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Home , Florida, Florida Mountains

FloridaMountains section of southwestNew overthrustbelt-a reeualuation by G A. Brown, Marshall R. Young Oil Company, City, OK, and R E Clemons, State University, Las Cruces, NM

Introduction more detailedaccounts of relationspre- subordinateclastic rocks that range in age from Late Cambrian to Early Permian with The FloridaMountains, 10 mi southeastof sented. all systemsbut Pennsylvanianrepresented; Deming in Luna , New Mexico, are 3) Upper Cretaceous-lowerTertiary Lobo an elongatenorth-trending range/ 10by 5 mi Stratigraphyand regional geology Forma-tion(which has been interpreted by in dimensions (fig. 1). High-relief terrain, The stratigraphyof the FloridaMountains, Lemley as a syntectonicclastic wedge combinedwith arid vegetation,provides ex- [1982] summarizedin fig. 2, includes: 1) Precam- relatedto Laramidedeformation); 4)Tertiary cellentgeologic exposures of complexstruc- alkali-feldspargranite to alkali-feldspar diorite/andesiteintrusives; and 5) Quater- tural relations. brian syenitebasement; 2) Paleozoiccarbonate and nary colluvial and alluvial deposits. Previous study in the Mountains includes: 1) geologic mapping by Darton (1917) and Corbitt (1.977,1974); 2) strati- Thick. graphicstudies by Kelley and Bogart (1952), System Stratigraphic units (f0 Description Bogart (1953),Kottlowski (1958),Lochman- Balk (1958,1974), Woodward (1970),Brook- Quaternary colluvial and alluviai 0-200 Present day arroyo deposits. Silt, ins (1974a, 1974b, 1980a,1980b), Brookins and deposits , gravel; locally carbonatece- mented, fan and bajadadeposits. Corbitt (1974),LeMone (1974),Loring and ---- angularunconlormitY -' Armstrong (1980),Clemons (1.982a,7982b), 'ertiary diorite/andesite Intrusive dikes and small plugs. and Lemley (1982);and 3) economicconsid- erationswere sfudied by Lindgren and others LowerTertiary 500 Conglomerate; reddish, cobble to (1910),Kottlowski (1957),Griswold (1961, Upper Cretaceous Lobo Formation boulder; sandstone. t974), McAnulty (1978), and Brookins and -- angular unconfor.mitY---- others(1978). Permian Hueco 410 Limestone; dark gray, medium to A comprehensivegeologic and mineral-re- massive bedded, fossiliferous ----- source investigation of the Florida Moun- ---- disconformitY (Clemons, 7982a, Mississippian RancheriaFormation 220 Limestone, chert, shale; bedded chert tains is near completion well developed at top. and Brown, in 1982b,in press; Clemons ------A more detailed study of the Maho- UL'LUILIUt ilLLLy press). Devonian Percha Shale 250 Shale; olive gray. One-ft limestone bed nev mine-Gym Peak of the Florida at base. Mountainswas completedas a masterof sci- encethesis study at New Mexico StateUni- Silurian FusselmanDolomite 1,480 Dolomite; six alternating dark and versity, Las Cruces, by Brown (1982).This light units, thin to thick bedded. paper summarizes the thesis and empha- Beddedchert at top Silicifiedcorals. ----- sizesevidence from the Mahoneymine-Gym ---- disconformity reader is referred to Brown Cutter Member 180 Limestone/dolomite; limy and Peak area. The dolomite increases up (in rich at base, (1982)and Clemonsand Brown press)for ward, chert lenses near top.

Aleman Member 150 Dolomite/limestoneichert; buff gray Montoya carbonatewith abundant nodular and Formation bedded chert Fossiliferous. ---- disconformity----- Upham Member 60 Dolomite; dark gray, massive. Five ft CableCanyon sandy zone at base Ordovician 'LUtLJUt IItLLy uPPer 190 Limestoneand chert; medium to darl. gray. Similar to middle unit but with abundant chert. Fossiliferous.

middle 900 Limestone; light to medium gray, thir El Paso to medium bedded, many textura. Formation variations, verv fossiliferous.

lower 160 Dolomite; dark gray, thin to mediurr bedded, coarse crystalline, silty al base, abundant oncolites.

BlissSandstone lCambrian 110 Arkosic to quartzose sandstone Grades upwaid to calcareous sand stone and silty limestone/dolomite. nonconformitY-' lPrecambrian syenite, Sranlte Alkali-feldspar syenite and granite diorite interlayered diorite south of reverst fault. FIGURE 1-lNpBx uep oF sruDy AREAsourHEAsr oF Drrranc FIGURE 2-srnertcnepruc suMMARYoF sourHERNFlonroa MouNrelxs

May 1983 Ntw MexicoGeology Throughout the Paleozoic the Florida ward and DuChene (1981)compared south- controlling factors:1) thrusting over homo- Mountains area was located south of the ern New Mexico to the overthrust belt in clinally tilted shata resulted in younger transcontinental arch (Turnet 1'962), and -. The present mountain range downdip rocks being displacedover older, shallow-shelf marine deposition prevailed. is a northeast-tilted(25 degrees) uplift formed updip rbcks; and 2) relief variations in the At least four epeirogenic upwarpings re- by extensionaltectonism of the Basin and Piecambrianbasement, due to faultinS, con- sulted in stratigraphic breaks (Middle Or- Range-RioGrande rift systems.This tilting tributed to complex thrust relations. Addi- dovician, Early Silurian, Late Silurian- must be removed to evaluate original atti- tionallv, extremecases of tectonicelimination Devonian, and Early Pennsylvanian(?)-Early tudes of older Laramide structures. (in exiess of 1,370ft in one locale)resulted Permian) evidenced bv unconformities and from thrusting and contributed to apParent gaps in the fossil record. Kottlowski (1958) hanging-wall-downrelations' explained the absence of Pennsylvanian strata Structural features The most prominent structural feature in in the Florida Mountains as a result of a Structuralrelations in the Florida Moun- the Florida Mountains is the Pennsvlvanian "Florida Island" which bor- tains suggest complex Laramide compres- Mountains reversefault that displacesPre- deredihe Orogrande and Pedregosa Basins sionaldeformation characterizedby 1) high- cambrian igneous rock against various Pa- to the east and west, respectively. Turner anglereverse faulting, 2) localizedlow-angle leozoicformations (fig. 3). After removal of (1962), expanding this concept, described the thrusting, 3) localizedfold developments,4) basin-and-rangetilting, the averageoriginal Deming axis (trending from southeast Ari- localizedextensive tectonic brecciation, and fault attitude strikesN. 50'W. and dips 85" zona to trans-Pecos, ) as a series of pos- 5) examplesof stratigraphicelimination along southwest. The thickness of the Paleozoic itive elements produced by epeirogenic thrust faults. Evidencefor pre-Laramidede- section(4,100 ft) representsa minimum stra- upwarping events active from Mississippian formationis generallyabsent but may be ob- tiqraphicseparation on the fault. Movement through Tertiary time. Elston (1958) sug- scuredby later Laramidestructures. A possible oi the south FloridaMountains reversefault gested that the Florida Mountains were a exceotionis a southeast-tiltedhomocline be- is interpretedto have generatedthree levels southeast extension of the Burro uplift in Early neath Gym Peak that strikes into and is of imbricate thrusting within the Paleozoic Cretaceous time. The west-northwest trend- crosscutby the south Florida Mountains re- rocks;the Victorio, Gym Peak,and Mahoney ing Texas lineament, which encompasses the versefault (to be discussed).This tilting may thrustsare named for the lower, middle, and Florida Mountains, was proposed by Moody have occurredearlier in the Mesozoicasso- upper'the levels,respectively. and Hill (L956) as a regional wrench fault ciatedwith the Burro uplift-Deming axis sys- Victorio thrust sheetis an intensely system, but this concept has failed to gain tem of epeirogenicupwarpings. deformed, locally brecciated, complex sheet acceptance by later workers (Turner, 1962; The low-anglefaults of the Mahoney mine- which displacedyounger Paleozoicrocks over Kng, L969; Thompson and Potter, 1981). Gvm Peakarea are controversialin that most older autochthonous Paleozoic rocks and Corbitt and Woodward (1970,1973) and Cor- hive younger over older stratigraphic dis- Precambrianbasement along a highly vari- bltt (1974) interpreted thrust faulting in the placementsbut alsoare noted to locallycarry able fault surface(relief on fault surfacepri- Florida Mountains as a of the Cor- older strata over younger in the more tra- marily due to normal fault displacementsin dilleran fold belt of ditional fashion of thrust faulting. The rocks below). Tectonicelimination is perva- that marks the northern erosional limit of thrusted recumbentfold in the steepnorth- sivealong the thrust surfacewith stratarang- thrusting associated with Laramide defor- ern cliffsof Gym Peakis an exampleof older ing from middle El Paso (Ordovician)beds mation of the Mexican Cordilleran geosyn- rocks displacedover younger rocks (fig. 3). to FusselmanDolomite (Silurian)resting on cline to the south. Drewes (1978) extended Considerableevidence was presentedby Precambriansyenite basement as well as the Cordilleran orogenic belt from Brown (1982)to document these low angle similar eliminationsbetween the autochtho- through southern and southwest faults as thrust faults which are best ex- nousand allochthonousPaleozoic rocks. The New Mexico to , Mexico. Wood- plained by the effectsof two deformation- present location of this thrust sheet, north

NE 6.800

Gym Peok thrust UPPer.level /- southFlorido Mountoins reversefouli /'Gim Peoklhrusl / lower level uem

5,OOO feet

MohoneyRidge

Boldy Peok sourn Florido l\4ohoneythrust unior ns reverse o,. .9t-

oem utm Peok fthrust Oifr r6E V ictorio thrusl

feet FIGURE 3-Tnur-scl.le cRosssEcloNs rHRoucH Gyv Pre< eNo MAHoNEyRroct. p€g, Precambrian granite; pCs, Precambrian syenites; O€b, Bliss Sandstone;Oel, lower El Paso Formation; Oem, middle El Paso; Oeu, upper El Paso; Ou, Upham member of Montoya Formation; Oa, Aleman member of Montoya; Oc, Cutter member of Montoya; Sf, FusselmanDolomite; Qc, undifferentiatedcolluvium, QPy, younger piedmont-slope arroyo alluvium.

NewMexico Geology May 1983 of and below the Gym Peak thrust, suggests thrusting is not supported by field evidence in the caseof the Florida Mountains where that rocks of this sheet may have had their presented in this studv. A basement-cored epeirogenic upwarpings have been docu- source in the present location of the Gym block uplift model, characteristic of Rocky mented dating back to early Paleozoic(Els- Peak thrust and were simply pushed north- Mountain foreland provinces (Osterwald. ton, 1958; Kottlowski, 7958; Turner, 1962). east to make room for the incoming Gym 7961; Berg, 1962; Pricha and others, 1965; Regionaloverthrusting should produce tel- Peak thrust. Woodward, 1959), best explains observed field escopingof facies and stratigraphicanom- The Gym Peak thrust in general displaced relations. The classic cases of large-scale aliesyet to be reported in the literature for younger over older strata except in the overthrusting (King, 1969; Osterwald, 1961) southwestNew Mexico.In fact,isopach con- northern cliffs of Gym Peak where a large involve thin-skinned (does not involve crys- tours by Kottlowski (1963)pass indiscrimi- recumbent drag fold developed with upp"er talline basement) deformation of extremely nately into the proposed Cordilleran and lower limbs thrusted; the Montova For- thick (25,000to 50,000ft) miogeosynclinalse- overthrustedregion. mation members here are clearly repeated quences. In contrast, basement-cored uplifts The south FloridaMountains fault may have three times with the middle section over- involve crystalline basement and typically, a a significant strike-slip component. Juxta- turned (fig. 3). The fold attitude and closure rather thin, cratonic sedimentary sequence. position of Precambriangranite in the hang- is consistent with generation by a northeast- The latter case certainly seems appropriate ing wall south of the fault and Precambrian yielding Gym Peak thrust with an estimated in the Florida Mountains where Precambrian syenitenorth of the fault is difficult to explain 2,000 ft of horizontal displacement. Within basement is obviously involved and strati- by simpleuplifting of the granite.Attitudes the Gym Peak thrust are anumber of normal graphic sequences are thin (Paleozoic meas- of Paleozoicstrata south of Gym Peak and faults which trend northeasterly and are ured section is 4,108 ft). An overthrust model in MahoneyPark indicate possible drag fold- truncated at the top by the Mahoney thrust requires large-scale horizontal movements ing associatedwith right lateral movement and at the base by the Gym Peak thrust. versus the dominantlv vertical movements along the south Florida Mountains fault These faults are interpreted as svntectonic of the block-uplift model. The dominant (W.R. Seageapersonalcommunication, 1982). with Laramide compreision forming parallel structure feature in the Florida Mountains is This fault was nearvertical before basin-and- to the maximum principal stress and the re- the south Florida Mountains reverse fault, range tilting and considerabletectonic brec- sult of tensional stresses localized in the al- and we conclude in this study that horizontal ciation occurred along the fault (typical of lochthonous sheet because of extreme relief movements on the genetically related thrusts strikeslipfaults). changes from faulting in the autochthonous are proportionately smaller than the vertical In conclusion,Laramide deformation in the rocks below. This relationship is analogous displacement of the reverse fault; certainlv Florida Mountains closely resembles the to extension across the crests of domes or the horizontal movements are much less than basement-coredblock uplifts of the Rocky folds. the common range of 2-3 mi for foreland Mountain foreland. Similar deformation is The Mahoney thrust is the highest level of block uplifts (Woodward, 1969). Prucha and documented elsewhere in southern New thrusting and displaced younger over older others (1965) note that thrust faults formed Metco (Seager,1981). We stressthat the scope strata. The thrust typically truncates under- during overthrusting should be geometri- of this study is limited to the Florida Moun- Iying structures suggesting that latest move- cally concave upward, and faults produced tains and no attempt is made to evaluatethe ment postdated movement of the lower thrust by vertical basement uplift should be con- proposed Cordilleran overthrust belt else- levels. This situation is analogous to an ex- downward. In general, the latter con- where. However, we suggestthat in light of perimental study by Sanford(1959) which figuration is true in the Florida Mountains the present study other parts of southwest showed that vertical uplift caused successive (figs. 3, 4) except where relief on the au- New Mexicoand perhapssoutheast Arizona imbricate thrust slices to develop with higher tochthonous basement causes local fluctua- may need to be objectivelyreexamined. levels having the most recent movements. tions. Woodward 0969\ noted that foreland ACKNOWLEDGMENTS-WethanK FranK block uplift areas typically have shown a long Kottlowski, Director of the New Mexico Bu- Regional interpretation historv of structurallv positive tendencies reau of Mines and Mineral Resources,who The proposed involvement of the Florida evidenced by thinnin! of units and uncon- arrangedBureau-funded field expensesfor Mountains in regional Cordilleran over- formities over positive areas. This seems true the study as well as offered encouragement to summarizeour work for this publication. Robin Brewster aided in the preliminarv summarydraft. Thanks also go td GregMack for suggestingthe block-uplift model and William Seagerfor invaluablediscussions on structuralrelations. Additional funding and support was provided by Phillips Petroleum Company, New Mexico Geological Society, Dowell Division of Dow Chemical,and Gene Cook of Deming, New Mexico.

References Berg,R R, 1962,Mountain-flank thrusting in the Rocky Mountain foreland, Wyoming and :American Association of Petroleum Geologists, Bull, v 45, p 2,0'19-2,032 ;:l:fia' Bogart, L E , "1953,The Hueco (Gym) Limestone, Luna :ia;:t.: County, New Mexico: M S thesis, University of New 'li]il: p ililllta::ili:lal. Mexico,91 l- ; .^-, Brookins, D G , 1974a, l'reliminary radiometric age de- terminations from the Florida Mountains, New Mexico: El Paso Geological Society, Guidebook 8, p 47-56 -, 1974b,R;diometric age determinations from the Florida Mountains, New Mexico: Geology, v 2, p 555- 557 -, 1980a, Paleozoic plutonism from southern New Mexico-Evidence from the Florida Mountains: Geo- FIGURE 4-AEruAL vIEw (LooKINGNoRTFrwEsr) oF sourH Flonne MouNrerNsREVERSE raurr (RF). Gvm peak physical Research Letters, v 7, p 741-744 Peak in upper right part of photo where southwest-dipping Gym thrust (GpT) is well exposed -, 1980b, Geochronologic evidence for Paleozoic displayingconcave-downward geometry BP, Baldy Peak;Sp,'South peak. plutonic activity in the Florrda Mountains, New Mexico

May 1983 Nm MexicoGeology (abs American Association of Petroleum Geologists, tains: El Paso Geological Society, Guidebook 8, p 7-15 ): Collection noled Program with Abshacts, v 64, p 681-682 Loring, A, K , and Armstrong, D. G., 1980, Cambrian- "An historicalvignette: Stephen- Brookins, D G, and Corbitt, L L, 7974, Preliminary Rb- Ordovician syenites of New Mexico: Geology, v 8, p. Nors, In the article Sr study of igneous rocks of the Florida Mountains, 344-348 son-Bennettmine" by RobertW Eveleth in the Feb- New New Mexico (abs ): E O S (American Geophysical Union McAnulty, W. N , 1978, Fluorspar in New Mexico: ruary 1983 issueof New Mexico Geology, v 5, no I Transactions), v 55,p 470-477 Mexico Bureau of Mines and Mineral Resources, Mem. l, p 9-13, 15, the superscnpt in table I (p 13) "1978, Brookins, D G., Rautman, C. A,, and Corbitt, L L, 34. o. 47 should appear only with the last two dollar values Hill, M. 1956,Wrench-fault tectonics: Uranium and thorium abundances and whole rock Moody, l. D., and J., '1"207 before the total chemistry of the Florida Mountains, New Mexicepre- Geological Society of America, BdL, v. 67, p liminary report: New Mexico Energy Institute, Uni- r,246 versity of New Mexico, NMEI rept no 77-7704-3, Osterwald. F W , 1951, Critical review ot some tectonlc 1/D problems in the Cordilleran foreland: American Asso- Brown, G A ,7982, Geology of the Mahoney mine-Gvm iiation of Petroleum Geologists, Bull., v. 45, p.219-237 4rnAnnunt- MttrRRls SvmPoslulvl Peak area, Florida Mountains, Luna County, New Mex- Prucha, J J, Graham, j A, and Nickelson, R P, 1965, CALIFOR PAPERS Wyoming ico: M S thesis, New Mexico State Universitt 82 P Basement-controlled deformation in the The 4th annual New Mexico Mineral Sym- Clemons, R E, 1982a, Petrography and age of plutonic province of the Rockv Mountain foreland: American Dosium,sponsored by the New MexicoBureau rocks of Florida Mountains, New Mexicepreliminary Association of Petroleum Geologists, Bull, v 49, p. bf Min"r und Mineral-Resources,the New Mex- report: New Mexico Geology, v 4, no 3, p 33-38 966-992 Mineralogical Society, the Albuquer- -, R., 1959, Analytical and experimental study ico Tech 7982b, Geology of the Florida Gap quadrangle, Sanford, A. Club, and the New Mexico of Mines of simple geologic structures: Geological Societv of oueGem and Mineral Luna County, New Mexico: New Mexico Bureau will be held No- and Mineral Resources, Geologic Map 52, scale 1:24,000 America, Bull., v, 70, p. 79-52 N4.tseu- of Natural History, -, (in press), Geology of the Capitol Dome quad- Seager.W. R., 1981,Ceology of the and vember 12 and 13, 7983,at the New Mexico rangle, Luna County, New Mexico: New Mexico Bureau southern , New Mexico: New Instituteof Mining and Technologyin Socorto, of Mines and Mineral Resources, Geologic Map 55, scale Mexico Bureau of Mines and Mineral Resources, Mem New Mexico.Two"days of presenfedtalks and 1:24,000 36.97o. a silentauction are Planned.Participants may Clemons, R E, and Brown, G A, (in press), Geology Thompson, S., III, and Potter, P. E., 7981, Paleocurrents alsotake self-guided, informal field trips in the of the Gym Peak quadrangle, Luna County, New Mex- of Bliss Sandstone (Cambro-Ordovician), southwest- Texas: New Mexico Bu- area. ico: New Mexico Bureau of Mines and Mineral Re- ern New Mexico and western registrationfor 1:24,000 reau of Mines and Mineral Resources, Annual Rept, Generalregistration is $10'00; sources, Geologic Map 58, scale (over age 60) is Corbitt, L L, 7971, Structure and stratigraPhy of the 1979-1980. p. 36-51 studentsand senior citizens Florida Mountains, New Mexico: Ph D dissertation, Turner, G. L;1962, The Deming axis, southeastern Ari- $5.00.In addition, PaPerson mineral occur- University of New Mexico, 115 p zona, New Mexico, and trans-Pecos, Texas; New Mex- rencesof New Mexicoare solicitedfor presen- -, 7974, Structure and stratigraphy of the Florida ico Geological Societv, Guidebook 13th field conference, tationin 20or 30 minute time blocks.Abstracts Mountains: EI Paso Geological Societv Cuidebook 8, p 59-7^\ o 16-29 Woodward, L A ,7969, Comparative tectonics rn Petro- Corbitt, L L, andWoodward, L A,1970, Thrustfaults leum : Oil and Gas Journal, v 67, p 706- of the Florida Mountains, New Mexico, and their re- 111 gional tectonic significance: New Mexico Ceological So- -. 7970. Precambrian rocks of southwestern New ciety, Guidebook 21st field conference, p 59-74 Mexico: New Mexico Geologic Society, Guidebook 21st -. 7973. Tectonic framework of the Cordilleran fold- field conference, p 27-31 belt in southwestern New Mexico: American Associa- Woodward, L A, andDuChene, H R, 1981,Overthrust North, New MexicoBureau of Mines and Min- iionof PetroleumGeologists, Bull , v 57, p 2,207 2,215 belt of southwestern New Mexico-Comparison with eralResources, Socorro, NM 87801,(505) 835- Darton, N H , 1,977,Description of the Deming quad- Wyoming-Utah overthrust belt: American Association 5246. rangle: U S Geological Survey, Atlas, Deming Folio, of Petrolium Geologists, Bull., v. 65, p.722-729 n no 207,75 p. Drewes, H ,7978,The Cordilleran orogenic belt between Nevada and Chihuahua: Geological Society ofAmerica, NewMexico Geological SocietY Bull,v 89,p 541.-657 Elston, W E,7958, Buno uplift, northeastern limit of FallField Conference sedimentary basins of southwestern New Mexico and southeastern Arizona: American Association of Petro- The 34th annual field conference of the New conference will be on "hands on" geology with leum Geologists, Bull , v 42, p 2,573-2,51.7 Mexico Geological Society will be held in the walking traverses of stratigraphic sections and Griswold, G B ,1961, Mineral deposits of Luna Counfy, Socorro area 13, 14, and 15, 1983. The detailed examination of structural features. Well- New Mexico: New Mexico Bureau of Mines and Mineral field trip will be bv 4-wheel-drive vehicles and illustrated road logs and more than 50 PaPers/ Resources, BuII 72,1.57 p will visit some spectacular canyon and mesa maps, and stratigraphiccharts will be published -,1974, Mineral deposits in the Florida Mountains: few people have seen. The first day in a hardbound euidebook for the conference. El Paso Geological Society, Guidebook 8, p 30-35 country that will contain significant new data Kelley, V C, and Bogart, L E, 1952, Cym Limestone, will emphasize low-angle detachment faulting The guidebook New Mexico: American Association of Petroleum Ce- (Laramide and/or late Cenozoic) and Late Paleo- on a wide variety of subiects including several ologists, Bull, v 35, p "1,(44-1.,648 zoic and Cretaceous stratigraPhy along the east papers bearing on exPloration for minerals and King, P B , 7969, The tectonics of North America-A side of the Socorro Valley The evening banquet energy fuels. An announcement and registration discussion to accompany the tectonic map of North will feature Dr. Warren Harnilton of the U.S form will be mailed in August. The Registration America: U S Geological Survey, Prof Paper 628,95 Geological Survey speaking on "Mode of Exten- Chairman, Dr Richard M. Chamberlin, can be p scale 1:5,000,000 , sion of Continental Crust " The second day's route reached at the New Mexico Bureau of Mines and Kottlowski, F E ,7957, High-purify dolomite deposiis of will cross the Lemitar Mountains, where severe Mineral Resources, Socorro, New Mexico 87801 south-cenhal New Mexico: New Mexico Bureau of Mines (505 and Mineral Resources, Circ 47, 43 p extension (100% + ), domino-style faulting, strong 835-5310). -, 7958, Pennsylvanian and Permian rocks near the rotation (50-70 degrees) of both bedding and early late Paleozoic Florida Islands: Roswell Geoloeical So- rift faults, and the Oligocene volcanic section ciety, Guidebook lL, p 79-87 will be the focus. The itinerary will also include -. 1963. Paleozoic and Mesozoic strata of south- extensive travertine deposits along the Rio Sa- western and south-central New Mexico: New Mexico lado. lacustrine delta deposits in the Eocene Baca Bureau of Mines and Mineral Resources, Bull 79, - Forrnation near Riley, and the detach- 100 p Jeter ment(?) fault along the east flank of the Ladron Lemley, L S , 1982, The Lobo Formation and lithologically similar units in Luna and southwestern Dofra Ana Mountains. An evening barbeque will be held in Counties, New Mexico: M S thesis, New Mexico State San Lorenzo Canyon where erosion has sculpted University, 95 p a scenic badlands from early rift fanglomerates LeMone, D V., 1974, The Lower Ordovician Florida and sandstones of the Popotosa Formation. The Mountains Formation statotype, Luna Counry New third day will focus on ihe Oligocene Socorro Mexico: El Paso Geological Socieiy, Guidebook 8, caldera with stops at the deposits, cauld- o 35-46 Low-anglefaults near Mesadel Yesothat seParatesteePly ron-facies tuff and intercalated breccias, resur- Lindgren, W, Graton, L C, and Gordon, C H, 1910, dipping Glorieta Sandstone(Pg) and San Andres very youn8 manganese The ore deposits of New Mexico: U S Geological Sur- gent dome, and Limestone(Ps) from nearly flat-lyin8 bedsof the Canas vey, Prof Paper 58, p.289-290 mineralization of the Luis Lopez district Member of the Yeso Formation (Pye) Another low- Lochman-Balk, C , 1958, The Capitol Dome section, Flor- Total distance traveled during the 3-day con- anglefault (covered)juxtaposes the CafrasMember ida Mountains: Roswell Geological Society, Guidebook ference will be only 150 , an NMGS record above Cretaceousbeds that are exposedin an arroyo 17, 'o. 47-52 for least miles driven. Emphasis throughout the behind the hill Stop 1', day 1', of field conference , 1974, The Capitol Dome section, Florida Moun-

NatsMexim Geology MaY 1983 29