Fracture study of the Paleozoic bedrock in a portion of east-central Indiana

Regional fracture patterns were determined from 2,419 fracture measurements collected from 11 quarries in a portion of East-Central Indiana. When the entire study area was considered, three orthogonal fracture systems were evident. The master system appeared at every station andhad fracture sets striking from N17W to N6W and N85E to N68E. The secondary systems were more inconsistent in respect to their appearance from quarry to quarry and had fracture sets striking approximately N45W and N48E, and N75W and N20E, respectively. The fractures were vertical or nearly so and were interpreted as being extensional in nature.The regional fracture patterns became apparent after data from several quarry walls, including fractures of varying persistence and intensity, were considered in combined plots for each data collection site.Suggested major mechanisms of fracturing include: 1) warping of the Cincinnati Arch, 2) the propagation of pre-existing joints in the basement rock upward into younger material, 3) the release of older residual stresses by the production of positive structural relief with associated erosional unloading, and 4) recent compressive stresses caused by the same mechanism that drives sea-floor spreading.Ball State UniversityMuncie, IN 47306Thesis (M.S.)--Ball State University, 1978