Dating techniques for piedmont landforms in Maricopa County

This dating technique assessment demonstrates how landform surface age estimates can be used in the evaluation of alluvial fan flood hazards in Maricopa County, Arizona. Detailed geomorphic mapping of alluvial fan surfaces combined with surface age estimates reveal the degree of flood hazards by identifying the most recently active active flooding areas. Geomorphic mapping and application of relative dating methods (surface morphology, degree of soil and desert pavement development, vegetation type and density, carbonate content and structure) should be performed prior to applying any numerical dating techniques. However, by themselves, relative dating techniques do not provide direct age estimates for Holocene surfaces. OSL and AMS radiocarbon dating methods are the most applicable numerical dating methods for dating alluvial fan sediments on fan landforms in Maricopa County. Cosmogenic nuclide dating and varnish microlamination correlation are the most favorable methods for estimating surface ages. Varnish microlamination (VML) is a correlative method and should be evaluated further in Maricopa County.This report is part of a larger product, Refinement of Methodology: Alluvial Fan Flood Hazard Identification & Mitigation Methods, prepared by J.E. Fuller on behalf of the Flood Control District of Maricopa County, Arizona.Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact azgs-info@email.arizona.edu