In search of lost time: raman thermochronology of FC-1 zircon
Translating thermochronological ages to geological models requires knowledge of the thermal sensitivity of the applied thermochronometer, i.e. the closure temperature or the partial annealing/retention zone. Zircon Raman dating is a thermochronometer that uses radiation-damage measurements and match...
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| Main Authors: | , , , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
January 2024
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| In: |
Contributions to mineralogy and petrology
Year: 2024, Volume: 179, Issue: 1, Pages: 1-15 |
| ISSN: | 1432-0967 |
| DOI: | 10.1007/s00410-023-02083-z |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1007/s00410-023-02083-z Verlag, lizenzpflichtig, Volltext: https://link.springer.com/article/10.1007/s00410-023-02083-z 
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| Author Notes: | Birk Hartel, Eva Enkelmann, Raymond Jonckheere, Thomas Ludwig, Joachim Krause & Lothar Ratschbacher |
| Summary: | Translating thermochronological ages to geological models requires knowledge of the thermal sensitivity of the applied thermochronometer, i.e. the closure temperature or the partial annealing/retention zone. Zircon Raman dating is a thermochronometer that uses radiation-damage measurements and matched analyses of actinide contents in zircon. Experimental work placed its closure temperature at 330-370 degrees C for the internal nu(2)(SiO4) and nu(3)(SiO4) Raman bands at 439 and 1008 cm(-1), and 260-310 degrees C for the external rotation (ER) band at 356 cm(-1). However, experimental annealing models also predict partial radiation-damage annealing over a broad temperature range (> 500 degrees C). We test these closure temperatures by dating zircon from the U-Pb reference material FC-1. We matched Raman-based radiation-damage measurements with U and Th concentrations measured with a secondary ion mass spectrometer. The zircon Raman ages for the nu(2), nu(3), and ER bands are 942 +/- 23 Ma (2 s), 978 +/- 38 Ma, and 1033 +/- 32 Ma. This is lower than the expected range of 1040-1080 Ma, between the apatite U-Pb (similar to 490 degrees C) and zircon (U-Th)/He (ZHe; similar to 200 degrees C) ages. We discuss long-term, low-temperature annealing of radiation damage during protracted cooling of the sample as a cause of age reduction. This explanation fits both, experimental annealing models and zircon Raman data from other geological settings. Long-term, low-temperature annealing complicates the interpretation of standalone zircon Raman data. However, exploiting this effect by combining zircon Raman and ZHe dating on the same sample provides thermal-history information beyond that revealed by either of them. |
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| Item Description: | Gesehen am 05.03.2024 Onlineversion: 13.Dezember 2023, Artikelversion: Januar 2024 |
| Physical Description: | Online Resource |
| ISSN: | 1432-0967 |
| DOI: | 10.1007/s00410-023-02083-z |