APPLICATIONS OF GOOGLE EARTH PRO© TO FAULT AND FRACTURE STUDIES OF LARAMIDE ANTICLINES IN THE ROCKY MOUNTAIN FORELAND

Google Earth Pro© (GEP) imagery was used by graduate students for a course project to identify, describe, and interpret fracture and fault patterns on two oil-producing anticlines in the northwestern Wind River Basin (Circle Ridge and Maverick Springs) and Thermopolis anticline in the southern Bighorn Basin, Wyoming. Using scales of observation that encompassed each structure, lineaments were mapped on images of the anticlines using the “path” tool in GEP and measured for length and orientation (heading) using the “ruler” tool; all measurements were recorded on a separate Excel spreadsheet. Orientation data were then plotted as rose diagrams and on stereonets using RockWare Stereostat© software and analyzed in terms of geometry, spatial distribution (fracture sets) and kinematic compatibility with respect to the overall structure. The various joint sets were classified based on their orientation with respect to the axial surface trace: fractures that varied >5° from a line orthogonal to the hinge line were classified as A-C; those that were parallel to (or within 5°) of the hinge line were classified as B-C; conjugate fractures were defined where two fractures crossed with an acute angle near 60° on the limbs; and fractures that were neither parallel nor perpendicular to the fold axis were classified as oblique. Our GEP geometric analysis, coupled with ground-truthing and kinematic measurements, suggests that the regional shortening direction was NE-SW, which is in agreement with published estimates of the regional Laramide shortening. In addition, these anticlines are proximal to the Owl Creek fault system which is a sinistral, basement-involved, transpressive array of en echelon thrust blocks; the fracture orientation results of our study are compatible with overall oblique sinistral shear along the western Owl Creek uplift. This project demonstrates that GEP is an excellent platform for remote mapping of structural lineaments and joints, particularly when coupled with ground-based measurements of kinematic data on fracture surfaces. Geometric data derived from GEP imagery is particularly useful for understanding the spatial distribution and compartmentalization of fractures at various stratigraphic levels as, for example, in the study of fractured petroleum reservoir rocks.