I collected this in the mid-1970s in the Rincon Mountain area, while working on metamorphic core complexes. I like the fact that the gory details of fault attributes are disclosed, revealing so clearly that faults are not simple ‘straight lines’ that neatly cut and displace ‘neat layers.’
Original limestone and chert were metamorphosed to a calc-silicate rock, probably during the mid-Tertiary. Deformation of these rocks included both folding and faulting. What is striking about this rock is the preservation of discrete faults that offset a conspicuous ‘microstratigraphy.’ This is the kind of structural system that can be retrodeformed in ways to recreate the original unfaulted relationships, and thus to provide a clear sense of nature and amount of shortening or extension.
Age & Formation
Horquilla Formation of Pennsylvanian age, ~320 Ma.