  We report on a trapped atom interferometer based on Bragg diffraction and
Bloch oscillations with alkaline-earth-metal atoms. We use a Ramsey-Bord\'e
Bragg interferometer with $^{88}$Sr atoms combined with Bloch oscillations to
extend the interferometer time. Thanks to a long coherence time for Bloch
oscillations of $^{88}$Sr atoms, we observed interference up to 1 s evolution
time in the lattice. A detailed study of decoherence sources during the Bloch
phase is also presented. While still limited in sensitivity by lattice lifetime
and beam inhomogeneity this result opens the way to high contrast trapped
interferometers with extended interrogation time.
