Cooling pattern and mineralization history of the Saint Sylvestre and western Marche leucogranite pluton, French Massif Central: II. Thermal modelling and implications for the mechanisms of uranium mi

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• 作者：Scaillet ; S. ; Cuney ; M. ; le Carlier de Veslud ; C. ; Cheilletz ; A. ; Royer ; J. J.
• 刊名：Geochimica et Cosmochimica Acta
• 出版年：1996
• 出版时间：December, 1996
• 年：1996
• 卷：60
• 期：23
• 页码：4673-4688
• 全文大小：1.97 M

文摘

A two-dimensional (2-D) thermal modelling of the Saint Sylvestre--western Marche leucogranite complex (northwestern Limousin, French Massif Central, FMC) was conducted to help constrain the cooling history and the uranium mineralization postdating the time of intrusion by 40-50 m.y. Numerical simulation of the post-emplacement cooling of the complex (< 700&deg;C) indicates that the pluton thermally equilibrated with its country rocks (at around 360-400&deg;C and a mean depth of 10.5 km) by conduction in as little as 4 m.y. after its intrusion age (324 ± 4 Ma). Integration of the regional⁴⁰ Ar/³⁹Ar muscovite data in the 2-D model with an assumed universal Ar closure temperature of 325 ± 25&deg;C reveals several sub-stages in the subsolidus cooling of the complex. The cooling pattern regionally defined by the muscovite data indicates that cooling was driven by the extensional exhumation and erosion of the thickened crust (+ intrusion) at a mean denudation rate of 0.3 mm y⁻¹. Complete cooling below 325&deg;C ended at 301 Ma via a transient faster denudation rate of 1.5 mm y⁻¹ at the Westphalian-Stephanian boundary.