Masters Theses

Date of Award

6-1981

Degree Type

Thesis

Degree Name

Master of Science

Major

Geology

Major Professor

G. Michael Clark

Committee Members

Don W. Byerly, J. B. Rehder

Abstract

Photogeologic fracture trace and lineament mapping and analysis in the Wartburg Basin reveals important new information on the nature of fracturing in this area.

Fracture traces and lineaments were mapped on ASCS black and white panchromatic aerial photographs and NASA high altitude color infrared imagery. To check the accuracy of the linear feature map, bedrock joint orientations measured at eighteen field sites were compared to histograms of photogeologic linear feature orientations surrounding each site. Similarities were found to exist between a number of the histograms. Dissimilar histograms were probably a result of either limited bedrock exposure or low photogeologic fracture density for that area.

Examples of alignments in soils, vegetation and topographic-erosional features were examined in the field. The soil fracture trace was composed of a dark alignment of soil with a dark green, lush vegetation covering. The alignment of vegetation consisted of a line of moisture-loving, dark-colored hemlock trees, probably due to groundwater seepage associated with a zone of bedrock fractures. For field sites containing erosional alignments which crossed bedrock exposures, strike maxima of bedrock joint histograms corresponded closely to the orientation of the photogeologic linear features.

The photogeologic linear feature map was analyzed by contouring fracture frequency (similar to fracture density) for two quadrangles. A comparison of the fracture frequency maps to geologic maps shows that, in general, photogeologic fracture density increases on the flanks and noses of folds where maximum folding has occurred. Fracture density was the lowest in areas where extensive strip mining and alluvium have obscured the photogeologic linear features.

To summarize the orientation data, histograms of lineament and fracture trace orientations were drawn across the study area. Using local fold axes in the eastern part of the study area as a reference, fractures appear to have originated from both tension and shear stress with tension fractures forming the largest class.

Data collected during this study indicate that photogeologic linear features can be used in this area not only for locating zones of increased fracture density reflected by individual fracture traces but also for locating local gentle folds. In unmapped areas of the Wartburg Basin, this technique might be useful for locating oil-bearing structures.

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