sign in sign up
<<
Home , Rio Grande Rift

# I 2 BUREAU OF ECONOiC GEOLOGY THE UNIVERSITY OF TEXAS AT AUSTIN W'M OCKET N0TROL lSt To78713-750-(512)471-1534or471-7721(jZE

*87 JIN -9 A1O:26 June 1, 1987 WM RecorgFile WM Project / /WI Docket No. 13 Dr. Theodore J. Taylor Salt Repository Project Office )rLPDRt adI9 n _ __ ta_ . U. 3* Uepdriinent UT Energy Dii b.iO 110 North 25 Mile Avenue ______- Hereford, TX 79045

Reference: Contract No. DE-AC97-83WM466t M ______Dear Dr. Taylor:

Per a request from Susan Heston to Chris Lewis, the status of the open-file report entitled *Basin and Range-Age Reactiviation of Rocky Mountain Structures in the Texas Panhandle, (OF-WTWI-1986-3),m by R. Budnik, is as follows. Dr. Budnik left the Bureau in August, 1986. The manuscript was revised by Dr. Budnik to reflect comments from GSA reviewers and resubmitted to the Journal before DOE comments were received at the Bureau. The article was published in the February, 1987 issue of Geology. Please note the title of the article was changed, it is now entitled nLate Reactivation of Ancestral Rocky Mountain Structures in the Texas Panhandle: A Response to Basin and Range Extension." Three copies of the reprinted article are enclosed. Also, the above referenced article supersedes OF-WTWI-1986-3. If you have any questions, please do not hesitate to contact me.

Sincerely,

Asoc iat cto Associate Director

DCR:CL:cl Enclosures

cc: P. Archer (BPMD) S. Heston (SRPO) F. Brown C. Lewis T. Clareson (BPMD/GRC) J. Raney S. Doenges F. Ross (NRC) L. Drover (BPMD/TIC) E. Washer (S&W) J. Ellenberger (SRPO) J.3 Williams (SRPO) L. Harrell - QA Files R. Helgerson (BMI/ONWI) --- 88123035 IMProjecti UN-16 OM Record File: 106 LPIR w/encl 6712I00O2 870601 E FDR Owl PDR AT PDR (Return to UK, 623-SS) 1416 / 710 Late Miocene reactivation of-Ancestral Rocky Mountain structures in the Texas Panhandle: A response to Basin and Range extension 3. Roy T. Budnik* Bureau of Economic Geology. University of Texas University Station Box X, Austin, Texas 78713

ABSTRACT Structural and stratigraphic evidence from the Ogallala Formation (Neogene) documents late Miocene tectonic activity within the Great Plalns Field and mibsurface studies hi the Texas Panhandle Indicate that parts .f the Adulo uplift, amajor element of the Penn-

__ sylvanian Ancestral Rocky Mountains, were elevated as much as 150 mduring Initial dep- osition of the Ogallala Formation. Beactiva- I. lion of these structures occurred In response to Basin and Range extension and opening of the hi central New and .

INTRODUCTION Investigations in the Texas Panhandle docu- ment late Tertiary tectonism within the Great Plains, more than 300 km beyond the known limits of contemporary Basin and Range faulting in central New Mexico. Evidence of tectonic activity within the panhandle comes primarily from the Ogallala Formation, a vast alluvial apron that was shed eastward from mountains bordering the Rio Grande rift in central New Mexico and. Colorado during Neogene time (Fig 1). Previous work in the panhandle sug- gested that distribution of the Ogaflala was con- trolled primarily by preexisting topography and by subsidence related to the dissolution of under- :::v: 2 lying evaporites (Seni, £980-, Gustavson and - Budnlk, 1985). However, recent neotectonic studies, part of alarger program examining the

22 2: * . 22 :1 it ::: kasihihty of siting a high-level nuclear waste repository in the Texas Panhandle, has shown 222 222 322. thatatleastlocallytectonicprocessesalsoaf- fected the distribution and structural attitude of the Ogallala Formation. This paper reports on research conducted along the Amarillo uplift in the central panhandle about 75 km northeast of fhenw,,,Afiwtnvvtp .4

ICOhu 0A6062 FIgure 1. of western United Stat.. (lop) and distribution of Neogene hi southern Rocky Mountains and western Great Plains (bottom). 'Present addrem RRl, Box 440.Aincnia, New Heavy fines In bottom figure are pm- faults. York 12501.

GEOLOGY, v. 15,p. 163-166, Febnuy 1987 163 I STRUCTURAL GEOLOGY OF THE High Plains (SchulZ 1977). The overlying Co- can () lacustrine deposits (Schultz, AMARILLO UPL1F etas Formation contains a Clarendonian verte- 1977) to the south of the uplift. The Amarillo uplift isa narrow basement pos- brate fauna (Schultz, 1977). Paleoctologic and itive element that is part of a complex zone of isotopic data indicate that Ogallala deposition LATE TERTIARY DEFORMATION horsis and extending west-northwest- ended during the Hemphillian Stage (late Ml- IN THE TEXAS PANHANDLE ward won the Texas Panhandle (Fig. 2). The ocene/early Pliocene) 4 to S Ma (Izett, 1975). Structures along the Amarillo uplift appear to Amarillo uplift and colinear Wichita uplift to The upper part of the OgalIala Formation is have been unaffected by the the southeast in Oklahoma form the southern undated in the vicinity of the uplift, but it is to the west, as indicated by parallelism of bed- margin of the Anadarko basin and are pert of lithologicafly similar to and in the same strati- ding in the lower part of the Ogallala Formation the Pennsylvanian Ancestral Rocky Mountain graphic position as the Dridwell Formation and underlying units. However, Permian, Tries- erogenic belt that extends from Oklahoma to (Evans, 1949) to the south, which is Hemphill- sic, and lower Ogallala strata dip as much as 1? Utah (ver Wiebe, 1930). Left-lateral motion of un in age (Winkler, 1985). Isotopic ages rang- off the southwest flank of the John Ray dome, as much as 120 km during the Pennsylvanian is ing from 4.5 to 6.6 Ma were obtained from ash documenting reactivation of the older structures indicated by the offset of lower strata beds near the top ofthe Ogallala Formation in after initiation of Ogallala deposition. An angu- seross the uplift (Budnlh, 1986). Hemphill County, just north of the uplift (Izett, hr unconformity lies between the Tertiary and Several thousand metres of structural relief 1975). The Ogallala islocally overlain by BIan- older units higher on the dome, and the Ogallala developed between the Amariflo uplift and ad- jacent basins to the northeast (Anadarko) and southwest (Whittenburg trough; Fig. 2) during the Pennsylvanian and Early Permian Reactiva- tion of Pennsylvanian structures since the Pa- leozoic is indicated by faulting of the Triassic Dockum Group against Permian strata won the Potter County , which separates the Wbittenburg trough from the Amarillo uplift. In addition, middle and Upper Permian and Tries- sic strata have been folded over en echelon basement horats (for example, the Exell and John Ray domes; Fig. 2) along the upthrown side of the fault. The Ogaflala Formation also has been folded this suggests that at least some

of the deformation occurred in the Cenozoic. 5 4 n .I FCIUII. boll wadownllwown sade LATE TERTIARY SYNTECTONIC DEPOSITION IN THE TEXAS Saa,.es, conto interval 1000 ft. 10000 ft Anodorl.o Basin PANHANDLE Along the Amarillo uplift, basal Ogaflala sands and gravels (called the Potter Formation; Patton, 923) include well-rounded siliceous clasts as large as 30 omin diameter transported from mountains along the eastern margin of the Rio Grande rift (Schultz, 1977). as well as blocks of dolomite and red mudstoce up to 45 cm in diameter derived from underlying Permian strata. The Potter Formation is more than 100 m thick within the Whittenburg trough, but thins abruptly onto the Amarillo up. lift woes the Potter County fault (Fig. 3). The unit is conformably overlain within the trough by finely laminated calcareous slltstone and mudstone (Coetas Formation; Patton, 1923). Undifferentiated upper Ogallala sand, silt, and W14T1ENBt.UG caliche blanket the entire area, including the ThcuG folds a4jacent to the Potter County fault. Toflay Ogollolo Fomaat.on EJ P,ftO1 lip Wallunirci Vertebrate fossil data from the Texas Pan- handle indicate onset of deposition of the Ogal- as tiassec Ooctwm Group meP.nruon strata . Fault lala Formation during the Clarendonian (late J Permian vaonles L Pcterczoac basement Miocene), about 10 Ma (Schultz, 1977; earn Winkler, 1985). The Potter Formation appar- FIgure 2. Structure contour map on top of basement (lop) and cross section of Amarillo uplift ently has no indigenous fauna preserved, but (bottom). BrO -Bravo dome; BuD - Bush dome; CB - Carson basin; JRO -John Ray dome; LFB Lefora basin; WDG - White Deer ; WT - Whlttenburg trough; XLD - Exell dome. Uplift of worn Gryphaea (Early Cretaceous) fragments Exell dome occurred prior to deposition of upper part of Ogallala Formation. Evidence to east are common in itand other basal Ogallala (Qar- (see Fig. 3) suggests that deformation took place during deposition @1lower Ogallala units endonian) deposits throughout the southern (Potter and Coetas Formations). which are not present along this En. of section.

164GEOLOGY. Febnuiy 1987 I%.% / fls sucusszvdy on the Dockum Group, or Extension across the Rio Grande rift wasac- proposed many years ago (ver Webe, 1930) 7erniian Strata, and Emily cc eroded Permiar commodated in part by reactivation of preexist- and termed variously the Wichita lineansent mcntheapexeicrure(Fig.3).k ing fault zones (Eaton, 1979; Tweto, 1979; (Sales, 1968), the Wichita megashear (Walper, 8ddition, the Ogaflala appears to lap onto thr Cordefi, 1982; Baldridge et a!, 1984). Faults 1970; Budnlk, 1986). the Olympic-Wichita Un- * dome so that the Potter Formation rests on thr associated with the north-northwest-trending Lament (Baars, 1976), and the Oklahoma-New Dockum Group within the Whitzenburg trough * Use-Gore fault system (Tweto, 1980) influenced Mexico-Colorado-Utah tectonic zone ([arson whereas the upper unit of the Ogalala rests di* the location of small, discontinuous rift basins in at aL, 1985). The use-Gore and Apishapa fault reedy on Perniian strata on the apex of the Johr central and northern Colorado (Fig. 1; Taylor, systems and Amarillo and Wichita uplifts, ele- Ray dom (Fig. 3). Dips decrease upward 1 1975; Chapin, 1979; Tweto, 1979). The ru ments of the Ancestral Rocky Mountains, con- -- widnthesectioaandtheupperpartoftlu and other north- to northeast-trending faults in stitute the central and eastern parts of the Ogailala is merely gently draped over the domt northern and central New Mexico border rela- megashear (Budnlk, 1986). Evidence oflateTer- (Fig 3). Abrupt thinning won basement fault tively wider, deeper, and more continuous axial tiary tectonic activity along the Amarillo uplift and incorporation of large Permian dolomits basins (Miller et a!, 1963; Chapin and Seager, and Use-Gore fault system suggests that the _ and mudstone fragments within the Potter For * 1975; Kefley, 1979; Tweto, 1979; Cordell, Wichita megashear was reactivated during the marion suggest growth of faults and unroofing cit 1982). Basins along the entire rift were filled Cenozoic the folds during deposition. with fluvial, colian, and lacustrine material (the The presence of this preexisting zone of and related units) derived from weakness appears to have influenced the pattern LATE TERTIARY DEFORMATION bordering uplifts primarily during the late Mio- of Basin and Range extension in the southern IN THE SOUTHERN cene to early Pliocene (Clarendonian and Hem- Rocky Mountains. The Rio Grande rift isa rela- ROCKY MOUNTAINS phillian stages; Galusba and Buck, 1971; Ted- tively wide and continuous feature in New Mex- Deposition and deformation of the OgalIalt ford, 1981). The decrease in fault activity at ico, but it becomes narrower and less continuous Formation along the Amarillo uplift coincidel I about4o5Maasindicatedbythepresenceof at its intersection with the megashear to the with Basin and Range extension and opening cit relatively undeformed basalt flows and Blancan north. This northward narrowing has been at- the R o Grande r in central New Mexico an I (Pliocene) ancestral Rio Grande fluvial deposits tributed to dockwise rotation of the Colorado - Colorado (Schulz 1977; Chapin, 1979; Car.* that unconformably overlie faulted, strongly Plateau about an Euler pole in central or north- deli, 1982; Baldridge eta!, 1984). Thee phase tilted, and eroded strata of the Santa Fe Group ern Colorado (CordeD, 1982). However, the of deformation have been recognized along tla (Chapin and Seager, 1975; Seager at a!, 1984). discovery of contemporaneous faulting in the sift (Chapin and Seager, 1975; Golombek eta!. Texas Panhandle necessitates a modification of I983 (1)formation of broad basins from abou MODEL OF LATE TERTIARY this model to account for deformation to the east 30 Ma until 10 or 12 Ma under west * DEFORMATION of the rift. The model herein proposed indudes southwest-east-northeast extension (Zoback e Coincidence in timing of late Tertiary defor- both clockwise rotation of the aL, 1981; Morgan and Goiombek 1984) mation in the southern Rocky Mountains and with respect to the midcontinent, with possible (2) acceleration of rifting and development ci the southern Great Plains suggests a tectonic right slip on the llse.Gore fault system, and also narrow fault-bounded basins and marginal up* connection between the two areas. This is con- counterclockwise rotation of eastern New Mex- lifts beginning about 10 to 12 Mn coincideni sistent with an older, througbgoing zone of ico and Texas, with possible left slip cc the Pot- with £ change to west-northwest-oriented a * weakness between Colorado and Texas that was ter County fault (Fig. 4). Late Tertiary wrench tension (Zoback at a!, 1981); and (3) reducec fault activity and development of throughgoin ax al drainage from about 4 to S Ma to th present

S N

J. -. .- * ...-. ---- -. -- - - .-. * -. . .

...... ***

o IMi o 1KI Figure 3. DIagrammatic cross section from Whittenburg trough to John GA 6067 Ray dome, Texas Panhandle. Neogene Ogallala Formation consists of Figure 4. Neogene tectonic setting of southern Rocky Mountains and three units: Tou -undifferentiated upper unit; Too- Coetas Formation; Great Plains. Large arrows indicate direction of extensIon 10 Ma to Top - Potter Formation. Tid - Dockum Group; P - Permian strata. present. Small arrows indicate proposed direction of movement on Dashed Unes wIthIn Tou and Top schematically Indicat, beddIng. No laulls. WIchita megashear brined boundary between stable mldcontl- vertical scale. nent and region Influenced by Basin and Range extension.

GEOLOGY, Febn2axy 1987 165 *iJ .. , '1 %m1 faulting has sotbeen reported from Colorado, Cordell, L, 1982, Extension hi the Rio Grande the mall, discontinuous rift basins in rift Journal of Geophysical Research, v. 57, this area are reminiscent of pull-apart grabens p. 85614569. Donovan, 3-N., Gilbert, M.C., Lizza, LV., Marchini, found elsewhere along strike-slip fault zones D., and Sanderaca, D., 1983, PossIble Qiater. Schultz, G.E., 1977, The Ogallal (Reading 1930). Likewise, no evidence o(Mio- airy movement on the Meets fault, southwestern vertebrate faunas in the Taza cene wrench faulting has been discovered hi the Oklaboaia Oklahoma Geology Notes, v. 43, Texas Panhandle, but the reactivation at en p. 124-131 Eaton, 0.?., 1979, A plate-tectonic model fur bre of the Texas Panhandle and a4ja4 echelon basement horsta along the Potter Cenozoic atLstal spreading Inthe western United West Texas State University County fault is at least consistent with such an States, hr Riecker, LE., ad., Rio Grande r Tic- hiterpretation. Thus, the eastern segment of the tonics and nragmarisnu Washington, D.C., megashear may have, in essence, formed an in- American Geophysical Union, p. 7-32. Marvin, R.F., 1984, New K-Ar tramtonic , separating the area Evans, GL, 1949, Upper Cenozoic of the High Plains, basalts and the evolution of the hi Cenozoic geology of the LImo Estanado and Grande r undergoing Basin and Range extension on the Rio Grande VafleT Midland, Texas, West Texas Ietrnv.9Sp.87-99. south from the stable midcontinent to the north Geological Society and New Mexico Geological (Fig. 4). Society Guidebook, p. 1-22. Galusha, T., and hick, S.C., 1971, Strarigraphy of versity of Texas at Austin, Durean of the Santa Fe Group, New Mexico: American Geology Report of Investiganons 105, IMPLICATIONS Museum of Natural History Bulletin, v. 144, Taylor, LB., 1975, Neogene tetzonh The Wichita megashear is a long-lived fea- p. 1-121 ture, the documented teconic activity occurring Golombek, M.P., McGill, G.E., and Drown, L, 1983, in the Cambrian (larson at ii., 1935), Pennsyl- Tectonic and geologic evolution of the Eapanola Geological Society of America vanian (Budnlk, 1986), and late Tertiary (this Basin, Rio Grande lift Structure, rate of exten- p.211-226. lion, and relation to the state of stress in the Tedford, RJL, 1981, Mammalian paper). Although recent activity has been recog- western United States: Tectonopbysics, v. 94, the late Cenormc banns of Ne nized along faults associated with the megashear p. 483-507. Geological Society of Amezu Dull in southwestern Oklahoma (the ; Gustavaca, T.C., and Budnik, 3-?., 1985, Structural p. 1008-1022. Donovan at at, 1983), the Texas Panhandle influences an geomorphic processes and physio- Tweto, 0., 1979, The RIO Grande rift (Budnik and Davis, 1985), and Colorado (Kirk. graphic features, Texas Panhandic Technical rado, hi Riecker, I.E., ad., Rio Graode¶j inues in siting a audear-waste repository tonics and magmansor. Washin 1 ham and Rodgers, 1981), the potential for Geologyv. 13, p. 173-176. American Geophysical Umon, p. 33-. further activity in the region has nor been fully keu. GA., 1975, Late Cenozoic sedimentation and -1980, Tectonic history of Colorado, tvaluated. Major zones of crustal weakness may deformation in northern Colorado and adjoining EC., and Porter, LW., ads., Cotorado'j have a significant impact on the tectonic stability areas, hi Curtis, LF., ad., Cenozoic history of the Denver, Colorado, Rocky Mountain Ais southern Rocky Mountains: Geological Society of Geologists, p. 5-9. of an otherwise relatively stable region. These of America Memoir 144, p. 179-209. ver Wiebe, WA., 1930, Ancestral Rocky Moo zones must be examined particularly closely Kelley, V.C., 1979. , middle Rio Grande lift, American Association of Petroleum Ge when assessing the neocectonios of a region for New Mexico, hi Riecker, I.E., ad., Rio Grande Bulletin, v. 14, p. 765-788. the purposes of siting a sensitive facility such as a lift Tectonics and magmatism Washington, Walper, iL, 1970, Wrench faulting in D.C., American Geophysical Union, p. 57-70. continent Shale Shaker, v.21, p.32-40. nuclear-waste repository. Kirkham, R.M., and Rodgers, W.P., 1983, Earth- Winkler, DJ, 1985, Stratigraphy, vertehii1 quake potential in Colorado-A preliminary tology, and deposizional history of th REFERENCES CITED evaloationi Colorado Geological Survey Bulletin Group in Bunco and Yeflowhowe Bears, Dl.. 1976, The Colorado Plateau anlacogen- 43, 171 p. aorthwestern Texas EPILD. thesis]: Aust Key to continental male basement rifting Pro- lArson, EL, Patterson, P.E., Curtis, 0., Drake, 3-, versity of Texas, 243 p. ceediop, International Conference on Basement and Mutachler, FL, 1985, Petrologic, paleo- Zoback, ML, Anderson, RL, and Thompacie Tectonics, 2nd: Denver, Colorado, Basement magnetic, and structural evidence ofa Paleozoic 1981, Cainozoic evolution ofthestat Tectonics Committee, Inc., p. 157-164. rift system in Oklahoma, New Mexico, Colo- and style of tectonism of the Baldridge, W.S., Olsen, LH., and Callender, S.F., rado, and Utalu Geological Society of America province of the western United Satr 3984, Rio Grande rift Pwbl and persectivcs, Bulletin, v.96, p.1364-1372. Society of London Philosophical Traita hi Baldridge, W.S., at al., ads., Rio (Irande rift Miller, SI., Montgomery, A., and Sutherland, P1., ser. A,v.300, p.4074 34 . Northern New Mexico: Socorro, New Mexico, 1963, Geology of pan of the southern Sangre do New Mexico Geological Society, 35th Field Caisto Mountains, New Mexico: New Mexico ACKNOWLWGMEPS Conference Guidebookp. 1-12. Bureau of Mines and Mineral Resources Memoir Funded by the US. Depaxtnrent(EWV Budnik, LT., 1986, Left-lateral iniraplate deforma- 11,106 p. contract DE-AC9743WM46651. 13- Delia lion along the Ancestral Rocky Mountains: Morgan, P., and Golombek, LIP., 1984, Factors con- Price, andi. Raney critically reviewed the man Implications for late Paleozoic plate motions: trolling the phases and styles of extension in the Publication authorized by the Dfrector Bin Tectonophysics. northern Rio Grande rift, hi Daidridge, W.S., Economic Geology, Th University ofli Budnik, LT., and Davis, S.D., 1985, Tectonic history at al., ads., Rio Grande rift Socorro, New otthe Amarlllo.Wichita uplift and its bearing on Mexico, New Mexico Geological Society, 35th Austin. recent deformation along the Meers faultt Seis- Field Conference Guidebook, p. 13-19. mological Society of America Notes, Patton, LT., 1923, The geology of Potter County Manusoipt received June 24, 1986 v. 55, p. 7. University of Texas, Austin, Bureau of Economic Revised manwoript received October 16,1 Chapin, C.E., 1979, Evolution of the Rio Grande Geology and Technology Bulletin 2330,180 p. Manuseript axepted October 24, 19861 rift-A summary, hz Lecher, LL, ad., Rio Reading, ILC., 1980, Characteristics and recognition Grande lift Tectonics and magniatism: Washing. of strike-slip fault systems, hi Ballance, P1., and ton, D.C., American Geophysical Union, p. 1-5. Reading, ILG., ads., Sedimentation in oblique- Ciapin, CL, and Seager, WIL, 1975, Evolution slip mobile sonen International Association of of the Rio Grmnde rift in the Socorro and Las Special Publication 4, p. 7-26. Cruces areas, hi Seager, Wi.., at at, eds., Las Cruces coun±zT. Socorro, New Mexico, New Mexico Geological Society, 26th Field Con- ference Guidebook, p. 297-321.

166Pilosed h USA. GEOWGY,