RG,
That seems to be the situation for the Bradshaws. Don't understand why it was touted as such a big mystery, as the information is very easy to come by. "Bulletin 782: Ore Deposits Of The Jerome And Bradshaw Mountains Quadrangles, Arizona" can be found on the Internet, as well as:
The Daily Courier - Feb 24, 1995
"In the fairly recent past we have had mild earthquakes in Yavapai County, often unnoticed by residents. Waldemar Lindgren, the mining geologist who made a detailed study of the faults in Central Arizona, wrote that there were more ancient fractures in the Bradshaw Mountains than anywhere in the country. These fractures were filled with dikes of diabase, andesite and rhyolite, and were most certainly accompanied by violent earthquakes at the time."
Mystery solved!
Take care,
Joe Ribaudo