LIGHT DETECTION AND RANGING (LIDAR) USE TO DEVELOP AN ALTERNATE PROCEDURE TO CONDUCT FRACTURE ANALYSIS IN THE ROCHFORD QUADRANGLE, BLACK HILLS, SOUTH DAKOTA

The past procedure for fracture analysis in the Black Hills of South Dakota has required the hand collection of numerous measurements along fracture surfaces within the area of study. Technological advances have afforded the opportunity to develop advanced methods for collecting fracture data in the Black Hills. Terrestrial light detection and ranging (LiDAR) has opened the digital and 3-dimensional realms to geologic measurement collection and analysis. The Rochford Quadrangle consists of metamorphosed Precambrian volcanic and sedimentary units. The age of these units is approximately 1.87-1.97 Ga and 2.2 Ga. These units have been folded and overturned creating steep foliations. While these orientations are well documented, a detailed fracture analysis has yet to be performed in this quadrangle. By applying the descriptive fracture analysis techniques developed by Anderson (2002) a fracture analysis has been completed by collecting hand measurements at several locations. The use of a Leica Geosystems HDS3000 LiDAR scanner is then implemented to scan outcrops and a geoprocessing model is developed to extract measurement data from the scan data. This data is compared to determine the accuracy and precision of the LiDAR method. Should the LiDAR method for collecting geologic measurements prove fruitful there are several advantageous reasons to adopt this method. Collecting the data with the LiDAR system will take about the same amount of time as collecting data by hand. An advantage is that after data collection the data can be stored for future use. This provides the ability to analyze the scans any time in the future. The scans can be looked at repetitively as needed without the need to go into the field if weather, time, or costs are a problem. Finally, if this method is adopted for all data collection then a database can be built containing Black Hills data for future use of continuing studies.