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1. Diffusion anisotropy of Ti in zircon and implications for Ti-in-zircon thermometry

   https://doi.org/10.1016/j.epsl.2021.117317  

   Bloch, E.M.; Jollands, M.C.; Tollan, P.; Plane, F.; Bouvier, A.-S.; Hervig, R.; Berry, A.J.; Zaubitzer, C.; Escrig, S.; Müntener, O.; et al (January 2022, Earth and Planetary Science Letters)
2. Constraining the timing and conditions of magmatism and metamorphism in the lower crust of the Southern California batholith using U-Pb zircon geochronology and Ti-in-zircon thermometry

   Robles, F.; Schwartz, J.; Miranda, E.; Klepeis, K.A.; and Mora-Klepeis, G. (October 2022, Geological Society of America Abstracts with Programs)

   The Southern California batholith contains a geologic record that can help clarify the timing of events that occurred during the Late Cretaceous (100-65 Ma) along the western margin of the North American Cordillera. The subduction of the oceanic conjugate Shatsky plateau beneath North America is postulated to have ended active magmatism in the arc at 88-70 Ma; however, the timing of this event is poorly constrained in Southern California. We use U-Pb laser ablation zircon petrochronology to document the timing and conditions of magmatism and metamorphism in the lower crust of the Cretaceous arc. We focus on the Cucamonga terrane in a part of the Southern California batholith located northeast of Los Angeles in the southeastern San Gabriel Mountains. These rocks contain exhumed lower crustal (7-9 kbar) rocks predominantly composed of granulite-facies metasedimentary rocks, migmatites, charnockite and dioritic to tonalitic gneiss. We report 20 new zircon dates from 11 samples, including 4 mafic biotite gneisses, 3 mylonitic tonalites, 2 charnockites, a quartzite, and a felsic pegmatite dike crosscutting granulite-facies metasedimentary rocks. New 206Pb/238U ages show that magmatism occurred in the Middle Jurassic (ca. 172-166 Ma), the Early Cretaceous (ca. 120-118 Ma), and the Late Cretaceous (88-86 Ma) at temperatures ranging from 740 to 800 oC. Granulite-facies metamorphism and partial melting of these rocks occurred during the 88-74 Ma interval at temperatures ranging from 730°C to 800oC. Our data indicate that high-temperature arc magmatism and granulite-facies metamorphism continued through the Late Cretaceous and overlapped in timing with postulated subduction of the conjugate Shatsky plateau from previous models. We speculate that termination of arc activity and cooling of the lower crust in response to plateau subduction must postdate ca. 74 Ma. 

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3. CHICXULUB ZIRCON (AND APATITE!)

   Wittmann, Axel (May 2018, Annual meeting of the Meteoritical Society)

   Poster presentation of shock metamorphic features of accessory minerals in drill core samples of the Lower Peak Ring section of the Chicxulub impact crater. 

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4. Chemical abrasion: the mechanics of zircon dissolution

   https://doi.org/10.5194/gchron-5-127-2023  

   McKanna, Alyssa J.; Koran, Isabel; Schoene, Blair; Ketcham, Richard A. (January 2023, Geochronology)

   Abstract. Chemical abrasion is a technique that combines thermal annealing and partialdissolution in hydrofluoric acid (HF) to selectively removeradiation-damaged portions of zircon crystals prior to U–Pb isotopicanalysis, and it is applied ubiquitously to zircon prior to U–Pb isotopedilution thermal ionization mass spectrometry (ID-TIMS). The mechanics ofzircon dissolution in HF and the impact of different leaching conditions onthe zircon structure, however, are poorly resolved. We present amicrostructural investigation that integrates microscale X-ray computedtomography (µCT), scanning electron microscopy, and Ramanspectroscopy to evaluate zircon dissolution in HF. We show that µCTis an effective tool for imaging metamictization and complex dissolutionnetworks in three dimensions. Acid frequently reaches crystal interiors viafractures spatially associated with radiation damage zoning and inclusionsto dissolve soluble high-U zones, some inclusions, and material aroundfractures, leaving behind a more crystalline zircon residue. Other acid pathsto crystal cores include the dissolution of surface-reaching inclusions andthe percolation of acid across zones with high defect densities. In highlycrystalline samples dissolution is crystallographically controlled withdissolution proceeding almost exclusively along the c axis. Increasing theleaching temperature from 180 to 210 ∘C results indeeper etching textures, wider acid paths, more complex internal dissolutionnetworks, and greater volume losses. How a grain dissolves strongly dependson its initial radiation damage content and defect distribution as well asthe size and position of inclusions. As such, the effectiveness of anychemical abrasion protocol for ID-TIMS U–Pb geochronology is likelysample-dependent. We also briefly discuss the implications of our findingsfor deep-time (U-Th)/He thermochronology. 

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5. The effects of experimental heating and alteration on melt inclusions in magmatic zircon

   https://doi.org/10.1016/j.chemgeo.2025.122900  

   Gonzalez, Joseph P; Kitajima, Kouki; Blum, Tyler B; Shimizu, Kei; Almeev, Renat R; Nachlas, William O; Kamo, Sandra L; Sobolev, Alexander V; Holtz, Francois; Spicuzza, Michael J; et al (June 2025, Chemical Geology)