ASSESSING POTENTIAL FOSSIL YIELD FOR THE STATE OF NEVADA

We have produced a potential fossil yield classification (PFYC) map for geological units exposed in the State of Nevada. The PFYC is a system that assigns a potential to geological units based on their potential for significant paleontological resources (1 is very low and 5 is very high) and is used to assess possible resource impacts and mitigation needs prior to authorizing land-disturbing projects. A literature review was conducted of paleontological recoveries across the state. Map scale for this project was usually around 1:250k resolution. Nevada county maps were digitized from referenced raster datasets. These were merged into a composite shapefile representing all state geology at 1:250k scale. Available 1:100k maps were digitized into the shapefile creating a robust representation of all surficial geology. Each polygon received attribute data relevant to the PFYC. The data includes over 36k polygons and over 400k attribute records. The PFYC assignments follow the geological history of the state. From the Ediacaran through the Paleozoic, units are representative of the miogeocline of western North America . These include shallow marine carbonates with a diverse invertebrate fauna, most of these received a PFYC of 3 (moderate paleontological significance). Exceptions, such as the Cambrian Pioche/Bright Angel Shale that exhibit Burgess-style lagerstatte preservation, received a PFYC of 5 (very high paleontological significance). Marine units of Mesozoic-age received PFYC of 3-4 depending on known vertebrate fossil abundance. Contractional orogenic events limit the Mesozoic terrestrial record; where terrestrial fossils are preserved, units were assigned a PFYC of 5. During the Cenozoic, Nevada went through widespread Basin and Range extension, which accommodates terrestrial deposition in Neogene basins across the state, many of these units are highly fossiliferous and warrant PFYC of 4-5. Many Quaternary units are highly fossiliferous and warrant PFYC ranging from 3-5 depending on fossil abundance and significance. There are also many karst structures, which have produced numerous significant fossils. Although an older marine carbonate may be assigned a PFYC of 3, the presence of Quaternary structures with significant fossils warrant higher assignments.