Flower Structures and Wrench Fault Tectonics
G. P. Bolden
Bolden Exploration, Midland, Texas
Shear stress and strain tectonics causes development of flower structures. Parallel Conjugate Riedel Shears west of Dryden, Texas in Terrell County, Texas are only 700 ft apart and have a rotation of 22o clockwise on a small hill. There is a fracture system 355o T that has rotated and formed a flower structure. One of the faults has 28 ft horizontal right lateral displacement. The area is highly wrench faulted, and 6 miles east is a Conjugate Riedel Shear with 2728 ft horizontal displacement with a maximum of 11 ft throw. Four miles southwest is a railroad cut with an overturned Cretaceous Buda bed and well exposed wrench faulting.
The Anacacho Mountains 6 miles east of Spofford in Kinney County, Texas are extensively wrench faulted with a 1/2 mile diameter negative flower structure.
In Terrell County, Texas there is a very prominent double Primary shear that makes a 25o direction change and a negative flower structure forms at the direction change. There is a much larger rotation.
In Shackelford, Stephens, Throckmorton and Young Counties there are some very large rotations along the Clear Fork of the Brazos River that may be three miles in diameter. There are circular fractures and/or faults in the area on the surface. I have studied the high altitude photography of over 700 sections and field checked much of it. It is extensively wrench faulted and has curved oil fields.
AAPG Search and Discovery Article #90905©2001 AAPG Southwest Section Meeting, Dallas, Texas