Fluid-induced magmatic and post-magmatic zircon and monazite patterns in granitoid pluton and related rhyolitic bodies

Hydrothermal alteration of chevkinite-group minerals: products and mechanisms. Part 1. Hydration of chevkinite-(Ce)

“…Similar textures, evidence of element mobility, low oxide and cation totals and the development of porosity, similar to those found in this study, have been recorded in many studies of the alteration of accessory minerals (Poitrasson, 2002;Poitrasson et al, 2002;Jiang, 2006;Vlach and Gualda, 2007;Nasdala et al, 2009;Ruschel et al, 2010;Lisowiec et al, 2013) and have most commonly been ascribed to hydrothermal alteration. We adopt a similar explanation here.…”

“…A further common feature is that the alteration is characterized by low analytical totals, which may indicate water incorporation during the process, the appearance of vacancies in certain sites and the development of porosity as numerous (sub-)micrometre sized voids (e.g. Poitrasson, 2002;Poitrasson et al, 2002;Jiang, 2006;Vlach and Gualda, 2007;Berger et al, 2008;Nasdala et al, 2009;Ruschel et al, 2010;Lisowiec et al, 2013). However, in the majority of unaltered areas, the sum of cations is in the range 13.0-13.3, close to the stoichiometric value of 13.0, which we consider to be of acceptable quality for this phase, especially as the cation sums would be lowered if some Fe 2+ were recalculated as Fe 3+ .…”

“…We adopt a similar explanation here. Several recent studies have invoked a coupled dissolution-reprecipitation process to explain the compositional variations during alteration, whereby the reactive fluid acts as a catalyst leading to the mineral phase being replaced either by a new composition of the same phase or by an entirely different phase (Putnis, 2002(Putnis, , 2009Harlov et al, 2011;Lisowiec et al, 2013). The process is coupled in that the dissolution and reprecipitation rates must be the same, such that the two phases are separated by only a thin fluid film with a thickness normally on the sub-micrometre scale.…”

“…Over the past two decades, many studies have been made of the low-temperature alteration of accessory minerals, the main carriers of the REE, actinides and HFSE in most rocks, including allanite (Poitrasson, 2002;Berger et al, 2008), britholite (Arden and Halden, 1999), fergusonite (Ercit, 2005;Tomašićet al, 2006;Uher et al, 2009;Ruschel et al, 2010), monazite (Berger et al, 2008;Seydoux-Guillaume et al, 2007Lisowiec et al, 2013), titanite (Hawthorne et al, 1991;Pan et al, 1993) and zircon (Aines and Rossman, 1986;Geisler et al, 2001Geisler et al, , 2002Rubin et al, 1989;Nasdala et al, 2009Nasdala et al, , 2010Lisowiec et al, 2013). Such studies have shown that that there is a large range of alteration mechanisms and that the efficiency and products of the hydrothermal alteration of accessory minerals depend on several factors, including temperature, whole-rock texture and composition and fluid composition, particularly the relative proportions of H 2 O, CO 2 and F.…”

Concordant U–Pb SHRIMP ages of U-rich zircon in granitoids from the Muruntau gold district (Uzbekistan): Timing of intrusion, alteration ages, or meaningless numbers

“…However, the situation appears ambiguous when hydrothermal formation or reequilibration of zircon cannot be excluded a priori (Fu et al, 2009;Kusiak et al, 2009;Lisowiec et al, 2013). Such processes may further complicate the U-Pb system of single crystals in addition to the common occurrence of old cores overgrown by younger magmatic rims.…”