Interpreting titanite U–Pb dates and Zr thermobarometry in high-grade rocks: empirical constraints on elemental diffusivities of Pb, Al, Fe, Zr, Nb, and Ce

Holder, Robert; Hacker, Bradley R.; Seward, Gareth; Kylander‐Clark, Andrew

doi:10.1007/s00410-019-1578-2

Cited by 29 publications

(18 citation statements)

References 72 publications

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“…The greatest uncertainty derives from a SiO2 ; if the assumed value is halved, the calculated temperatures still exceed 650–675°C. In comparison, Pb‐diffusion closure temperatures in these titanites are ~775–830°C using the Dodson (1973) formulation, diffusive parameters for Pb in titanite from Holder et al (2019), an effective diffusion radius of 50 μm, and cooling rates of 10–100°C/Ma.…”

Section: Resultsmentioning

confidence: 99%

Petrochronology of Wadi Tayin Metamorphic Sole Metasediment, With Implications for the Thermal and Tectonic Evolution of the Samail Ophiolite (Oman/UAE)

et al. 2020

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Ophiolite metamorphic soles preserve important records of ophiolite emplacement, but there have been few detailed investigations into their non-mafic portions. We present new thermobarometric and petrochronologic data from a metasediment and mafic restite in the upper Wadi Tayin sole exposure in the Samail (Oman-UAE) Ophiolite. Thermodynamic modeling suggests metasedimentary garnet nucleation at~4 kb,~550°C and final growth at 7.5 ± 1.2 kbar, 665 ± 32°C, occurring by 93.0 ± 0.5 Ma (Lu-Hf isochron). Zircon U-Pb dates of 106.9 ± 2.3 (detrital) and 98.7 ± 1.7 to 94.1 ± 1.6 Ma (metamorphic) bracket the initiation of metamorphism, and monazite U-Pb dates from~97-89 Ma suggest a lengthy period of growth or recrystallization. A mafic titanite U-Pb age of 92.2 ± 1.8 Ma records the earliest possible juxtaposition of high-and lower-grade sole rocks. These and other data suggest that (i) the Wadi Tayin sole preserves an inverted metamorphic, metasomatic, and age gradient,(ii) metasediment metamorphism occurred during, or soon after, crystallization of the overlying ophiolite (≤96.5 Ma); and (iii) sole metasediments define a thermal gradient continuous with hotter, higher-P amphibolites. Some of these data conflict with existing models for sole formation, and we propose several hypotheses to explain them. Cooling of the sole below Ar closure by~92 Ma suggests that strain rapidly partitioned away from the sole, leading to large-scale, thinskinned thrust emplacement of the ophiolite >100 km across the continental margin and the late, cool underthrusting of the continental margin.

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Section: Resultsmentioning

confidence: 99%

Petrochronology of Wadi Tayin Metamorphic Sole Metasediment, With Implications for the Thermal and Tectonic Evolution of the Samail Ophiolite (Oman/UAE)

et al. 2020

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“…In contrast, studies by Corfu and Muir (1989), Corfu and Ayres (1991), Verts et al (1996) and others suggested that variations in titanite U–Pb ratios may reflect multiple or protracted metamorphic and/or metasomatic events. A growing number of studies of natural titanite over the past decade suggest that volume diffusion rates of Pb are greatly overestimated (Gao et al, 2012; Garber et al, 2017; Hartnady et al, 2019; Holder & Hacker, 2019; Holder et al, 2019; Kohn & Corrie, 2011; Kohn, 2017; Smye et al, 2018; Spencer et al, 2013; Stearns et al, 2016; Walters & Kohn, 2017). Revised estimates for Pb diffusion coefficients range from 1 × 10 −20 to 1 × 10 −26 (m 2 s −1 ) (Holder et al, 2019; Kohn, 2017), equivalent to the experimentally derived diffusion rate for Sr in titanite (Cherniak, 1995).…”

Section: Introductionmentioning

confidence: 99%

“…A growing number of studies of natural titanite over the past decade suggest that volume diffusion rates of Pb are greatly overestimated (Gao et al, 2012; Garber et al, 2017; Hartnady et al, 2019; Holder & Hacker, 2019; Holder et al, 2019; Kohn & Corrie, 2011; Kohn, 2017; Smye et al, 2018; Spencer et al, 2013; Stearns et al, 2016; Walters & Kohn, 2017). Revised estimates for Pb diffusion coefficients range from 1 × 10 −20 to 1 × 10 −26 (m 2 s −1 ) (Holder et al, 2019; Kohn, 2017), equivalent to the experimentally derived diffusion rate for Sr in titanite (Cherniak, 1995). These data suggest that volume diffusion is unlikely to disturb U–Pb dates in titanite metamorphosed at temperatures <850°C at most metamorphic time scales.…”

Section: Introductionmentioning

confidence: 99%

Strengths and limitations of in situ U–Pb titanite petrochronology in polymetamorphic rocks: An example from western Maine, USA

Walters

Cruz‐Uribe

Song

et al. 2022

Journal Metamorphic Geology

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Titanite is a potentially powerful U–Pb petrochronometer that may record metamorphism, metasomatism, and deformation. Titanite may also incorporate significant inherited Pb, which may lead to inaccurate and geologically ambiguous U–Pb dates if a proper correction is not or cannot be applied. Here, we present laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS)‐derived titanite U–Pb dates and trace element concentrations for two banded calcsilicate gneisses from south‐central Maine, USA (SSP18‐1A and SSP18‐1B). Single spot common Pb‐corrected dates range from 400 to 280 Ma with ±12–20 Ma propagated 2SE. Titanite grains in sample SSP18‐1B exhibit regular core‐to‐rim variations in texture, composition, and date. We identify four titanite populations: (1) 397 ± 5 Ma (95% CL) low Y + HREE cores and mottled grains, (2) 370 ± 7 Ma high Y + REE mantles and cores, (3) 342 ± 6 Ma cores with high Y + REE and no Eu anomaly, and (4) 295 ± 6 Ma LREE‐depleted rims. We interpret the increase in titanite Y + HREE between ca. 397 and ca. 370 Ma to constrain the timing of diopside fracturing and recrystallization and amphibole breakdown. Apparent Zr‐in‐titanite temperatures (803 ± 36°C at 0.5 ± 0.2 GPa) and increased XDi suggest a thermal maximum at ca. 370 Ma. Population 3 domains dated to ca. 342 Ma exhibit no Eu anomaly and are observed only in compositional bands dominated by diopside (>80 vol%), suggesting limited equilibrium between titanite and plagioclase. Finally, low LREE and high U/Th in Population 4 titanite dates the formation of hydrous phases, such as allanite, during high XH2O fluid infiltration at ca. 295 Ma. In contrast to the well‐defined date–composition–texture relationships observed for titanite from SSP18‐1B, titanite grains from sample SSP18‐1A exhibit complex zoning patterns and little correlation between texture, composition, and date. We hypothesize that the incorporation of variable amounts of radiogenic Pb from dissolved titanite into recrystallized domains resulted in mixed dates spanning 380–330 Ma. Although titanite may reliably record multiple phases of metamorphism, these data highlight the importance of considering U–Pb data along with chemical and textural data to screen for inherited radiogenic Pb.

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“…Typically, these modifying processes do not affect all minerals and/or isotopic systems in the same way, so employing a diverse range of analytical techniques on a variety of mineral phases can reveal the entire tectono-metamorphic history (Cioffi et al, 2019;Holder et al, 2019;Kirkland et al, 2020Kirkland et al, , 2017Pollington and Baxter, 2010;Rocha et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…), making the post‐magmatic evolution generally more difficult to unravel (Lanari et al, 2013; Lanari & Duesterhoeft, 2019). Typically, these modifying processes do not affect all minerals and/or isotopic systems in the same way, so employing a diverse range of analytical techniques on a variety of mineral phases can reveal the entire tectono‐metamorphic history (Cioffi et al, 2019; Holder et al, 2019; Kirkland et al, 2017, 2020; Pollington & Baxter, 2010; Rocha et al, 2017). Geochronological and geochemical studies of ancient terranes commonly contribute to supercontinent reconstructions; however, better tectonic inferences may be made when the timing and conditions of metamorphism are also considered (e.g., Volante et al, 2020; Wan et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

From microanalysis to supercontinents: Insights from the Rio Apa Terrane into the Mesoproterozoic SW Amazonian Craton evolution during Rodinia assembly

Ribeiro

Finch

Cawood

et al. 2021

Journal Metamorphic Geology

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The accepted version of an article is the version that incorporates all amendments made during the peer review process, but prior to the final published version (the Version of Record, which includes; copy and stylistic edits, online and print formatting, citation and other linking, deposit in abstracting and indexing services, and the addition of bibliographic and other material.Self-archiving of the accepted version is subject to an embargo period of 12-24 months. The standard embargo period is 12 months for scientific, technical, medical, and psychology (STM) journals and 24 months for social science and humanities (SSH) journals following publication of the final article. Use our Author Compliance Tool to check the embargo period for individual journals or check their copyright policy on Wiley Online Library.

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Interpreting titanite U–Pb dates and Zr thermobarometry in high-grade rocks: empirical constraints on elemental diffusivities of Pb, Al, Fe, Zr, Nb, and Ce

Cited by 29 publications

References 72 publications

Petrochronology of Wadi Tayin Metamorphic Sole Metasediment, With Implications for the Thermal and Tectonic Evolution of the Samail Ophiolite (Oman/UAE)

Petrochronology of Wadi Tayin Metamorphic Sole Metasediment, With Implications for the Thermal and Tectonic Evolution of the Samail Ophiolite (Oman/UAE)

Strengths and limitations of in situ U–Pb titanite petrochronology in polymetamorphic rocks: An example from western Maine, USA

From microanalysis to supercontinents: Insights from the Rio Apa Terrane into the Mesoproterozoic SW Amazonian Craton evolution during Rodinia assembly

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