  We study the disordered XYZ spin chain using the recently developed Spectrum
Bifurcation Renormalization Group (SBRG) numerical method. With strong
disorder, the phase diagram consists of three many body localized (MBL) spin
glass phases. We argue that, with sufficiently strong disorder, these spin
glass phases are separated by marginally many-body localized (MBL) critical
lines. We examine the critical lines of this model by measuring the
entanglement entropy and Edwards-Anderson spin glass order parameter, and find
that the critical lines are characterized by an effective central charge
c'=ln2. Our data also suggests continuously varying critical exponents along
the critical lines. We also demonstrate how long-range mutual information can
distinguish these phases.
