The closure temperature(s) of zircon Raman dating
<p>Zircon Raman dating based on irradiation damage is a debated concept but not an established geo-/thermochronological method. One issue is the temperature range of radiation-damage annealing over geological timescales. We conducted isochronal and isothermal annealing experiments on radiatio...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-05-01
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| Series: | Geochronology |
| Online Access: | https://gchron.copernicus.org/articles/3/259/2021/gchron-3-259-2021.pdf |
| _version_ | 1797230176554188800 |
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| author | B. Härtel R. Jonckheere B. Wauschkuhn L. Ratschbacher |
| author_facet | B. Härtel R. Jonckheere B. Wauschkuhn L. Ratschbacher |
| author_sort | B. Härtel |
| collection | DOAJ |
| description | <p>Zircon Raman dating based on irradiation damage
is a debated concept but not an established geo-/thermochronological
method. One issue is the temperature range of radiation-damage annealing
over geological timescales. We conducted isochronal and isothermal annealing
experiments on radiation-damaged zircons between 500 and 1000 <span class="inline-formula"><sup>∘</sup></span>C
for durations between 10 min and 5 d to describe the annealing
kinetics. We measured the widths (<span class="inline-formula">Γ</span>) and positions (<span class="inline-formula"><i>ω</i></span>) of
the <span class="inline-formula"><i>ν</i><sub>1</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>), <span class="inline-formula"><i>ν</i><sub>2</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>), and <span class="inline-formula"><i>ν</i><sub>3</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>) internal Raman bands, and the external rotation Raman
band at <span class="inline-formula">∼974</span>, 438, 1008, and 356 cm<span class="inline-formula"><sup>−1</sup></span> after each
annealing step. We fitted a Johnson–Mehl–Avrami–Kolmogorov and a distributed
activation energy model to the fractional annealing data, calculated from
the widths of the <span class="inline-formula"><i>ν</i><sub>2</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>), <span class="inline-formula"><i>ν</i><sub>3</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>), and
external rotation bands. From the kinetic models, we determined closure
temperatures <span class="inline-formula"><i>T</i><sub>c</sub></span> for damage accumulation for each Raman band. <span class="inline-formula"><i>T</i><sub>c</sub></span>
ranges from 330 to 370 <span class="inline-formula"><sup>∘</sup></span>C for the internal <span class="inline-formula"><i>ν</i><sub>2</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>)
and <span class="inline-formula"><i>ν</i><sub>3</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>) bands; the external rotation band is more
sensitive to thermal annealing (<span class="inline-formula"><i>T</i><sub>c</sub>∼260</span> to
310 <span class="inline-formula"><sup>∘</sup></span>C). Our estimates are in general agreement with previous
ones, but more geological evidence is needed to validate the results. The
<span class="inline-formula"><i>T</i><sub>c</sub></span> difference for the different Raman bands offers the prospect of a
multi-closure-temperature zircon Raman thermochronometer.</p> |
| first_indexed | 2024-04-24T15:24:20Z |
| format | Article |
| id | doaj.art-36b2a485ef8d4d1c8ce624a3860e9707 |
| institution | Directory Open Access Journal |
| issn | 2628-3719 |
| language | English |
| last_indexed | 2024-04-24T15:24:20Z |
| publishDate | 2021-05-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Geochronology |
| spelling | doaj.art-36b2a485ef8d4d1c8ce624a3860e97072024-04-02T06:48:41ZengCopernicus PublicationsGeochronology2628-37192021-05-01325927210.5194/gchron-3-259-2021The closure temperature(s) of zircon Raman datingB. HärtelR. JonckheereB. WauschkuhnL. Ratschbacher<p>Zircon Raman dating based on irradiation damage is a debated concept but not an established geo-/thermochronological method. One issue is the temperature range of radiation-damage annealing over geological timescales. We conducted isochronal and isothermal annealing experiments on radiation-damaged zircons between 500 and 1000 <span class="inline-formula"><sup>∘</sup></span>C for durations between 10 min and 5 d to describe the annealing kinetics. We measured the widths (<span class="inline-formula">Γ</span>) and positions (<span class="inline-formula"><i>ω</i></span>) of the <span class="inline-formula"><i>ν</i><sub>1</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>), <span class="inline-formula"><i>ν</i><sub>2</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>), and <span class="inline-formula"><i>ν</i><sub>3</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>) internal Raman bands, and the external rotation Raman band at <span class="inline-formula">∼974</span>, 438, 1008, and 356 cm<span class="inline-formula"><sup>−1</sup></span> after each annealing step. We fitted a Johnson–Mehl–Avrami–Kolmogorov and a distributed activation energy model to the fractional annealing data, calculated from the widths of the <span class="inline-formula"><i>ν</i><sub>2</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>), <span class="inline-formula"><i>ν</i><sub>3</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>), and external rotation bands. From the kinetic models, we determined closure temperatures <span class="inline-formula"><i>T</i><sub>c</sub></span> for damage accumulation for each Raman band. <span class="inline-formula"><i>T</i><sub>c</sub></span> ranges from 330 to 370 <span class="inline-formula"><sup>∘</sup></span>C for the internal <span class="inline-formula"><i>ν</i><sub>2</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>) and <span class="inline-formula"><i>ν</i><sub>3</sub></span>(SiO<span class="inline-formula"><sub>4</sub></span>) bands; the external rotation band is more sensitive to thermal annealing (<span class="inline-formula"><i>T</i><sub>c</sub>∼260</span> to 310 <span class="inline-formula"><sup>∘</sup></span>C). Our estimates are in general agreement with previous ones, but more geological evidence is needed to validate the results. The <span class="inline-formula"><i>T</i><sub>c</sub></span> difference for the different Raman bands offers the prospect of a multi-closure-temperature zircon Raman thermochronometer.</p>https://gchron.copernicus.org/articles/3/259/2021/gchron-3-259-2021.pdf |
| spellingShingle | B. Härtel R. Jonckheere B. Wauschkuhn L. Ratschbacher The closure temperature(s) of zircon Raman dating Geochronology |
| title | The closure temperature(s) of zircon Raman dating |
| title_full | The closure temperature(s) of zircon Raman dating |
| title_fullStr | The closure temperature(s) of zircon Raman dating |
| title_full_unstemmed | The closure temperature(s) of zircon Raman dating |
| title_short | The closure temperature(s) of zircon Raman dating |
| title_sort | closure temperature s of zircon raman dating |
| url | https://gchron.copernicus.org/articles/3/259/2021/gchron-3-259-2021.pdf |
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