Abstract: Orientations of crustal stresses are inferred from stressinduced breakouts (well bore enlargements) in the eastern part of the Anadarko basin in central Oklahoma, the Marietta basin in south-central Oklahoma, and the Bravo dome area of the central Texas Panhandle. Inferred directions of maximum horizontal principal stress (SHmax) are east-northeast for the eastern Anadarko basin and northeast for the Marietta basin and the Bravo dome area. The relative magnitudes of the three principal stresses (S,, S2, S3) are known for the Bravo dome area from existing hydraulic-fracturing measurements, and a normal-faulting stress regime (Sv>SHmax >SHmIn) is implied. For the eastern Anadarko basin and the Marietta basin, the magnitudes of the principal stresses are not known. Possible left-lateral oblique slip on the Meers fault during the Quaternary implies that strike-slip (SHmax >Sv>SHmln) and reverse (SHmax

SHmln >Sv) faulting has occurred in south-central Oklahoma. Thus, the study region may be a transition zone between extensional stress in the Texas Panhandle and compressional stress in Oklahoma. Breakout data from the eastern Anadarko basin yield a single consistent SHmax orientation, whereas data from the Marietta basin and the Bravo dome area yield bimodalorthogonal distributions believed to consist of northwestoriented breakouts and northeast-oriented fracture-related wellbore enlargements. This northeast (orthogonal) trend in data from the Marietta basin and the Bravo Dome area is probably related to drilling-induced hydraulic fracturing of the wellbore or to preexisting natural fractures or joint sets intersecting the wellbore. On dipmeter log records, breakouts and fracture-related enlargements have similar elliptical cross sections. Orthogonally oriented breakout and fracturerelated wellbore enlargements are therefore differentiated by comparing their long-axis orientations with directions of known or inferred horizontal stress. The mean orientations of either the breakout or fracturerelated orthogonal trends in the Marietta basin and the Bravo dome area data sets are not as well constrained as the mean orientation of breakout data for the eastern Anadarko basin. Poorly constrained mean orientations give the appearance of data scatter or dispersion among wellbore enlargement orientations within the northwest and northeast bimodalorthogonal trends. Drill holes in the Marietta basin and Bravo dome area are located primarily between northwest-striking subparallel faults. Mean data orientations calculated for either orthogonal trend for individual well data sets appear to rotate counterclockwise across these two fault-bounded study areas. Stress trajectory rotation between suparallel faults within the Marietta basin and the Bravo dome study areas may account for the data scatter. Although breakouts and fracture-related enlargements formed in all parts of the thick sequences of sedimentary rocks logged, they are primarily in limestone, shale, and dolomitic rock, p