Experimental alteration of monazite in granitic melt: Variable U–Th–Pb and REE mobility during melt-mediated coupled dissolution-precipitation
| dc.contributor.author | Varga, J. | |
| dc.contributor.author | Raimondo, T. | |
| dc.contributor.author | Daczko, N.R. | |
| dc.contributor.author | Adam, J. | |
| dc.date.issued | 2020 | |
| dc.description.abstract | Monazite U–Th–Pb geochronology of high-temperature and melt-bearing metamorphic rocks sometimes produces a continuum of concordant ages (‘smear’) without well-defined age populations. In combination with textural and geochemical criteria, these datasets are typically interpreted to infer either variable Pb-loss between two discrete events or protracted metamorphism lasting >50 Myr. We experimentally react monazite with granitic melt (0.7 GPa and 750 °C) to produce a range of complex monazite textures and age patterns similar to those found in natural high-temperature rock samples. Our observations show that within a short duration (≤24 h experiment time), variable REE, Y, Th, U and Pb mobility is achieved via coupled dissolution-precipitation in a melt-bearing system. An ultra-local interface melt is saturated in dissolved components, including the U–Th–Pb isotopic character of the original monazite, such that newly precipitated monazite may copy or partly inherit the age of a precursor grain. This implies that monazite grown via coupled dissolution-precipitation may not faithfully record the age or duration of metamorphism in melt-bearing rocks typical of a variety of geodynamic settings. | |
| dc.description.statementofresponsibility | Jan Varga, Tom Raimondo, Nathan R.Daczko, John Adam | |
| dc.identifier.citation | Chemical Geology, 2020; 544:1-16 | |
| dc.identifier.doi | 10.1016/j.chemgeo.2020.119602 | |
| dc.identifier.issn | 0009-2541 | |
| dc.identifier.issn | 1872-6836 | |
| dc.identifier.orcid | Raimondo, T. [0000-0001-9115-9196] | |
| dc.identifier.uri | http://hdl.handle.net/2440/126941 | |
| dc.language.iso | en | |
| dc.publisher | Elsevier | |
| dc.relation.grant | http://purl.org/au-research/grants/arc/DP160103449 | |
| dc.rights | © 2020 Elsevier B.V. All rights reserved. | |
| dc.source.uri | https://doi.org/10.1016/j.chemgeo.2020.119602 | |
| dc.subject | Monazite; experimental petrology; U–Th–Pb; coupled dissolution-precipitation; metamorphism | |
| dc.title | Experimental alteration of monazite in granitic melt: Variable U–Th–Pb and REE mobility during melt-mediated coupled dissolution-precipitation | |
| dc.type | Journal article | |
| pubs.publication-status | Published |