Southeastern Section - 66th Annual Meeting - 2017

Paper No. 21-13
Presentation Time: 8:00 AM-12:00 PM

MAPPING THE UNKNOWN NEIGHBORHOOD: A SIMPLE APPROACH COMBINING TRADITIONAL GEOLOGICAL MAPS AND REMOTE SENSING DATA


ROJAS, Alexis, Division of Invertebrate Paleontology, Florida Museum of Natural History, P.O. Box 117800, University of Florida, Gainesville, FL 32611, arojas@flmnh.ufl.edu

Lithological units have been delimited in the traditional geologic maps using qualitative assessments of aerial photography and ground-based observations. Here, I evaluate the applicability of Landsat-8 data for reproducing a traditional geological map and establishing a framework for mapping nearby unexplored areas. I present a case study on mapping Cretaceous sedimentary rocks in Zapatoca, Santander Province of Colombia. The mapping approach described here is a straightforward process: a base—geologic map is used to establish the number and spatial extent of lithostratigraphic units (i.e., lithological classes). The working area is a subset of the map where all lithological classes occur. The remaining area is called the unknown neighborhood and it is used for cross validation. Training samples (n=180), including lithological classes (i.e., Giron, Los Santos, Rosablanca, and Paja) and Rural, Vegetation and Water land cover classes, are collected from Landsad-8 data for the working area. The location of those training samples was stablished using Google Earth imagery. Finally, a supervised classification based on a machine learning algorithm is performed over the full Landsat-8 data (i.e., working area + unknown neighborhood). This approach provides geologically plausible predictions in nearby areas beyond the geological map extent. In average, 44% of the pixel of the Landsat-8 image were classify into the correct lithostratigraphic unit. However, Paja Formation could not be identified and only a few areas of Rosablanca Formation (36%) matched the base—geologic map reflecting the limitations of Landsat-8 data for mapping sedimentary basins with complex tectonic history, high vegetal coverture and extensive weathering.