Varga, J.Raimondo, T.Daczko, N.R.Adam, J.2020-08-112020-08-112020Chemical Geology, 2020; 544:1-160009-25411872-6836http://hdl.handle.net/2440/126941Monazite 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.en© 2020 Elsevier B.V. All rights reserved.Monazite; experimental petrology; U–Th–Pb; coupled dissolution-precipitation; metamorphismJournal article100002112510.1016/j.chemgeo.2020.1196020005371997000042-s2.0-85084594065532730Raimondo, T. [0000-0001-9115-9196]