Experimental Pb isotope studies of cassiterite from Hnilec granite, Slovakia

摘要

Quantitative experiments on cassiterites from the greisen in Hnilec Granite (Slovakia) were undertaken to investigate the leaching behaviour of lead and distribution of lead isotopes between included phases and the host mineral. Disentangling non-equ8ilibrium leads contributed by mineral inclusions from that bound in the cassiterite lattice and achieving a quantitative uptake of lead is crucial for obtaining high quality isotope data for age dating. An improvement in sample processing which overcomes the difficulty of dissolving cassiterite and methods for assessing the influence from non-equilibrium leads using chemical digestion procedures and direct reduction to tin metal in a radio frequency induction furnace are presented. Potential non-equilibrium leads can be identified and excluded from the data by combining the two methods. Application of these methods should improve the potential for using cassiterite to directly date ore deposits. A late Variscan age is indicated from the preliminary data.