HR: 0800h
AN: NG41C-0673    [Abstracts]
TI: Point Pattern Analysis of Star-Dune Fields
AU: * Ewing, R C
EM: rce@mail.utexas.edu
AF: Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, 1 University Station C1100, Austin, TX 78712, United States
AU: McElroy, B J
EM: bmcelroy@speer.geo.utexas.edu
AF: Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, 1 University Station C1100, Austin, TX 78712, United States
AU: Andrews, B J
EM: andrewsb@mail.utexas.edu
AF: Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, 1 University Station C1100, Austin, TX 78712, United States
AB: Star dunes are among the largest and most complex aeolian dunes in nature. Varying morphologies of star dunes are well documented; however, the dune-field scale properties of the pattern have received relatively little attention. This study addresses the spatial organization of star dune field patterns in the Erg Oriental, Edeyen Murzuq, Rub-al-Khali and the Gran Desierto. Areas targeted in each dune field display a transition from a simple dune pattern, in which only star forms occur, to a complex dune pattern where star dunes occur superimposed on relict linear and crescentic dune topography. Star-dune peaks determined from SRTM 90 digital elevation data are treated as points for point pattern analysis. Nearest-neighbor statistics are calculated across each dune field over 2500 sqkm intervals to characterize changes in the pattern. Dune peak spacing in simple star-dune patterns is highly disperse (R = 1.8), indicating a significant departure from a random point pattern. Simple star patterns also show a strong correlation between nearest neighbor spacing and height. Complex star dune patterns show a lower degree of dispersion and a weaker correlation between nearest neighbor spacing and height. Ultimately, these differences reflect both the control of the relict-dune pattern on the organization of the superimposed star-dune pattern and the overall maturity of the star-dune pattern.
DE: 4435 Emergent phenomena
DE: 4460 Pattern formation
DE: 4485 Self-organization
SC: Nonlinear Geophysics [NG]
MN: 2007 Fall Meeting