Metamictization
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Calibrating chemical abrasion: Its effects on zircon crystal structure, chemical composition and U Pb age Open
The present sub-permil precision of single zircon chemical abrasion, isotope-dilution, thermal ionisation mass spectrometry (CA-ID-TIMS) UPb dates often reveals age dispersions that are outside of analytical uncertainty. Interpreting these…
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Zircon ages in granulite facies rocks: decoupling from geochemistry above 850 °C? Open
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…
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Why natural monazite never becomes amorphous: Experimental evidence for alpha self-healing Open
Monazite, a common accessory rare-earth orthophosphate mineral in the continental crust widely used in U-Pb geochronology, holds promise for (U-Th)/He thermochronology and for the immobilization of Pu and minor actinides (MA) coming from s…
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Zircon M127 – A Homogeneous Reference Material for <span>SIMS</span> U–Pb Geochronology Combined with Hafnium, Oxygen and, Potentially, Lithium Isotope Analysis Open
In this article, we document a detailed analytical characterisation of zircon M127, a homogeneous 12.7 carat gemstone from Ratnapura, Sri Lanka. Zircon M127 has TIMS ‐determined mean U–Pb radiogenic isotopic ratios of 0.084743 ± 0.000027 f…
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Divergent T–ƒO2 paths during crystallisation of H2O-rich and H2O-poor magmas as recorded by Ce and U in zircon, with implications for TitaniQ and TitaniZ geothermometry Open
During solidification of magma chambers as systems closed to chemical exchange with environs, the residual siliceous melt may follow a trend of rising, constant, or decreasing oxidation state, relative to reference buffers such as nickel +…
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Monazite Microstructures and Their Interpretation in Petrochronology Open
The phosphate mineral monazite (LREE,Y,Th,Ca,Si)PO 4 occurs as an accessory phase in peraluminous granites and Ca-poor meta-psammopelites. Due to negligible common Pb and very low Pb diffusion rates at high temperatures, monazite has recei…
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Age discordance and mineralogy Open
Observations of discordant ages, meaning that an age given by one mineral geochronometer is different from the age given by another geochronometer from the same rock, began in the early days of geochronology. In the late 1950s and 1960s, d…
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The formation of large neoblasts in shocked zircon and their utility in dating impacts Open
Uranium-lead (U-Pb) geochronology of individual shocked zircon grains has unique potential for dating bolide impact events. Neoblasts in granular-textured zircon have been recognized as the shock-related feature most effective at recording…
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Secondary magnetite in ancient zircon precludes analysis of a Hadean geodynamo Open
Significance The Earth’s geodynamo is critical in protecting our atmosphere, and thus plays an important role in the habitability of our planet. As such, the Earth’s magnetic field has likely played a crucial role in the emergence of life …
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Chemical lattice expansion of natural zircon during the magmatic-hydrothermal evolution of A-type granite Open
Although thermal lattice expansion is a well-documented nature of crystals, including zircon and zircon-type minerals, chemical lattice expansion of natural mineral is rarely reported. Here we present a comprehensive investigation on three…
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The importance of high precision in the evaluation of U-Pb zircon age spectra Open
We present high-precision isotope dilution-thermal ionization mass spectrometry (ID-TIMS) U-Pb zircon data from the Carboniferous Punteglias granodiorite from the Central Alpine basement in the Aar massif in Switzerland. These analyses yie…
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Measurement of strains in zircon inclusions by Raman spectroscopy Open
We have carried out ab initio hybrid Hartree-Fock/Density Functional Theory simulations to determine the structure and vibrational modes of zircon, ZrSiO4, as a function of different applied strains. The changes in phonon-mode wavenumbers …
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Prograde zircon growth in migmatites Open
Empirical studies of zircon in migmatites document features compatible with growth during heating at suprasolidus conditions. However, numerical modelling of zircon behaviour suggests that suprasolidus zircon is expected to grow only durin…
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New insights into the zircon-reidite phase transition Open
The structure, the elastic properties, and the Raman frequencies of the zircon and reidite polymorphs of ZrSiO4 were calculated as a function of hydrostatic pressure up to 30 GPa using HF/DFT ab initio calculations at static equilibrium (0…
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Hydrothermal zircon: Characteristics, genesis and metallogenic implications Open
Zircon is a principal source of zirconium and hafnium, as well as a key mineral both for petrogenetic modeling and age dating. Although zircon occurrences have been reported from hydrothermal mineral systems, detailed studies on zircon tha…
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Chemical abrasion: the mechanics of zircon dissolution Open
Chemical abrasion is a technique that combines thermal annealing and partial dissolution in hydrofluoric acid (HF) to selectively remove radiation-damaged portions of zircon crystals prior to U–Pb isotopic analysis, and it is applied ubiqu…
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Long-lived Nb-Ta mineralization in Mufushan, NE Hunan, South China: Geological, geochemical, and geochronological constraints Open
The Mufushan Complex (MFSC), located in northeastern Hunan, is a significant producer of Nb-Ta-Li-Be rare metals in South China. The present study examines the genetic relationship, material provenance, fluid evolution, and metallogeny of …
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In situ U–Pb analysis of shocked zircon from the Charlevoix impact structure, Québec, Canada Open
Laser ablation inductively coupled plasma‐mass spectrometry ( LA ‐ ICP ‐ MS ) U–Pb geochronology of shocked zircon grains in a vesicular‐fluidal impact melt rock from the ≥54 km Charlevoix impact structure, Québec, Canada, suggests an Ordo…
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<sup>238</sup>U/<sup>235</sup>U measurement in single-zircon crystals: implications for the Hadean environment, magmatic differentiation and geochronology Open
We present novel analytical methods allowing the precise determination of the uranium isotopic composition (238U/235U) of single zircon crystals.
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Micro-Raman—A Tool for the Heavy Mineral Analysis of Gold Placer-Type Deposits (Pianu Valley, Romania) Open
In the current study, different heavy minerals typical of gold placer deposits were identified by means of micro-Raman spectroscopy, and their chemical composition analyzed and discussed (garnet, kyanite, staurolite, zircon, allanite, mona…
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Metallic Pb nanospheres in ultra-high temperature metamorphosed zircon from southern India Open
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 metalli…
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Hydrothermal alteration of monazite-(Ce) and chevkinite-(Ce) from the Sin Quyen Fe-Cu-LREE-Au deposit, northwestern Vietnam Open
The Sin Quyen deposit in northwestern Vietnam is composed of Fe-Cu-LREE-Au ore bodies hosted in Proterozoic metapelite. There are massive and banded replacement ores with variable amounts of monazite-(Ce) and chevkinite-(Ce) crystals, whic…
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Gaining from loss: Detrital zircon source-normalized α-dose discriminates first- versus multi-cycle grain histories Open
Detrital zircon U–Pb ages are widely employed as an archive of geological processes through time. Changes in detrital zircon age patterns within sediments reflect changes in source areas that are often related to tectonic and/or climatic p…
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Oligocene Nb-Ta-W-mineralization related to the Xiaruleucogranite in the Himalayan Orogen Open
Himalayan leucogranites are abundant within a ~2000-km-long, E-W trending belt on the Tibetan Plateau. Recently, it has been shown that several leucogranites and pegmatites (including aplites) of the Himalayan leucogranitic belt are closel…
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U–Pb geochronology, REE and trace element geochemistry of zircon from El Fereyid monzogranite, south Eastern Desert, Egypt Open
The monzogranite of El Fereyid is one of the rare metal–rich granites, where zircon is one of the ore minerals. Thus, studying zircon here is of vital importance. Most of the studied zircon grains are metamict and thus the loss of radiogen…
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Contrasting Nb-Ta mineralization between the Mufushan and Lianyunshan granites, South China: Evidence from whole-rock and zircon geochemistry and geochronology Open
The Mufushan (MFS) and Lianyunshan (LYS) granitic complexes are located in northeastern Hunan (South China) and host important Nb-Ta mineralization. Fine-grained muscovite granites (FGMGs) occur as intrusions within the Lengjiaxi Group and…
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Alteration and chemical U-Th-total Pb dating of heterogeneous high-uranium zircon from a pegmatite from the Aduiskii massif, middle Urals, Russia Open
The U-Th-Pb isotope system in the accessory mineral zircon may be disturbed, as for instance by the secondary loss of radiogenic lead. The recognition of such alteration is crucial for the sound interpretation of geochronology results, in …
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Using the elastic properties of zircon-garnet host-inclusion pairs for thermobarometry of the ultrahigh-pressure Dora-Maira whiteschists: problems and perspectives Open
The ultrahigh-pressure (UHP) whiteschists of the Brossasco-Isasca unit (Dora-Maira Massif, Western Alps) provide a natural laboratory in which to compare results from classical pressure (P)–temperature (T) determinations through thermodyna…
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Biologically mediated crystallization of buddingtonite in the Paleoproterozoic: Organic-igneous interactions from the Volyn pegmatite, Ukraine Open
The Volyn pegmatites from Volodarsk-Volynskyi in the Zhytomyr Oblast, NW Ukraine, are associated with granites genetically related to the Paleoproterozoic Korosten pluton. Their late-stage evolution is characterized by the formation of opa…
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Garnet, zircon, and monazite age and REE signatures in (ultra)high‐temperature and high‐pressure rocks: Examples from the Caledonides and the Pamir Open
Rare earth element (REE) signatures of high‐U/Pb and high‐Th/Pb accessory minerals are typically used to link their ages to specific petrological processes (‘petrochronology’)—most notably the growth or breakdown of garnet. Although this a…