Minimizing the effects of Pb loss in detrital and igneous U–Pb zircon geochronology by CA-LA-ICP-MS
<p>Detrital zircon geochronology by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) is a widely used tool for determining maximum depositional ages and sediment provenance, as well as reconstructing sediment routing pathways. Although the accuracy and precision of U–Pb...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2024-03-01
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| Series: | Geochronology |
| Online Access: | https://gchron.copernicus.org/articles/6/89/2024/gchron-6-89-2024.pdf |
| _version_ | 1827307806362959872 |
|---|---|
| author | E. E. Donaghy M. P. Eddy F. Moreno M. Ibañez-Mejia |
| author_facet | E. E. Donaghy M. P. Eddy F. Moreno M. Ibañez-Mejia |
| author_sort | E. E. Donaghy |
| collection | DOAJ |
| description | <p>Detrital zircon geochronology by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) is a widely used tool for determining maximum depositional ages and sediment provenance, as well as reconstructing sediment routing pathways. Although the accuracy and precision of U–Pb geochronology measurements have improved over the past 2 decades, Pb loss continues to impact the ability to resolve zircon age populations by biasing affected zircon toward younger apparent ages. Chemical abrasion (CA) has been shown to reduce or eliminate the effects of Pb loss in zircon U–Pb geochronology but has yet to be widely applied to large-<span class="inline-formula"><i>n</i></span> detrital zircon analyses. Here, we assess the efficacy of the chemical abrasion treatment on zircon prior to analysis by LA-ICP-MS and discuss the advantages and limitations of this technique in relation to detrital zircon geochronology. We show that (i) CA does not systematically bias LA-ICP-MS U–Pb dates for 13 reference materials that span a wide variety of crystallization dates and U concentrations, (ii) CA-LA-ICP-MS U–Pb zircon geochronology can reduce or eliminate Pb loss in samples that have experienced significant radiation damage, and (iii) bulk CA prior to detrital zircon U–Pb geochronology by LA-ICP-MS improves the resolution of age populations defined by <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msup><mi/><mn mathvariant="normal">206</mn></msup><mi mathvariant="normal">Pb</mi><msup><mo>/</mo><mn mathvariant="normal">238</mn></msup><mi mathvariant="normal">U</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="57pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="0e7f0274f6f359dc8ea519812ebbfe44"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="gchron-6-89-2024-ie00001.svg" width="57pt" height="15pt" src="gchron-6-89-2024-ie00001.png"/></svg:svg></span></span> dates (Neoproterozoic and younger) and increases the percentage of concordant analyses in age populations defined by <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msup><mi/><mn mathvariant="normal">207</mn></msup><mi mathvariant="normal">Pb</mi><msup><mo>/</mo><mn mathvariant="normal">206</mn></msup><mi mathvariant="normal">Pb</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="63pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="4f76918bf46952e9a1d0aa2655ac0b4d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="gchron-6-89-2024-ie00002.svg" width="63pt" height="15pt" src="gchron-6-89-2024-ie00002.png"/></svg:svg></span></span> dates (Mesoproterozoic and older). The selective dissolution of zircon that has experienced high degrees of radiation damage suggests that some detrital zircon age populations could be destroyed or have their abundance significantly modified during this process. However, we did not identify this effect in either of the detrital zircon samples that were analyzed as part of this study. We conclude that pre-treatment of detrital zircon by bulk CA may be useful for applications that require increased resolution of detrital zircon populations and increased confidence that <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msup><mi/><mn mathvariant="normal">206</mn></msup><mi mathvariant="normal">Pb</mi><msup><mo>/</mo><mn mathvariant="normal">238</mn></msup><mi mathvariant="normal">U</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="57pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="a94b44ac17a21e8a00968d93dcdc8b6b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="gchron-6-89-2024-ie00003.svg" width="57pt" height="15pt" src="gchron-6-89-2024-ie00003.png"/></svg:svg></span></span> dates are unaffected by Pb loss.</p> |
| first_indexed | 2024-04-24T18:45:50Z |
| format | Article |
| id | doaj.art-eb9036dbc12d4924be5a698676702a10 |
| institution | Directory Open Access Journal |
| issn | 2628-3697 2628-3719 |
| language | English |
| last_indexed | 2024-04-24T18:45:50Z |
| publishDate | 2024-03-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Geochronology |
| spelling | doaj.art-eb9036dbc12d4924be5a698676702a102024-03-27T06:45:59ZengCopernicus PublicationsGeochronology2628-36972628-37192024-03-0168910610.5194/gchron-6-89-2024Minimizing the effects of Pb loss in detrital and igneous U–Pb zircon geochronology by CA-LA-ICP-MSE. E. Donaghy0M. P. Eddy1F. Moreno2M. Ibañez-Mejia3Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47907, United States of AmericaDepartment of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47907, United States of AmericaDepartment of Geosciences, University of Arizona, Tucson, AZ 85721, United States of AmericaDepartment of Geosciences, University of Arizona, Tucson, AZ 85721, United States of America<p>Detrital zircon geochronology by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) is a widely used tool for determining maximum depositional ages and sediment provenance, as well as reconstructing sediment routing pathways. Although the accuracy and precision of U–Pb geochronology measurements have improved over the past 2 decades, Pb loss continues to impact the ability to resolve zircon age populations by biasing affected zircon toward younger apparent ages. Chemical abrasion (CA) has been shown to reduce or eliminate the effects of Pb loss in zircon U–Pb geochronology but has yet to be widely applied to large-<span class="inline-formula"><i>n</i></span> detrital zircon analyses. Here, we assess the efficacy of the chemical abrasion treatment on zircon prior to analysis by LA-ICP-MS and discuss the advantages and limitations of this technique in relation to detrital zircon geochronology. We show that (i) CA does not systematically bias LA-ICP-MS U–Pb dates for 13 reference materials that span a wide variety of crystallization dates and U concentrations, (ii) CA-LA-ICP-MS U–Pb zircon geochronology can reduce or eliminate Pb loss in samples that have experienced significant radiation damage, and (iii) bulk CA prior to detrital zircon U–Pb geochronology by LA-ICP-MS improves the resolution of age populations defined by <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msup><mi/><mn mathvariant="normal">206</mn></msup><mi mathvariant="normal">Pb</mi><msup><mo>/</mo><mn mathvariant="normal">238</mn></msup><mi mathvariant="normal">U</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="57pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="0e7f0274f6f359dc8ea519812ebbfe44"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="gchron-6-89-2024-ie00001.svg" width="57pt" height="15pt" src="gchron-6-89-2024-ie00001.png"/></svg:svg></span></span> dates (Neoproterozoic and younger) and increases the percentage of concordant analyses in age populations defined by <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msup><mi/><mn mathvariant="normal">207</mn></msup><mi mathvariant="normal">Pb</mi><msup><mo>/</mo><mn mathvariant="normal">206</mn></msup><mi mathvariant="normal">Pb</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="63pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="4f76918bf46952e9a1d0aa2655ac0b4d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="gchron-6-89-2024-ie00002.svg" width="63pt" height="15pt" src="gchron-6-89-2024-ie00002.png"/></svg:svg></span></span> dates (Mesoproterozoic and older). The selective dissolution of zircon that has experienced high degrees of radiation damage suggests that some detrital zircon age populations could be destroyed or have their abundance significantly modified during this process. However, we did not identify this effect in either of the detrital zircon samples that were analyzed as part of this study. We conclude that pre-treatment of detrital zircon by bulk CA may be useful for applications that require increased resolution of detrital zircon populations and increased confidence that <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msup><mi/><mn mathvariant="normal">206</mn></msup><mi mathvariant="normal">Pb</mi><msup><mo>/</mo><mn mathvariant="normal">238</mn></msup><mi mathvariant="normal">U</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="57pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="a94b44ac17a21e8a00968d93dcdc8b6b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="gchron-6-89-2024-ie00003.svg" width="57pt" height="15pt" src="gchron-6-89-2024-ie00003.png"/></svg:svg></span></span> dates are unaffected by Pb loss.</p>https://gchron.copernicus.org/articles/6/89/2024/gchron-6-89-2024.pdf |
| spellingShingle | E. E. Donaghy M. P. Eddy F. Moreno M. Ibañez-Mejia Minimizing the effects of Pb loss in detrital and igneous U–Pb zircon geochronology by CA-LA-ICP-MS Geochronology |
| title | Minimizing the effects of Pb loss in detrital and igneous U–Pb zircon geochronology by CA-LA-ICP-MS |
| title_full | Minimizing the effects of Pb loss in detrital and igneous U–Pb zircon geochronology by CA-LA-ICP-MS |
| title_fullStr | Minimizing the effects of Pb loss in detrital and igneous U–Pb zircon geochronology by CA-LA-ICP-MS |
| title_full_unstemmed | Minimizing the effects of Pb loss in detrital and igneous U–Pb zircon geochronology by CA-LA-ICP-MS |
| title_short | Minimizing the effects of Pb loss in detrital and igneous U–Pb zircon geochronology by CA-LA-ICP-MS |
| title_sort | minimizing the effects of pb loss in detrital and igneous u pb zircon geochronology by ca la icp ms |
| url | https://gchron.copernicus.org/articles/6/89/2024/gchron-6-89-2024.pdf |
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