High-spin states and collective oblate bands in Nd139

High spin states in Nd139 nucleus have been reinvestigated with the reaction Te128 (O16, 5n) at a beam energy of 90 MeV. The level scheme has been expanded with spin up to 47/2. At low spin, the yrast collective structure built on the νh11/2-1 multiplet shows a triaxial shape with γ≈32° according to calculations of the triaxial rotor-plus-particle model. The configurations for some high spin states have been discussed from a systematic comparison with neighboring nuclei. Three collective oblate bands with γ≃60° at high spin were identified for the first time. A band crossing is observed around ω∼0.4 MeV in one oblate band based on the 25/2- level. The characteristics for these oblate bands have been discussed.