Strontium distribution and origins in a natural clayey formation (Callovian-Oxfordian, Paris Basin, France): a new sequential extraction procedure C. Lerouge a, *, E.C. Gaucher a , C. Tournassat a , P. Negrel a , C. Crouzet a , C. Guerrot a , A. Gautier a , P. Michel a , A. Vinsot b , S. Buschaert c a BRGM, BP36009, 45060 Orléans Cédex 2, France b ANDRA, Meuse/Haute-Marne Underground Research Laboratory (URL), RD 960, 55290 Bure, France c ANDRA, Scientific Management, 1-7 Rue Jean-Monnet, 92298 Châtenay-Malabry Cedex, France * Corresponding author. E-mail address: c.lerouge@brgm.fr (C. Lerouge) Final version January 2010 1 hal-00552939, version 1 - 6 Jan 2011 Author manuscript, published in "Geochimica et Cosmochimica Acta 74, 10 (2010) p. 2926-2942" DOI : 10.1016/j.gca.2010.02.013