Outline of the Stratigraphy and Structure of the Sacramento Mountain Escarpment Lloyd C

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Outline of the stratigraphy and structure of the Sacramento Mountain escarpment Lloyd C. Pray, 1954, pp. 92-107 in: Southeastern New Mexico, Stipp, T. F.; [ed.], New Mexico Geological Society 5th Annual Fall Field Conference Guidebook, 209 p.

This is one of many related papers that were included in the 1954 NMGS Fall Field Conference Guidebook.

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andgreen, the cleanliness of its vast expanse, and its way betweenthe east and westborders of the state, 1 appealto thelover of theunexplored mark it as an thesemountains extend northward for 40 milesfrom a areawhich attracts those discerning travelers who pointabout 40 milesnorth of the Texasborder. The U would~’ see Nature’smasterpieces. mountainsare sharplyasymmetrical and riseabruptly g in two majorsteps to a mileabove the TularosaBasin on the west.From the crest,the range slopes almost REFERENCES CITED ¯ imperceptiblyeastward to thePecos River, 80 miles g awayand about6000 feet lower. Although the crest n 1. Botkin,C.W, (1933)(abs) The WhiteSands Na- of therange lies about 9000 feet for more than 20 miles, tionalMonument, Pan-Am. Geologist, v 60, no partis as highas 9700feet. The SacramentoMoun- ¯ tainsare a largeeast-dipping cuesta, uplifted on:the n 4 304-305. westside along a normalOr gravityfault zone. In this sense,they are structurally similar to, and en echelon 2. Dart0n,N.H. (1928) Red bedsand associatedfor- withthe GuadalupeMountains to the southeast,and theOscura Mountains to the northwest.The stratigra- n mationsin New MexicoS U.S.Geol. Survey Bull. phicsection is almostentirely composed¯ of Paleozoic 794,59, 216-218. rocks,ranging in agefrom Cambrian (?) to middlePer- g mian.Rock units of thisarea have many similarities 3. Meinzer,O.E. and Hare,R.F. (1915) Geology and withthe Paleozoicsections of the BasinRanges far- waterresources of TularosaB-asir~ I NewMexi- therto the west,visited by theprevious Field Con- ¯ co, U.S.Geol, Survey Water Supply Paper 343, ference,and withthe down-dipsubsurface sections of [] southeasternNew Mexico.The outcropsalong the 317pp, 19 pis,51 figs. SacramentoMountain escarpment are the closestmajor ii : surfaceexposures in thestate to the subsurfacepre- ¯ 4. Richard,L.M.(1932) White Sands nomadicin na- r Permianstratigraphic section of southeasternNew Mex- tore,may enterAlamogordo in about4097 A.D., ice,a partof thesection which has been of increasing significancein petroleum exploration i n recentyears, The AlamogordoNews, August 4, 1932. n II 5. Russell,C.P. (1935)The whitesands of Alamo- Thisbrief paper is designedto supplementthe road gordoThe NationalGeogr~ Mago, v 68, n 2, 250- log andthe discussion at thestops in presentingthe lib salientgeological features of thewestern escarpment [] 264. Of the SacramentoMountains, with particular:reference to thosefeatures that will be seenduring the Fifth 6. Talmage,S, B,, and Wootton,T. P.,(1937)The Non- FieldConference. An indexmap of the westernpart n MetallicMineral Resources of New Mexicoand of the¯SacramentoMountains is included.A general- U 1"heirEconomic Features, N~w/~exicQ_ School of izedgeologic map of the northwesternpart of thees- Mines,Bull~ 12, 103-107. carpmentarea that will be viewedor visitedduring ¯ the FieldConference accompanies this paper. Essen- [] 7. Winchester,D. E. ! 1933)The Oil and Gas Resources tiallythis same map was usedduring the 1949 G.S.A. of New Mexic.o~New MexicoSchool of Mines,Bull, fieldtrip sponsored by theWestTexas Geological So- am 9,48-49. ciety(King, et al 1949).A compositestratigraphic g ¯ sectionof thepre- Cambribn and Paleozoic rocks will OIJTLINE OF THE STRATIGRAPHY=AND be foundin thegu.idebook and the structural features STRUCTURE OF THE SACRAg~ENTO alongtwo east-westcross sections from the baseto n MOUNTAIN ESCARPMENT thec~est of therangeare given elsewhere in thisguide- book.Several aerial views of thewestern :escarpment LloydC. Pray* are shown, n II INTRODUCTION The writerhas workedintermittently in the escarpmentarea of the SacramentoMountains since 1947, and The SacramentoMount.iris form one of the major has mappedmost of the westernescarpment and part g mm mountainmasses in southernNew Mexico.About mid- of the crestof therangeat a scaleof twoinches equals onemile. Geologic maps and e reportwill be published ¯ Divisionof GeologicalScience, California Insti- by the New MexicoBureau of Minesand MineralRe- [] tuteof Technology. [] 92 ! I J i i QUATERNARY / ¯ Alluvium,l colluviumspring deposits eft.

--~r--~r~, l÷ r~ ?00 Limestoneand minorinterbedded dolomite, erosional i SAN ANDRES " I, ~ uppersurface. GUADALUPIAN LS, "~~’~MBR. ~E~:=:~~in upper pelt ...... 0-150’ Limestone and dolomite;cleon quartz sandstone -- I HONDO i ~ Ill70 O 0 ’ ~=’,~-~Z_~ IPOO-IBO0’Limestone red end yellowmudstone, gypsum, PERMIAN YES() FM. and m nor fine quartzsandstone. L E O N A R D I A N "--~’--~-~:: II I 60O OI - ~

UPI~ERTONGUE -7,-.’’ I I I I ~ 200-550’ ~rk ..... d red mudsf.... Thin beddedlime.tone WOLFCAMPIAN ABO FM, PENDEdO TONGU~ ~.-~ in I LOWERTONGUE. ~"" "" " " -~"-- ""--- southernandgraypartSheofe area.(Pendej° tongueof Hueco fm) BURSUM FM, ~~=-~-- 0- 350’ Shale, gray and red sandstone;limestone I M i:~ \end limest ...... gl .....re, l .... I]5oo0’ A ~...... ¯ --~---7.,.~ VIRGILIAN "x " ~.’,,c~.L~ 0-850’Limestone Qray and red calcareousshale, 1 G HOLDER FM. sandstoneand ~onglomerote.8ioherms ° 4000’ A ~ O-500’ Shale,argilla(:eous limestone and feldspothic BEEMAN FM.")(" ~~I .....’~ m sandstone. L ~- -- I MISSOURIAN _~. _I~=~ i, PENNSYLVANIAN E G-X-

B BuG SCUFFLE LS, A 0-1600’ Limestonesandstone end shale, Coarse quartz 3000’ B MBR. LOCALLY ~-~ sandstonein lower part. Massivegrey, cherty i L ==== mestoneBug Scuff e mestonernb~, grades DES MOINESIAN DIFFERENTIATED "~ l E ----’-- laterallyinto sandstone and 6hole. I R G ~ T-"r- r’--E ATOKAN __ R, M.F ~’~:"I : ~I":~ "~ I JSCALE CHANGE, I I MORROWAN (?) 1 ~~ _~’= shale, Id2000,1 CHESTERIAN HELMS P’M. i=-~ ~_-~_TI 0-60’ Limestone end I I i-- p I

RANCHERIA AND 1~! I~ O- 300’Limestone, silty, dark gray. thinbedded. i MERAMECIAN ~:~: LAS CRUCES (?) EM. ¯-r.. i~

LAKE ~ O-200 Limestone,dark gray, argillaceous,thin 1500’ ARCENTE MBR~.’=Z~: bedded,and calcareousshale. VALILE Y ~ __-- " " __ " ~-T~- OSAGIAN TIERRA BLANC~ ~ 0 - 140’ Limestone,gray, cherty,cr~noidol, FM, MSR ,M~ NUNN MBR, ~Limestone and crinoidol marl~ - I I >~ , ALAMOGORIDO ~P 0 l 400 Limestone1 cherty; I O ¢ ~l, bioherm facies. AND£E~ITO MBR,~~~5’ Limestone silty L and shale. KIN OERHOOKIAN CABALLEROI FM," ~--~’~’~-J~-~i~3 .~.~_c~.~__% -~ .~-c~’~--~---~_15-60’ Limestonenodularand .colaareousshale, 1 I UPPER ISLY GAP& PERCHA (?) FM. --I~-----:~---~I~- 0-45’ Shale and llmeet .... Blockshale ot top moy be DEVONIAN ON~6.TE FM. ~-~-~ 0-60 Siltstone, dalomitic. ~equlvolent to Percho sh, I I J~IODI~E I I0001 I SILURIAN II L~? ) FUSSELMAN FM" ~~=lCO’ Dolomite. dark, Gherty~ resistant,

15012~5’ Dolomite lightgray sublithacjrephic thin bedded. VALMONT DOL, i~r~ ~ ~ ~ ’--~ ClNCINNATIAN "._~5L~-) MONTOYA FM ’ ~ 140-250’Dolomite, upper member cherty lower member massive; I O-I2’OuottZsandslone at th~ bose. ORDOVICIAN L , 500’ I ";",""~

CANADIAN EL PASO FM, ~ 420’ Dolomite,thin bedded,some quartz .sandstone, ..... ~oo’ I =[ ...... ’~ 200 I CAMBRIAN (?) UPPER (?) BLISS SS ~::-:’;!~(;;~}!~!’~:~ I10’ Quartz sandstone, glauconitic. I00’ ¯-’ ~ ¯ ~+~.-~.---80’+Quartz s~ndsfone.-siltstone and shale,slightly PRE - CAMBRIAN (7) metamorphosed,diobese $[1[$. O’ I L l l l ~’~ r" pRAY=54 COMPOSITE COLUMNAH SECTION, SACRAMENTO MOUNTAINS, OTERO 00.,NEW MEXICO * Manuscript name

! NEW MEXICO GEOLOGICAL ,SOCIETY * FIFTH FIELD CONFERENCE * SOUTHEASTERN NEW MEXICO !

sourcesas Bulletin35. A 1952report and o prelimin- tainarea are sediments, largely siltstones, shale, and I arycopy of themaps are on openfile at theBureau fine-grainedsandstone. These crop out only in the officein Socorro.Financial support, here gratefully vicinityof NiggerEd Canyon.Associated with the Ill acknowledged,has beenfurnished for the workby the sedimentsare intrusivesi IIs,mostly of diabase.Some New MexicoBureau of Minesand MineralResources, aremarkedly porphyritic, and locallybear a superficial and theCalifornia Institute of Technology.Referen- resemblanceto plutonicintrusives. The sedimentsand m ces to previouslypublished data most pertinent to the thelater intrusives are separatedfrom the basalPale- ¯mm areaof the SacramentoMountain escarpment is given ozoicrocks by an unconformitywith about 10 degrees in thebibliography, of angulardiscordance. The stratigraphic position, the absenceof fossils(except for obscure fucoidal mark- ¯ STRATIGRAPHY ings),and the absenceof deformationor regionalmet- !1 amorphism aresuggestive of latepre-Cambrian age. The stratigraphyof the SacramentoMountain escarp- Thesurface section is remarkablysimilar to thaten- J mentis almostentirely that of Paleozoicrocks. AI- counteredin the SouthernProduction No. 1 Cloudcroft ! thoughthe compositethickness of the Paleozoicsec- well,which drilled about 100 feet into a pre-Bliss tionis nearly8000 feet, the actual thickness in most sectionof quartzsandstone containing two bodiesof placesis considerablyless than this maximum amount, diabase, g The Paleozoicstrotigraphic sequence can be conven- Ill ientlygrouped into three parts, of a approximatelyequal Blisssandstone: compositethicknesses. The lowestof theseincludes Thisbasal unit of the Paleozoicsequence in south- i rocksranging in age fromCambrian (?) throughMiss- ern New Mexicois exposedin the NiggerEd Canyon II issippian.These strata are mostly carbonate rocks of areain the SacramentoMountains. There it consists marineorigin, deposited on relativelystable, shallow of 110 feetof quartzsandstone, with sandy, brown- gig shelfareas. The olderpart of thesequence is mostly weatheringdolomitic beds interbedded in the upper g dolomite,with limestone occurring in theUpper De- thirdof thesection. Glauconite is abundantin someof vonianand Mississippianstrata. Terrigenous elastics thelayers. Fossils consist of a few linguloidbrach- areminor comoonents in thislower part of the sequence, iopods,and numerous worm (?) borings,and add little Ill andmost are at the base,or withinthe thin Devonian to thecontroversey regarding the ageof theBliss sand- Ill section.The middle third of the Paleozoicsection stone.Flower ( 1953a) indicatesthat the unit is time consistsof Pennsylvanianstrata, largely but not ex- transgressive,and thatboth Late Cambrian and Early Ill clusjvelyof marineorigin. These form a complexin- Ordovicianfaunas are knownin the state.The Residue I! terbeddedsequence of limestone,sandstone, and shale. ResearchLaboratory of Midlandindicates the Bliss of Permianrocks form the upper third of the Paleozoic thisarea to be Cambrianon thebasis of theircorrela- section,and include both marine and non-marinestrata, tions(Roswell Geological Society 1953, p. 20).The II Redbeds are a conspicuouspart of allbut the top of baseof the Blisssandstone is an angularunconform- Ig the Permian~quence and evaporitesare commonin ityin thisarea. themiddle part of thissequence. ¯ El Pasoformation: II The stratigraphiccomments below are primarily con- The onlycomplete El Pasosection exposed in the cernedwith the physicalattributes of thesection ex- escarpmentarea is at the southnear Nigger Ed Can- Ill posedintheescarpmentarea. Evidence concerning yon,where the formation is about420 feet thick. The ! theage of manyOf the rockunits in southernNew Mex- surfacesection and thatin the SouthernProduction No. ico,can be found:in theexcellent summary by Flower 1 Cloudcrofttest are closely similar in thicknessand ( 1953b) in the guidebookfor the1953 New Mexico lithology.The El Pasoconsists largely of mediumlight FieldConference. grayto olivegray dolomite, that ranges in texturefrom I veryfine to mediumgrained. Much of it is lightolive The surfacedata of the escarpmentarea has recent- grayand fine-grained. Thin to mediumbeds predomin- I ly beensupplemented by record of a dryhole drilled to ate,and theformation weathers to a lightbrownish !1 pre-Cambrianrocks by the SouthernProduction Co. slope,commonly with only a few ledgesmore than 10- (No.1 CloudcroftUnit) at a pointjust east of thecrest 20 feethigh. Chert occurs as sporadicnodules and Ill in themiddleof the range. formsbuta minorpart of theformation. Dolomitic quartz g sandstoneis commonin thelower third of the formation, Pre-Cambrian: and quartzsand grains, rarely forming as muchas half ~oT-de-estrocks exposed in the SacramentoMoun - therock, occur locally in theupper third of theEl Pa- I 94 i 1 DEADMAN CANYON SAGRAM ENTO MOUNTAINS SEC.5, T 17 S., R. I0 E. I 245- ~*,Hardblock 80- I ITIERRA ~ --~DONA ANA ~ ~limestone, " ~ 160 " ~ I ~M " 325-

~RECIT075- --~ 2"°1 ~ " ~ J55-- ~_ ~- ~ 5hole filled 320--

0 ~ 6ray thin bedded ~ 6ray to b locJkS, ~" / ~chipp,, siltstone ’ - -"1~j often we~lhered, ~,’1 / ~ .o,d*rev Y --,o a27 I ~ crineidal limeston, 230 _l~soft.gray shale l ~lnf’~’rl~dded 65-- ~ 1 ~ ~witb soft, gray #~jj~) with .....ional . ~ / I~shale. ~ marl bed& 145-- 7f’-~’--~’Jff~) | ~ 510- ~ ~ - "’T"1 Corr,..bit, ~ / i chertthroughout, 7.,I "~’1

"~ I:’:--1":/’asiltsfoneVery s°ft’graY55 inter- -- ~r,,-~,~~ ~20~ ¯ ~;~l~?eCd wit h ~ =r~l"~# Th n bedded 1 ¯ graymarl . I ~. ~ I~ "" ’1 dovegray relo- 55 300- l ~ g ~ ’ ~ ~ tively soft, siltq hJ~ ~ ~ sto.ebed~ that / 1 I I ~I I ~ ~ " ’,,,antherto ~151 - ~" ~Massive d t° Qrav’ ~ nodulor.... rubbly ’-I ~M~ssive,d .... E--~=~ ] IImestonBl ~01 l @ slopes. B’added / ~ ...... iycrystalline ~ w th soft thin I -T4~g~oy to black~ 295- I--.~zq--’ff~~,~t~7-~=.~ / ¯ ~----~.,~bedded si’lty shale.~ I I Icrinoida[limestone. ~ 8oft, veryfinely45- I~I~G ...... >- ~8ilt$t .... 210’~ )"- T-~:J:~=~lnterbe~idedwith ~.~_~.~_’~bedded,gray to ~ C’-"-~q J’ inoldolIs" W ~ predominate I UJ I I I grayerinoidol marl ~1~’~ dark,morlyshele -d ~ . d ~]~"~~toward the top, / d I I Jetbase, ~=~-~-_~.~.J.interbeddedwifh "~[ ~r~J.~_~L’mestonec°nB12-5~ ~Sbalemoreprom- I ~ I I IEssentially290- I~’~ .... ded~harder~ :>.-3~-~-:zf ~ "~ inent ot base, / ~ ~wifhout chert, I grey, nodular4 -- - -- Gray’ shuly’ marll /- ’ Monotonously,, ,..,-~ -- Ily.Afewzonesl [:-oc4!.lyvery LL] --’~ ~ ~ .... I ) ’O,Silif...... ~ " IllllDI Massivegrey 120- ~ ~ sparsely toS2tll)fT~ I ~ ~ 285- ~d 5o--< dll~q-, herd...... ei’;naidalyingiorgo,-$ ~B[;oUz~enemS’oej;e’uobundont¯ I "~ I ~ Local sparsely / ~ I whte chert nodu es - I~’i --~" -- ~ I ~ crinoldal zones./

¯ ~ ~ ~/’~, ~7~-’.q:~"~ /~ ~ I (9roycrlnoidol I~.~z~,~.~----~"-j~.-Jlimestoneinter- h II~ ~ ~ -F~.~.~_~-~2"bedded with soft25 I’ "I ~ / ~=~ond marl. I ® / ,oo_N ’ I .oo- [-~-_C~.°~ ;=~_4-~G r o ~.Oreen ~ / .,’~’~-’1~ c:- ) , 15- ~ cri noidal [s. ~ 180 4 Relativelyhard, I ~ ~ / thenbed ded,groy~l ------~-’:-:[-’T~"~tnhjd;orlimeetane 95- ~ I ~lkl ~ / ~oo- ’. I ~c~_~’~’~oWt,’Ce-groy mot ¯ L~-.~ beddedwith thin, ~ / I ~’~" g.ray,shale beds IO-i ~’~ and nodular Is. ~ 1?5-1

t.... ~90 Mgseive,- block, ¯ 255- ~;y].... ~ / ~ ,~ ~ cherty limestone. ~ | ~ ~ ~- ;&Aj~ ~ ,~o-I~-~,- I ~ ~Zr4=~ ----~---q, I DEV. ~ ~5- ~ i ~ 250- ~F~-q~kSlack shele .~ / . I LAUDON & BOWSHER (1949)

I 9.4a I I ...... ¯ :’ N

~.trr,u~’,-~~¯-!; ~:...... ~"i., !...... :-¯ii--¯:~’~...... "-~ ~ : ~...... :~;...... ,3"--:...... --f J~:’;q"" " ! iiII ~ ~-. L ....! "

PY :. i ". I . " ¯ -.. ~’" ] | .... "~ .,11 i" ~i "\ .... " ; 1 .:’ i...... i " -...;~J ’. P~a . ’i"... " ...... %,~?! ~ ...... i.... , i ,-~..... , i ,,aa~.o,:~ ’ "" ,.i / I "::" ..... i :’ ----,.:...... ~...... "...... :i,"...: ..,. ....,p,o. "’’v’".; ...... T~...... ;;4-::;,,._...... i~"--:-v-.l., ...... 7:...... ::::i_’-- .. ; ’, . .i ...... ! P~. jj~ i -" ...... ’" ¯, ’,q--Luz_ i ":.’,- j ...."..... i"i i .... i,.~, ¯ ’ ...... " :’;¯ i~;" ’~-’Jp,~;’ ~’II II ICHAV’"" ;JJ° --"~’---’i:I -,,.."" ...... L.. I I I " I~]’...... ~~a~Z~J~I’IZ...... ,.I~’ ~I IIIZIIIiII::iIIi I’’III~IIIIII III~I’ ;~...... I~’~II’II~}~I;Y ...... ~’’IIIIZ ...... kS’. .... , III II"/ ’I’ /I / ...... i i~ "II,.I ," ’*..I,_ ~..""...... ’.,.’:- ":i c "h.- .... i,i: " ...... "--. ,," -’-- ~" II....J ’ i -N’:""Z;-"~ ’";’~,}’i "-’-S;-"...... I..._..:.I"Z_!.L.__~ ’"...... I..._.Z ...... ’;.!1%...... ~’- ...... !...... Z-P-.L~L__.."._:.I..’,:_:.J:...:i?~’_ .....i!’..’.)-.._;.i~’,3-.Ii.m IIIIII:I’IIIII:IIIIII i

...... ,,"[ a: ~,~’ i I;,..,II,!~-~;IT.,--~ ...... ~I...... I .I.---/ "",..I:~ ~ ’., ’ I il_ " i "~’~!.... ,...... i ":...... ,’ ,¯ " . ..",,....

"~I-I:~ i.~(;,., ~. ~ ¯ ..,":... " ~4-~__.L. = ".’~’,s,

...... i...... I .... !~...... :."...... :.,, L...... i2 .:...... ~-.,!;’" ...... i...... i...... ! 0~"...... EXPLANATI~ON ’ , ~ s.... ~, ~eo,,~o ’ ~- < SEDIMENTARY ROCKS " -- Pedimen!grgvel bJ ~ ~ . Maroonshale silt~tone, ~dstone~ °.,~<~. .~% z.,i°r.I-,,°n.,.1°.arkose,and conglomerate. ¯ Maroon~nd tan shale, sandstone, arkose, Mo0’...... andconglomerate, i ¯ Light-greycolcar~oos sandstone with SOme shale. 2 13_ " ~ TamShale oad sandstone with $0m¢ cool-5~ds:" ¯ ,o,~ IGNEOUS. AND METAMORPHIC ROCKS ’~ " M ...... hole ~(~ ; Extrusi..... k5 r~ Greytoten ,~hale and sandstone. <[ Flows,tufts, and o~sociofed rock~,

f~ D~kotaoandston~ " ~ Grayshale osso¢i=t)d wilh tan sandstone ~LLI Im~USlVeraC~S maslly porph)’ries " andconglomerate¯ ’~-- Sillsdike~,ptugs, and s~cko, (3’ (Z[ w ...... ~ e. Dockumgroup, undlvided (~ ¯ Maroon$hale, sJltstone, sandstone, and PrO-Cambrianroe~s undivided ~ ~ Quartzite{~nd o~a~ia[¢d rocks. .: -- conglomerate: ..... ~,,,, Carnalfor mo~’ion Chleflypink and ton sill and shale wilh. ~_ somegypsum: . ~..~.----~.~.. . -. . . . Z ¯¯ :. ¯ ¯ Sl~l~Endr~ formation FouH Graylime~Jne ~;th some siltstone and ~andsfo.e ,oso,near....bose ,iand gypsum in upperPort...... Graylimestone end ~lyp~um ~58~Jclated with :" Ionand pink ~{llsto=~ and shale,

... . REIGONNAISSANCE .MAP OF AN AREA SOUTHEAST OF SIERRA BLANCA ¯ IN LINCOLIXI~ OTERO, AND CHAVES GOUNTIES~ NEW MEXICO ’ - ¯ by ¯ .. u~ George O, 8ochmon ..... I / ¯, , . ~ ,-:,. .,,"-, _ -1

NEW MEXICO GEOLOGICAL SOCIETY * FIFTH FIELD CONFERENCE * SOUTHEASTERN NEW MEXICO

sandstoneat the base,the Uphamdolomite (cliff-form- ter dolomiteof southwestemNew Mexico(Kelley and ing lowermember), and theAleman dolomite ( cherty Silver,1952), although of somewhatdifferent facies. uppermember). They also named the nextoverlying It correlateswith strata that form the lower 160 feet of rockunit (Darton’s lower Fusselman) the Cutterdolo- the Fuseslmansection in the typearea of theFranklin mite,and included it as theuppermost formation of the Mountains.The Valmontdolomite of the escarpment Montoyagroup. Detailed studies in the typearea of the arearanges from 150 to 225feet, commonly is about Montayaand Fusselman(Franklin Mountains) and else- 180feet thick, and is composedalmost entirely of me- whereconvince the writerof the correctnessof Darton’s diumto verylight gray, sublithographic to very fine pioneerwork in consideringthe strata in NewMexico graineddolomite. The finenessof grainresults in a thatoccur above the upperMontoya member (or Ale- conchoidalfracture, a characteristic feature. Most bed- man)to correlatedirectly with the Iowerpart of the dingplanes are sharply defined, lateral ly persistentand typeFusselman section. This evidence, and the fact spaceda fewinches to twofeet apart. Chert is scarce, thatthe Montoya is initiallydefined formed a readily althoughbrownish-weathering seams and largenodules recognizablerock unit as such,and one whichsince of partiallysilicified dolomite are conspicuous in the has beenwidely correlated as Montoyain bothsubsur- upperpart of the formation.A zone of argillaceousdol- faceand surface areas suggests to the writerthe ad- omite40-70 feet above the baseforms a persistent visabilityof not expanding the original limits of the nicheon the Valmontslope, and separatesthe forma- Montoyato includea partof theFusselman section, tioninto upper and lowermembers. The factthat Upper Ordovician faunas occur above the top of the Montaya(Pray and Bowsher,1952: Flower, The basalcontact is at thechange from very cherty 1953b)should not be a factorin thenomenclature of dolomiteor solidchert upward into finer grained dolo- rockunits, mitewith little or no chert.Although this change ap* pearsto be at a persistentstratigraphic horizon in this The Montoyaof the SacramentoMountain escarpment area,and locallyis sharplydefined the contactdoes rangesfrom about 140 to 2,50feet thick. It is 200-225 not appearto representa disconformity. Upper Ordo- feetthick in muchof thearea. Very coarse grained to vicianfossils occur in thelower member. The upper granuliticquartz sandstone (Cable Canyon sandstone) membercontains a zoneof favositidcorals, but itsage occursat t~ebase at almostall localities and rea~’hes is not established.The entireValmont is tentatively a maximumthickness of about12 feet.It generally consideredof UpperOrdovician age. gradesupward into sandy dolomite and thenceto sand- freedolomite that forms the bulk of thedark lower mere- Fusselmanformation: bar (Uphamdolomite). This is composedof fineto me- The Fusselmanformation of the SacramentoMountain diumgrained, olive gray to mediumdark gray dolomite, escarpment,the uppermember of the Fusselmanof Dar- thickbeddedto massive, with little or no chert.It is ton(1928), forms conspicuous cliffs in mostof the generally80 to 100feet thick in theescarpment area. area.It is composedof chertydolomite, medium to fine- It appearsto gradeupward by an increasein theamount ly crystalline,of color that ranges from light gray to of chert,a decreasein grainsize, and a changeto thin- oliveand brown-gray,and whichcommonly weathers to nerbeds and to a lightercolor into the slope forming- a colordarker than the fresh surface. Chert is: abun- conspicuouslycherty, upper member (AJeman dolomite), dant,but erratically distributed, and occursas nodules Thisunit is generally100 to 120feet thick. The tap andmasses that are smallerand more irregular than in contactis at thetop of a verycherty zone, which Io- the Montoyaor Valmont.Bedding is commonlyobscure. callyconsistsof 1 -3 feetof solidchert. ’ Theformation is generallyabout 70 feetthick. It does notexceed 100 feet in thicknesswithin the areaof the The basalcontact of theMontoya is a remarkably escarpment,and is absent,presumably by laterSilurian smoothsurface of disconformjty.Fossils are locally or Devonianerosion, from the northernmostpre-Devon- abundantnear the base,and top of the Montoyaand are Jan outcrops, lesscommon in the centralportion. Corals and brach- iopodspredominate, and are consideredto be Upper Wellpreserved fossils are rare. A faunaof about25 Ordovicianin age. generacollected in thisarea has beenstudied by A.L. Bowsher,who considersthat.many forms are similarto Valmontdolomite: thoseof the lower.SilurianEdgewood limestone of Mis- Thisterm was appliedby the Writer(Pray, 1953) souri,and that diagnostic Niagaran or MiddleSilurian the distinctiverock unit of theSacramento Mountain formsare missing in the collections.The writerhas areatermed the lowermember of the Fusselmanby Dar- not recognizedin the thickFusselman sequence in the ton (1928).It appearsto be theequivalent of the Cut- 96

NEW MEXICO GEOLOGICAL SOCIETY * FIFTH FIELD CONFERENCE * SOUTHEASTERN NEW MEXICO

Devonianformations: cherisinto the central and northern part of theescarp- Threerock units of Devonianage are recognisedalong ment. the SacramentoMountain escarpment. These show a gen- eralthough not precise, correspondence with rock units Caballeroformation: recognised by Stevenson(1945) in south-centralNew Thisdistinctive l ithologic unit consists largely of Mexico. mediumgray, markedly nodular limestone and interbeddedcalcareous shale, It occursthroughout the The Onate,the basalunit, occurs throughout the area. lengthof the escarpment.Thicknesses range from about It consistsnearly everywhere of mediumdark gray or 60 feetin thenorth to about15 feetwhere exposed far- brown-gray rock that is composedof aboutequal amounts thestto the south.The faunais consideredKinder- of veryfine grained dolomite mixed granularly with hookianin ageand is abundant,though of rathersmall coarsesilt to veryfine sand size quartz grains. Beds forms.The basal contact is a disconformity,marked aresomewhatmassive and one to threefeet thick, by a zoneabout an inchthick with abundant small, it- Shaleis minor,but increasestoward the south. The regularlyshaped, black siliceous nodules, and occas- Onateis about60 feetthick in thecentral part of the lanaibone fragments or fishteeth. Dark gray or "black" escarpment,and thins to boththe north and south. It shalesare not a partof theformation, although common- can be easilyrecognized in theSouthern Production ly occurringdirectly below the Caballeroand above no- No.1 Cloudcroftwell, where it is about25 feetthick, dularlimestones of the Sly Gap that locally are differ- Faunais consideredupper Middle Devonian, and large- entiatedfrom the Caballerowith difficulty. The Cabal- ly of bryozoansand brachiopods, lerohas been tentatively ident’ified in the subsurface of easternLea County( RoswellGeol. Sac., 1953, p. The SlyGap consists of up to 50 feetof calcareous, 24). yellowgray to darkgray shale, with irregular nodular limestonebeds becoming predominant in the upperpart LakeValley formation: of the section.Some layers of darkgray "black" non- Thisformation has a maximumthickness of about fissileshale up to 6 feetthick occur in theupper par- 400feet in thenorthern and central parts of theSacra- tion.Fauna is abundantand considered to be lower mentoMountains, and thinsto the eastand southward UpperDevonian by Stevenson(1945) and Stainbroak alongthe escarpment,probably both by non-deposition, (1935,1948). It occursin the SouthernProduction Co. and by tiltingand subsequent erosion following its de- No.1 Cloudcroftwell, but appearsto be absentin the position.It is absentfrom the easternmostexposures southernhalf of the escarpment.The lowercontact may in the escarpmentarea, and is notknown to occurfar- representa disconformity in the escarpment area. therto the south.The Lake Valley formation has been subdividedinto six membersby Laudonand Bowsher Darkgray "black" non-calcareous shale considered (1949).All six are typicallydeveloped in the Deadman the equivalentof a partof thePercha shale (Steven- Canyonarea of AlamoCanyon where Laudon and Bow- son’snomenclature) occurs in thesouthern part of the sher(1949) measured the sectionreproduced in this escarpment,thickens southward and is recognisedfar- guidebook.Therange in thicknessesof themembersof thersoutheast in thesubsurface as partof theWood- the LakeValley formation in the’areais givenon the ford(Lloyd, 1949; Ellison, 1950). The only equivalent compositesection. The basalmember of the LakeVal- of thisunit recognised in thenorthern part of theMoun- leyformation is theAndrecito. It is relativelyuniform tainsis in upperMarble Canyon, where 30-40 feet of in lithologyand depositional thickness in theescarp- similarshale occurs in a localchannel filling cut into mentarea, and is composedlargely of argillaceousto theSly Gap formation, silty,thin to mediumbedded,medium gray limestone and interbeddedcalcareous shale. Themost character- Mississippianformations: isticfeatures are the abundance of the swirl-likebranch- ...... The rockunits established for southern New Mexico . ingpatterns of thefossil, Taonurus; the relatively even by Laudonand Bawsher( 1941,1949)are very well ex- bedding;and thenon-resistant nature of the unit,which posedand developedin the SacramentoMountain region, formsslopes in markedcontrast to the prevailingcliff Mappinghere has indicatedthe soundnessof theirde- or scarpof the overlyingAlamogordo member. The ba- tailedwork, and hasrequired only minor modification salcontact is a disconformity,locally showing low an- of theirdata regarding lithology. Thickness, and areal gslardiscordance. distributionof the units. Perhaps themajor changes in thelatter were the recognition of the Helms in thesouth- Spectacularbioherms profoundly affect the thickness, ernescarpment area, and of the persistenceof theRan- distribution,andto a lesserdegree, the lithology of the

98 ! NEW MEXICO GEOLOGICAL SOCIETY * FIFTH FIELD CONFERENCE * SOUTHEASTERN NEW MEXICO

I uppermostfive members of the LakeValley formation, not alreadystopped it. Thebasal Arcente contact ap- The biohermalstruc~res are mostabundant in the north- pearsdisconformable in the southernpart of the escarp- emmostpart of the area,between Indian Wells and AI- ment,but perhapsis gradationalwith the Tierra Blanca I amo Canyons.In thisarea many of thestructures are to thenorth. The DanaAna memberis gradationalwith elongatealong north-south trends. The largest of all theArcente, and marks a returnto clearseas and pro- thebiohermal structures occur along the central part of fusedevelopment of crinoids.The DanaAna is a cher- i ¯ theescarpment, in the vicinity of SanAndreas Canyon, ty,coarse light gray, irregularly bedded crinoidal lime- whereseveral are nearly400 feetin thickness.These stone,very similar to the TierraBlanca. The Arcente appearto be circularin plan,rather than elongate. The and DanaAna are absentin the northernmostoutcrops, I photographsshow the majorfeatures of one of these wherethey probably were removed by pre-Pennsylvan - largebiohermal structures. One shows a cross-sec- Jan erosion.They are largely absent from the southern tionalview of oneof theelongate structures of theAI- partof the,range, where they may have initially been areaCanyon ¯area. The biohermsappear to haveformed but thinlydeveloped, and from which they were stripped I duringthe depositionof thelower part of thelake Val- by erosionprior to 1fiedeposition of the Rancheria form- leyformation. Many are largely restricted to theAla- ation. mogordomember. The largerones commonly rise from I withintheAlamogordomember. The genesisof these Rancheriaformation: structuresis notwell under6tood, but several indepen: Thisformation consists largely of mediumto dark dentinvestigations currently are in progress.The bi- gray,¯ argillaceous andsilty, locally siliceous, thin ohermalcores appear to representareas-of profuse crin- beddedlimestone, with minor calcareous shale and I oidalgrowth, at leastsome of whichclearly stood high- somemassive strata of medium-graycrinoidal lime- er thanthe levelof adjacentcontemporaneous deposi- stone.The Rancheriais about300 feetthick in the tion,though perhaps not abovewave base. A puzzling southernend of the escarpment,and thins progressive- i aspectof someof themore abrupt structures is theap- ly northwardto MuleCanyon. A thinshoreward remnant parentabsence of a sedimentbinding organism, such as may occurlocally in AlamoCanyon. The formationis colonialalgae, that could build and maintain the steep- similarto the sectiohof the Franklinand Hueco Moun- i ly-slopingstructures. The biohermalcoresconsist taJns.itispossiblethatthe lithologicallysimilarkas largelyof lightgray, essentially massive, very fine Crucesformation that underlies the Rancheria formation grainedlimestone that contains abundant partially re- in theFranklin Mountain area may be includedwith the crystallized,crinoidal debris; some of it concentrated Rancheriain the southernpart of the SacramentoMoun- I in streaksor irregularlayers, and some as isolated rains.The northernmost,onlapping part of theRancher- fragmentsin thedense matrix, ia alongthe escarpment has characteristicsof shallower waterthan most of theformation, which has a basinal i The Alamogordomember, where not directlyaffected aspect.The sparsefauna is consideredto be Mereme- by thebiohermal structures, is a mediumlight gray, clanin age by/audonand Bowsher,but Wellerand somewhatcherty, calcilutite; commonly about 35 feet othersconsider the samefauna as uppermostOsagian. B thickwhere not affectedby subsequenterosion. The (Seediscussion in Jones,1953). The basalcontact II Nunnmember is a softcrinoidal marl, which ranges is a clearlymarked unconformity that progressively cuts widelyin thicknessand is locallynot developed.Most outthe underlyingLake Valley and Caballeroformation of thespecimen crinoids are collected from this mere- fromnorth to south.Locally angular discordances of I ber.The TierraBlanca is a coarse,well cemented, 5- 10 degresshave been noted. crinoidallimestone that forms conspicuous light color- ed cliffs,in manyplaces showing very irregular beds. Helmsformation: i Chertis common.The TierraBlanca thins gradually TheHelms occurs in the southernpart of the area awayfrom the majorareas of bioherms, and extendsnorthward to nearDog Canyon.It is a max- imumof 60 feetin thickness,and consists of thinbed- The uppermosttwo membersof the lakeValley form- ded,argillaceous limestone and yellowand grayinter- i ation,the Arcente and theoverlying Dana Ana, appear beddedshale. It is similarin lithologyand fauna to the to havebeen deposited in muchof the escarpmentarea thickersections of the Huecoand FranklinMountains, afterthe major ~0eriod of biohermalgrowth. The condi - exceptthat sandstone is almostabsent in the Sacra- I tionsthat led to thedeposition of thethin bedded, me- mentoMountains area. It containsChesterian fossils. diumgray, argillaceous limestone and darkcalcareous Thebasal contact is probablya disconformity butlittle shaleof theArcente probably were distinctly unfavor- physicalevidence of thisrelationship has beenobserv- ablefor crinoidal growth, if emergenceof theareahad I ed in thelocalarea. ! NEW MEXICO GEOLOGICAL sac ETY *.FIFTH FIELD CONFERENCE * SOUTHEASTERN NEW MEXICO I P.ennsylvani.an.~, to 2500feet, and includes Virgilian s~’rata at thetop. The Pennsylvaniansection of the SacramentoMoun- Pre-Aboerosion is morepronounced to the east~where tainarea stands in sharpcontrast to theolder Paleo " the Abo in manyplaces overlies strata of Desmoinesian zoicsection. It is as thickor thickerthan the entire and Missourianage, and locallyhas removedall of the I underlyingPaleozoic section, it containslarge amounts Pennsylvaniansection. of terrigenouselastics, and lithologic changes both lat- erallyas wellas verticallyin-the section occur with The basal-Pennsylvanianstrata of-the area were de- I rapiditythat leads to despairif oneattempts to subdi- positedon a surfacethat had at least100. feet of local. videthe Pennsylvaniansection on the basisof mappable relief.The low parts of thissurface, some of them abruptchannels, are commonlyfilled with. coarse quartz rockunits that will prove recognizab:le over the entire I escarpmentarea. The Pennsylvaniandeposits clearly sandstoneorwith cobble conglomerates of Mississipp- reflectthe increasing degree of tectonicinstability that Jan cherts.Shales and darklimestones are commonly occurredduring this period in theregion, an instability inter!ieddedwith the lower 200 to 500feet of thePenn- thatresulted in theformation of morelocalized basins sylvaniansection, but ral’ely occur in thelowest parts i and sourceareas than previously had existed in earlier of the basal-Pennsylvanian. surface. The coarseness Paleozoic~time.This more localized aspect of Penn- andamount of the terrigenousclastics in thelowest partof the Pennsylvaniansection diminishes toward sylvaniansedimentation, combined with probably fie- I quenteustatic changes in sealevel, resulted in the thesouth. complexityof depositsfound in the escarpmentarea of Overlyingthe lower200-500 feet of the Pennsylvan- the SacramentoMountains. Jan sectionare two contrastingcontemporaneous fac- I In general,the SacramentoMountain escarpment ap-. ies.One of these,a shelflimestone facies, and region- allythe more extensive, consists almost entirely of pearsto lieto thesoutheast of a positivearea that fur"~ nishedterrigenous clastics intermittently during Penn- somewhatcherty calcilutites, up to about1000 feetin I sylvaniantime. The positivearea was termedthe Ped- thickness.These are .conspicuous.along.thewestern ernalLandmassby Thompson(1942). Though of major, escarpmentsouth to AlamoCanyon, and alsoto the northeastinupper Fresnal Canyon. Separating these importancein earlyPermian and latestPennsyl.vanian. I time,its role is lessclear earlier in thePennsylvanian shelflimestones and .grading into them with extreme period.It seemsprobable that the outlines of thispos- abruptnesstis a comparablethickness of quartzsand- stones,subgraywackes, shales, and minorlimestones. itivearea, and its degreeof activity, varied widely dur- I ing Pennsylvaniantime. U.nfortunateiy, thedetails may Thissequence is considereda deltaic facies. The n’ever.belearned.. Much of thepertinent record was ob- shelflimestone facies and thedeltaic facies are both literatedby erosionthat occurred during the major up- largelyof Desmoinesianage,bu:t extendinto the Miss- liftof thisarea at the.end of Pennsylvanianandin ear- ourian. I ly Permiantime. Moreover, Permian strata now blanket muchof thearea, and thelikely prospect of encounter- As muchas 500 feetof thinbedded, argillaceous limestoneand shale of Missourianage overliesthe ing pre-Cambrianstrata directly beneath the Permian I undoubtedlywilidiscourage much drilling of pertinent shelflimestone, and deltaic facies. In mostof thearea areas." theseare of somewhatbasinal aspect, but locally se- quencechanges.laterally into massive limestones, with g The Pennsylvanian’sectionof the SacramentoMoun- interbeddedlimestone conglomerates, and othersug- tainshas a maximumthickness of about3000 feet,, and gestiansof.cyclical deposition in a turbulent,ishallow thedepos~its appear to spana timerange from possible .waterenvironment. The uppermostPennsylvanian de- ¯ Morrowanat the basethroughout the remainderof Penn- positsare thoseof Virgilianage. The base of these. [] sylvaniantime (Thompson, 1942). Most strata .are reflectsanother change in typeof depositionas algal marineorigin. Field.evidence suggests that deposition reefs,and reef-likemasses up to 100 feetin thickness wereformed throughout most of the area.The Virgilian continued.withno major interruptions throughout this I time,at least,no persistenterosional surfaces have stratagrade upward into more uniformly bedded, light beenrecognisedwithin the Pennsylvaniansection in coloredlimestone~ interbeddeci with shale and minor ¯ themapping of the escarpmentarea. Three.formations sandstone.Red shales,andlimestone conglomerates and one memberhave been..used in mappingto subdivide are repeatedsomewhat cyclically with non-red shales, i thePennsylvanian section in thisarea. Along most of andmassive to nodularlimestones in the uppermost the westernedge of the mountainsthe Pennsylvanian Pennsylvanianstrata in the area.The depositsappear sectionis nearlycomplete, ranges commonly from 2000 to indicate,in additionto repeatedfluctuations of the I 100 ! ! NEW MEXICO GEOLOGICAL SOCIETY * FIFTH FIELD CONFERENCE * SOUTHEASTERNNEW MEXICO I depthof deposition,a gradual transition toward emer- miticlimestone, and non-redshales. This middle se- genceof the area.The finalemergence was followed quencethickens southward all the way to the Hueco by erosionof previousdeposits at the endofthe period Mountains,changes from brackish to marinefacies, and in mostof thearea. formsmost of the Wotfcampianportion of the Huecolime- stonein the HuecoMountains. The uppertongue of Abo Bursumand ABO formations: red beds(the entire Abo of Darton)can be tracednear- m in theescarpment area, the strata Of Wolfcampian Jy to the Texasborder, and forms the Deer Mountains age are assignedto the Bursumand Abo formations, redshale of the Huecolimestone. The lower tongue of Rapidchanges in faciesand thicknessoccur in strata Abo red beds probablycorrelates with the Paw-wow I of thisage,in respanseitothe~deformation that occurred conglomerateof the Huecolimestone. in latePennsylvanian and earlyWolfCampian time, and somecontinued structural disturbances that l ingeredin- Throughoutthe areaof the SacramentoMounta:in es- to laterPermian time. For the purposesof thisbrief carpment,exclusive of thesmall northwestern sector, m out!ine,the areaof theescarpment can be dividedinto theAbo liesabove an angularunconformity cut on fold- twounequal parts, a sectorthat extends to thenorth ed and faultedpre-Permian strata. This angular un- andwest from a pointalong the Fresnal fault west of conformityis believedto be coextensiveand con~temp- I HighRolls ( see geologicmap), and a muchlarger area oraneousin developmentwith theangularunconformity thatlies east and south of thispoint, at the baseof the Huecolimestone over wide areas of theDiablo Platform to thesouth. In thenorthwestern sector, detailed investigations I haverecently been completed by C. Otte(Otte, 1954). Yesoformation: Theseindicate that deposition in a basinthat occurred Thisunit, considered Leonardian in age,but notdat- in thissector north of the vicinityof La LuzCanyon ed in theescarpment area, is 1200to 1800feet thick. I was essentiallycontinuous from Pennsyivanian through It consistsof theusual widely varying lithologies so Wolfcampiantime, and probablyon intomiddle Permian characteristicof the Yeso.These include carbonates, time.In thisbasin, a gradualt’ransition from marine to mostlylimestone; red, yellow, and graysiltstones and I non-marineconditions occurred, accompanied by re- shales;evaporites,largelyanhydrJte(.gypsumat sur- peatedfluctuations of the strand line in thearea of pre- faceexposures) with some halite; and yellowish, silty, sentexposures. Lower Wolfcampian strata, correlated finegrained sandstones. Rapid lateral and vertical var- withthe Bursum formation and datedon thebasis of iationin lithologyis normalto theYeso. Carbonates I containedfusulinids, are about400 feet thick a mile becomeincreasingly prevalent in theupper part of the northof La Luz Canyon.These strata thin to the south- section,and red bedsand evaporitesare mostabundant easttoward the Fresnalfault, change into a non-ma- in thelower part. Exposures Of the Yesoare toopoor I rinesection of red bedsand limestoneconglomerates in mostof theescarpment area to makeit feasibleto in a few miles.Traced further, they appear to pinch subdividethe Yeso.The basalcontact appears con- outin theunconformity that represents much of lower farmablewith the Abo. I Wolfcampiantime’on the deformedand positivearea eastand south of theFresnal fault. San Andreslimestone: The San Andreslimestone forms the resistantupper- The Abo formationwas deposited over the entire es- moststrata of the crestand of muchof theeastern slope I carpmentarea, but variesconsiderablyin the two areas of the SacramentoMountains.A!thou~ over 1000 feet mentionedabove. In thebasinal area east of Tularosa thickto theeast, less than half this thickness is pre- it is about1,100 feet thick and composedprincipally servedalong most of thecrestal portion of the moun- I of darkreddish brown mudstone and arkose.Here it rains.Progressively thinner sectionsoccurto the gradesinto underlying latest early Wolfcampian marine south.The San Andresis composedlargely of thinto strata(Otte, 1954). The ABOthins rapidly toward the mediumbedded limestone, of variousshades of gray. positiveblock to thesoutheast, and is about400 feet Somestrata are dolomitic.Fusulinids are not known I thickin theHigh Rolls area. It I~ereis composedof in the San Andreslimestone in theescarpment area, basalquartzite cobble conglomerates, and an overlying andthe knownfauna adds little to theproblem of the muchthicker sequence Of darkreddish brown mudstones age of theSan Andre s withrespect to thetype Permian I and arkose.Farther tO the southalong the escarpment, sections. it is 200to 550feet thick, and splits into an uppermost and a basalseries of red beds,and a middlesequence In mostof thecrestal part of therange, quartz sand- I composedprincipallyof thinbedded limestone, dol0 stonesof t~e"Glorieto" type ( clean,rounded, frosted, 101 i

I NEW MEXICO GEOLOGICAL SOCIETY * FIFTH FIELD CONFERENCE * SOUTHEASTERN NEW MEXICO

I northof Cloudcraft.The rocks here consist largely of be largelythe result of upliftwith respect to theTul - olive,gray, and purplish shales, variegated quartz silt- arosaBasin along a normalor gravityfault zone that stones,and somequartz sandstones, locally conglom- is at or closeto thepresent base of theescarpment. I eratic.They probably are correlative with a partof the The upliftprobably began in lateCenozoic time, and Mesozoicsection reported in theSierra Blanca and Cap- appearsto stillbe in progress.The faulting hypothe- itanregion to thenorth (Allen and Jones, 1952). sis accordswith that of mostgeologists familiar with I theIarea butis notshared by thewriters of thetwo most Tertiarystrata maywell be presentbelow the pre- extensivepublished accounts of thestructure of the sentsurface of theTularosa Basin, but in theabsence SacramentoMountain. Darton (1928) considered the of theBasin deposits, this will be difficultto determine, mountainsare essentially anticlinal, somewhat modi- I fledby faulting.Baker (1928) appears to havebeen un- STRUCTURE decidedas to a faultor foldorigin for the uplift of the range.According to thehypothesis for the origin of the i Theoverall structure of theSacramento Mountains is rangeby folding~the visible part of therange repre- thatof a largecuesta, with a regionaldip to theeast sentsessentially the eastern gentle limb of a major of aboutone degree. Along the crestal part of theblock north-trendinganticline, and the muchmore steeply I nearthe north and south ends, the strata dip several dippingwesternlimbis interpretedtohavebeenremov- degreesto thenorth and south respectively, a reflec- ed by erosion.Abundant surface evidence appears to tionof thelesser amount of upliftin thesedirections favorthe fault hypothesis, whereas evidence at thesur- thanalong the centralzone. facefor the foldingand removal by erosionof the west- I ern limbappears to be scanty,at best. The mappablestructure of thearea of the westernes- carpmentis in few placesas simpleas the broadregion- Alluvialor piedmontscarplets occur along much of I al picturewould suggest. Gentle folding and some fault- thelength of therange at thebase of theescarpment. inghas affected the Permian strata in mostof theas- Thesescarps are up to 80 feetin height,all observed carpmentarea so thatthe local picture rarely reflects facethe basin, and although largely in alluvialmaterial, I the regionalgentle cuesta structure. The pre-Permian bed-rockis commonlyvisible on themountain side of strataare moreintensely deformed than the Permian, the scarpswhere they have been dissected by recent as a resultof deformationby both folding and faulting drainage.These piedmont scarps are excellentevi- durirLglate Pennsylvanian and early Wolfcampian time. danceof majordislocation in recent time along the I Additionalcomplications of the broadsturctural picture westernedge of the escarpment. occuralong the marginof the escarpment,and presum- ablyare related to theuplift of themountain block. A hostof minorfaults near the edge of themountain I block,that appearto be sympatheticstructures along Mostof thestructural features of the escarpmentarea a majorgravity fault zone, furnishes additional evidence havea northerlytrend. An indicationof thetypes of forthe presenceof a majorfault zone at thewestern structural features andtheir magnitudes can be noted edgeof theblock, it is strikingto note theincrease in I on the drawing,which shows two cross-sections from number,and to a lesserdegree, in themagnitude of dis- theTularosa Basin to thecrest of the rangein thenor- placementof faults,as oneapproaches the outermost thernpart of theescarpment area. These two sections portionof the mountainblock. Most faults are west- I aretypical of thefeatures found throughout the length dipping,gravity faults with a predominantdip-slip of theescarpment, movement.In manyplaces dips steepen abruptly toward thewest in the outermost100 feetof exposuresalong i Genetically,the structuralfeatures of theSacramento thebase of the escarpment.These effects are consider- Mountainescarpment can be dividedinto to majorgroups, ed to be causedby dragalong the frontalfault zone. thosewhich are relatedto thelate Cenozoic deformation thatresulted in theuplift of therange, and those struc- The baseof the escarpmenttrends generally slightly I turalinheritances that pre-date the uplift of therange, westof northfor much of itslength, but is irregularand andwhich have either been unaffected or butslightly somewhatangular in detail.There is a notablelack of modifiedsince the inceptionof BasinRange deforma- of correspondencebetween its traceand either the vis- I tion. iblestructure of themountain block, or theerosional resistanceof the strata that locally form the edge of Featuresrelated to theuplift of therange the mountains.It wouldappear that any detectablean- I Thepresent mountains are believedby the writerto ticlinalstructure in the areaof theSacramento Moun- 103 ! II NEW MEXICO GEOLOGICAL SOCIETY * FIFTH FIELD CONFERENCE * SOUTHEASTERN NEW MEXICO rainescarpment is exceedinglygentle, and showsno blockis almostentirely unknown. Clastic fragments in I moreindication of westerndips than would be expected Paleozoicsediments indicate that areas of provenance nearthe faulted edge of a tiltedblock the size of the forquartzite, granite, and some other intrusive and met- ¯ SacramentoMountains. amorphicrocks occur in theregion, probably to the | northeast.Direct observations only indicate that a The presentneed is fordata on themissing part of slightlymetamorphosed sedimentary terrane, injected thestructure that underlies the alluvium of the Tularosa withdiabasic intrusives, was slightly tilted prior to I Basinto the west.Some geophysical work has been cam- erosionand the subsequentdeposition of thebasal mm pletedin recentyears along the eastern edge of theba- Paleozoicclastics. sin,and it is to be hopedthat at leastthe broad re- ¯ suitsof theseseismic, gravity, and magnetometersur- The areaof theescarpment,in common with much of veyswill be madegenerally available. Surface and well southernNew Mexico,appears to havebeen tectonical- dataat presentis meagre.It consistslargely of scat- [y stable,subject only to epeirogenicwarping, intermit- ¯ teredoutcrops of Permianstrata (Yeso-San Andres) tentmarine inundations, and minor erosion from late | 10 to 15 mileswest of the baseof the range,and sev- Cambrianinto Devonian time. Known disconformities eralwater wells drilled at Alamogordoand Valmontto in thisarea occur at the baseof the Montoya,the Fus- depthsof about1200 and 1800feet, respectively. These selman,and the Onateformations, and may be present I arereported to havebottomed in alluvialmaterial. It at the baseof the El Pasoand Sly Gap formations.Dur- ra wouldseem likely that the alluvialfill is a maximum ing laterDevonianand Mississippian time somewhat in- thicknessnear the baseof the escarpmentalong the .creasingstructural distur~0ances is recorded. Discon- ¯ centralpart of themountains, and that it.decreases in formitiesoccur at thebase of the Percha(?), the Cab- thicknessto thenorth, south, and west. allero,.andthe Lake Valley formations; possibly at the baseof the Arcentemember ofthe Lake Valley forma- I Totalamounts of displacementon the hypothetical tion,and a lowangular discordance at the base of the | boundaryfault are highlyspeculative On the basisof Las Cruces(?) and Rancheriaformations can be de- thepresent data. On .theassumption of 2000feet of al- tectedthroughout most of the escarpment.The uncon-. luviumwest of the boundarystructure, and on an alluv- formityat the baseof the Pennsylvaniandeposits, and 1 ium-bedrock contact at thelevel of theYeso -san An - the recordof the ensuingPennsylvanian strata clearly drescontact, the amountof displacementalong the cen- indicatemore tectonic instability in the local area than tral15 milesof theescarpment would be of the orderof at any previoustime during the PaleozoicEra. The ¯ 7000feet. This figure is probablya minimum,rather increasingunrest culminated in the majordeformation thana maximum, duringlatest Pennsylvanian and earlyWolfcampian timewhen many of the internalstructural features of I In thesoutheastern part of theescarpment area, a the SacramentoMountain escarpment were formed, majornorthwest trending fault, and associated sharp I flexurein thePermian strata, as wellas severalsmall ¯ Structuralfeatures suchas theCaballero anticline, faultsof similartrend, may havebeen formed contemp- the Dry Canyonsyflcline, the AlamoPeak, Fresnal, and 1 oraneouslywith the major uplift of therange. ArcenteCanyon faults (see geologic map) were largely l formedduring the latePennsylvanian-early Permian ~Featuresthat pre-date the late. uplift of theran q deformation.Most of theseand othercontemporaneous ¯ Mostof thestructural features of theSacramento Moun- structuretrend roughlynorth - south.The folds are open | tainblock appear to havebeen formed prior to thelate to moderatelytight, with undulatory axial c~®,~ts and upliftof theblock. These earlier structural features of troughs.Domes are conspicuousfeatures ~iiong some of the mountainblock were largely formed during Paleozoic theanticlinal crests. Faults are high angle and dip . 1 time,although some deformation occurred duringthe slipdisplacements range up to a thirdof a mile.The J mesozoicor earlyCenozoic. The datingof the Paleo- basalAbe:unconformity truncates parts of allof these zoicdeformation is relatively precise owing to theas- structures,with local angular discordance as high as ¯ satiatedsedimentary record, but thevirtual absence of 60°. As Virgilianstrata occur below the basalAbo l Mesozoicand of pre-QuaternaryCenozoic strata renders unconformityin parts of thearea, the age of thedeform- speculativethe ageof thepost-Paleozoic events. In ationand subsequent erosion is largelylate Pennsyl- / thefollowing brief survey, the structural events are vanianand earlyWolfcampian. This deformation in the | discussedin chronologicalorder. SacramentoMountain area is consideredto be a partof thatlong known in thearea to the southand southeast The pre-Cambrianstructural history of the mountain thatpreceded the deposition of theHueco formation ..,I 104 !

NEW MEXICO GEOLOGICAL SOCIETY * FIFTH FIELD CONFERENCE * SOUTHEASTERN NEW MEXICO

conformitysuch as postulatedby King(1948) for the Jones,T. S. (1953)Stratigraphy of the PermianBasin SummitPeneplain of the GuadalupeMountains. of westTexas, with special reference to tilecross sectionsof 1949,1951, and 1953:West Texas Geol- Thatsome activity occurred prior to mid-Tertiaryis ogicalSociety. suggestedby therelationship of the igneous intrusives of thearea to thesmall thrust faults that are a minor, Kelley,V. C. & Silver,C. (1952)Geology of the Cabal- butconspicuous feature along the central part of the leroMountains: Univ. New Mex..Publications in Ge- escarpmentnear the front of the range.Many faults with ologyNo. 4. displacementsof a fewhundred feet, which dip to the westat anglesof 15-30° havebeen noted in the older King,P.B. (1948) Geology of the SouthernGuadalupe partof thesection. These appear to be earlierthan the Mountains,Texas. U.S. Geol. Survey, Prof. Paper intrusionof dikesand sills, commonly of hornblende 215. andesiteporphyry, into the sedimentarysection. The igneousactivity would appear to be relatedto thatbet- King,P.B. et al (1949)Pre-Permian rocks of Trans- terknown in the SierraBlanca and Capitan regions (AI- Pecosarea and southernNew Mexico:Guidebook lenand Jones, 1952) directly to thenortheast of the FieldTrip No. 5, WestTexas Geological Society. SacramentoMountains. They date igneous activity similarto thatin theSacramento area as mid-Tertiary. Lang,W.B. (1937) The Permianformations of the Pecos Valleyof New Mexicoand Texas:Am. Assoc.Petrol- eumGeologists Bull., vol. 21, pp.833-898. BI BLIOGRAPHY Laudon, L. R. & Bowsher,A. L. ( 1941) Mississippian Allen,J. E. &Jones,S. M. (1952)Geology of Capitan formationsat the SacramentoMountains, New Mexi- Quadrangle,New Mexico(Abstract). Geol. Soc. co:Am. Assoc.Petroleum Geologists Bull., vol. 25, Amer.Bull., vol. 63, p. 1319. pp. 2107-2160.

Baker,:C.L. (1928)Desert range tectonics of Trans- (1949)Mississippian form- PecosTexas: Pan-Amer. Geologist, vol. 50, pp. ationsof southwesternNew Mexico:Geol. Sac. Am- 341-373. ericanBull., vol. 60, pp. 1-88.

Bose,Emil (1920)On the Ammonoidsof the Abo sand- Lloyd,E. R. (1949)Pre-San Andres stratigraphy and stoneofNew Mexico:Am. Jour.Sci., 4thser., vol. oil-producingzones in southeasternNew Mexico: 49,pp. ¯57-60. N. Mex.Bur. Mines Min. Res. Bull. 29.

Darton,N.H. (1917) A comparisonof Paleozoicsec- Otte,Carel, Jr. (1954)Unpublished Ph.D. thesis tionsin southernNew Mexico:U.S. Geol. Survey UpperPennsylvanian and LowerPermian stratigra- Prof.Paper 108-C. phy of the northernmostSacramento Mountains, New Mexico:on file,Califomia Institute of Technology (1928)Red.Beds, and associatedforma- and New MexicoBur. Mines and Min.Res. tionsin New Mexico;witth an outlineof thegeology of theState: U.S. Geol. Survey Bull. 794. Plumley,W.J., and Graves, R.M., Jr. (¯19.53) Virgilian reefsof the SacramentoMountains, New Mexico: Ellison,S.P. Jr. (1950)Subsurface Woodford black Jour.Geology, vol. 61, no. 1, pp.1-16. shale,west Texas and southeasternNew Mexico; Univ.Texas, Bur. Econ. Geol., R ept.Invest., No. 7. Pray,L. C. (1949)Pre-Abo deformation in the Sacra- mentoMountains, Otero County, New Mexico( ab- Flower;R.H. (1953a) Age of the Blisssandstone, New stract):Geol. Soc. America Bull., vol. 60, no. 12, Mexico:Am. Assoc.Petroleum Geol. Bull., vol. pp. 1914-15. 37,pp. 2054- 55. (1952)Unpublished Ph.D. thesis (1953b)Paleozoic sedimentary rocks stratigraphyof the escarpmentof the Sacramento southwesternNew Mexico:C~ i debookof s0u~hwest- Mountainsi OteroCounty, New Mexico:on file,Cal- ern New Mexico,4th FieldConference, New Mexico iforniainstitute of Technologyand New MexicoBur. GeologicalSociety Mines,Min. Res. 106

" I i NEW MEXICO GEOLOGICAL SOCIETY * FIFTH FIELD CONFERENCE * SOUTHEASTERN NEW MEXICO I Pray,L. C. & Bowsher,A.L. (1952)Fusselman lime- SacramentoMountains near Alamogordo, New Mex- stoneof the SacramentoMountains, New Mexico ico:Jour. Paleontology, vol. 21, no. 4, pp.297-328. (abstract):Geol. Soc. America Bull., vol. 63, I 1342. (1948)Age and correlationof theDe- (1953)Upper Ordovician and vonianSly Gap bedsnear Alamogordo, New Mexico: Silurianstratigraphy of Sacramento Mountains, Otero Am.Jour. Sci., vol. 246, no. 12, pp. 765-790. i County,New Mexico:Am. Assoc.Petroleum Geolo* gists.Bull., vol. 37, no. 8, pp.1894-1918. Stevenson,F.V. (1945) Devonian of New Mexico:Jour. Geology,vol. 53, no.4, pp. 217-245. I RoswellGeological Society (1950) Pre-Permian Strat- ¯ Thompson,M.L. (1942)Pennsylvanian system in New igraphyof the SacramentoMountains, New Mexico: Gu’idebook,Field Trip No. 2, Dec.8 & 9, 1950. Mexico:New Mex.Bur. Mines Min. Res. Bull. 17. I Note:Three abstracts containing material pertinent to (1952)Surface structures the escarpmentof the SacramentoMountains have been of thefoothill region of theSacramento and Guada- acceptedby theGeol. Soc. America in connectionwith lupeMountains: Guidebook,FieldTripNo.6,May the 1954annual meetings in November.These will be i 9 & 10, 1952. printedin theDecember issue of theBull. Geol. Soc. America,and areas follows:Otte, Carel Jr., Lower (1953)Stratigraphy of the Wolfcampiandeposition in the northemmostSacramento i westfront of the SacramentoMountains: Guidebook, Mountains;Pray, L. C. & Graves,R. M. Jr.,Desmoines- FieldTrip No. 8, Dec.4 & 5, 1953. ianfacies of the SacramentoMountains; and Pray,/.C. & Otto,Carol, Jr., Age and Correlation of the Aboform- i Stainbrook,M.A. (1935) A DevonianFauna from the ationin south-centralNew Mexico.

THE OCCURRENCEAND DISTRIBUTIONOF of earlierformations ef the Ochoa series. POTASSIUM MINERALS IN SOUTHEASTERN Extensiveevaporite depc~sits are found in olderPer- I NEW MEXICO mianformations; but unlikethe evaporite deposits of the by Ochoaseries, the older deposits are restricted entirely to theback-reef or shelfarea~ The evaporitedeposits 2 I C.k.Jones of the Ochoaseries are more extensive and are better The closingepoch in Permiantime is especiallyknown knownbecause of theireconomically important deposits forthe extensive evaporite deposits that fill the Dela- of potassiumminerals. As the potashdeposits repre- ¯i wareBasin and extendacross the Capitanreef zone for senta specialphase of theevaporite deposits, a brief considerabledistances over the shelf area~ This epoch descriptionof thesaline rocks should be presentedbe- forediscussing the occurrence and distribution of the ml is representedby the strataof theOchoa series, which includesthe following formations: potassiumminerals. I Dewey Lake redbeds The Ochoaseries is conformablyunderlain by strata Rustlerformation belongingto the Guadalupeseries and unconformably I Saladoformation overlainby stratabelonging to theUpper Triassic Dock- Castileformation um group.Outcrops of the Ochoaseries are not repre- sentativeof the thicksequence found in the subsurface. I Extensivedeposits of haliteand anhydrite occur in each The DeweyLake red bedsappear to be entirelycon- of the formationsexcept the DeweyLake, which does finedto thesubsurface; and the outcrops of theRustler, / notcontain evaporite deposits and ~vhich is composed Salado,and Castile formations contain only the insal- entirelyof red sandstone,siltstone, and minor amounts ubleor moreslowly soluble constituents~ Wherever these .I of shale.The DeweyLake red bedsform the protective formationshave been exposed to weatheringconditions coverthat serves to retardthe dissolution and removal duringeither pre-Dockum time or post-Triassictime, I of the solublesalts comprising the evaporite deposits allthe halite and a partof theanhydrite have been dis- solvedand removedby groundwater and surfacestreams; 1 Publicationauthorized by the Director,U.S. Geol- the anhydriteremnants hove been completely altered ogicalSurvey. .. to gypsum~Thus the outcropscontain only the morein- 2 Geologist,U.S. Geological Survey, Carlsbad, N. t~ex. 107 r,