The Determination of the Fracture Architecture and Deformational Behavior of the Fish Lake Valley Fault Zone, California: A Digital Approach Using Photorealistic Surface Mapping with Lidar.

摘要

Located in the Eastern California Shear zone (ECSZ), the Fish Lake Valley fault zone (FLVFZ) is a 250 km right-lateral fault and the longest active structure of the ECSZ. It offsets Pre-Cenozoic monzonite and metasediments and contains an estimated net displacement of 50 to 65 km. Just north of Death Valley, the FLVFZ passes through the Cucomungo Canyon Restraining Bend (CCRB), a step over 15 km wide. Recent uplift of the CCRB within the last million years has exposed Miocene and Pliocene deposits and internal structures of the fractures in the FLVFZ. The Mesozoic monzonites of the FLVFZ contain fault zones hundreds of meters wide consisting of alternating cataclasites and fractured rock. This work comprises a portion of the Miles Project, a multidisciplinary project implementing field mapping, Geophysics and terrestrial lidar scanning techniques to determine the deformation regime and motion of the faults. Mapping the well-exposed fractures in the CCRB with terrestrial lidar scanning serves as an example of the application of photorealistic surface models and tools to extract fracture structures and orientations in 3D. Building a photorealistic model consists of processing the lidar data, creating a triangulated irregular network mesh, georeferencing the site with global navigation satellite system coordinates and draping the photos onto the model. The mapped fracture patterns and orientations are utilized to determine the deformational behavior and movement in the fault zone. These data are combined with fieldwork to enable geologists to resolve and revisit field sites at any time.