A system includes a turbine combustor that includes a head end portion having a head end chamber, a combustion portion having a combustion chamber disposed downstream from the head end chamber, a cap disposed between the head end chamber and the combustion chamber, and a flow separator configured to separate a first exhaust flow from an oxidant flow. The flow separator is configured to direct the first exhaust flow into the head end chamber. The turbine combustor also includes a mixing region configured to mix the first exhaust flow with the oxidant flow to provide an oxidant-exhaust mixture.