  A local classification of spacelike surfaces in Minkowski 4-space, which are
invariant under spacelike rotations, and with mean curvature vector either
vanishing or lightlike, is obtained. Furthermore, the existence of such
surfaces with prescribed Gaussian curvature is shown. A procedure is presented
to glue several of these surfaces with intermediate parts where the mean
curvature vector field vanishes. In particular, a local description of
marginally trapped surfaces invariant under spacelike rotations is exhibited.
