Distinctive sedimentary features of cold-climate eolian deposits, North Park, Colorado
Abstract Cold-climate eolianites contain diagnostic sedimentary features that contrast with the sedimentary features of warm-climate eolianites. Distinctive tensional, compressional, and dissipation sedimentary structures related to freezing, thawing and snow melting characterize eolian dune-sand deposits in North Park, Colorado. The North Park dunes have few of the characteristics considered to be diagnostic eolian indicators. A significant difference is the heterogeneous texture and composition of the sand. The migration rate of these active dunes is slow (⩽1.7 m/year) due to freezing of moisture in the sand or to burial of the sand by snow during half of the year, even though the dunes occur in a unimodal, high-energy wind environment. Bioturbation is common in both active and inactive dunes, although the dunes occur at a high elevation (∽ 2500m) in a cold climate (3.0°C mean annual temperature). The distinctive sedimentary features observed in this cold-climate (snow-related) dune field should aid in the interpretation of eolianites and the paleoclimates in which they formed.