A variable turbine geometry turbine turbocharger (1) includes a vane pack (50) disposed in the exhaust gas path upstream of the turbine wheel (12). The vane pack (50) includes vanes (30) that are rotatably supported between a pair of vane rings (34) and configured to adjustably control the flow of exhaust gas to the turbine wheel (12). In addition, a retainer (60, 160) secures the vane pack (50) to the bearing housing (16) in such a way that the vane pack (50) is mechanically decoupled from the turbine housing (4).