Stratigraphyandstructure ol the Klondike Hills, southwesternNew Mexico byMichael G. Rupert,State of ldaho,Division ot EnvironmentalQuality, Boise, lD, 83720,and Eusse// E. Clemons,New Mexico State Universi$, LasCruces. NM 88003

Introduction (scale1:62,500) of the CedarMountains (now One sample of the weathered granite yielded The Klondike Hills are in southwestem New called Cedar Mountain Range). Armstrong an Rb/Sr age of 1390* Ma (M. Shafiqullah, Mexico approximately 30 mi (48 km) south- (1970)focused on the stratigraphy of the Mis- written communication, 1983). west of Deming, at the northwestem end of sissippian rocks that form the northwestern the Cedar Mountain Range(Fig. 1). They are end of the Klondike Hills. Attracted by the Bliss Sandstone characterized by low relief and complexly structural complexity of the area, Corbitt et An incomplete section of Bliss Sandstone faulted Paleozoiccarbonate rocks, although al. (1978)mapped (scale1.:50,000) the south- crops out south of the granite in the west- brecciation, dolomitization, and silicification ern two-thirds of the Klondike Hills. Thor- central part of sec.22,T265, R13W(Fig. 2). locally obscure primary lithologies. The man and Drewes (1981)mapped the Klondike The base is not exposedand the uppermost stratigraphic section includes Precambrian Hills as part of the Gage SW quadrangle at beds are faulted against the overlying El Paso granite, Upper Cambrian to Pennsylvanian a scaleof l:24,00f. The objectiveof this re- Formation. The Bliss includes about 10 m of carbonate and subordinate clastic rocks, lo- port, based on the work of Rupert (1985)is dark reddish-brown, fine- to medium-grained, cally derived Upper Cretaceous/lowerTer- to illustrate the complex structural relations crossbedded quartz arenite in this outcrop. tiary conglomerate, Oligocene ash-flow tuff exposed in the Klondike Hills at an even more Many of the grains are frosted and the sand and rhyolite, and Quaternary colluvial and detailed scale (1:8,000).With this, elucida- is cementedby silica, calcite,and minorhem- alluvial deposits. Laramide-style structural tion of Laramide structural history is some- atite. r? features include a high-angle fault with dip- what better. slip and probable strike-slip offset, low-angle faults with both elimination and repetition Shatigraphy of stratigraphic units, small-scalefolds, and Alsoin thisissue localized extensive brecciation. Precambrian Darton's (1916) geologic map of Luna Medium-crystallinegranite occurs in the PajaritoY-Zr deposit,Otero County was one of the first to show Paleozoic west-centralp art of sec.22, T265, R13W(Fig. County p.21 rocks in the Klondike Hills. Bromfield and 2). The rock is intensely shattered, deeply Background perspectives Wrucke (1961)further defined the agesof the weathered, mostly coveredby alluvium, and and Paleozoicrocks in their reconnaissancemap forms topographically low poor exposures. on the PajaritoY-Zl deposit p.22 Stratigraphyand structureof the KlondikeHills p.23 TenthNew Mexico Mineral SymposiumAbstracts p. 30 NMBMMRMineral Museum Lord.burg notes p.33 Legendand correlationlor stategeologic map p. 34 Thompsonand Callaghan memorials p.37 SugariteCanyon State Park p. 38 1990NMGS fall field conference p. 43 Galleryof Geology-Toothof Time p. 43

Columbus Secondtransfer of cephalopods p.44 Upcomingmeetings p.45 NMMNHmineralexhibits p. 45

zo ml ServiceiNews p. 46 Staffnotes p. o 1o 2okm 48 Gomingsoon Commercialtravertine in NewMexico CimarronCanyon State Park Mineralsol NewMexico FIGURE l-Location map of southwest New Mexico showing location of Klondike Hills area of Fig. 2

Nan Mexico Geology May 1990 D El Paso Formation cludes all four membersas defined by Hayes interbedded wackestone, packstone, and (1975)and Clemons (1988b,in press a, b). grainstone. Allochems present in approxi- The El Paso Formation crops out exten- The basal Hitt Canvon Member is thin- to mate order of decreasingabundance are in- sively in the southern part of the Klondike medium-bedded, hifhly bioturbated, silty, traclasts, peloids, echinoderms, hilobites, Hills. As a result of intense faulting, a com- light- to medium-grey limestone or dolo- Naia, spicules, gastropods,and brachio- plete El Paso section is not preserved but stone. The silt and fine sand content de- pods. Massive stromatolite mounds are com- partial sections were measured by Rupert creasesupward. The dolostone is believed to mon in the upper part of the Hitt Canyon. (1986).His sections indicate that the unit is be mostly if not completely of hydrothermal These mounds are complexesof narrow, col- a minimum of 300 m thick (Fig. 3) and in- origin (Clemons, 1988a).The limestonesare umnar, stacked hemispheroidal heads (Fig. @o

Q: alluvlum,colluvlum

Ta: ash-flow tuff \zt Kr: Ringbone Fm \Mk Mh Ph: Horqullla Ls -n -.a Mp: Paradlse Fm \'t Mh: Hachlta Fm \MK N Mk: Keatlng Fm

I.. Dp: Percha Sh I 28\ I Sf: Fusselman Dol Oem rl Om: Montoya Fm

Op: Padre Mbr

Oem: McKelllgonMbr

Oh: Hltt Cenyon Mbr

€b: Bllss Ss pg: granlte It l6 uu r-/ lt / 'l t'z 1+tl lts ,t l< , lzr tlzt ilto l2s 1

20 23 trult oh T26S R13W, ts I cage SW Qradrangle .-,-)lon >t oh

IP ''.7

26 A FIGURE 2-Geologic map of Klondike Hills generalizedfrom Rupert (1985).

May 1990 Nar Metico Geology 4) separatedby distinctive channels. Oncol- frosted, monocrystalline quartz grains, with SYSTEM STRATIGRAPHIC UNIT TH ICKNESS ites (0.5 to 1..5cm diameter) are locally abun- (n) (ft) undulose extinction and thin hematite rims, dant in the Hitt Canyon. TERTIARY Ash-f]ow luff 30 98 in variable amounts of silicaand/or carbonate

The overlyinglose Member is mostly thin- CRET.? Rlngbone Fn 50 cement. Member is a very dark gray, bedded, dark-gray to black, silty to sandy, PENN. Horouilla Ls 20 67 The Upham massive dolostone, black oolitic limestone with a few interbeds of me- Paladise Fn 220 coarsely crystalline, dium-gray limestone and orangish-gray do- MISS Escabrosa Gp to dark reddish-brown on fresh surface. It dacnata !m 90 295 lostone. Most of the limestone is lithoclastic KeatiDo Fn 700 has much quartz sand at the base, but the and bioclastic grainstones. Dedolomit2ed DEV Percha Sh 30 98 sand fraction rapidly decreasesupsection as ooids with baroque and saddle-shapedcal- SIL. FuEselman Dol t52 500 the unit grades to a featurelessand rather cite are quite common and locally concentric Montoya Fm homogeneousdark-gray, coarselycrystalline Cutter Mbr 66 grains in the ooids are present. Bioclasts are mostly tri- Afeman Mbr 18 59 dolostone. A few of the quartz lobites and echinoderms with minor gastro- I 26 Cable Canyon Member and lower Upham cable canyon Mbr 3-6 t4 pods and Nuia. Allare rounded and typically ORD. bl Paso !m exhibit a characteristic blue tint when ex- Padre Mbr a2 267 lens. No fossils were have thick micritized rims. V^r6lli-^n Mhr t0'7 350 amined with a hand The Member is overlain conformably Jose Mbr 9 30 found in the Upham Member in the Klondike Jose Hitt Canyon Mbr 100 328 by the McKelligon Member which is me- Hills. CAMB. ? BtlSS 5 30 98 dium- to thick-bedded, light- to medium-gray The Aleman Member consists of light- PRECA.I"IB. qtanlce limestone or dolostone. The dolostone is brown to medium-gray, finely crystalline do- probably a product of hydrothermal altera- FIGURE3-Rock units exposedin the Klondike lostone with abundant medium-gray chert as tion common in the Klondike Hills. The lime- Hills. elongate nodules and lenticular beds. The stones are interbedded wackestone, chert constitutes 30 to 40Voof the rock and packstone,and grainstone.Allochems in the weathers in a very characteristiccontrasting McKelligon beds include all those found in Otherwise the Padrewackestones, pack- relief. No fossils were observed in the Ale- stones, and grainstonescontain the sameal- the Hitt Canyon and |ose Members except man Member exposedin the Klondike Hills. for the ooids, and siliciclasticdetritus is no- lochems as the lower strata. The contact with the overlying Cutter Mem- tably absent even at the base of the Mc- ber is gradational over approximately 1 m Kelligon. Silicified cephalopod siphuncles Montoya Formation and is characterized by a decreasein chert appear to be more abundant in the Mc- The best exposures of the Montoya For- and a change to the massivelight-brown do- Kelligon beds. A few, small (1 m high, 1-2 mation are in the west-central part of sec. lomite of the Cutter Member. m long) sponge-Calathium mounds are inter- L6, T255, R13W (Fig. 2). The Montoya also The lower three-fourths of the Cutter bedded in the lower McKelligon strata. The crops out on SheepMountain and along the Member is chert-poor, medium-bedded, light- mound rock is predominantly spicular crest of the long ridge south of SheepMoun- brown, tinely crystalline dolostone with a few wackestone whereas the enclosing beds in- tain but is extremely faulted and fractured in small, broken brachiopod fragments. The clude packstone and grainstone. the latter fwo areas. upper part of the Cutter Member is a slightly The Padre Member conformably overlies The basal Cable Canyon Member is a light darker light-brown, finely crystalline dolo- the McKelligon Member in the Klondike Hills. reddish-brown, crossbedded, fine- to me- stone with increasing amounts of nodular Padre beds contain traces of siliciclastic silt dium-grained, moderately sorted quartz ar- chert up-section, although the chert rarely and very fine sand, but the sandstone and enite, which typically forms prominent ledges. exceeds2\Voby volume. The uppermostbeds sandy dolostone beds characteristicof lower The contactwith the underlying PadreMem- are essentially chert-free, finely crystalline, Padre strata at Bishop Cap and in the Frank- ber of the El PasoFormation is very sharp. light-brown dolostone. The contact with the lin Mountains (LeMone, 1969;Clemons, in The contactwith the overlying Upham Mem- overlying Fusselman Dolomite is an ero- press b) are absent. The Padre in the Klon- ber of the Montoya Formation is gradational sional disconformity and is marked by a not- dike Hills contains thin-bedded, dark-gray, over about I m and is marked by a change able upward decreasein nodular chert and cherty limestone. A few beds have silty, cross- from quartz arenite to coarsely crystalline, a sharp change from the light-brown, finely stratified laminations. Nuia is less abundant dark-gray dolomite of the Upham Member. crystalline dolostone of the Cutter to the me- in the Padrethan in the lower members;trace Petrographic examination of the Cable Can- dium dark-gray, slightly coarse crystalline amounts of ostracodsare presentin the Padre. yon shows it contains mostly well-rounded, Fusselman Dolomite. re

FIGURE 4-Stromatolites in the Hitt Canyon Member of the Klondike Hills. FIGURE5-Ringbone(?) conglomerate3.75 mi (6 km) south of Klondike Hills.

Nm MexicoCeology May1990 Fusselman Dolomite exposedin sec.5 (Fig.2), butArmshong (1970) Drewes (1981),is a west-northwest-trending A complete section of the FusselmanDo- mapped and described about 67 m of more fault with a curvilinear surfacetrace (Fig. 6a)-. lomite is not exposed in the Klondike Hills. extensively exposed Paradise in the north- The fault dips 78"southward in the northeast The largest exposure is in the west-central westem Klondike Hills. The limestones are part of sec. 21..In the west-central part of part of sec. 16, T265, R13W (Fig. 2). Most typically ooid packstonesand grainstoneswith sec.23, the fault zone forms a tectonicbreccia other exposures of the Fusselman in the some lime mudstones and wackestones. 5-10 m wide with an approximately vertical Klondike Hills are highly brecciated to the attitude. Much of the Cedar Mountain fault point of total obliteration of any original bed- Horquilla Limestone is characterizedby a brecciazone of variable ding or texture. No fossils weie observedin Several small poorly exposed outcrops of width, locally only a meter wide but ranging the Fusselmanin the Klondike Hills. Horquilla Limestoneare mapped in the west- upward to 10 m wide. The lowermost 17 m of the FusselmanDo- centralpart of sec.5 (Fig. 2). Armstrong (1970) A striking aspectof Cedar Mountain fault lomite is a medium dark-gray, coarselycrys- reported that about 20 m of Horquilla over- is the contrast of tectonicsWles on either side talline, medium-bedded tomassive dolostoire. lies the ParadiseFormation in the northem of the fault. The southern block comprises This is overlain by about 7 m of dark-gray Klondike Hills. He also reported that 2-3 m mostly Ordovician and Silurian carbonate dolostone with very characteristic alternai- of sandstoneare overlain by medium- to thick- rocks that are complexly cut by both low- and ing light and dark, millimeter-thickbanding bedded, cherty limestones.The limestones high-angle faults. Except for Sheep Moun- (varve{ike in appearance).Above this are 36 are.peloidand ooid grainstones,packstones, tain, the northern block is moderately de- m of dark-gray, massive, coarselycrystalline and lrme mudstones. formed Mississippian Keating Formation. A dolostone with isolated lenses ind-knobbv small slice of Keating Formation near the west- pods of chertand 15m of medium dark-gray, Ringbone(?) Formation central edge of sec. 23 is bounded by El Paso massive, fine- to medium-crystalline dolo- and Montoya strata. Apparently, this slice A small outcrop of clast-supported,cobble of stone with no chert. The tof 83 m of Fus- Keating is a small horse incorporated along conglomerate, unconformable on El Paso selman are coarselycrystalline, light-brown, the Cedar Mountain fault zone. Formation, in the southeast comer of sec. massivedolostone. Cedar Mountain fault displays more than 17, T265, R13Wis tentatively correlatedwith 600 m of vertical stratigraphic separation the RingboneFormation. Clists include most in Percha sec. 21 where Ordovician rocks to the south Shale of the lithologies of Precambrianand Paleo- arejuxtaposed againstMississippian rocks to Armstrong (1970)mapped about 30 m of zoic formations described in the Klondike the north. The small exposure of Precam- Percha Shale in the norlhwestern Klondike Hills. This conglomerate is probably correl- brian granite in the west-centralpart of sec. Hills. The only outcrop of Percha in the ative with about 15 m of limestone conglom- 22 indicates that basement was involved southem Klondike Hills is the erate resting on Mississippian-Pennsylvanian in east-central the faulting. part of sec. 8, T265, R13W (Fig. 2) where bedsmapped 6 km to the south by Bromfield CedarMountain fault splitsinto threesplays about 1 m ofgrayish-green, calcareousshale and Wrucke (1951) and Vamell (fSZ6). fnis -the in the western part of map areu.'The is.poorly exposed in a small gully. A tailings southem exposure contains (Fig. 5) abun- northern splay has a curvilinear trend with pile in the north-central part of sec.27,T2d5, dant rounded cobblesand bouldersof rud- a large amount of stratigraphic separation R13W also contains Peicha. Thorman and istid limestones derived from the Lower that places mostly Ordovician rocks on the Drewes (1981)reported that the nearby shaft CretaceousU-Bar Formation. It also shows south and west against Mississippian rocks is 18 m deep with Perchaat the bottom. about 22 m of relief on the lower contact. on the north and east.The middle splay sep- Similar rocks in the Florida and Little Hatchet aratesHitt Canyon Member on the south from Escabrosa Mountains are the Lobo and Ringbone For- Group uppermost El Paso, Montoya, and Fussel- mations respectively.The Ringboneand Lobo Armstrong (1970)mapped and described man Formations on the north. The south- , are considered to be syntectonic with Lar- about 300m of EscabrosaGroup in the north- ernmost splay has minor post-Oligocene amide deformation in- southwestern New westem Klondike Hills. He subdivided the normal movement, offsetting the ash-flow tuff Mexico, Ringbone ranging from Late Creta- group into the lower, Keating Formation and by 10-30 m. ceousto Paleocene(Wilson et al., 1989),Lobo upper, Hachita Formation. Outcrops The most shiking of Es- probably Paleocene (Lawton feature of the near-ve4- cabrosa in the southem to Eocene et al., Klondike Hills are 1989). tical Cedar Mountain fault is apparentdrag restricted to the north side of the Cedar folding (Fig. 6a), which suggests probable Mountain fault. The one exception is left-lateral slip (Fig. 6b). The strike the Ash-flow tuff of a northwestem part of sec.27. Furthermore, plunging anticlinal axis exposedat the west- the HachitaFormation only cropsout in secs. Ash-flow tuff crops out in secs.77 and20, central edge of sec. 23 changesfrom almost 5 and 8 to the northwest plui a small ex- T265, R13W on the southwest side of the due north to almost due easfwith increasing posure north of SheepMountain in sec. 15. Klondike Hills (Fig. 2). Itis a pale-redto gray- proximity to Cedar Mountain fault. In ad- The Keating forms moit of the outcropsnorth ish-red to light brownish-gray, massive dition, strike of the Keating Formation ex- of the Cedar Mountain fault. weathering,crystal-vitric, rhyolitic ash-flow posed in secs.16 and 2| changesfrom north tuft. Some zones - The Keating Formation comprisesme- contain pumice fragments to northwest with increasing proximity to the dium-bedded, light- to mediumlgray lime- as large as 15 cm. Phenocryst fragments in- fault (Fig. 6a). No field evidence was ob- stones. The lower few meters are mostlv clude quartz, sanidine, plagioclase, biotite, served to indicate the amount of left-lateral echinoderm packstone with minor bryozia and hornblende. Sphene and clinopyroxene movement. and brachiopodfragments. The bulk irf the are presentin traceamounts. This fuff is about Keating exposed is lime mudstone with 30 m thick and forms gently northeast-tilted Low-angle faults abundant chert nodules and lenses. The cuestas. Thorman and Drewes (19S1)indi- Hachita Formation is mostly chert-free, mas- cateda probableOligocene age for this ash- Two levels of low-angle faulting are ex- sive-bedded, light-gray, irinoidal wacke- flow tuff. posed in the Klondike Hills (Fig. 7). The lower stones and packstones. Locally there are level placesolder strata on younger, thus re- interbeddedcoated-bioclast grainstones. Structural geology peating the section, with underlying beds locally overturned. The upper level of low- angle faulting is characterized by younger Paradise Formation Cedar Mountain fault beds on oldeibeds, with part of ih6 section The Paradise Formation is thin- to me- The most prominent structure in the Klon- tectonically eliminated (Fig. 7). These faults dium-bedded yellowish-gray silty limestone dike Hills is the Cedar Mountain fault (Fig. are termed "low-angle" instead of "thrus/' and interbedded shale and siltstone. It is onlv 2). This feature, named by Thorman and faults, because,for the upper level of fault-

May 1990 New Mexico Geology 1 mi attitudes of Mississippian t- F "tr"t, \, I N cei si"";:=-,,Iil,s e. \ \ I 14i\ r" J ilj J ').:::::ii',,TFI,.r\rltttt,,];.,tJrFLrjrrt--| o -Yg '.ttt I lll tt ttlr lt,,,rr/r//, t, t r trrr,,

fault, Sheep Mountain, FIGURE 6a-Drag features along Cedar Mountain q) and brecciaridge (from Rupert, 1988,with permission from the New Mexico Geological Society). - o I CI'

-n P) =

FIGURE 6b-Dagram showing possible features superimposed on strain ellipse resulting from left- lateral stress. Note orientation of normal faults. o (After Harding, L974, with permission from the / Association of Petroleum Geologists.) \ c

EE g -t 96 3 \' S s itt* a. s tb A o l(r\ g s os*!'"1." CD 5000 oe- ;* o:+Z-9 5000 0m UE Oe> e,b oe Me 4ooo' g zDP 4000' Oe cb, ------_---_-- : €b-., i p€ ll st ,p€ p€ ll, 3ooo' 3ooo/

.-oCC Er w ?a) B Oq, .O ro I I breccla I rldge p€. 9b Oe Sooo' 5000 ge-=: =---r-- -ci Qb' 4ooo' 4000 p€ pO 3ooo' 3000

FIGURE 7-Cross sectionsshowing two levels of low-angle faulting (from Rupe_rt,1988, with Permission from the New Mexico GeologicalSociety). See Fig. 2 for line of sections. Symbols same as Fig. 2 except Oe indicates undifferentiated El PasoFormation. r?

New Mexico Geology May 19fr ing, it is unclear whether the faulting is low- mation. with the Padre Member of the El continuous allocthon that has been eroded angle normal faulting or thrust faulting with Pasomissing. This low-angle fault occursjust to its present form. Thesesimilarities include bedding at a steeperangle than the fault. below the Cable Canyon SandstoneMember correlative structural features, sequencesof Faults showing older-on-youngerrela- of the Montoya for the most part, presum- rock units, and elevations of low-angle fault tions are exposedin the SW1/esec. 21, along ably becausethe thin-bedded limestones of planes. Crosscutting relations suggest this the south-central edge of sec.22, and in the the underlying Padre Member act as a de- allocthon moved subsequentto vertical northeast corner of sec.22 (Fig. 2). In the SW collement surface between the overlying movement on the Cedar Mountain fault. 1A s€c. 21, the low-angle fault places lower- Montoya dolostonesand underlying El Paso The origin of the low-angle faulting is de- most thin-bedded Hitt Canyon Member of Iimestones. The upper plate is complexly batable becausethese faults could represent the El PasoFormation above the dolomitized faulted and brecciated. either low-angle, listric norrnal faults (Fig. uppermost part of Hitt Canyon Member with 10) (Armstrong, 1972;Wernicke and Burch- a stratigraphic separation of approximately High-angle faults fiel, 1982; Reynolds and Spencer, 1985),or 70 m. Beds of the upper plate are complexly Relatively minor (lessthan 150m displace- thrust faults with dips steeperthan those of folded, with highly variable orientation of ment) high-angle faulting is common south the underlying rocks (Fig. 11) (Brown, 1982). fold axes. An older-on-younger low-angle of the Cedar Mountain fault. These faults Resolution of this debate is not simple, as fault places thin-bedded lowermost Hitt appear to be high angle as suggestedby their Dickinson (1984)has shown. Listric normal Canyon Member on top of McKelligon Mem- linear surfaceexpression, but it is not certain faulting has been documented on the flanks ber at the south-central edge of sec. 22 (Fig. whether they have reverse or normal dis- of Laramide uplifts in south-central New 7, B-B'). Beds of the underlying McKelligon placements. Crosscutting relations, such as Mexico (Nelson and Hunter, 1986),with these Member form an overtumed syncline, which those exposed ih the south-central part of uplifts presumably supplying the required is exposed in a window in the allocthonous sec.21 and north-central part of sec.27, sug- slope. The intensely deformed character of plate. In the northeast comer of sec. 22 an gest many of these faults postdate low-angle the upper plate exposed on brecciaridge re- older-on-younger low-angle fault placesHitt faulting. sembles that which would be expected in a Canyon Member on top of Keating Forma- listric normal fault environment. However, tion at the base of Sheep Mountain (Fig. 8). Basin and Range faulting and tilting similar styles of faulting are exposed in the The Hitt Canyon Member is folded into a Florida Mountains, where Brown (1982)quite north-trending syncline. The only faulting in the Klondike Hills that convincingly argued for thrust faulting. De- Younger-on-older low-angle faulting ex- can be positively attributed to Basinand Range velopment of a justifiable model in the Klon- posed on Sheep Mountain (Fig. 8) places extensional deformation is in the west-cen- dike Hills is limited by the low relief of the Montoya Formation on top of Hitt Canyon tral part of the map area. There, an ash-flow area. The Klondike Hills lack the exposure tuff, tentatively dated as Oligocene (Thor- Member with Jose, McKelligon, and Padre of a basement-rooted reverse fault, which Members missing. The upper plate is in- man and Drewes, 1981),has beentilted ap- would be necessaryto prove thrusting sim- tensely deformed by both high-angle and low- proximately 25" to the north-northeast. ilar to that seen in the Florida Mountains. angle faults. Many low-angle faults within Laramide attitudes can be estimated by ro- The Klondike Hills area also lacks a topo- this upper plate repeat various members of tating the tuffs back to horizontal. When this graphic high, which would supply the nec- the Montoya. is done, the CedarMountain fault still retains essary slope for normal listric faulting. If either Younger-on-older,low-angle faults are ex- its near-vertical character,and both levels of of these features etsted in the past, they posed in the south-central and easternparts low-angle faulting retain their low-angle ori- presumably were located south or southwest of sec. 22 and extending into the south- entation. of the Klondike Hills and have been ob- westem part of sec. 23, on a ridge herein scured by subsequentBasin and Rangefault- called breccia ridge, for the pervasive cata- Discussion ing and volcanic activity. clastic nature of the rocks forming the ridge SheepMountain (Fig. 8) and brecciaridge Comparison of the Klondike Hills to the (Figs. 7, .A-A', 9). The younger-on-older (Fig. 9) respectively north and south of the regional overthrust (Corbitt et al., 1978)and faulting exposed on breccia ridge places Cedar Mountain fault. have similarities in- basement-coredblock uplift models (Brown, Montoya Formation on top of El Paso For- dicating they may have been part of a once- 1982; Brown and Clemons, 1983) suggests

FIGURE 8-Looking north at SheepMountain. Younger-on-older,Iow-angle FIGURE 9-View north to breccia ridge. Younger-on-older,low-angle fault fa-ultnear top of mountain placesMontoya Formation on top of Hitt Cany-on near top of ridge places Montoya Formation on top of El Paso Formation Member with Jose, McKelligon, and Padre Members missing. Olderion- with a part of the El Pasomissing. Older-on-younger,low-angle fault at base younger/ low-angle fault at base of Sheep Mountain places Hitt Canyon of breccia ridge places Hitt Canyon and McKelligon Members on top of Member on top of KeatingFormation. McKelligon Member.

May 1990 Nm Meilco Geology younger and younger-on-older low-angle iaulting; 2) localized tectonic brecciation; 3) localized fold development; and 4) vertical and left-lateral movement on the Cedar Mountain fault. Involvement of the crystal- line basementwith the uplift along Cedar Mountain fault is suggestedby 1) outcrop of the basement in one locality; 2) predomi- nanceof Lower Ordoviciansedimentary rocks south of Cedar Mountain fault suggeststhat -'^--^---==- -.--s!]c Mtn basement is close to the surface; 3) linear . extent of Cedar Mountain fault; and 4) ver- tical displacement on Cedar Mountain fault. Left-lateral movement on Cedar Mountain fault is shown by drag folding of Keating Formation, drag of an antidinal fold axis north of Cedar Mountain fault, and attitudes of high-angle faults south of Cedar Mountain faitt. Stiite-slip faulting is also implied by widespread, exheme brecciationand braided pattern of Cedar Mountain splay faults. Crosscuttingrelations indicate the follow- ing sequenceof events:1) verticalmotion on FIGURE l.0-Listric faulting model for the Klondike Hills. Note multi-phase structural development Ce-darMountain fault placing Keating For- with vertical movement on Cedar Mountain fault occurring first, followed by gravity sliding along low- mation against El Paso Formation; 2) for- Cedar angle normal faults from a topographic high to the south followed by leftlateral movement on mation of two levels of low-angle faulting; (seeFigure 2 for same as Fig. 2, except Oe indicates undifferentiated Mountain fault legend). Symbols left-lateral movement on Cedar Mountain Formation and Me indicatesundiffereniated Escabrosa Group. T (toward observer)and A (away 3) El Paso that displaced from observer) indicate left lateral movement on Cedar Mountain fault. fault; 4) high-angle faulting low-angle faults; 5) high-anglefaulting and tilting that offsets Oligocene ash-flow tuffs. Acrruowr-ppcMENrF-This paper repre- sents part of the senior author's MS thesis completed at New Mexico State University. The work was supported by a New Mexico Geological Society scholarship and a grant from the New Mexico Bureau of Mines and Mineral Resources.These funds made pos- sible the extended field mapping. We also their or.""n,"-"-l3j_l_uJ1""" -- om,Ti:o "tn thank Glen Brown and Tim Lawton for o"--]-- constructive reviews of the preliminary ..i.i"t.aig\ ." manuscript and Gus Armstrong for com- ments on the final version.

3to! References o o Armshong, A. K., 1970,Mississippian stratigraphy and 3 geology of the northwestern part of the Klondike Hills, a iouthwestern New Mexico:New MexicoGeological So- ciery Guidebook to 2lst Field Conference,pp. 59-63 Amstrong, R. L., 7972,Low-angle (denudational)faults, FIGURE 11.-Basement-coredblock uplift model for the Klondike Hills. Note multi-phase structural hinterland of the Sevier orogenic belt, eastem Nevada America, Bul- development with vertical movement on Cedar Mountain fault occurring first, followed by thrusting and western Utah: GeologicalSociety of letin, v. 83, pp.7729-1754. along low-angle faults rooted in a high-angle basement-coredreverse fault, and then left-lateral move- Bromfield, C. S., and Wrucke, C. T., 1961, Reconnais- ment on Cedar Mountain fault. Symbols same as Figs. 2 and 10. sancegeologic map of the Cedar Mountains, Grant and Luna Counties, New Mexico: U.S. GeologicalSurvey, Miscellaneous Field Shrdies Map MF-159, scale1:52,500. left{ateral Brown, G. A., 1982,Geology of the Mahony Mine-Gym that the Klondike Hills more closelyresemble occurrence of both vertical and Peakarea, Florida Mountains, Luna County, New Mex- the basement-coredblock uplift model. Fea- strike-slip movement on a high-angle, base- ico: Unpublished MS thesis, New Mexico State Uni- fures associatedwith regional overthrusting ment-involved fault (Cedar Mountain fault), versity, Las Cruces, 82 pp. include dominantly horizontal movement of and localized, small-scale,low-angle faulting Brown, G. A., and Clemons, R. E., 1983,Florida Moun- Mountain tairs section of southwest New Mexico overthrust belt- a thick geosynclinal sequencealong major in close proximity to the Cedar a re-evaluation: New Mexico Geology, v. 5, no. 2, pp. d6collement surfaces,with telescopedsedi- fault. This interpretation is consistent with 2629. mentary sequences(Woodward and Du- work by other authors in the area (Drewes Clemons, R. E., 1986,The Florida Mountains: revisited: Chene, 1981).Features associated with and Thorman, 1980a,b; Thormanand Drewes, El Paso Geological Society,Field Trip Guidebook, pp. Seage47983; r26-1.N. basement-coredblock uplifts include domi- 198L;Brown and Clemons, 1983; Clemons, R. E., 1988a,Dshibution of dolomite in Lower nantly vertical movementsalong high-angle, Clemons, 1986). Ordovician El PasoFormation (abs.):American Asso- basement-involved faults through relatively ciation of Petroleum Geologists,Bulletin, v. 72, p. 99. thin cratonic sequences,with minor thrust Clemons, R. E., 1988b,Lithostratigraphic conelation of Formations and El PasoMenbers from cen- faults produced from drag during uplift (Pru- Ellenburger Conclusions tral Texas to easternArizona (abs.):American Associ- cha et al., 1965;Seager,1983). Features that ation of Petroleum Geologists,Bulletin, v.72, p. 172. suggest the Klondike Flills more closely match The Klondike Hills exhibit Laramide-style Clemons, R. E., (in pressa), Geologyof the Florida Mouru the basement-coreduplift model include the deformation with 1) small scale, older-ori-

New Mexico Geology May 7990 tains, southwestem New Mexico: New Mexico Bureau of Mines and Mineral Resources, Memoir 43. Abstracts Clemons, R E., (in press b), Peuography and deposi- tional environments of the Lower Ordovician El Paso Formation: New Mexico Bureau of Mines and Mneral NewMexico Mineral Symposium Resources,Bulletin 125. Corbitt, L. L., Nials, F. L., and Vamell, R. J.,1978, l_ar The Tenth Annual New Mexico Mineral amide thrust faulting, Klondike Hills, southwestem New Symposium was held November 1'1,-12,1989, Mexico: New Mexico Gmlogical Society, Guidebook to at 29th Field Conference, pp.297-ffi. New Mexico Institute of Mining and Tech- Darton, N. H., 7916,Geology and underground water of nology, Socorro. Following are abstractsfrom Luna County, New Mexico: U.S. Geological Survey, talks given at the symposium that concern Bulletin 518, 19 pp. New Mexico. The numbers in parentheses Dickinson, W. R., 1984, Reintemretation of Lime Peak refer to locations on the map. thrust as a low-angle nomal fault: lmplications for the tectonicsof southeastemArizona: Geology, v. 72, pp. 610-513. MINERALS AND RocK FoRMS IN LAVA TUBESoF EL MAL- Drewes, H., and Thorman, C. H., 1980a,Geologic map PAIS NATToNAL MoNUMENT, Craola Coulrv, Nrw o{ the Steins quadrangle and the adiacent parl of ttre MEXIco, by Kent Carlton, El Malpais National Vanar quadrangle, Hidalgo County, New Mexico: U.S. Monument, Grants, NM 87020, and Christopher Geological Survey, MiscellaneousGeologic Investiga- G. McKee, New Mexico Bureau of Mines and tions Map I-1220, scale7:24,00f,. Mineral Resources,Socorro, NM 87801(1) Drewes, H., and Thorman, C. H., 1980b,Geoloqic map of the Cotton City quadrangleand the adlacenfpart of El Malpais National Monument was established the Vanar quadrangle, Hidalgo County, New Mexico: recently by Congress.One of the outstanding fea- U.S. Geological Suruey, Miscellaneous Geologic Inves- tures of the monument is its lava-tube systems. L-_j tigations Map l-1221, scale1:24,0fi). The concentrationof tubes is so high hire that Flarding, T. P., 1974, Petroleum traps associatedwith Hatheway and Herring (1970)chose EI Malpais as wrench faults: American of this tunnel another north-trending inclined tun- Associationof PetroleumGe- a terrestrial analog to what are believed to be sim- ologists, Bulletin, v 58, pp. L2%-l3f4. nel proceeds approximately 500 ft before inter- ilar structurescalled "rills" Hayes, P. T. and Cone, G. C.,7975, Cambrian and Or- that occur on the moon. cepting the water table. The geology and mineralogy The El dovician rocks of southem Arizona and New Mexico Malpais tubes are also significant because of the Carnahan mine was looked at most exten- and westernmost Texas: U.S. Geological Survey, of the length of many of the systems.For example, sively in 1903(Yung and McCaffery). More recent one tube ProfessionalPaper 873, 98 pp. systemwithin the monument is reported studies have, in most cases,cited the mineralogical Lawton, T. F., Mack, G. H., Lucas, S. G., to be 17.9 (28.6 and Kietzke, mi km) Iongby Elstonand Wohletz findings of Yung and McCaffery in reporting oc- K. K., 1989, Nonmarine stratigraphy of latest Creta- (1987). Such a considerablelength is not believed currences of specific minerals. Northrop (1959), ceous and early Tertiary age, southwestem New Mex- to be typical of lava tubes in other locales.Further, ico (abs.):American Association crediting Dale Carson, cited a number of oxidized of Peholeum Geologists, the intact (cave)portions of El Malpais Bulletin, v. 73, p. 7l(A. lava tubes minerals including anglesite,cerussite, botryoidal are often noteworthy relative to LeMone, D. V., 1969, Cambrian-Ordovician in El Paso tube lengths ob- hematite, limonite, possibly minium, pyrolusite, served border region, in Kottlowski, F. E. and LeMone, D. V. elsewhere.Four lava caveswithin the mon- and native silver. Since 1985,however, a number (eds.), Border stratigraphy symposium: New Mexico ument exceedone kilometer in length and one is of new specieshave been identified from the Car- Bureau of Mines and Mineral Resource, Circular 104. two kilometers. Finally. the size of many of the El nahan rnine, speciesthat were either overlooked pp. 17-25. Malpais tubes appears to be uncommonly large. by earlier investigators or possibly misidentified. Nelson, E. P, and Hunber, 1985,Iiramide thin-skinned Tubes J., that exceed50 ft in height and 60 ft in width With the help of microprobe (PaulHlava, personal defornation in Permian rocks, Fra Cristobal Range, are not uncommon. Kent Carlton collected cave south-centralNew Mexico: communications 1989)and x-ray diffraction/SEM New Mexico GeologicalSo- minerals during a 1988lava-tube inventory and ciety, Guidebook to 37th Field Conference,p. i15-121. (Peter Modreski, personal communications 1989) - submitted them to New Mexico Institute Mining Prucha, f. f., Graham, A., and Nickelson, il. p., 1955, of analyses,20 speciesnew to the Carnahanmine l. and Technology Basement-controlleddeformation in the Wyoming for identification. Chris McKee have been confirmed. Two of the species(adamite analyzed the province of the Rocky Mountain foreland: American samples by x-ray diffraction. The and hetaerolite) are the first reporied occurrences Association of Petroleum samples contain quartz, Geologists, Bulletin, v. 49, feldspar, calcite, thenar- of these mineralsin New Mexico.The new min- pp.96-992. dite, gypsum, trona, and burkeite. erals are all secondaryminerals resulting from the Reynolds, S. J., and Spencer,J. E., 1985, Evidence for oxidation of primary iron, copper, zinc, and man- large-scale bansport on the Bullard detachment fault, References west-centralArizona: Geology, v. 13, pp. 353-356. ganese sulphides. They include one native ele- Rupert,_M. G., 19tX, Stnrcture and stritigraphy ment (copper), oxides, carbonates,sulfates, of the Hatheway, Klondike Hills. southwestern New Mexicb: Unpub- A. W., and Herrin9, A K.,1970,Bandera arsenates,a molybdate (wulfenite), and silicates. lava lished MS thesis, New Mexico State Universitv, Las tubes of New Mexico, and lunar implica- Although galena and pyrite have been found in tions: Cruces, 138 pp. University of Arizona, Communications the oxidized zone, the predominant occurrenceof Rupert, M. G., 1988,Klondike Hills, southwestem New of the Lunar and Planetary Laboratory,v. 8, part primary sulphides is r-eputedby Atkinson (1961) Mexico: evidence for Laramide strike-slip deformation: 4, pp.298-j27. to occur below the ground-water level approxi- New Mexico C,mlogicat Society,Cuidebook to 3fth Field Elston, W. E., and Wohletz, K. H., 1987, Conference,pp. Quater- mately 400 ft below the surface. Most of the sec- l5-f9. nary basalt fields of west-centralNew Mexico- Seager,W. R., 1983,Laramide wrench faults, bas€ment- ondary copper minerals were found in a very McCartys pahoehoeflow, Zuni Canyon aa flow, cored uplifts, and complementary basins in southem restricted zone substantiallydown the tunnel. The New Mexico: New Mexico Geology,v. S, no.4, p. G9- Zuni ice cave,Bandera crater and Zuni Salt Lake arsenates,adamite, and agardite-(Y)were found 76. maar; in Beus, S. S. (ed.), Rocky Mountain Sec- in associationwith cuprite octahedronsthat were Thorman, C. H., and Drewes, H.,1981, Geologicmap of tion of the GeologicalSociety of America:Geo- partially or completely altered to rosasite, mala- the Gage SW quadrangle, Grant and Luna Counties, logical SocietyAmerica,Centennial Field Guide, chite, and chrysocolla. Native copper commonly New Mexico: U.S. Geological Survey, Miscellaneous v.2,pp. 437-436. occurs in the coresof the less altered cuprite Geologic Investigations Map I-1231, scale1:24,000. octa- Varnell, R. hedrons.Adamite most often occursai transpar- 1., 7976, Geology of the Hay Top Mountain MmEnals op rnE CARNAHANMrNE, SANrA FE CouNry. quadrangle, Grant and Luna Counties, ent greenspheres, but crystalmoqphology is evident New Mexico: NEw MExrco, by RamonS. DeMark and,ludithL. Unpublished MS thesis, University of Texasat El Paso, on some of the balls. This adamite is cuprian, which DeMark,6509Dodd Place, Albuquerque, 52 PP, NE, NM accountsfor the greencolor. Some individual col- (2) Wemicke, B., and Burchfiel, B. C., 1982,Modes of ex- 87170 orless crystals to 0.5 mm are very low in copper tensional tectonics: Journal of Structural Geology, v. 4, The Carnahan mine, located in the San Pedro content (Hlava, personal communication 1989). pp.105-115. Mountains (New Placers district) of Santa Fe None of the Carnahan mine adamite is fluores- Wilson, D. A., Lawtorr, T. F., and Basabilvazo,G. T., 1989, County, New Mexico, has not been a major ore cent. Aurichalcite and azurite, Stratigraphy and depositiona.lenviroments although scarce,were of the Skunk producer. Nonetheless, Ranch Formation, Little Hatchet Mountains, it has had a long, but in- also found in association.Agardite-(Y) occurs in south- termittent, production western New Mexico (abs.): New Mexico Geology, v. record of of lead-silver, zinc, very fine acicular spraysand tufts. Linarite occurs 11, no. 3, p. 63. and manganese ore;. Since 1968, the mine has as sky-blue, bladed crystals about 0.1 mm long Woodward, L. A., and DuChene, H. R., 1981,Overthrust been owned by the SanPedro Mining Corporation and also as fine sprays of crystals about 0.3 mm belt of southwestern New Mexico----comparisonwith (Patrick Freeman, personal communication 1989). across.They are found in associationwith pyrite, Wyoming-Utah overthrust belt: American Association The mine workings consistpredominantly of an galena, and green spheresthat appear to be a mix- of Petroleum Geologists,Bulletin, v. 55, pp. 722-729. inclined tunnel (5-20') trending N75'E to N90'E ture of malachiteand brochantite (Hlava, personal with minor drifts and some stoping. Near the end cornmunication 1989).The pyrite in some casesis

May 1990 Nao Mexico Geology