Deformation-induced trace element redistribution in zircon revealed using atom probe tomography

Piazolo, Sandra; Fontaine, Alexandre; Trimby, Patrick; Harley, Simon L.; Yang, Limei; Armstrong, Richard; Cairney, Julie M.

doi:10.1038/ncomms10490

Cited by 159 publications

(129 citation statements)

References 45 publications

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“…Investigations of the location of Pb in zircon on the atomic scale using atom probe tomography (APT) have been reported by several groups (Valley et al 2014(Valley et al , 2015Peterman et al 2016;Piazolo et al 2016). All of these studies documented clustering of Pb atoms in zircon but not the formation of metallic Pb spheres similar to those observed in UHT zircon by TEM (this study; Kusiak et al 2015Kusiak et al , 2017.…”

Section: Discussionmentioning

confidence: 53%

Metallic Pb nanospheres in ultra-high temperature metamorphosed zircon from southern India

et al. 2017

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A transmission electron microscope (TEM) study of Paleoproterozoic zircon that has experienced ultra-high temperature (UHT) metamorphism at ca. 570 Ma in the Kerala Khondalite Belt (KKB), southern India, documents the occurrence of metallic Pb nanospheres. These results permit comparison with a previous report from UHT zircon in Enderby Land, Antarctica, and allow further constraints to be placed on possible mechanisms for nanosphere formation. As in Enderby Land, the nanospheres in the KKB occur in non-metamict zircon, emphasising that radiogenic Pb redistribution can occur with only partial interconnectivity of radiation damaged zircon. In contrast, the nanospheres reported here are not closely associated with Si-rich glass inclusions, which is inconsistent with a silicate liquid-metal immiscibility model proposed in the earlier study. Formation of these Pb nanospheres effectively halts Pb-loss from zircon, even under extreme conditions, and can adversely affect geochronological interpretations due to decoupling of Pb from U.

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Section: Discussionmentioning

confidence: 53%

Metallic Pb nanospheres in ultra-high temperature metamorphosed zircon from southern India

et al. 2017

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“…Crystal plastic deformation is unlikely to be responsible for the bulk of our observations. Element redistribution under dry conditions without a chemical or structural sink (Piazolo et al 2016) usually occur on the sub-micrometre scale (e.g. Valley et al 2014) and are unlikely to have a dominant influence on our LA-ICP-MS data obtained with spot sizes of 44 to 32 µm.…”

Section: Heterogeneities Between and Within Individual Samplesmentioning

confidence: 98%

“…Vonlanthen et al 2012) or redistribution (e.g. Reddy et al 2006;Timms and Reddy 2009;Piazolo et al 2016). Mechanisms proposed as being responsible for these effects include metamictisation due to radiation damage (e.g.…”

Section: Introductionmentioning

confidence: 99%

Zircon ages in granulite facies rocks: decoupling from geochemistry above 850 °C?

Kunz

Regis

Engi

2018

Contrib Mineral Petrol

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Granulite facies rocks frequently show a large spread in their zircon ages, the interpretation of which raises questions: Has the isotopic system been disturbed? By what process(es) and conditions did the alteration occur? Can the dates be regarded as real ages, reflecting several growth episodes? Furthermore, under some circumstances of (ultra-)high-temperature metamorphism, decoupling of zircon U-Pb dates from their trace element geochemistry has been reported. Understanding these processes is crucial to help interpret such dates in the context of the P-T history. Our study presents evidence for decoupling in zircon from the highest grade metapelites (> 850 °C) taken along a continuous high-temperature metamorphic field gradient in the Ivrea Zone (NW Italy). These rocks represent a well-characterised segment of Permian lower continental crust with a protracted high-temperature history. Cathodoluminescence images reveal that zircons in the mid-amphibolite facies preserve mainly detrital cores with narrow overgrowths. In the upper amphibolite and granulite facies, preserved detrital cores decrease and metamorphic zircon increases in quantity. Across all samples we document a sequence of four rim generations based on textures. U-Pb dates, Th/U ratios and Ti-in-zircon concentrations show an essentially continuous evolution with increasing metamorphic grade, except in the samples from the granulite facies, which display significant scatter in age and chemistry. We associate the observed decoupling of zircon systematics in high-grade non-metamict zircon with disturbance processes related to differences in behaviour of non-formula elements (i.e. Pb, Th, U, Ti) at high-temperature conditions, notably differences in compatibility within the crystal structure.

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“…2580 Ma to 2500-2480 Ma, consistent with the interpretation of Kelly and Harley (2005) of long-lived UHT metamorphism with a duration of >50Myr. The combination of this with Ti-in-zircon thermometry indicate that UHT conditions in excess of 900 o C in the Napier Complex persisted for more than 90 Myr and followed by a prolonged near-IBC evolution into the early Palaeoproterozoic (Harley, 2016). The record of anatectic zircon growth at various times in the period from 2.58 to 2.50 Ga implied that its formation was controlled by localised melt-rock interactions under UHT conditions (Harley, 2016;Kelly and Harley, 2005).…”

Section: Accepted Manuscriptmentioning

confidence: 95%

“…Zircon U-Pb ages coupled with zircon-garnet REE distribution evidence in anatectic leucosomes (Harley, 2016;Hokada and Harley, 2004) indicate that UHT occurred from ca. 2580 Ma to 2500-2480 Ma, consistent with the interpretation of Kelly and Harley (2005) of long-lived UHT metamorphism with a duration of >50Myr.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Zr-in-rutile resetting in aluminosilicate bearing ultra-high temperature granulites: Refining the record of cooling and hydration in the Napier Complex, Antarctica

Mitchell

Harley

2017

Lithos

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Zr-in-rutile resetting in aluminosilicate ultra-high temperature granulites: refining the record of cooling and hydration in the Napier Complex, Antarctica Ruairidh J. Mitchell, Simon L. Harley PII:S0024-4937(16)30425-X Please cite this article as: Mitchell, Ruairidh J., Harley, Simon L., Zr-in-rutile resetting in aluminosilicate ultra-high temperature granulites: refining the record of cooling and hydration in the Napier Complex, Antarctica, LITHOS (2016), ABSTRACTThe relative validity and closure temperature of the Zr-in-rutile thermometer for recording UHT metamorphism is process dependent and hotly debated. We present an integrated petrological approach to Zrin-rutile thermometry including phase equilibrium (pseudoseciton) modelling in complex chemical systems with updated mineral a-X models and systematic in-situ microanalysis of rutile. This study is centred on highpressure rutile bearing UHT granulites from Mt Charles, Napier Complex, Antarctica. P-T phase equilibrium modelling of two garnet bearing granulites (samples 49677, 49701) constrains an overall post-peak near isobaric cooling (IBC) evolution for the Napier Complex at Mt Charles; from ~14kbar, 1100 o C with moderate decompression to ~11kbar, 800-900 o C. Local hydration on cooling over this temperature range is recorded in a kyanite bearing granulite (sample 49688) with an inferred injection of aqueous fluid equivalent to up to 9 mol% H 2 O from T-MH 2 O modelling. Further late stage cooling to <740 o C is recorded by voluminous retrograde mica growth and partial preservation of a ky-pl-kfs-bt-liq bearing equilibrium assemblage. Overall, Zr-in-rutile temperatures at 11kbar (Tomkins et al., 2007) are reset to between 606 o C and 780 o C across all samples, with flat core-rim Zr concentration profiles in all rutiles. However, zircon precipitates as inclusions, needle exsolutions, or rods along rutile grain boundaries are recrystallised from rutiles in qz/fsp domains. Reintegrating the Zr-in-rutile concentration 'lost' via the recrystallization of these zircon precipitates (e.g. Pape et al., 2016) can recover maximum concentrations of up to ~2.2wt% and thus maximum peak temperatures of ~1149 o C at 11kbar. Rutile Nb-Ta signatures and rounded rutile grains without zircon precipitates in hydrated mica domains in sample 49688 provides evidence for fluid-mediated mobility of Zr and Nb during retrograde cooling in hydrated lithologies. Aqueous fluid supplemented excess H 2 O liberated by melt crystallisation, interacting with rutile on cooling of sample 49688 to reset Zr-in-rutile temperatures (606-780 o C) at the Mt Charles locality. The wide range of geochemical and petrological characteristics ofNapier Complex rutile highlights that Zr-in-rutile reintegration and a broad petrological approach is required for successful interpretation of Zr-in-rutile geothermometry for long-lived regional UHT metamorphism.

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Deformation-induced trace element redistribution in zircon revealed using atom probe tomography

Cited by 159 publications

References 45 publications

Metallic Pb nanospheres in ultra-high temperature metamorphosed zircon from southern India

Metallic Pb nanospheres in ultra-high temperature metamorphosed zircon from southern India

Zircon ages in granulite facies rocks: decoupling from geochemistry above 850 °C?

Zr-in-rutile resetting in aluminosilicate bearing ultra-high temperature granulites: Refining the record of cooling and hydration in the Napier Complex, Antarctica

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