University of Texas at El Paso DigitalCommons@UTEP Open Access Theses & Dissertations 2012-01-01 Grain Size Distribution With Geomorphology On Gypsum Dunes In The White Sands Erg, White Sands National Monument, New Mexico Slade Jones University of Texas at El Paso, [email protected] Follow this and additional works at: https://digitalcommons.utep.edu/open_etd Part of the Geology Commons, Geomorphology Commons, and the Sedimentology Commons Recommended Citation Jones, Slade, "Grain Size Distribution With Geomorphology On Gypsum Dunes In The White Sands Erg, White Sands National Monument, New Mexico" (2012). Open Access Theses & Dissertations. 2112. https://digitalcommons.utep.edu/open_etd/2112 This is brought to you for free and open access by DigitalCommons@UTEP. It has been accepted for inclusion in Open Access Theses & Dissertations by an authorized administrator of DigitalCommons@UTEP. For more information, please contact [email protected]. GRAIN SIZE DISTRIBUTION WITH GEOMORPHOLOGY ON GYPSUM DUNES IN THE WHITE SANDS ERG, WHITE SANDS NATIONAL MONUMENT, NEW MEXICO SLADE BROWNING JONES Department of Geological Sciences APPROVED: ____________________________________ Richard P. Langford, Ph.D., Chair ____________________________________ Thomas E. Gill, Ph.D. ____________________________________ John Walton, Ph.D. _____________________________ Benjamin C. Flores, Ph.D. Dean of the Graduate School Copyright© By Slade Browning Jones 2012 DEDICATION This thesis is dedicated to my wife Lilia and my children Alanna, Aidan, Kai, and Anya, and to my mother Robbins and my sister Carrie, without whose love, support, and tolerance neither this work nor I would have been fulfilled. GRAIN SIZE DISTRIBUTION WITH GEOMORPHOLOGY ON GYPSUM DUNES IN THE WHITE SANDS ERG, WHITE SANDS NATIONAL MONUMENT, NEW MEXICO BY SLADE BROWNING JONES, BIS THESIS Presented to the Faculty of the Graduate School of The University of Texas at El Paso in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Department of Geological Sciences THE UNIVERSITY OF TEXAS AT EL PASO December 2012 ACKNOWLEDGEMENTS The author would like to thank the members of his committee for their invaluable assistance and guidance with this thesis. In addition, Robbins and Carrie Jones helped fund this research and assisted with statistical analysis, Erik Day and Nicole Kyger provided enormous help with field data collection, Dr. Gary Kocurek of the University of Texas generously provided data from his LIDAR surveys of the White Sands, and the Rangers of the National Park Service were extremely patient with a sandy and sample-laden geologist arriving back at his car after closing time. A final thanks to the Park Service for allowing samples to be collected on National Park land and travel across normally protected areas. Without the support and assistance of all those mentioned, this work would not have been possible. The author offers his heartfelt thanks to all mentioned, and to anyone else he may have forgotten. v ABSTRACT In order to examine grain size distribution over dunes at the White Sands dune field in New Mexico, 1214 geolocated surficial samples were collected and analyzed by laser diffraction. Local variations in dunes such as neighboring interdune types and the presence of vegetation, scour features, and granule ripples on the dunes were noted. This study indicates that recrystallization of gypsum and the generation of fresh sediments is occurring in significant quantities within vegetated and erosional interdunes, providing both high and low anomalies in grain size distribution by acting as point sources through much of the central portion of the dune field. Other local variations as previously mentioned such as scour surfaces on dunes and local topographic alteration of air movement all overprint more field-scale effects. Coarse grains (>1.4mm) are found in granule ripples in troughs and swales and in avalanche deposits on the slipface apron. Saltating sand samples selected by microscopy from the stoss face of dunes showed a general coarsening trend with relative elevation. Samples collected on the lee side of dune crests were generally finer-grained than those on the stoss side, and interdune samples collected within 10-60m of the slipface aprons may indicate a lee “sheltering” influence extending a substantial distance across the interdune. Patches of finer-grained sediments were found on dunes downwind of vegetated interdunes, and where it was present on dunes, vegetation was associated with deposition of comparatively finer grains in its immediate vicinity. To effectively model transport, these variations will all have to be taken into account. vi TABLE OF CONTENTS Page ACKNOWLEDGEMENTS .................................................................................................................... v ABSTRACT ........................................................................................................................................ vi TABLE OF CONTENTS...................................................................................................................... vii LIST OF TABLES ................................................................................................................................ ix LIST OF FIGURES ............................................................................................................................... x Chapter 1. INTRODUCTION ........................................................................................................................... 1 2. FIELD-SCALE GRAIN SIZE ANALYSIS AND COMPLICATIONS FROM LOCAL FACTORS ON A GYPSUM DUNE FIELD, WHITE SANDS, NEW MEXICO ......................................................... 4 2.1 Introduction .................................................................................................................. 4 2.2 Setting ........................................................................................................................... 6 2.3 Methods ........................................................................................................................ 9 2.4 Results ......................................................................................................................... 11 2.5 Discussion .................................................................................................................... 25 2.6 Conclusions ................................................................................................................. 28 vii 3. LOCAL EFFECTS ON GRAIN SIZE OVER BARCHAN AND BARCHANOID RIDGE DUNES, WHITE SANDS, NEW MEXICO ....................................................................................................... 30 3.1 Introduction ................................................................................................................ 30 3.2 Setting ......................................................................................................................... 32 3.3 Methods ...................................................................................................................... 35 3.4 Results ......................................................................................................................... 37 3.5 Discussion .................................................................................................................... 50 3.6 Conclusions ................................................................................................................. 52 4. CONCLUSION ............................................................................................................................. 53 REFERENCES .................................................................................................................................. 56 APPENDIX A: LOCATION DATA, SIZE PARAMETERS, & TYPE ......................................................... 59 APPENDIX B: GRAIN SIZE DISTRIBUTION DATA............................................................................. 85 CURRICULUM VITA ...................................................................................................................... 108 viii LIST OF TABLES Page Table 2.1 Survey granulometric results ...................................................................................................... 14 Table 2.2 Statistical results ......................................................................................................................... 24 Table 3.1 Dune granulometric results .................................................................................................... 37-38 Table 3.2 Statistical results .................................................................................................................... 48-49 ix LIST OF FIGURES Page Figure 2.1 Location Map ............................................................................................................................... 6 Figure 2.2 Sub-environment locations & characteristics ............................................................................ 13 Figure 2.3 Granule ripple population environment & photomicrographs ................................................. 15 Figure 2.4 Vegetated interdune population environment & photomicrographs ....................................... 17 Figure 2.5 Erosional interdune population environment & photomicrographs ......................................... 19 Figure 2.6 Dune sand population environment