Cathodoluminescence guided zircon Hf isotope depth profiling: Mobilization of the Lu–Hf system during (U)HP rock exhumation in the Woodlark Rift, Papua New Guinea

Zirakparvar, N. Alex

doi:10.1016/j.lithos.2015.01.026

Cited by 7 publications

(3 citation statements)

References 74 publications

(125 reference statements)

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“…Examination of the data on a cycle‐by‐cycle basis can minimize, but not eliminate this problem fully given that there could be domains of similar age but with different U‐Pb systematics. (e.g., Zirakparvar, ; Zirakparvar et al, ). Dating zircon multiple times, and in different locations, can enable internal Discordia lines to be identified (e.g., Guitreau & Blichert‐Toft, ), and if the zircon history is not too complex, these lines, contrary to single spots, can reveal actual crystallization and disturbance ages.…”

Section: Introductionmentioning

confidence: 99%

“…When plotted together on a Concordia plot, data for different zones within a same crystal can provide information regarding the crystallization and the disturbance histories of the analyzed crystal. This traverse‐based approach provides a time effective alternative to the more labor intensive method of taking the zircon crystal out of the mount once it has been analyzed, and then sectioning it to examine the analytical volume in relation to the CL/BSE image (e.g., Zirakparvar, ; Zirakparvar et al, ). To test our U‐Pb dating approach, we analyzed zircons from Acasta gneisses because they are well‐documented examples of ancient zircon populations that exhibit complex U‐Pb patterns (e.g., Bauer et al, ; Bowring & Williams, ; Guitreau et al, ; Iizuka et al, ; Mojzsis et al, ; Reimink et al, ; Stern & Bleeker, ).…”

Section: Introductionmentioning

confidence: 99%

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Crystallization and Disturbance Histories of Single Zircon Crystals From Hadean‐Eoarchean Acasta Gneisses Examined by LA‐ICP‐MS U‐Pb Traverses

Guitreau

Mora

Paquette

2018

Geochem Geophys Geosyst

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Zircon U‐Pb geochronology is a very robust dating method but the accuracy of determined ages can sometimes be compromised. This is because, as commonly observed, the U‐Pb isotope system can be reopened during the post‐crystallization evolution of a zircon. The present manuscript investigates the capability of traverses by LA‐ICP‐MS to identify zones of well‐preserved U‐Pb isotope systematics within zircon crystals. The data for the different zones can be used to construct internal Discordia lines that provide age information about crystallization and metamorphism of single zircon crystals. To test our approach, we analyzed zircons from three ca. 3.96 Ga Acasta gneisses. Results demonstrate that such a method allows retrieval of original crystallization age in most of the studied zircons, even in those that experienced ancient U‐Pb disturbances resulting in discordant U‐Pb data. It was also possible to estimate disturbance ages, though not as precisely as for the igneous crystallization, in many of the studied crystals.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Crystallization and Disturbance Histories of Single Zircon Crystals From Hadean‐Eoarchean Acasta Gneisses Examined by LA‐ICP‐MS U‐Pb Traverses

Guitreau

Mora

Paquette

2018

Geochem Geophys Geosyst

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“…As such, although whole‐rock Sr–Nd isotopic heterogeneities can be caused by the incongruent melting of crustal sources (e.g. McLeod, Davidson, Nowell, & de Silva, ; Zeng, Asimow, et al, ), zircon Hf isotopic variations within migmatites and granites are thought to reflect either contributions from protolith zircons and other Hf‐bearing minerals or the derivation of Hf from different sources (Chen, Gao, & Zheng, ; Farina, Stevens, Gerdes, & Frei, ; Tang et al, ; Zirakparvar, ). However, the factors and processes that generate large zircon Hf isotopic variations within migmatites and granites are still unclear.…”

Section: Discussionmentioning

confidence: 99%

Migmatites record multiple episodes of crustal anatexis and geochemical differentiation in the Sulu ultrahigh‐pressure metamorphic zone, eastern China

Zhou

Chen

Zheng

et al. 2019

Journal Metamorphic Geology

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Partial melting of ultrahigh‐pressure (UHP) metamorphic rocks is common during collisional orogenesis and post‐collisional reworking, indicating that determining the timing and processes involved in this partial melting can provide insights into the tectonic evolution of collisional orogens. This study presents the results of a combined whole‐rock geochemical and zirconological study of migmatites from the Sulu orogen in eastern China. These data provide evidence of multiple episodes of crustal anatexis and geochemical differentiation within the UHP metamorphic rocks. The leucosomes contain higher concentrations of Ba and K and lower concentrations of the rare earth elements (REE), Th and Y, than associated melanosomes and granitic gneisses. The leucosomes also have homogenous Sr–Nd–O isotopic compositions that are similar to proximal (i.e. within the same outcrop) melanosomes, suggesting that the anatectic melts were generated by the partial melting of source rocks that are located within individual outcrops. The migmatites contain zircons with six different types of domains that can be categorized using differences in structures, trace element compositions, and U–Pb ages. Group I domains are relict magmatic zircons that yield middle Neoproterozoic U–Pb ages and contain high REE concentrations. Group II domains represent newly grown metamorphic zircons that formed at 230 ± 1 Ma during the collisional orogenesis. Groups III, IV, V, and VI zircons are newly grown anatectic zircons that formed at 222 ± 2 Ma, 215 ± 1 Ma, 177 ± 2 Ma, and 152 ± 2 Ma, respectively. The metamorphic zircons have higher Th/U and lower (Yb/Gd)N values, flat heavy REE (HREE) patterns with no significantly negative Eu anomalies relative to the anatectic zircons, which are characterized by low Th/U ratios, steep HREE patterns, and negative Eu anomalies. The first two episodes of crustal anatexis occurred during the Late Triassic at c. 222 Ma and c. 215 Ma as a result of phengite breakdown. The other two episodes of anatexis occurred during the Jurassic period at c. 177 Ma and c. 152 Ma and were associated with extensional collapse of the collision‐thickened orogen. The majority of Triassic anatectic zircons and all of the Jurassic zircons are located within the leucosomes, whereas the melanosomes are dominated by Triassic metamorphic zircons, suggesting that the leucosomes within the migmatites record more episodes of crustal anatexis. Both metamorphic and anatectic zircons have elevated εHf(t) values compared with relict magmatic zircon cores, suggesting that these zircons contain non‐zircon Hf derived from material with more radiogenic Hf isotope compositions. Therefore, the Sulu and Dabie orogens experienced different episodes of reworking during the exhumation and post‐collisional stages.

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The anatectic effect on the zircon Hf isotope composition of migmatites and associated granites

Chen

Gao

Zheng

2015

Lithos

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Cathodoluminescence guided zircon Hf isotope depth profiling: Mobilization of the Lu–Hf system during (U)HP rock exhumation in the Woodlark Rift, Papua New Guinea

Cited by 7 publications

References 74 publications

Crystallization and Disturbance Histories of Single Zircon Crystals From Hadean‐Eoarchean Acasta Gneisses Examined by LA‐ICP‐MS U‐Pb Traverses

Crystallization and Disturbance Histories of Single Zircon Crystals From Hadean‐Eoarchean Acasta Gneisses Examined by LA‐ICP‐MS U‐Pb Traverses

Migmatites record multiple episodes of crustal anatexis and geochemical differentiation in the Sulu ultrahigh‐pressure metamorphic zone, eastern China

The anatectic effect on the zircon Hf isotope composition of migmatites and associated granites

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