  We study novel electronic properties of the Hubbard model on a triangular
lattice using the cellular dynamical mean-field theory. The interplay of strong
geometric frustration and electron correlations causes a Mott transition at the
Hubbard interaction $U/t=10.5$ and an unusual suppression of low energy spin
excitations. Doping of a triangular Mott insulator leads to a quasiparticle
peak (no pseudogap) at the Fermi surface and to an unexpected increase of low
energy spin excitations, in stark contrast to the unfrustrated square lattice
case. The present results give much insight into strongly frustrated electronic
systems. A few predictions are made.
