apparently fault breccia is a cataclasite, which are cemented rocks. However, my notes say that fault breccia consists of angular fragments set in an un-cemented matrix of wall-rock material.
Pressure is the key factor in the formation of a fault breccia. The term breccia is used to describe the coarser grained types. Much finer fault zone rocks are actually clay sized particles. These can be lithified by pressure (no cement). Mylonites would be an example. Perhaps the rocks in question are a combination of the two. (?)
