Sur les invariants d'Iwasawa des \Z_p^*/+-1-extensions
  In this paper we give bounds for the Iwasawa invariants of the Igusa tower of curves investigated by Mazur and Wiles. We give an upper bound for the mu invariants and a lower bound for the sum of the lambda invariants, in terms of the genus and number of supersingular points of the base curve. 
Marc Perret, Nicolas Saby