| Scope and method of study. This study is aimed at gaining a better understanding of the complexity of natural fracture systems within the orogenic foreland of the Ouachita thrust belt. To do this, four localities, in central and north Texas, within the Ordovician-Pennsylvanian limestone units were chosen to study the fractures in the surface using classic field methods. They are (1) Possum Kingdom Lake; (2) Lake Brownwood Spillway; (3) Bend River; (4) Archer Ranch.; Findings and conclusions. Two prominent sets were found: (1) an east-west set attributed to Ouachita tectonism, and (2) a northeast-southwest set attributed to the opening of the Gulf of Mexico. Fracture orientations obtained from outcrop were compared to subsurface data from Formation Micro Imaging logs. Orientations from both fracture sets were similar, and therefore correlative in regards to their origin and cross-cutting relationships. This correlation will help in understanding the complexity and regional extent of fracture systems formed by both compressive and extensional forces. |
