibrium with garnet and therefore date theUHT metamorphism in the KKB. The maximum apparent207Pb/206Pb age obtained from the unsupported radiogenicPb concentrations is also consistent with formationof the Pb patches during this event. The superimposed charnockitization event appears to have caused additionalPb-loss in the cores and recrystallization of the rims. Theresults of depth-profiling of the scanning ion tomographyimage stack show that the Pb-rich domains range in sizefrom <5 nm to several 10 nm (diameter if assumed to bespherical). The occurrence of such patchy Pb has previouslybeen documented only from UHT metamorphiczircon, where it likely results from annealing of radiation-damaged zircon. The formation of a discrete, heterogeneouslydistributed and subsequently immobile Pb phaseeffectively arrests the normal Pb-loss process seen at lowergrades of metamorphism.

Place, publisher, year, edition, pages
2014. Vol. 168
Keyword [en]
Secondary ion mass spectrometry · Zircon · Ion imaging · Ion tomography · Ultrahigh-temperature metamorphism · Kerala Khondalite Belt
National Category
Geochemistry
Research subject
The changing Earth
Identifiers
URN: urn:nbn:se:nrm:diva-824DOI: 10.1007/s00410-014-1042-2OAI: oai:DiVA.org:nrm-824DiVA: diva2:757021
Funder
Swedish Research Council, G5103-20006231/2000
Available from: 2014-10-20 Created: 2014-10-20 Last updated: 2017-12-05Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Whitehouse, Martin
By organisation
Department of Geology
In the same journal
Contributions to Mineralogy and Petrology
Geochemistry

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 61 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf