Abstract: Fault and Joint Measurements in Austin Chalk, Superconducting Super Collider Site, Texas
H. S. Nance, S. E. Laubach, A. R. Dutton
Structure maps of 9.4 mi of nearly continuous tunnel excavations and more than 10 mi of other exposures and excavations in Austin Chalk at the Superconducting Super Collider (SSC) site in Ellis County, Texas, record normal-fault and joint populations in the subsurface within the northern segment of the Balcones fault zone with unmatched resolution for such a long traverse. Small faults (<10 ft net slip) occur in clusters or swarms that have as many as 24 faults. Fault swarms are as much as 2000 ft wide, and spacing between swarms ranges from 800 to 2000 ft, averaging about 1000 ft. Predominantly northeast-trending joints are in swarms spaced 500 to more than 21,000 ft apart.
AAPG Search and Discovery Article #90983©1994 GCAGS and Gulf Coast SEPM 44th Annual Meeting, Austin, Texas, October 6-7, 1994