We show that a topological gauge structure in an e ective description of the t-J model gives rise to a global phase diagram of antiferromagnetic (AF) and superconducting (SC) phases in a weakly doped regime. Dual confinement and deconfinement of holons and spinons play essential roles here, with a quantum critical point at a doping concentration xc≃0.043. The complex experimental phase diagram at low doping is well described within such a framework.