Stability of Zircon and Its Isotopic Ratios in High-Temperature Fluids: Long-Term (4 months) Isotope Exchange Experiment at 850°C and 50 MPa

Bindeman, Ilya N.; Schmitt, Axel K.; Lundstrom, Craig C.; Hervig, R. L.

doi:10.3389/feart.2018.00059

Cited by 28 publications

(9 citation statements)

References 50 publications

(73 reference statements)

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“…9a-f). Among mineral phases in high-silica rocks, zircon is generally taken as the most reliable recorder of magmatic d 18 O values owing to its slow O self-diffusivity and robustness to alteration (Valley, 2003;Bindeman et al, 2018). [Garnet, although considered a phase often resistant to weathering, is not always present in high-silica rocks, with SPGs being a notable exception (King & Valley, 2001). ]…”

Section: Oxygen Isotopes In Archean and Proterozoic Spgsmentioning

confidence: 99%

Strongly Peraluminous Granites across the Archean–Proterozoic Transition

Bucholz

Spencer

2019

Journal of Petrology

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Strongly peraluminous granites (SPGs) form through the partial melting of metasedimentary rocks and therefore represent archives of the influence of assimilation of sedimentary rocks on the petrology and chemistry of igneous rocks. With the aim of understanding how variations in sedimentary rock characteristics across the Archean–Proterozoic transition might have influenced the igneous rock record, we compiled and compared whole-rock chemistry, mineral chemistry, and isotope data from Archean and Paleo- to Mesoproterozoic SPGs. This time period was chosen as the Archean–Proterozoic transition broadly coincides with the stabilization of continents, the rise of subaerial weathering, and the Great Oxidation Event (GOE), all of which left an imprint on the sedimentary rock record. Our compilation of SPGs is founded on a detailed literature review of the regional geology, geochronology, and inferred origins of the SPGs, which suggest derivation from metasedimentary source material. Although Archean and Proterozoic SPGs are similar in terms of mineralogy or major-element composition owing to their compositions as near-minimum melts in the peraluminous haplogranite system, we discuss several features of their mineral and whole-rock chemistry. First, we review a previous analysis of Archean and Proterozoic SPGs biotite and whole-rock compositions indicating that Archean SPGs, on average, are more reduced than Proterozoic SPGs. This observation suggests that Proterozoic SPGs were derived from metasedimentary sources that on average had more oxidized bulk redox states relative to their Archean counterparts, which could reflect an increase in atmospheric O2 levels and more oxidized sedimentary source rocks after the GOE. Second, based on an analysis of Al2O3/TiO2 whole-rock ratios and zircon saturation temperatures, we conclude that Archean and Proterozoic SPGs formed through partial melting of metasedimentary rocks over a similar range of melting temperatures, with both ‘high-’ and ‘low-’temperature SPGs being observed across all ages. This observation suggests that the thermo-tectonic processes resulting in the heating and melting of metasedimentary rocks (e.g. crustal thickening or underplating of mafic magmas) occurred during generation of both the Archean and Proterozoic SPGs. Third, bulk-rock CaO/Na2O, Rb/Sr, and Rb/Ba ratios indicate that Archean and Proterozoic SPGs were derived from partial melting of both clay-rich (i.e. pelites) and clay-poor (i.e. greywackes) source regions that are locality specific, but not defined by age. This observation, although based on a relatively limited dataset, indicates that the source regions of Archean and Proterozoic SPGs were similar in terms of sediment maturity (i.e. clay component). Last, existing oxygen isotope data for quartz, zircon, and whole-rocks from Proterozoic SPGs show higher values than those of Archean SPGs, suggesting that bulk sedimentary 18O/16O ratios increased across the Archean–Proterozoic boundary. The existing geochemical datasets for Archean and Proterozoic SPGs, however, are limited in size and further work on these rocks is required. Future work must include detailed field studies, petrology, geochronology, and constraints on sedimentary source ages to fully interpret the chemistry of this uniquely useful suite of granites.

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Section: Oxygen Isotopes In Archean and Proterozoic Spgsmentioning

confidence: 99%

Strongly Peraluminous Granites across the Archean–Proterozoic Transition

Bucholz

Spencer

2019

Journal of Petrology

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“…Reconstructing the detailed formation history of Mud Tank zircon is beyond the scope of this contribution, but it was clearly not in equilibrium with mafic-ultramafic melts at magmatic temperatures. On the other hand, Mud Tank zircon has a strong mantle signature of Hf isotope composition (the average e Hf at 731 Ma is +7.0 based on recent data of Gain et al 2019 and CHUR Hf/ 177 Hf o = 0.282785 and 176 Lu/ 177 Hf o = 0.0336 of Vervoort 2014), despite elemental and isotopic diffusion that are extremely sluggish (Cherniak 2010) and unable to lead to internal homogenization in the presence of melts or fluid (e.g., Bea et al 2018;Bindeman et al 2018). Thus, it appears likely that these zircon megacrysts are related to mantle metasomatism with little or no crustal contribution, in agreement with conclusions of Currie et al (1992) concerning the origin of the Mud Tank Carbonatite complex as a whole and a detailed geochemical study of Mud Tank zircon crystals and the zircon-hosted inclusions (Gain et al 2019).…”

Section: Discussionmentioning

confidence: 99%

Zircon survival in shallow asthenosphere and deep lithosphere

Borisova

Bindeman

Toplis

et al. 2020

American Mineralogist

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Zircon (ZrSiO4) is the most frequently used geochronometer of terrestrial and extraterrestrial processes. To shed light on question of zircon survival in the Earth's shallow asthenosphere, high-temperature experiments of zircon dissolution in natural mid-ocean ridge basaltic (MORB) and synthetic haplobasaltic melts have been performed at temperatures of 1250–1300 °C and pressures from 0.1 MPa to 0.7 GPa. Zirconium measurements were made in situ by electron probe microanalyses (EPMA) at high current. Taking into account secondary fluorescence effects in zircon-glass pairs during EPMA, a zirconium diffusion coefficient of 2.87E-08 cm2/s was determined at 1300 °C and 0.5 GPa. When applied to the question of zircon survival in asthenospheric melts of tholeiitic basalt composition, the data are used to infer that typical 100 mm zircon crystals dissolve rapidly (~10 h) and congruently upon reaction with basaltic melt at pressures of 0.2–0.7 GPa. We observed incongruent (to crystal ZrO2 and SiO2 in melt) dissolution of zircon in natural mid-ocean ridge the basaltic melt at low pressures <0.2 GPa and in the haplobasaltic melt at 0.7 GPa pressure. Our experimental data raise questions about the origin of zircon crystals in mafic and ultramafic rocks, in particular, in shallow oceanic asthenosphere and deep lithosphere, as well as the meaning of the zircon-based ages estimated from these minerals. The origin of zircon in shallow (ultra-) mafic chambers is likely related to the crystallization of intercumulus liquid. Large zircon megacrysts in kimberlites, peridotites, alkali basalts, and carbonatite magmas suggest fast transport and short interaction durations between zircon and melt. The origin of zircon megacrysts is likely related to metasomatic addition of Zr into the mantle as an episode of mantle melting should eliminate them on geologically short timescales.

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“…2 Myr consistently shows low‐δ 18 O values (average +4.51‰ ± 0.24; n = 55; Figure 7a) relative to the mantle. These signatures cannot be produced by fractionation between silicate melts and minerals (Valley, 2003), nor by postcrystallization modification of oxygen isotopes in zircon by diffusion at near‐magmatic temperatures (Bindeman et al., 2018; Cisneros de León & Schmitt, 2019). Moreover, Miocene zircon xenocrysts within TBJ tephra ( n = 2) yielded mantle‐like compositions (∼+5.5‰) that differ significantly from TBJ zircon.…”

Section: Discussionmentioning

confidence: 99%

“…melts and minerals (Valley, 2003), nor by postcrystallization modification of oxygen isotopes in zircon by diffusion at near-magmatic temperatures (Bindeman et al, 2018;Cisneros de León & Schmitt, 2019). Moreover, Miocene zircon xenocrysts within TBJ tephra (n = 2) yielded mantle-like compositions (∼+5.5‰) that differ significantly from TBJ zircon.…”

Section: Multicomponent Assimilation In Tb Magma Genesismentioning

confidence: 96%

Zircon and Melt Extraction From a Long‐Lived and Vertically Extensive Magma System Underneath Ilopango Caldera (El Salvador)

León

Schmitt

Kutterolf

et al. 2021

Geochem Geophys Geosyst

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The Tierra Blanca (TB) eruptive suite comprises the last four major eruptions of Ilopango caldera in El Salvador (≤45 ka), including the youngest Tierra Blanca Joven eruption (TBJ; ∼106 km 3 ): the most voluminous event during the Holocene in Central America. Despite the protracted and productive history of explosive silicic eruptions at Ilopango caldera, many aspects regarding the longevity and the prevailing physicochemical conditions of the underlying magmatic system remain unknown. Zircon 238 U-230 Th geochronology of the TB suite (TBJ, TB2, TB3, and TB4) reveals a continuous and overlapping crystallization history among individual eruptions, suggesting persistent melt presence in thermally and compositionally distinct magma reservoirs over the last ca. 80 kyr. The longevity of zircon is in contrast to previously determined crystallization timescales of <10 kyr for major mineral phases in TBJ. This dichotomy is explained by a process of rhyolitic melt segregation from a crystal-rich refractory residue that incorporates zircon, whereas a new generation of major mineral phases crystallized shortly before eruption. Ti-in-zircon temperatures and amphibole geothermobarometry suggest that rhyolitic melt was extracted from different storage zones of the magma reservoir as indicated by distinct but synchronous thermochemical zircon histories among the TB suite eruptions. Zircon from TBJ and TB2 suggests magma differentiation within deeper and hotter parts of the reservoir, whereas zircon from TB3 and TB4 instead hints at crystallization in comparatively shallower and cooler domains. The assembly of the voluminous TBJ magma reservoir was also likely enhanced by cannibalization of hydrothermally altered components as suggested by low-δ 18 O values in zircon (+4.5 ± 0.3‰).

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Stability of Zircon and Its Isotopic Ratios in High-Temperature Fluids: Long-Term (4 months) Isotope Exchange Experiment at 850°C and 50 MPa

Cited by 28 publications

References 50 publications

Strongly Peraluminous Granites across the Archean–Proterozoic Transition

Strongly Peraluminous Granites across the Archean–Proterozoic Transition

Zircon survival in shallow asthenosphere and deep lithosphere

Zircon and Melt Extraction From a Long‐Lived and Vertically Extensive Magma System Underneath Ilopango Caldera (El Salvador)

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