Page 5 - muehlberger1954
P. 5


                       The  date  of the  folding  and metamorphism of the  Pelona  schist

           is not known,  but it assuredly is  pre-Tertiary.  Tertiary rocks  have

           been  either  tilted or deformed into  broad open folds,  although locally

           near  the  major  faults  nearly isoclinal folds  are  found.        Almost with-

           out  exception,  these  folds  plunge  to  the  west or  southwest.

                       The  numerous faults  are the most prominent  structural

          features  of the Soledad basin.        Normal  faults  which trend generally

           east were  formed in post-Martinez,  pre-Vasquez time.                Displacements

           occurred throughout Vasquez time  and ceased prior to  Tick Canyon

          time.     The  Pelona fault may have  been  reactivated just prior to  Mint

          Canyon time.  Offsets on these  normal faults  are as much as  10,000  to

           15, 000  feet.  The normal  faults  indicate  that the  minimum compressive

           stress was  oriented nearly north-south.  On the  other hand,  the  post-

          Mint Canyon,  pre-Saugus  faults  indicate  a  maximum compressive

           stress oriented north-south,  which  resulted in a  number  of northeast-

          trending left-hand faults  with displacements  up to  10, 000  feet.  None  of

          the  faults  of the Soledad basin have  been  reactivated in  spite  of Pleisto-

          cene and Recent offsets along the  San Andreas  fault.
   1   2   3   4   5   6   7   8   9   10