OUTCROP-SCALE STUDY OF THE PERMIAN BONE SPRING FORMATION, BONE SPRING CANYON, GUADALUPE MOUNTAINS, TEXAS: FRACTURE CHARACTERIZATION

Abstract

A light detection and ranging- (LiDAR) focused outcrop study was conducted on Upper Leonardian Bone Spring limestone in the Bone Canyon, Delaware Basin of West Texas. LiDAR technology is very useful in modeling fracture systems from outcrop data. It provides several advantages such as accessibility to regions where hand measurements are not possible, a greater density of data, and a convenient PC-powered platform for interpretation. Using LiDAR data, a population of 7449 fracture planes was delineated and characterized. Fracture planes represented 3 major sets: E-W trending Fracture Set-1, N-S trending Fracture Set-2, and NE-SW trending Fracture Set-3. Fracture sets were used to delineate stress fields within the Bone Canyon. Fracture Set-1 is more systematic (containing closely spaced fractures and is characterized with uniform strikes) and older corresponding to a N-S sigma 3. Fracture Set-2 and Set-3 is less systematic (containing variably spaced fractures and is characterized with less uniform strike) and are younger corresponding to present day stress field that corresponds to a general E-W and NW-SE sigma 3, respectively. Statistics of fractures planes across rock units on the north and south canyon walls showed some variations indicating that parameters such as bed thickness and bedding pattern (whether a rock unit is thinly or thickly bedded) can influence the distribution of fractures, their density, and intensity. The north wall has an average fracture density of 2.6 fractures/m2 while the south wall has an average fracture density of 1.23 fracture/m2.