  We uncover a novel mechanism for inducing a gapful phase in interacting
many-body quantum chains. The mechanism is nonperturbative, being triggered
only in the presence of both strong interactions and strong aperiodic
(disordered) modulation. In the context of the critical antiferromagnetic
spin-1/2 XXZ chain, we identify an emerging dimerization which removes the
system from criticality and stabilizes the novel phase. This mechanism is shown
to be quite general in strongly interacting quantum chains in the presence of
strongly modulated quasiperiodic disorder which is, surprisingly,
perturbatively irrelevant. Finally, we also characterize the associated quantum
phase transition via the corresponding critical exponents and thermodynamic
properties.
