APPLYING LIDAR AND GEOSPATIAL TOOLS TO IDENTIFY DEFORMATIONAL FEATURES USING THE CARTHAGE COLTON SHEAR ZONE AS A TEST CASE

The use of LiDAR data in conjunction with geospatial tools has been previously applied to topographic features surficial geology typical of glacially processes such as drumlins and eskers. In this study, similar techniques were utilized to study the Carthage-Colton Shear Zone (CCSZ), the ~1.0 Ga boundary between the Adirondack Lowlands and Highlands. The location of the CCSZ is primarily known from the 1:250,000 scale New York State Geological Map (Adirondack Sheet). Although several detailed studies have focused on various areas and tackled specific questions along the CCSZ, it has not been holistically or comprehensively studied along its entire length since the 1980s. In this pilot study we have used LiDAR data and geospatial tools to address several fundamental questions: 1) can ductile features in the bedrock be distinguished from brittle features; 2) can zones of highly deformed rock be uncovered; 3) can structural dislocations be verified; and 4) what limitations/constrains on these methods may apply in a glaciated terrane? An area south of Russell, NY, bisected by the presumed trace of the CCSZ, was selected for field mapping and served as ground truth for the observations originating from digital data. We used FEMA 1m derived digital elevation models and the Reclassification tool in ArcGIS to identify areas of steep slope (<35 ^o) characteristic of exposed bedrock are expressed as elongate ridges formed by deformed and tilted bedrock units which in turn, have a slope angle signature of these steeper slopes. Brittle deformation was clearly identified by the orientation of linear valleys, often segmenting bedrock ridges. The orientation of ridge-elongate polygons defined by converting the regions of highest angle slope into polygons using the Minimum Bounding geometry were plotted on Rose Diagrams for areas of interest and displayed drastic (near 90^o) changes in ridge elongation across the trace of the CCSZ south of Russell. Areas of heavy glacial cover were readily recognized due to their lack of slope and elongation and the total relief of the area in question was <30m. This work is a step towards a new and powerful approach to use digital data to document the detailed structure of deformed bedrock terranes.