Stratigraphy, paleontology, and depositional systems of theEocene Gub Mountain Formation, Lincoln County, New Mexico-

a preliminary reportby Spencer G. Lucas, New Mexico Museum of Natural History, P. 0. Box 7010, Albuquerque, New Mexico 87194;

Steven M. CatherNew Mexico Bureau of Mines and Mineral Resources, Socorro, New Mexico 87801;Paul Sealey New Mexico Museum ol Natural History, P. 0. Box 7010, Albuquerque, New Mexico 87194;andJ. Howard Hutchison Museum of Paleontology, University of Calilornia, Berkeley, California 94720

IntroductionBodine (1956) first used the name Cub

Mountain Formation to refer to "Laramide"shata that lie above the coal-bearing Mesa-verde Group and below the volcaniclastic andvolcanic rocks of the Sierra Blanca basin inwestern Lincoln County, New Mexico (Fig.1). Although it was then clear that the ageof the Cub Mountain Formation must be LateCretaceous and/or early Tertiary, no preciseage data were available. This resulted in var-ied age assignments and differing interpre-tations of the stratigraphic relationships ofthe Cub Mountain Formation to nearby "Lar-amide" units. Furthermore, no precise in-formation on the depositional environments,provenance, and evolution of the CubMountain depositional basin has been pub-Iished. In this paper we present a prelimi-nary effort to determine the stratigraphy, age,depositional environments, and provenanceof the Cub Mountain Formation near its typesection.

Previous studiesPtior to L956, strata of the Cub Mountain

Formation either were included in the UpperCretaceous Mesaverde Group or apparentlywere not recognized (e.9., CampbelI, L907;Wegemann, 1914; Sidwell, 1946; Allen andfones, 1951). Bodine (1956, p.8) introducedthe term Cub Mounta in Format ion andmapped its distribution in the vicinity ofCapitan. Although he indicated that the for-mation name was for Cub Mountain southof. Carraozo, Bodine did not designate ordescribe a type section for the Cub MountainFormation. (A footnote inadvertently omit-ted from Bodine's article would have cred-i ted the concept of the Cub Mounta inFormation to R. H. Weber and explained thatproper definition of the unit was forthcom-ing in an article by Weber.) Nevertheless,Bodine (L956, p.9) presented evidence thatat least 100 m of strata are missing betweenthe Cub Mountain Formation and underly-ing Mesaverde Group. Although he notedthat the Cub Mountain Formation could beas old as Late Cretaceous or as young asMiocene, Bodine (1955, p. 10) concluded that"apparently, the Cub Mountain formation isanother Tertiary intermountain deposit, sim-ilar to the Baca formation of Socorro County,the Galisteo formation of north-central NewMexico, and possibly the McRae formationof south-central New Mexico."Griswold (1959,p. 12) noted the similarity of the Cub Moun-tain Formation to the Baca Formation of west-central New Metco and assigned it an "early

FIGURE 1-Outcrops of the Cub Mountain Formation and intrusive igneous rocks in "icit

lty of SierraBlanca basin (modified from Dane and Bachman, 1965).

quartzite, silicic volcanic rocks, chert, gran-ite, and petrified wood. He also noted vol-canic debris in the upper part of the CubMountain Formation and suggested it mightprovide a basis for dividing the Cub Moun-tain into two members, a lower, nonvolcanicmember and an upper, volcanic member.Weber (1954, p.106) very tentatively corre-lated the Cub Mountain with the Eocene BacaFormation.

In the two decades that followed Weber's(1964) article, very little work was done onthe Cub Mountain Formation. Thompson(1966, p.17-19) argaed on a lithologic basisfor identity of the Cub Mountain Formationand the McRae Formation in the ElephantButte area of Sierra County. He also -unpf9

vo

-- l ' ' -srERRA

.4" ( Bhtf"'o

Intrusive stocks, plugs, andsi l ls (dikes not depicted)

Outcroos ofCub Mounta in Format ion

20 miles

Tertiary" age. Lochman-Balk Q96a, p. 58)listed a "latest Upper Cretaceous(?) (sic) -Eocene(?)" age for the Cub Mountain For-mation, and Kelley and Thompson (19(4, p.120) equated the Cub Mountain and McRaeformations (also see Thompson, l9U, 1966,1972) and assigned them a "Laramian andPaleocene" age.

Weber Q96a, p. 105) designated and de-scribed a type section of the Cub MountainFormation in Sanders Canyon between Cuband Chaves Mountains (Fig. 2), from theSW1/6W1/a, sec. L6 to the SW1/+SW1/+, sec.24, T9S, R10E. According to Weber 09e),the Cub Mountain type section is about 730m of light-colored arkosic sandstone inter-bedded with dominantly red mudrock andminor conglomerate consisting of pebbles of

20 km

. l ' , . , . : . o4

New Metico Ceology February 7989

4 J

contac t bo lwoenMoaav6rd€ Gaoup( lo N) dndCub Mounta ln .m€aaurodFormi l lon ( to S) \ .gc t lon' \ ' 1 -

N Mloca lr 3 4 4

M€!av€rd€ Grouo

/ / (o w, .nd/ Cub Mounlaln

\ I

Formai lon ( to E)

\)\i \ 1 6

J

\----j,1( 7 , \ - '

,K:/ MOUNTATN

/ (-\

To

S

R l O E FIGURE 2-Location of fossil localities, measured stratigraphic section and

cub Mountain-Mesaverde Group contact in the Chavez Canyon-Little cub

YBU'"uthe distribution of the "McRae Formation"in the Sierra Blanca-Cub Mountain area

Kottlowski (1981, p. 22) indicated a Creta-ceous-Paleocene age. Smith et al. (1985) as-signed a middle Eocene-early Oligocene ageto the Cub Mountain Formation.

StratigraPhY and dePositionalenvironments

We examined two stratigraphic sections ofthe Cub Mountain Formation, one partial andone complete, during fune, L987. The,partialsection is located on the northern flank ofLittle Cub Mountain (Fig. 3A); the complete

FIGURE 3-Some outcrop photographs of the Cub Mountain Formation' A,

Overview of section on-norther-n flank of Little Cub Mountain' B, Basal

conglomerate of Cub Mountain Formation near Little Cub Mountain (Unit 5

of rieasured section in Figure 4). C, Interbedded sandstone and mudstone

at the stratigraphic level of vertebrate-fossil occurrences at NM localities 1384,

1385 and 1586 (sandstone outcroP is about 5 m thick). D, Root traces and

burrows in red mudstone exposed in Chaves Canyon.NI

February 1989 New Merico Ceology

section is exposed along Chaves and SandersCanyons (Fig. 2). At both sections, the CubMountain Formation disconformably over-lies strata of the Upper Cretaceous Mesa-verde Group. Al though no angularunconformity is apparent locally, Kelley andThompson (1964) and Kelley (1971) noted thatthe Cub Mountain Formation oversteps pro-gressively older Cretaceous units to the east.The basal contact is exposed in Chaves Can-yon in the SW'/4, sec. 16, T9S, R10E and northof Little Cub Mountain in the NEl/+, sec. 11,T9S, R10E (Fig. 2). A basal conglomeraticsandstone (Fig. 38) marks the upsectionchange from drab mudstone, sandstone, andrare pebbly sandstone of the MesaverdeGroup to the coarser sandstone, variegatedred mudstone, and conqlomerate of the CubMountain Formation (Fig. a).

No precise lithologic definition of the CubMountain Formation has been published.Perhaps because of ambiguities in its defi-nition, Arkell (1983, 1986) extended the termCub Mountain to include beds mapped asMesaverde Group by Weber (1964) andThompson (1966). Our work supports as-signment of these beds to the MesaverdeGroup because of their lithologic similarityto Mesaverde exposures to the west and theirdissimilarity to the coarser grained, morebrightly hued beds that overlie them, In ourview, Arkell's (1983) basal unit and lower partof the main body of the Cub Mountain For-mation are correlative with the MesaverdeGroup and are separated from superjacentTertiary strata by an unconformity.

The Cub Mountain Formation is about 730m thick (Weber, 1964), although the upperpart of the section in Sanders Canyon maybe repeated by faulting. Estimated averaBeconglomerate:sandstone:mudstone ratio isabout 5:70:25 in exposures near Cub Moun-tain, and the unit becomes finer grained up-section. Sandstone is the dominant lithologyand mainly occurs as gray to pink tabularunits that contain abundant horizontal andlow-angle stratification and minor troughcrossbedding (Fig. 3C). Conglomerate islargely restricted to the lower one-third ofthe formation and commonly occurs in scoursin the basal portions of sandstone units (Fig.38). Pebbles are dominantly chert andquartzite with subordinant felsic volcanic,sandstone, siltstone, Iimestone and silicifiedwood clasts. Maximum clast size is about 10cm. Mudstone units are tabular in shape andtypically display variegated red coloration.Evidence of bioturbation in mudstones iscommon (Fig. 3D), and calcareous nodulesof probable pedogenic origin were occasion-ally noted.

Stratification styles in the sandstone lith-osome are similar to those described by McKeeet al. (1975) for modern flood deposits ofephemeral Bijou Creek, Colorado. Inter-bedded mudstones presumably accumulatedin vegetated flood basins and ponds adjacentto aggrading channel complexes. Overall, fa-cies characteristics are quite similar to thoseof distal-fan deposits of the Eocene Baca For-mation (Cather and Johnson, 7984, 1986), aI-

Eocene foss i l s , NMlocal i t ies 1384. 1385, and 1 386

.g6 c: . 9= P

6E>E^ o:rro

unconformity

MesaverdeGroup

TI 5 meterst

conolomerate /conl lomeratic ss

t rough-crossbeddedsandstone

p lanar -c rossbeddedsandstone

mass ive sands tone

b io tu rba tedsandstone

sha le /mudstone

ironstoneconcretions

si l tstone

FIGURE 4-Measured stratigraphic section of the lower part of the Cub Mountain Formation on thenorthern slope of Little Cub Mountain. See Figure 2 for location of section and Table 1 for descriptionof lithologic units. 13

New Mexico Geology February 7989

though the Cub Mountain Formation containssignificantly more mudstone.

The upper contact of the Cub MountainFormation is defined by the first upsectionoccurrence of abundant volcaniclastic detri-tus. Although poorly exposed in SandersCanyon and its tributaries, the contact ap-pears to be conformable, with interbeddingof volcanic and nonvolcanic sandstone andmudstone occurring over a stratigraphic in-terval of at least several tens of meters.

Paleontology and correlationWe collected fossil bone from the Cub

Mountain Formation at four localities (Fig-2): 1) NM locality 1384 in the NE1/6EV+NEr/a NEtLNEl/r, sec. "l.l,T9S, R10E; 2) NMlocality 1385 in the NE1/4SEI/+NEr/+NWI/+NEl/a, sec. LL,T9S, R10E;3) NM locality 1385in the SWr/4SWr/4NEr/4NWr/*NEr/+, sec. 11,T9S, R10E; and 4) NM Iocality 1387 in theNW1/+SW1/+NW1/4NEI/4NW1/a, s€c. 15, T9S,R10E. NM localities 1384, 1385 and 1386 arewithin about 0.5 km of strike in the sameinterval of grayish-red mudstone, 94-98 mabove the base of the Cub Mountain For-mation (Fig. a; Table 1). NM locality 1387,

which only produced unidentifiable bonefragments, is in similar mudstone on thesouthwestern flank of Cub Mountain about3 km southwest of the other localities.

Four identifiable vertebrate fossils, of un-questionable Eocene age, were collected atthese localities. Three of these are turtles.NMMNH (New Mexico Museum of NaturalHistory) P-3501 from locality 1385 consistsof ventral fragments of the right third andfourth peripherals articulated with a frag-ment of the hyoplashal buttress, the distalpart of a posterior peripheral, and four costalfragments. NMMNH P-j602 from locality1385 is a fragment of the medial part of ahypoplastron and a peripheral 7 fragment.Both of these specimens pertain to BaptemyssP.

Two of the costal fragments exhibit ripple-like omamentation, and one of them is crossedby the sinusoidal tract of a pleural sulcus.The fragment of plastron and the associatedperipherals (Fig. 5A) are tightly articulatedwith the hyoplashal buttress extending ontothe third peripheral. The marginal4-5 sulcusis finely incised and irregular. The axillaryscale extends just lateral to the peripheral-plastral sufure, and the area covered by the

scale is inflated ventrally. The free edge ofthe posterior peripheral fragment is bluntlyacute. The fine texfure of the extemal bonesurfaces, where undamaged, is smooth.

Only two species of Baptemys are recog-nized here as valid: Baptemys garmanii (Cope,1872) (:Baptemys tricarinata Hay, 1908, andDermatanys costilntus Cope, 1872) and Bap-temys wyomingensis Leidy, 1870 (:8. fluain-tilis Hay, 1908). The two taxa are distinguishedon the basis of size, omamentation of thecarapace (carinae), and expansion of theplastral lobes and bridges. Although the CubMountain fragments are fully consistent withassignment to the genus Baptemys, they arenot clearly diagnostic at the species level.Size approximates that of large B. garmanii.In Wyoming, where the best samples areknown, there is a general increase in sizethrough time. The Cub Mountain materialagrees well in s2e with that of B. garmaniiand an undescribed taxon from the Cathe-dral Bluffs Member of the Wasatch Forma-tion of Wyoming that is intermediate inmorphology berween B. garmanii and B. uryo-mingensis. The sculpture of the shell agreesbest with that of the intermediate taxon. Thegenus Baptemqs is presently known to range

LithologyThickness

(m)

TABLE 1-Measuted stratigraphic section of part of the Mesaverde Group and Cub Mountain Forrnation north of Little Cub Mountain in the E'l:NEf /+ NWli+NEt/r, sec. f 1, T9S, R10E, and the SEI/+SE1/ISW1l+SEll+, sec. 2, T9S, R10E, Lincoln County. Strata dip about 15'to south-southeast. Colorsare those of Goddard et al. (1948). Section measured by S. G. Lucas and P. Sealey during June 1987 using Brinton compass and 1.5-m staff.

Unit LithologyThickness

(rn) Unit

Cub Mountain Formation (Eocene)Sandstone, same color and lithology as unit 18.Mudstone, grayish-red (10 R 412), slightly calcareous.Fossils (NM localities 1384, 1385, and 1386) occur inlower 3.3 m, upper 18 m much covered by colluvium.Sandstone, pale-red (70 R 612), weathers to grayish-red (10 R 4/2), quartzose, medium-grained, well-sorted,subrounded to rounded, hematitic. Multiple scoursurfaces divide beds with low-angle, large-scale, ar-cuate crossbeds and planar beds with a thin (0.3 m)lenticular (-3 m of strike) bed of limestone pebbleconglomerate like unit 11 in midd.le.Sandy mudstone, variegated grayish-red (5 R 2/4 andn R 4/4, medium light gray (N 6), light bluish-gray(5 B 5/1), calcareous; much covered by colluvium.Sandstone, very pale orange (10 YR 8/2), quartzose,fine to very coarse grained, poorly sorted, rounded,noncalcareous; trough crossbeds.Shale, light olive-gray (5y 6lI), weathers olive-gray(5 Y 411), noncalcareous, much covered; some mud-stone like unit 19.Sandstone, grayish orange-pink (5 YR 7 l2), weathersto pale-brown (5 YR 5/2), quartzose, fine-grained, well-sorted, subrounded to rounded, hematitic, noncal-careous; platey weathering of beds.Mudstone, grayish-red (10 R 4/2), noncalcareous.Sandstone, same color and lithology as unit 10.Conglomerate: matrix is pale yellowish orange (10 YR8/6); clasts are light gray (N 6), matrtx supported.Maximum clast size is about 1 cm. Clasts are lime-stone, siltstone, and cherf matrix is quartzose, fine-to medium-grained, poorly sorted, subangular to sub-rounded sandstone, slightly calcareous, massive.Sandstone, white (N 9) and very light gray (N 8),quartzose, medium- to coarse-grained, poorly sorted,subrounded, noncalcareous, hematitic, massive.Covered.

3.087

Covered. Lower 0.9 m is sandstone like unit 7.Sandstone, pale yellowish-orange (10 YR 8/6) andgrayish-orange (10 YR 714), weathers pale-brown(5 YR 5/2), quartzose, fine-grained, poorly sorted,subrounded, hematitic, slightly calcareous, troughcrossbedded; some carbonaceous material on beds.Sandstone, pale yellowish-orange (10 YR 8/6) and darkyellowish-orange (10 YR 6/6), weathers pale yellow-ish-brown (10 YR 6/2), quartzose, medium- to coarse-grained, moderately sorted, subangular to sub-rounded, noncalcareous, hematitic; planar crossbeds,some thin (3 cm) gravel beds, scoui surfaces.Conglomerate and sandstone. Conglomerate is clastsupported; clasts are dominantly quartzite pebbles asmuch as 12 cm in diameter (minor chert and felsicvolcanics). Sandstone is same lithology as unitT , gray-ish-orange (10 YR 714), weathers moderate-brown(5 YR a/a); clasts are dark yellowish orange (10 YR616), \ght gray (N 8) medium light gray (N 6) andmedium gray (N 5).disconformitvMesaierde Croup (IJpper Cretaceous)Siltstone, light greenish-gray (5 GY 8/1 and 5 G 8/1),noncalcareous; some ironstone concretions like unitz .

Sandstone, pale yellowish-orange (10 YR 8/6) andgrayish-orange (l0YR7/4), quartzose, fine- to coarse-grained, poorly sorted rounded, hematitic, noncal-careous, massive, friable.Shale, medium light gray (N 6), weathers yellowish-gray (5 Y 8/1), noncalcareous; contains ironstone con-cretions that are moderate brown (5 YR 3/4), duskyyellowish brown (10 YR UZ), noncalcareous.Sandstone, very light gray (N 8), weathers moderate-brown (5 yR Aq, quartzose, noncalcareous, biotur-bated-

2079

18

13t211

not measured

24.4

t2 .2

18.3

4.0

7.6

12.8

3.0

t7

76

I J

0 .63.6o - /

6.19 . 1

0.910

February 7989 Neu Mexico Geology

from the late Graybullian through Bridgerian(Hutchison, 7980). Baptemys garmanii is knownfrom the later Graybullian through Lostca-binian, the intermediate taxon from earliestBridgerian (Bridger A and Cathedral BluffsMember of the Wasatch Formation), and B.wyomingensis from middle to late Bridgerian(Bridger B-E).

NMMNH P-3603 from locality 1385 is frag-ments of peripherals (6), costals (2), epiplas-tra (3) and other bones (8) of a turtle weidentify as Echmatemys sp. The epiplastralfragments (Fig. 58, C) have extensive overlapof the gular scales medially on the dorsalsurface. Thickened lateral gular projectionsenclose a depressed hough medially on thedorsal side, but this trough is not reflectedventrally. The hypoplastral fragments showthat the humeral-pectoral sulcus lies poste-rior to the entoplastron, and that there is athick and nonkinetic sufure between the hyo-and hypoplashon. Other fragments show thatthe plastral buttresses rise vertically from theplastron and are set medial to the marginsof the plastral lobes (Fig. 5D). The pleural-marginal sulcus lies above the proximal su-ture of peripheral 11. The plastral scalesoverlap extensively the dorsal margins of theplastral lobes. The single proximal fragmentof either costal 3 or 5 indicates the presenceof an octagonal neural in the neural seriesand lacks any indication of swelling at thepleural-vertebral margin. The fragments in-dicate a plastral length of as much as ap-proximately 23 cm.

The broad plastra with thickened gularprojections, extensive overlap of the plastralscales dorsally, especially on the medial partof the epiplastron, post-entoplastral positionof the humeral-pectoral sulcus, vertical andmedial position of the plashal buttresses, anddorsal position of the posteriormost mar-ginal scales are consistent with or diagnosticof the common Eocene batagurid Echmate-mys. The systematics of the species withinthis genus are in need of extensive revision.The Bridgerian species are clearly over split.In the Wyoming sections where the genus ismost extensively known and abundant, thereis a general increase in size through time.The Cub Mountain material appears to lie inthe size range of later Wasatchian to earliestBridgerian Echmatemys in the Wyoming sec-tions. The Wasatchian species from Wyo-ming, moreover, are characterized by aswelling of the costal bones just lateral to thevertebral-pleural sulcus that is lacking fromthe Bridgerian and Uintan species (as in theCub Mountain taxon). This swelling, how-ever, may be absent or only weakly devel-oped in the Sanfose Formation E. ktiiertebralis(Cope, 1875). The posterior placement of thehumeral-pectoral sulcus is generally typicalof the Wasatchian species, whereas it typi-cally overlaps the entire plastron of theBridgerian species. In species from the Ca-thedral Bluffs Member of the Wasatch For-mation, however, the modal conditionresembles that of the Wasatchian species.Echmntemas in North America is character-istic of arid limited to the Eocene. The com-

1 c m

FIGURE S-Fossil turtles from the Cub Mountain Formation. A, Baptemys sp., NMMNH PJ501, ventraland dorsal views of part of right axillary region compared to ventral view of plastron of B. uryomingensis.YD,Echmatemys sp., NMMNH P-3602, 3603, dorsal views of right and left epiplastral fragments (8,C) and left hypoplastral fragment (D) compared to a dorsal view of a late Wasatchian Echmatemys fromWyoming. Scale line refers only to Cub Mountain specrmens.

of w-$aped ectoloph

lingual cusp

FIGURE 6-NMMNH P-3604, fragments of brontothere(?) molars from the Cub Mountain Formation.A, occlusal view of upper molar fragment preserving part of w-shaped ectoloph and a lingual cuspB, lateral view of lower molar(?) cuspid fragment.

bination of characters in the Cub MountainEchmatemys in comparison with the standardsequence in Wyoming and Utah indicates alate Wasatchian or earliest Bridgerian age.

NMMNH P-3ffi4 is two fragments of amammalian upper cheek tooth from locality1384 (Fig. 6). These fragments represent abunolophodont tooth with at least one low,blunt lingual cusp and a shallow w-shapedectoloph labially. The minimum width of thistooth is 20 mm, and parts of its enamel arefinely lineated. Clearly, this is the tooth of arelatively large mammal. Overall closest sim-

ilarity is to upper molars of Palaeosyops and,Manteoceras (sensu Osborn, L929) grad,ebrontotheres. These are Bridgerian taxa, anda brontothere of similar grade is known fromthe Baca Formation in the Carthage area ofSocorro County (Lucas et al., 1982).

Thus, the fossil evidence from the CubMountain Formation indicates, withoutquestion, an Eocene age. More precisely, alatest Wasatchian or early Bridgerian age,about 50 +- 2Ma, is probably indicated. Thisage is consistent with radiometric-ag" d*

New Mexico Geology February 7989

on dikes and dike swarms that post-date CubMountain deposition. Moore and Foord (1986,p. 31) recently reported ICAr age-determi-nations of 47.7 + 2.9 Ma provided by R. F.Marvin of the U.S. Geological Survey on al-kali-gabbro and monzo-gabbro dikes and dikeswaflns in the Sierra Blanca vicinitv.

Paleocurrents and provenancePaleoflow during deposition of the Cub

Mountain Formation, as shown by pebbleimbrication and parting-step lineation, wasnortheasterly in the study area (Fig. 7). Be-cause the study area is located in the westernpartof the Sierra Blanca basin, paleoflowwasroughly tangential to the present basin mar-gin. These data indicate that Eocene drain-age in the Sierra Blanca basin was notcentripetal, which supports the concept thatsynclinal downwarping of the basin postdateddeposition of the Cub Mountain Formation(Kelley and Thompson, 1964; Kelley, l97l).

Most detrital components of Cub Moun-tain sandstones and conglomerates were de-r ived f rom older sedimentary sources.Quartzite, chert, and subordinant felsic vol-canic pebbles dominate conglomerates in thestudy area; pebbles of these lithologies occurin trace amounts in the underlying Mesa-verde Group and are common in conglom-erate beds of the Ash Canyon Member of theCrevasse Canyon Formation (Wallin, 1983)to the southwest. Other pebble varieties(limestone, sandstone, siltstone, silicifiedwood) in the Cub Mountain Formation wereclearly derived from Mesozoic and Paleozoicsedimentary units. Although Weber (1964)reports minor granitic clasts in the CubMountain Formation, none were noted dur-ing the present study.

Preliminary petrographic analysis of threesandstones indicates a dominance of sedi-mentary rock fragments in the lithic fraction.Contributions from crystalline basement rocksappear to be minimal. Minor but persistentamounts of volcanic rock fragments, plagio-clase, and biotite are present throughout theCub Mountain Formation. However, as notedabove, this material may have been recvcledfrom the underlying Mesaverde Gioup.Provenance of the Cub Mountain Formationthus can be only loosely constrained at pres-en! source terranes were to the southwestand consisted primarily of older sedimen-tary rocks. At least two potential source re-gions can be postulated.

The Rio Grande uplift (Fig. 8) of Seagerand Mack (1986) was a northwest-trending,late Laramide uplift in south-central NewMexico that shed clastic detritus (Love RanchFormation) mostly during Eocene time. Sed-iments were transported both to the south-west into the Potrillo basin and northeastinto the Love Ranch basin. Deposits of theLove Ranch basin become markedly finer to-ward the northeast, in the direction of theSierra Blanca basin. Clast types are locallyvariable and include Mesozoic, Paleozoic, andPrecambrian lithologies (Seager, L981; Seagerand Mack, 1985).

FIGURE 7-Paleocurrent-rose diagram based on20 rneasurements of pebble imbrication and parFing-step lineation from the Cub Mountain For-

I::"" * Chaves Canyon-Little Cub Mountain

An altemative source region for the CubMountain Formation is the Tularosa uplift(Fig. 8; Herrick, L9M, p. 75; Eardley, 1962,p.399; Kottlowski et al., 1955, p. 73; Chapinand Cather, 798L), a poorly documented andcontroversial uplift that may have collapsedto form the present Tularosa Basin. With theexception of Mesozoic units penetrated bythree wells in the exheme northeastern partof the Tularosa Basin near Three Rivers (Kingand Harder, 1985), borehole and outcrop dataindicate poorly consolidated Quaternary toTertiary(?) sediments directly overlie Per-mian strata throughout the eastem part ofthe basin. Where absent, Mesozoic sedimen-tary units may have been stripped duringbroad upwarping, possibly during the LateCretaceous or early Tertiary. Alternatively,these units may have been eroded duringlate Tertiary crustal extension (W. R. Seageaoral comm. 1988). At present, the Tertiarystructural development of the Tularosa Basinarea is poorly understood, primarily due tolack of borehole and seismic data on the \A/hite

Sands Missile Range, in the critical westernpart of the basin.

SummarY

Near its type locality, the Cub MountainFormation is as much as 730 m of inter-bedded sandstone, mudstone, and minorconglomerate that were deposited by north-east-flowing braided streams. Fossil verte-brates collected about 100 m above the baseindicate an Eocene age (near the Wasatchian-Bridgerian boundary, about 50 -r 2 Ma).Lithologic and paleocurrent data for the CubMountain Formation suggest derivation fromsource terranes to the southwest that ex-posed dominantly older sedimentary rocks.Potential source regions include the Lar-amide Rio Grande and Tularosa uplifts al-though further study is needed to betterconstrain the provenance of the Cub Moun-tain Formation.

AcxNowr-EoctrcNrs-We thank the own-ers of the Stephenson Ranch, Inc. for accessto Cub Mountain outcrops and C. E. Chapinand R. M. Chamberlin for assistance in thefield. We benefited from reviews by R. M.Chamberlin, C. E. Chapin, E. H. Lindsay,W. R. Seager, and R. H. Weber. The A. M.Alexander endowment of the University ofCalifornia Museum of Paleontology fundedthe artwork in Figure 5, and R. Pence drewthe artwork for Figure 6.

ReferencesAllen, J. E., and Jones, S. M., 1951, Capitan-Canizozo-

Chupadera Mesa region: Roswell Geological Society,Guidebook to 5th Field Conference, 12 pp.

Allen, J. E., md Kotdowski, F. E., 1981, Roswell-Ruidoso-Valley of Fires: Socono, New Mexico Bureau of Minesand Mineral Resources, Scenic Trip 3, 3rd edition, 96PP.

Arkell, B. W., 1983, Geology and coal resources of theCub Mountain area, Siena Blanca coal field, New Mex-ico: unpublished M.S. thesis, New Mexico Institute ofMining and Technology, Socono, 104 pp.

Arkell, B. W., 1986, Stratigraphy of western part of SienaBlanca basin; in Ahlen, J. L., Hanson, M. 8., andZidek,J. (eds.), Southwest Section ofAAPG Transactions andGuidebook of 1986 Convention. Ruidoso. New Mexico:New Mexico Bureau of Mines and Mineral Resources,pp.73-75.

Bodine, M. W., Jr.,7956, Geology of the Capitan coal field,Lincoln County, New Mexico: New Mexico Bureau ofMines and Mineral Resources, Circular 35,27 pp.

Campbell, M. R.,1907, Coal in the vicinity of Fort Stantonreseruation, Lincoln County, New Mexico: U.S. Geo-logical Suruey, Bulletin 315, pp. 431.-4U.

Cather, S. M., and Johnson, B. D., 1984, Eocene tectonicsand depositional setting of west-central New Mexicoand eastem Arizona: New Mexico Bureau of Mines andMineral Resources, Circular 792,33 pp.

Cather, S. M., and Johnson, B. C., f986, Eocene depo-sitional systems and tectonic framework of west-centralNew Mexico and eastem Araona; lz Peterson, J. A.(ed.), Paleotectonics and sedimentation in the RockyMountain region, United States: American Associationof Petroleum Geologists, Memoir 41, pp,623-552-

Chapin, C. E., and Cather, S. M., 1981, Eocene tectonicsand sedimentation in the Colorado Plateau-RockyMountain area: Arizona Geological Society Digest, v74, pp. 1.73-798.

Dane, C. H., and Bachman, G. O., 1965, Geologic mapof New Mexico: U.S. Geological Survey, 2 sheets, scale1:500,000.

Eardley, A. J., 1962, Structural geology of North America:Harper and Row, New York, 2nd edition, 743 pp.

Goddard, E. N., Trask, P D., DeFord, R. K., Rove, O. N.,Singewald, J. T., and Overbeck, R. M., 1948. Rock-colorchart: Geological Society of America, Boulder.

Griswold, G. 8., 1959, Mneral deposits of Lincoln County,

,p, t. i' o ^ \ I

r"to^ \ Ix,>+{.- -\ J

/y ' . . , i S;e,,o Blonco

\tr:r;t:i/ bosrn\-II

*l-\/ \ - Tuloroso

{ u p l i f t- . t - - - - - -

L__i/ o u " , o n "

po leo f low

FIGURE gl,".urnia" paleogeographic mapshowing Sierra Blanca basin, average paleoflow inthe study area, and postulated source areas for theCub Mountain Formation.

February 1989 Nru Mexico Geology

New Mexico: New Mexico Bureau of Mines and MineralResources, Bulletin 57, 117 pp.

Herrick, C. L., 1904, Lake Otero, an ancient salt lake basinin southeastern New Mexico: The American Geologist,u. 34, pp. 174-189.

Hutchison, J. H., 1980, Turtle stratigraphy of the Will-wood Formation, Wyorning-preliminary results: Uni-versity of Michigan, Museum of Paleontology, Paperson Paleontology 27, pp. 175-77E.

Kelley, V C.,1977, Geology of the Pecos countrt south-eastem New Mexico: New Mexico Bureau of Mines andMineral Resources, Memoir 24, 78 pp.

Kelley, V C., and Thornpson, T. 8., 1954, Tectonics andgeneral geology of Ruidoso-Carrizozo region, centralNew Mexico: New Mexico Geological Society, Guide-book to 15th Field Conference, pp. 1.1.0-727.

King, W. E., and Harder, V M., 1985, Oil and gas poten-tial of the Tularosa Basin-Otero platfom-Salt Basin gra-ben area, New Mexico and Texas: New Mexico Bureauof Mines and Mineral Resources, Circular 198, 36 pp.

Kottlowski, F E., Flower, R. H., Thompson, M. L., andFoster, R. W., 79fi, Stratigraphic studies of the SanAndres Mountains, New Mexico: New Mexico Bureauof Mines and Mineral Resources, Memoir 1, 132 pp.

Lochrnan-Balk, C., 1964, Lexicon of stratigraphic namesused in Lincoln County, New Meico: New MexicoGeological Sooety, Guidebook to 15th Field Confer-ence, pp. 57-61.

Lucas, S. G., and Ingersoll, R. V, 1981, Cenozoic conti-nental deDosits of New Mexico-an overview: Geoloq-ical Sociei of America, Bulletin, Part I, v. 92, pp. 91/-932.

Lucas, S. G., Wolberg, D. L., Hunt, A., and fthoch, R. M.,1982, A middle Eocene titanothere from the Baca For-mation, southtentral New Mexico: Journal of Paleon-tology, v 56, pp.542-!45.

McKee, E. D., Crosby, E. J., and Benyhil,H. L.,Jr.,1967,Flood deposits, Bilou Creek, Colorado, June L955: Jour-nal of Sedimentary Petrology, v.37, pp.839-851.

Moore, S. L., and Foord, E. E., 1986, Roadlog from Innof the Mountain Gods to the Ruidoso SkiArea on SienaBlanca Peak; in Ahlen, J. L., Hanson, M. E., and Zidek,J. (eds.), Southwest section of AAPG Transactions andGuidebook of 1986 Convention, Ruidoso, New Mexico:New Mevico Bureau of Mines and Mineral Resources,PP.29-36.

Osborn, H. F.,7929, The titanotheres of anoent Wyo-ming, Dakota, and Nebraska volume t: U.S. GeologicalSuruey, Monograph 55, pp. 1-701.

Seager, W. R., 1981, Geology of the Organ Mountains andsouthern San Andres Mountains, New Mexico: NewMexico Bureau of Mines and Mineral Resources, Mem-oir 36,97 pp.

Seager, W R., and Mack, G. H., 1986, Laramide paleo-tectonics of southern New Mexico; in Peterson, ). A.(ed.), Paleotectonics and sedimentation in the RockyMountain region, Uruted States: American Associationof Petroleum Geologists, Memoir 41, pp. 569-685.

Sidwell, R., 19,16, Effects of dikes and displacement move-ments on sediments in Capitan quadrangle, New Mex-ico: American Mineralogist, v.31, pp. 65-70.

Smith, L. N., Lucas, S. G., and Elston, W 8., 1985, Pa-leogene stratigraphy, sedimentation and volcanism ofNew Mexico; ir Flores, R. M., and Kaplan, S. S. (eds.),Cenozoic paleogeography of the west-central UnitedStabes: Denver, Rocky Momtain Section SEPM, pp.293-315.

Thompson, T. 8., 1964, A stratigraphic section of the SienaBlane volcmics in the Nogal Peak area, Lincoln County,New Mexico; New Mexico Geological Society, Guide-book to 15th Field Conference , pp. 76-77.

Thompson, T. 8., 796, Geology of the Sierra Blanca, Lin-coln and Otero Counties, New Mexico: UnpublishedPh.D. dissertation, University of New Mexico, Albu-querque, 1it6 pp.

Thompson, T. 8., 7972, Siena Blanca igneous complex,New Mexico: Geological Society of America Bulletin, v.83, pp. 2341-2356.

Wallin, E. T., 1983, Stratigraphy and paleoenvironmentsof the Engle coal field, Siena County, New Mexico:Unpublished M.S. thesis, New Mexico Institute of Min-ing and Technology, Socono, 104 pp.

Weber, R. H., 19&, Geology of the Carrizozo quadrangle,New Mexico: New Mexico Geological Society, Guide-book to 15th Field Conference, pp. f00-109.

Wegemann, C. H., 1974, Geology and coal resources ofthe Siena Blanca coal field, Lincoln and Otero Coun-ties, New Mexico: U.S. Geological Sutret Bulletin 541,

New Merico Geological Society Frank Wayne GampbellSpring Meeting

The New Mexico Geological Society willhold its annual spring meeting on Friday,April 7, 1988 in Macey Center at the NewMexico Institute of Mining and Technology,Socorro, New Mexico. This meeting pro-motes the dissemination of the results of re-cent research on the geology of New Mexico.The morning sessions cover geophysics/petrology/structural geology and stratigra-phy/sedimentologyipaleontology. The after-noon sessions cover geochemistry/economicgeology and hydrology/environmental geol-ogy. Registration materials are available fromVirginia T. Mclemore, New Mexico Bureauof Mines and Mineral Resources, Socorro,New Mexico 87801, (505) 835-5521.

Fall Field ConferenceThe New Mexico Geological Society will

hold its 40th annual field conference in theAcoma-Grants-Zuni-Gallup area of west-central New Mexico from September 29 toOctober 1, 1989. Several stops on this bustour will emphasize the southeastern Colo-rado Plateau as a zone of tectonic transitionwhere Laramide strike-slip faults and mon-oclinal uplifts have partially collapsed in re-sponse to la te Cenozo ic ex tens ion andmagmatism. Other stops will address ad-vances in furassic, Cretaceous, and Tertiarystratigraphy; the relationship of coals tobasement structures and shore lines; and therecognition of paleoweathering zones. Stopsat the scenic Acoma and Zuni Pueblos willallow for brief shopping sprees and culturalenrichment. The conference will convene at,and return to Albuquerque, just prior to theAAPG Rocky Mountain Section meeting. Foradditional information contact co-chairmenOrin Anderson (505/835-5722) or RichardChamberlin (505i835-5310) at the New Mex-ico Bureau of Mines and Mineral Resources,Socorro. New Mexico 87801.

(1s47-1988)

Frank W. Campbell was born on May 31,1947 in Long Beach, California, the son ofPaul and Zella Campbell. He came to NewMexico Institute of Mining and Technologyto study geology and graduated with a BSdegree in1971, the same year he married SueLynn Rose. They moved to Rapid City, SouthDakota where Frank attended the SouthDakota School of Mines. He received an MSdegree in geology there in 1975. Job openingsin geology were scarce at that time, so Frankand Sue moved back to California, where heoperated a pet shop and indulged his loveof tropical fish.

In 1978, when there was an increased in-terest in coal in New Mexico, the New Mex-ico Bureau of Mines and Mineral Resources(NMBMMR) had three openings for coalgeologists. Frank applied, along with manyothers, and was hired to fill one of thesepositions. His projects included the mappingand stratigraphic interpretation of coal out-crops in the Fence Lake-Salt Lake coal field;he set up and directed the drilling programin this field. Frank has been one of the prin-cipal investigators in the NMBMMR's four-year study of the quality and quantity of NewMexico strippable coals.

Beginning in the early 1980's Frank de-veloped a coal anaiytical laboratory at theNMBMMR capable of determining heatingvalues, proximate and ultimate analyses,forms of sulfur, ash-fusion temperatures,water-soluble alkalies, maior oxides, and trace-element composition of coals. He was thefirst professional staff member to routinelyuse a personal computer for his work. At atime when PCs were not in use in the Bureau,he bought one himself and installed it in hisoffice. Frank's scientific accomplishments areevident through his many published papersand open-file reports. At the time of his deathpublication was imminent of GM-62, Ceologyand coal resources of Fence Lake 1:50,000 quad-rangle, Nerrl Mexico, a compilation by Frankof eight 1:24,000-scale quadrangles in west-central New Mexico.

Frank loved science fiction, military his-tory, classical music, and opera. But his mostimportant interest away from his job was hisfamily. He adored his wife Sue and their twochildren, Elizabeth Katie born in 7975 andPaul Clayton born in 1981.

Frank Campbell died on December 3, 1988.Throughout the years and final months ofhis illness he showed us all how to laugh inspite of pain and how to live in spite of dying.He was a shining example of quiet courage.

-Iyn Brandaold

New Mexico Geology February \989 "17

pp. 479-542 tr