Apatite laser ablation Lu-Hf geochronology: A new tool to date mafic rocks

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dc.contributor.authorKharkongor, M.B.K.
dc.contributor.authorGlorie, S.
dc.contributor.authorMulder, J.
dc.contributor.authorKirkland, C.L.
dc.contributor.authorChew, D.
dc.contributor.authorKohn, B.
dc.contributor.authorSimpson, A.
dc.date.issued2023
dc.descriptionAvailable online 13 July 2023
dc.description.abstractMafic rocks are the most common type of igneous rocks on Earth, however, constraining the crystallization age of mafic rocks can be challenging. Apatite is a common accessory phase in mafic rocks and is amenable to dating using the U–Pb system. However, the U–Pb system in apatite has a relatively low closure temperature (~350◦- 550 ◦C) and is therefore prone to resetting by later thermal and metasomatic events. Here, a recently developed Lu–Hf dating method using laser ablation reaction-cell mass spectrometry is applied to apatite from mafic rocks. The Lu–Hf system in apatite has a higher closure temperature (~650◦-750 ◦C) compared to U–Pb, increasing the chances of obtaining primary crystallization ages. Furthermore, the laser-ablation method allows rapid data collection compared to traditional solution-based Lu–Hf dating techniques. Four study areas were selected to compare the Lu–Hf vs U–Pb systematics of apatite in mafic igneous rocks: the Paleoproterozoic Sudbury Igneous Complex (Canada), the Neoproterozoic Borborema Province (NE Brazil), the Paleoproterozoic Fennoscandian Shield (Finland), the Archean Yilgarn Craton and adjacent Mesoproterozoic Albany Fraser Orogen (Western Australia). For all analyzed samples that have apatite trace element compositions typical of an undisturbed primary mafic igneous lithology, the Lu–Hf system retains primary igneous apatite crystallization ages, whereas the U–Pb system in the same grains often records isotopic disturbance or a cooling age. In few cases, the Lu–Hf system has also been disturbed in response to recrystallization, however, such disturbance is readily detected e potential of laser ablation apatite Lu–Hf dating to primary crystallization ages for otherwise difficult to date mafic rocks.
dc.description.statementofresponsibilityMelissa B.K. Kharkongor, Stijn Glorie, Jacob Mulder, Christopher L. Kirkland, David Chew, Barry Kohn, Alexander Simpson
dc.identifier.citationChemical Geology, 2023; 636:121630-1-121630-16
dc.identifier.doi10.1016/j.chemgeo.2023.121630
dc.identifier.issn0009-2541
dc.identifier.issn1872-6836
dc.identifier.orcidKharkongor, M.B.K. [0000-0001-5631-0719]
dc.identifier.orcidGlorie, S. [0000-0002-3107-9028]
dc.identifier.orcidSimpson, A. [0000-0001-6029-0116]
dc.identifier.urihttps://hdl.handle.net/2440/139129
dc.language.isoen
dc.publisherElsevier
dc.relation.granthttp://purl.org/au-research/grants/arc/DP200101881
dc.relation.granthttp://purl.org/au-research/grants/arc/FT210100906
dc.rights© 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
dc.source.urihttps://doi.org/10.1016/j.chemgeo.2023.121630
dc.subjectMafic rocks; apatite; U–Pb dating; Lu–Hf dating; LA-ICP-MS/MS; Closure temperature; recrystallisation
dc.titleApatite laser ablation Lu-Hf geochronology: A new tool to date mafic rocks
dc.typeJournal article
pubs.publication-statusPublished

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