  We explore to what extent the relation between the absolute continuous
spectrum and non-existence of subordinate generalized eigenvectors, known for
scalar Jacobi operators, can be formulated also for block Jacobi operators with
$d$-dimensional blocks. The main object here which allows us to make some
progress in the above direction is the new notion of the barrier
nonsubordinacy. We prove that the barrier nonsubordinacy implies the absolute
continuity for block Jacobi operators, thus it can be treated as a partial
generalization of the non-existence of subordinate solutions. We also present
an example showing that the reverse implication in general does not hold.
Finally, we extend to $d \geq 1$ some well-known $d=1$ conditions guaranteeing
the absolute continuity and we give applications of our results to some
concrete classes of block Jacobi matrices.
