  We determine the quark condensate and the dressed Polyakov loop from the
finite temperature Landau gauge quark propagator evaluated with U(1)-valued
boundary conditions in an approximation to quenched QCD. These gauge invariant
quantities allow for an investigation of the chiral and deconfinement
transition. We compare results from Dyson-Schwinger equations on a lattice with
infinite volume continuum results and study the temperature and quark mass
dependence of both quantities. In particular we investigate the chiral
condensate and the dressed Polyakov loop in the chiral limit. We also consider
an alternative order parameter for the deconfinement transition, the dual
scalar quark dressing, and compare with the dressed Polyakov loop. As a result
we find only slightly different transition temperatures for the chiral and the
deconfinement transition at finite quark masses; in the chiral limit both
transitions coincide.
