Fractures and surface lineaments in northeastern Utah

This investigation was an attempt to determine the relation­ ships among the orientations of surface lineaments that appear on space-satellite imagery, the orientations of fractures in rock out­ crops, and the state of stress of an area. The procedure was: 1) to construct the lineament map from lineament data taken from space- satellite imagery and from topographic relief maps; 2) to construct the orientation-frequency diagram of the lineament data, and statistically analyze the data using a standard x2 test for goodness of fit and the "Tukey x2 test"; 3) to gather fracture data from measurements at 93 outcrop stations and two "statistic" outcrop stations; 4) to construct equal-area net diagrams and orientation- frequency diagrams of the fracture data, and statistically analyze the data using the tests escribed in 2) plus a test using the cumulated terms of the Poisson Exponential Binomial Limit; 5) to compare the areal relationships between the strike directions of lineaments and those of fractures; 6) to try to find any statisti­cally significant orientations and/or coherent patterns of fractures and lineaments from the above analyses, and apply the theory of the relationship between stress directions and fracture orientations (fracture theory) to the fracture and lineament data to help interpret the state of stress of the area.From this analysis of lineament data of northeastern Utah, I conclude that while the lineament data are nonrandomly oriented (statistically) and while preferred directions of lineaments may exist, any coherent patterns of lineaments that may be of tectonic significance are virtually lost in the noise" of apparently random directions. The analysis of fracture data of northeastern Utah shows that the strike directions are generally randomly oriented and the dips concentrate at relatively high angles. Also the comparison of fracture and lineament data shows that there appears to be no clear correlation between the orientations of fractures and those of lineaments, that is, some lineaments probably are frac­ture related while others are not. Therefore, this work has failed to produce any clear relationships among orientations of lineaments on space-satellite imagery, orientations of rock fractures, and regional state of stress. In view of the amount of data gathered, the deliberately con­ servative procedure of analysis, and a geotectonic situation in northeastern Utah that would appear to be ideal for development of coherent lineament patterns, this work appears to cast a modicum of doubt on the procedures used in much of the lineament work done from space-satellite imagery found in present (1970-1975) literature. It is, therefore, the conclusion of this thesis that a re-evaluation of the current data gathering and analysis procedures as well as the fundamental basis for the interpretation of lineament patterns is necessary.