Comparative use of TIMS and SHRIMP for U–Pb zircon dating of A-type granites and mafic tholeiitic layered complexes and dykes from the Corsican Batholith (France)

摘要: The Corsica-Sardinia batholith in the southern realm of Hercynian belt Europe shows evidence for gravitational collapse this part mountain belt, causing major felsic and mafic magmatism. latest intrusions are composed leucomonzogranite late metaluminous alkaline granite, associated with tholeiitic layered complexes dykes. Three dating methods on zircon (Pb-evaporation, ID-TIMS SHRIMP) were used to unravel chronology these rocks. Dating zircons by conventional U–Pb method, using TIMS after dissolution, achieved an analytical uncertainty 1 Ma favourable cases. Pb-evaporation technique resulted ages range 4 8 Ma. After 15 20 analyses SHRIMP a precision ranging from 2 5 was obtained (all at 2σ). three applied same population extracted four A-type granites, show that ranges within 2–5 according sample. This error seems correspond real geochronological can be achieved. The results all six tested granites emplaced during very short interval about 3–5 288 Ma, almost contemporaneous emplacement (291–287 Ma) ended formation. In addition, there is no significant gap age magmatism (around 286 crosscutting “A-type” granites. definitely do not up here as precursors Tethyan rifting began 170 i.e. some 100 their emplacement. It thus necessary examine if alternative hypotheses anorogenic model Younger Granite province better fit new data. A involving depleted continental-crust derived magma should compatible timing geodynamical constraints far isotopic data concerned.