Simultaneous resetting of the muscovite K-Ar and monazite U-Pb geochronometers: a story of fluids
Abstract
Although water is ubiquitous in the continental crust, its effect on geochronometers through mineral reequilibration is rarely taken into account. Herein, we present 40Ar/39Ar analyses on muscovite and U-Pb isotopic data on zircon and monazite from a Variscan syn-tectonic granite from western France. Both the K-Ar in the muscovite and U-Pb in the monazite isotopic systems were hydrothermally reset, whereas the U-Pb radiogenic system in most of the zircons was unaffected and dates the granite emplacement age. Titanium chemical maps obtained on muscovites from various dated samples display a spectacular overprinting of their magmatic zoning resulting from increasing fluid-rock interaction. These results reiterate the need to combine geochronological data with petrological, mineralogical and geochemical studies to accurately interpret ages obtained in this type of geodynamical settings.
Domains
Earth Sciences
Origin : Files produced by the author(s)
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