ORIGIN OF SHAFTER, WHALEN. AND LAZY X RANCH LAKE BASINS, ANDREWS COUNTY, TEXAS by ROGER M. DOCKERY, B.S. A THESIS IN GEOLOGY Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Approved Accepted December 1989 C^'^ ACKNOWLEDGEMENTS I would like to express my sincerest gratitude to Dr. C.C. Reeves, Jr., for providing this project and for his friendship, advice and guidance, to Dr. S.E. Cebull and Dr. A.D. Jacka for their advice and serving as committee members, and to Dr. G.B. Asquith for his helpful advice. I would like to thank the Midland Energy Library tor providing data used for this project, and the Texas Tech Department of Geosciences for financial support. Thanks to Judy Vincent and Dan McCrummen for their helpful suggestions. I am very grateful to my parents for their never- ending love and support, without their support I could not have completed this project. 11 TABLE OF CONTENTS ACKNOWLEDGEMENTS ii LIST OF FIGURES iv CHAPTER I. INTRODUCTION 1 Location and Description of Study Area 1 Purpose of Study 5 Method of Study 6 Previous Studies 7 II. REGIONAL GEOLOGY 14 Structure 14 Stratigraphy 18 III. GEOLOGY OF SHAFTER, WHALEN, AND LAZY X RANCH BASINS 25 Permian Salt Dissolution 26 Structural Displacement in the Triassic 42 Structural Displacement on the Base of the Ogallala Formation 51 IV. SUMMARY AND CONCLUSIONS 56 BIBLIOGRAPHY 62 APPENDICES A. SHAFTER LAKE WELL LOCATIONS 69 B . WHALEN LAKE WELL LOCATIONS 7 5 C. LAZY X RANCH DEPRESSION WELL LOCATIONS 79 111 LIST OF FIGURES Index map of the Southern High Plains showing the location of Andrews County, Texas. (After Finley and Gustavson, 1981) 2 Index map of Andrews County, Texas, showing the locations of Shafter Lake, Whalen Lake and I the Lazy X Ranch Depression 3 n. Stratigraphic column showing formations examined and stratigraphic positions of marker beds f correlated in the study area 8 t 4. Map of Permian salt dissolution limits in the Texas Panhandle. (Copied from Gustavson et al., 1980) 11 5. Index map of the major structural features of West Texas. Asterisk (*) indicates location of the study area 15 |i 6. Well location map of the Shafter Lake Basin area, Andrews County, Texas. The dotted area represents the present playa area 27 7. North-South cross section of the Shafter Lake Basin area, Andrews County, Texas 28 I 8. East-West cross section of the Shafter Lake Basin area, Andrews County, Texas 29 9. Structure map on the Rustler Formation in the Shafter Lake Basin area, Andrews County, Texas. The dotted area represents the present playa area 31 10. Well location map of the Whalen Lake Basin area, Andrews County, Texas. The dotted area represents the present playa area 32 11. North-South cross section of the Whalen Lake Basin area, Andrews County, Texas 33 12. East-West cross section of the Whalen Lake Basin area, Andrews County. Texas 34 iv 13. Structure map on the Rustler Formation in the Whalen Lake Basin area, Andrews County, Texas. The dotted area represents the present playa area....36 14. Well location map of the Lazy X Ranch Depression area, Andrews County, Texas. The dotted area represents the present basin area 37 l^. North-South cross setion of the Lazy X Ranch Depression area, Andrews County, Texas 38 16. East-West cross section of the Lazy X Ranch Depression area, Andrews County, Texas 40 17. Structure map on the Rustler Formation in the Lazy X Ranch Depression area, Andrews County. Texas. The dotted area represents the present basin area 41 18. Structure map on Marker Bed #4 in the Shafter Lake Basin area, Andrews County, Texas. The dotted area represents the present playa area 43 19. Structure map on Marker Bed #5 in the Shafter Lake Basin area, Andrews County, Texas. The dotted area represents the present playa area 44 20. Structure map on Marker Bed #4 in the Whalen Lake Basin area, Andrews County, Texas. The dotted area represents the present playa area 47 21. Structure map on Marker Bed #5 in the Whalen Lake Basin area, Andrews County, Texas. The dotted area represents the present playa area 48 22. Structure map on Marker Bed #4 in the Lazy X Ranch Depression area, Andrews County, Texas. The dotted area represents the present basin area 49 23. Structure map on Marker Bed #5 in the Lazy X Ranch Depression area, Andrews County, Texas. The dotted area represents the present basin area 50 24. Structure map on the base of the Ogallala Formation in the Shafter Lake Basin area, Andrews County, Texas. The dotted area represents the present playa area 52 Structure map on the base of the Ogallala ]5. Formation in the Whalen Lake Basin area, Andrews County, Texas. The dotted area represents the present playa area , 53 26. Structure map on the base of the Ogallala Formation in the Lazy X Ranch Depression area, Andrews County, Texas. The dotted area represents the present basin area 55 VI CHAPTER I INTRODUCTION Location and Description of Study Area Andrews County, Texas, lies in the southern part of the Southern High Plains of West Texas (Fig. 1). The specific study areas of Shafter Lake, Whalen Lake, and the Lazy X Ranch Depression, are all located west of Andrews in Andrews County, Texas (Fig. 2). The Southern High Plains, also known as the Llano Estacado, is the eroded remnant of a vast piediment alluvial plain which formed on the eastern slope of the southern Rocky Mountains during Tertiary time. Bordered on the north by the Canadian River valley, on the east by the "Caprock" Escarpment, on the west by the Mescalero Escarpment, and on the south by the Edwards Plateau, the essentially flat, plateau-like surface of the Southern High Plains has an average southeasterly slope of approximately 8 to 10 feet per mile. Local relief is provided by tens of thousands of natural depressions with maximum relief occuring around the larger saline lake basins where sand dunes have accumulated along the downwind flanks. The Southern High Plains is a semi-arid region with an average precipitation of 18 to 20 inches per year, but 1 OHJ /'. l;.;-;-:J «oulMrnHlgl<nfln> AfKb^M Cauntr Figure 1. Index map of the Southern High Plains showing the location of Andrews County, Texas. (After Finley and Gustavson, 1981) X >1 CJ> N c ro •« J 5 0 O x: x; W J-) »n n c ro ro X 0) (U E- ^ ro . J >i 4J c C (U 3 r-l 0 ro u s: 3: m 5 * (U 0) ;j ii -o ro c J < j-i U-4 0) 0 JJ w a ro ro J= E w X «-i C cj 0 0 T! •H c m O M C tn 0 Q) -H Ul . JJ c rs ro o U Q <u 0 1^ r^ r^ 3 "u Di QJ c •H x: ro lu JJ Cti with an average annual evaporation of approximately 60 ' inches. The prevailing wind direction is dependent upon time of year; winds from the southeast prevail during the summer months with southwest winds prevailing during the remainder of the year. The average wind speeds are approximately 10.4 miles per hour (United States Department of Agriculture, Soil Survey, 1974). Climatic conditions for Andrews County (United States Department of Agriculture, Soil Survey, 1974) are considered cool-temperate and dry with low precipitation and high evaporation. Average precipitation is approximately 13.89 inches per year, the majority falling between April and October. Evaporation is reported by the United States Department of Agriculture, Soil Survey (1974) to be approximately 58 inches greater than the annual precipitation. The Shafter Lake Basin is located approximately 6.8 miles north and 4.5 miles west of Andrews, Texas (Fig. 2). The Whalen Lake Basin is located approximately 5.9 miles north and 14.8 miles west of Andrews (Fig. 2), and about 9.8 miles west of the Shafter Basin. The Lazy X Ranch Depression, named for the Lazy X Ranch, is located about 6.1 miles due west of Andrews and approximately 6.8 miles south of the Shafter Lake Basin (Fig. 2). However, whereas both the Shafter and Whalen basins contain saline playas, the Lazy X Ranch Basin is covered by the entisol of the Krade soil series, and the aridisols of the Blakeney, Conger, and Ratliff soil series (United States Department of Agriculture, Soil Survey, 1974), no lacustrine playa is obvious. Purpose of Study Approximately 17,000 small playa lake basins, which intermittently contain freshwater during climatically wet periods, exist on the Texas portion of the Southern High Plains of West Texas (Parks, 1967). Also present throughout the West Texas and eastern New Mexico area are at least 44 larger lake basins (Reeves, 1989) which tend to contain salty water and/or salt encrusted playas. Wood and Jones (1988) classify these basins as saline based on high pH values and high concentrations of sulfate and chloride; however, studies show that pH values are seldom over 8.0, thus the term "saline" is preferred. Recent studies (Gustavson and others, 1980; Reeves and Temple, 1986; Reeves, 1989) of the large saline basins reveal that some are underlain by areas of deep- seated Permian salt dissolution. The purpose of this study, therefore, is to determine if Shafter, Whalen, and the smaller Lazy X Ranch basins in Andrews County, Texas, are surficial manifestations reflecting the dissolution 6 of underlying Permian salt beds or simply the result of surficial weathering processes.