Rivista Italiana di Paleontologia e Stratigrafia volume 109
MICROFACIES AND MICROFOSSIL ASSEMBLAGES (SMALLER FORAMINIFERS, ALGAE, PSEUDOALGAE) OF THE HUECO GROUP AND LABORCITA FORMATION (UPPER PENNSYLVANIAN-LO\TER PERMIAN), SOUTH-CENTRAL NE\tr MEXICO, USA
KARL KRAINER'!, DANIEL VACHARD'I'I & SPENCE,R G. LUCAS,'>I:I
Receitted March 25, 20A2; accepted November ), 20a2
Keywords: microfacies, algae, pseudoalgae, smaller foraminifers, Carnic Alps. biostratigraphy, Upper Pennsylvanian, Lower Permian, Bursumian, Wolfcampian, Laborcita Formation, Hueco Group, New Mexico (USA) Rídssunto. Il margine orientale del Orogrande Basin nel New Mexico centro-meridionale. durante il Carbonifero terminale e nel Per- Abstract. Durìng the latest Carboniferous and earliest Permian miano inferore, fu orlato da una stretta piattaforma, tettonrcamente \Wolfcampian), (Virgilian - the easre rn margin of the Orogrande Basin instabile. Su di essa si depositarono i sedimenti delle formazioni Laborci- in south-central New Mexico was rimmed by a narrow, tectonically ta and Abo. Invece i sedimenti del Gruppo Hueco si accumularono sul unstable shelf, on which sediments of the Laborcita and Abo forma- margine occidentale, più stabile, del Orogrande Basin. tions were deposited. Sediments of the Hueco Group accumulated on Sulla piattaforma orientale, la Formazione Laborcita della parte the more stable western margìn of the Orogrande Basin. settentrionale delle Sacramento Mountaìns rappresenta la transizione On the eastern shelf, the Laborcita Formation of the northern dalle facies marìne a quelle continentali ed è costituita da cicli carbona- Sacramento Mountains represents a transition from marrne to terre- to-clastici. I calcari si accumulavano durante gli intewalli di stazìona- strial facies and is composed of clastic-carbonate cycles. Limesrones mento alto in condizìoni di piattaforma marina poco profonda. I sedi- accumulated during relative sea-level highstands in a shallow marine menti clastici si accumulavano durante gli interoalli di stazronamento shelf environment. Clastic sediments were deposited during relative basso, quando I'influsso terrigeno era piir sensibiìe negli ambienti vicini sea-level lowstands when there was strong clastic influx in a nearshore alla costa o continentali. La sovrastante Formazione Abo è formata da to tcrrestrial environment. The overlying Abo Formarion is corn- red beds continentali. po'ed oI rerresrrial red beds. Sulla piattaforma occidentale, la Formazione Shalem Colony del On the western shelf, the Shalem Colony Formation of the Gruppo Hueco, equivalente della Formazione Laborcita, è formata in Hueco Group, equivalent to the Laborcita Formation, is composed of prevalenza da calcari di piattaforma marina poco profonda, con minori mostly normal marine shallow shelf limestones with only minor intercalazioni terrigene. La Formazione Robledo Mountains del Gruppo interbedded clastics. The Robledo Mountains Formation of the Hueco riflette la tendenza da condizionì di piattaforma confinata e piane Hueco Group reflects a trend from a restricted shallow shelf and tidal tìdali terrigene nella parte inferiore, a condizioni di mare più aperto nella flat clastics facies in the lower parr ro more open marine conditions in parte superiore, che pure prevalsero durante la deposizione della sopra- the upper part, which also prevailed during deposition of the overly- stante Formazìone Apache Dam. rng Apache Dam Formation. I calcari della Formazìone Laborcita e del Gruppo Hueco con- Limestones of the Laborcita Formation and Hucco Group tengono piccoli foraminiferi, alghe e microfossili calcarei problematici. contain smaller foraminifers, algae and problematic carbonare micro- Tutti i taxa, ad eccezione di due pseudoalghe lasciate in nomenclatura fossils. All taxa except two pseudoalgae in open nomenclarure aperta (Litostroma (?) sp. e "problematicum gen. 1") sono forme già (.Litostroma (?) sp. and "problemat:icum gen. 1") are raxa alreadv descritte in letteratura. Operando un confronro con quelle delle Alpi described. Compared with the Carnic Alps (Austria/Italy), the Carniche (Italia/Austria), le associazioni a piccoli foraminiferi delle for- assemblages of smaller foraminifers o{ the Laborcita Formation and mazioni Laborcita e Shalem Colony sono molto simili a quelle delle for- Shalem Colony Formation are very similar to those of the Auernig mazioni Auernig e Carmzza (Gruppo dell'Auernig), e del Calcare a Pseu- and CarnizzaFormations (Auernig Group), and Lower Pseudoschwa- doschwagerina Inferiore (Gruppo di Rattendorf), indicando quindi gerina Limestone (Rattendorf Group), indicating an Orenburgian un'età da Orenburgìana ("Bursumian") ad Asseliana. I piccoli foraminiferi ("Bursumian") to Asselian age. Smaller foraminifers of the Robledo della Formazione Robledo Mountains consentono la correlazione con la Mountains Formation allow correlation with the Grenzland Forma- Formazione Grenzland e il Calcare a Pseudoschwagerina Superiore tion and Upper Pseudoschwagerina Limestone (Rattendorf Group) (Gruppo di Rattendorf) delle Alpì Carniche, che vengono riferirite of the Carnic Alps, dated as Asselian to Sakmarian. Smaller all'Asseliano e Sakmariano. I piccoli foraminiferi della Formazione Apache foraminifers of the Apache Dam Formation suggest an Artinskian Dam suggeriscono un'età Artinskiana e sì possono correlare con il \Wolf- age, correlating with the V/olfcampìan, or the Trogkofel Group of the campiano, o il Gruppo del Trogkofel delle Alpi Carniche.
'! Institut fùr Geologie und Palàontologie, lnnsbruck Universitàt, Innrain 52, A-6020 Innsbruck (Austria). [email protected] '!'! lJniversité des Sciences et Technologies de Lille, UFR des Sciences de la Terre, UPRESA 8014 du CNRS, Laboratoire LP 3, Bàtiment SN 5, F-59655 Villeneuve d'Ascq Cédex (France). E mail: Daniel.Vachard@univ-lille 1.fr :r)i+ New Mexico Museum of Natural History and Science, 1801 Mountain Road N.\M, Albuquerque, New Mexico 87104, USA. SLu- cas @nmmnh.state.nm.us K. Krainer, D. Vachard & S. G. Lucas
Introduction NEW In New Mexico, uppermost Pennsylvanian and MÉX}CO lowermost Permian strata record a'transition from a marine environment represented mostly by marine shelfal limestones of the Madera Group, to a terrestrial environment represented by red beds of the Abo For- ù mation reflecting increased tectonic activity of the Ancestral Rocky Mountain orogeny. In many sections of central New Mexico, transi- I) rì* tional beds of latest Pennsylvanian to early \flolfcampian age, termed Bursum Formation, occur between the = /,,. 'r\- marine carbonates and the nonmarine red beds. In the northern Sacramento Mountains, these transitional beds 25 km are represented by the Laborcita Formation. In the Rob- ledo Mountains, Bursum-equivalent limestones are Fig. 1 - Map of part of southern New Mexico showing locations included in the lowermost part of the Hueco Group of the studìed sections in the northern Sacramento (Vahlman 8e King 2002). Throughout south-central Mountains (1 Laborcita Canyon, 2 Fresnal Canyon) and New Mexico, Abo terrestrial red beds prograde south- Robledo Mountains 13 Robledo Peak. 4 north of Picacho ward and interfinger with marine limestones of the Mountain). FIueco Group. \il/hereas fusulinids from these Upper Pennsylvan- Laborcita Canyon northeast ofLaLuz and along a road ian and Lower Permian limestones have been studied in Fresnal Canyon east of La Luz (north of Alamogor- quite extensiveiy (e.g. Needham 1932; Thompson 1954; do; Fig. 1). UTM coordinates (NAD 27 danm) for Skinner Er Vilde 1965r Williams 1966: Steiner & Laborcita Canyon are 4132408, 3Q52756N, zone 13 Villiams 1968; \X/ilde 1975; Ross 1984; Myers 1988; (base of section) and 4145958, 3652131N, zone 13 (top Ross Er Ross 1994; Spencer & Ross 1997; Lucas 1.995; of section). For Fresnal Canyon the UTM coordinates Lucas et al. 2OOO; Lucas & Vilde 2000; Wahlman 8r King are 414536E, 3649595N, zone 1J (base of section) and 2002), little is known about smaller foraminifers 41.4733F,,3649563N, zone 13 (top of section). Samples (Toomey et aL. 1.977), which have been studied in other were also collected from the Laborcita Formation at North American paleoprovinces (Toomey 1974; Groves Scorpion Mound in Tirlarosa Canyon, and from the & Wahlman 1997; Prnard & Mamet 1998; Groves tr underlying Holder Formation af Dry Canyon. Boardman 1,999; Groves 2000). Some algae from New We investigated limestones of the lower Hueco Mexico were illustrated and discussed by Toomey et al. Group (Shalem Colony Formation and Robledo Moun- (1977) and Wahlman (1988). tains Formation) in the Robiedo Mountains (Figs. 2, 3). The aims of the paper are (1) to present a microfa- There, we studied an almost complete section that cies analysis, (2) to discuss the depositional environ- encompasses the Pennsylvanian-Permian boundary and ments, (3) to describe the smaller foraminifers, some corresponds to the upper part of the Bursum equivalent algae and pseudoalgae, and (4) to discuss the stratigraphy and the lower part of the Flueco Group (section L of of the Laborcita Formation of the northern Sacramento Wahlman & King 2002). This section (Robledo Moun- Mountains and part of the Hueco Group (Shalem Colony tain A on Fig. 3) is exposed just west of Robledo Moun- Formation and Robledo Mountains Formation) of the tain (location 3 on Fig. 1) and is assigned to the lower Robledo Mountains, and (S) to correlate these sequences part of the Shalem Colony Formation. The coordinates with the late Paleozoic succession of the Carnic Alps for Robledo Mountain A are 3182708,35901.49N (base (Austria/Italy). This study illustrates again the relative of section) and 318291E, 3589563N (top of section), paucity and the low diversity of North American smaller zone 1-3. foraminifers and calcareous algae compared to the \fle measured another section about 500 m of Tethyan region. The correlations proposed by Dai,ydov V Robledo Peak, which is correlated to the upper part of (1996) for the Virgilian, "Bursumian" and \X/olfcampian the Shalem Colony Formation at Robledo Mountain are confirmed by comparison of material from New Me- (Robledo Mountain B); coordinates are 31.82918, xico and the Carnic Alps (Vachard & Krainer 2001 a, b). 3589563N (base of section), and 318241F, 3589538N (top of section), zone 1.3 (location 3 on Fig. 1, section B on Location and methods Fig. 3). Limestones from the Robledo Mountains Forma- The Laborcita Formation was studied in the tion and the lowermost part of the Apache Dam Forma- northern Sacramento Mountains at the type locality at tion were studied at outcrops about 3.2 km north of Microfacies and microfossils from Sowth Central New Mexico 5
F;o 2 Stratigraphic correlation of Carnic Alps lorthern Sacramentc Robledo American '1. and (Krainer & Davydov; 1998) l\4ountains Mountains Stages Late Pennsylvanian Early c E Permian strata of the norrh- .q b ern Sacramento Mountain', Apache Dam Yeso Formation G (New 'F Trogkofel Group Formation c Robledo Mounraìns q) c c Mexico, USA) and Carnic z g .o z (Austria/Itaìy). 'ca Robledo Mountains o o Alps E o upper q) E E Formation G G E Pseudoschwageri na O O =É. uJ J Abo Formation o UJ o- Limestone =o =o o- Community Pil C Formation o €) O 'o E = Grenzland Formation E o E E a c f c ú q) I .O LOWET o Shalem Colony o o Pse u d oschwageri n a c o .g É. Formation E l o Limestone o o f E É. Laborcita Formation G f É. ut -oc Carntzza Formation o uJ * 4) f c 5 z al Auernig Formation m .E z o = o @ o f o É. C Corona Formation c É. .9 (5 o .G c e (J 6 Holder Formation Atrasado Formatiot o) É. Pizzul Formation 0) G = É. IJJ N l 0) IJJ o- O ! o- o- Meledis Formation o- f luoDermost oart)
Picacho Peak (ca. 11 km northeast of Las Cruces; sec- can scale. Two solutions have been advocated, either tions A, B, and C of Krainer Ec Lucas 1995). extend the Virgilian upward to the new system boundary The sections mentioned above were measured and or create a new stage ("Bursumian") for the early Volf- sampled rn detaii. and a total of 2+l large thin sections campian interval that is now Carboniferous (Fig. 2). were prepared for microfacies analysis and the determi- Recognition of a "longer" Virgilian in the Mid- nation of smaller foraminifers, algae and pseudoalgae. conrinent (Baars et aI. 1992; l994a,b; Barrick 8c Heckel In the Robledo Mountains, Pennsylvanian lime- 2000) so that it partly corresponds to what were for- stones below the Hueco Group are attributed to the merly lower Wolfcampian deposits (Thompson 1954; Atrasado Formation of the Madera Group by Kues Wilde 1925, 1990) is controversial (Lucas Ec Vilde (2001). Limestones of the Madera and Hueco Groups 2000). The designation of the early rWolfcampian as a exposed in the Robledo Mountains were deposited on "Bursumian" stage is justified by fusulinacean biostrati- the Robledo shelf between the Florida uplift to the west graphy (Ross Ec Ross 1994; Dai.ydov 1996; Wardlavr & and Orogrande Basin to the east. Dalydov 2000) . However, if the Bursumian correlates to an Orenburgian/Asselian interval (Darydov 1.996), the Carboniferous/Permian boundary crosses through the Chronostratigraphy "Bursumian" (Wardlaw Er Davydov 2000). The Bursum Formation was established by The main chronostratigraphical problem \flilpolt er al. (t9+C), and used extensively by Thompson addressed here is the interpretation and correlation of (1954). Although not mentioned by Ross (1984), the the "Bursumian"-lWolfcampian with the Gzhelian, the name "Bursumian" appears in Ross & Ross (1987) and Permo-Carboniferous boundary, and the Cisuralian of was first correlated with the Daixina sokensis fusulinid the Urals and the Carnic Alps. zone on the Russian platform. According to Vilde The Carboniferous (Pennsylvanian)/Permian (1990), the "Bursumian" represents the first zone, P\7-1, boundary in North America (classically equivalent to of the Wolfcampian stage. Ross & Ross (1994) advocat- the Virgilian/\folfcampian boundary) has been studied ed the necessity of a "Bursumian" stage for the North by many authors, using, for example, the ranges of the American stratigraphic scale. Darydov (1996) detailed fusulinacean s Triti c ite s, L ep to triti c ite s, " S chw agerinA" and the correlation of the "Bursumian" and Wolfcampian Psewdoschwagerina: e.g.,Thompson (1954), Ross (1984), with the Orenburgian, Asselian, Sakmarian and Artin- Vilde (1975, 1990), Vardlaw 8c Darydov (2000), Ross skian. Lucas and \7ilde 12000) considered the "Bursumi- 6c Ross (1.994), and Lucas 8c Wilde (2000) among o- an" as the upper part of the Uhradaixina (Bosbytawella) thers. Flowever, the newly defined GSSP for the Car- zone, which was initially interpreted as the base of the boniferous-Permian boundary places this boundary Permian (Chuvashov et al. 1986). within the North American Wolfcampian. This means Lucas et al. (2000) demonstrated that the fusuli- that the Carboniferous-Permian boundary no longer nid fauna of the Bursum type section is characteristic of corresponds to a stage boundary on the North Ameri- the early Volfcampian, and that the distribution of the K. Krainer, D. Vachard G S. G. Lucas
fusulinid fauna of the type secrion indicates that the base Group in the Robledo Mountains is 491 m. Krainer et al. of the lithostratigraphic unit Bursum Formation does (2000) confirmed that there is no lithologic basis for not correspond to the base of a fusulinid zone. The base identifying the Bursum Formation in the Robledo of a "Bursumian" stage, if it corresponds to a fusulinid Mountains and that the "Bursum" interval of Thompson zone, lies stratigraphically lower, within the Madera (1954) should be assigned to the Hueco Group. Lime- Group. The problem of the "Bursumian" stage is dis- stones referred to the Bursum equivalent, which are cussed in length by Dar,1'dov (2001) and Lucas et al. dated as "Bursumian" (latest Pennsylvanian) by QAA4, who list a number of reasons to abandon the Wahlman & King (2002), are included in the Shalem "Bursumian" stage. Colony Formation sensu Lucas et al. (tllSb). Our investigations of smaller foraminifers in New Mexico confirm that "Bursumian" and Orenbur- gian are coeval, as previously indicated on the basis of Facies of the Shalem Colony Formation at Robledo Peak conodonts and fusulinids by Chernyk & Ritter (1994), In the Robledo Mounrains, section A represents Darydov (1996), Nilsson Ec Davydov (1997), Dar,ydov the lower part, and section B the upper part of the er al. (1997), Darydov Er Nilsson (1999), and \fardlaw Shalem Colony Formation (see Fig. 3). & Dar'ydov (2000). Our data also support Dar,ydov's (1996) conclusion that the Wolfcampian srage cor- Section A (lower Shalem Colony Formation): Section responds more or less to the Asselian, Sakmarian and A is 56.5 m thick and is assigned to the Hueco Lime- Artinskian stages of the international Cisuralian series stone of Thompson (1954, fig.8). The sequence srarts (see Fig. 2). on top of a several meter thick cliff formed of massive limestone of the uppermosr Atrasado Formation (Fig. Hueco Group 3). The lower part (0 - 29 m) is composed of different types of gray, bedded limestones, nodular limestones The term Flueco limestone was established by and intercalated reddish marly shale with limestone no- Richardson 09A4) as a sequence up to 15OO m thick, dules. The upper part (29 - 56.5 m) consists of indis- composed mainiy of massive, fossiliferous limestone, tinctly bedded, laminated limesrone, locally bioturbated, and locally including beds of shale and sandstone. It was dm-bedded limestone, algal limestone, nodular lime- named after the Flueco Mountains in El Paso County, stone and intercalated grainstone beds, all gray colored. West Texas. Limestones are mostly composed of different Later, this thick sequence was divided into the types of wackestones, all being nonlaminated, bioturba- Helms Formation (Mississippian), the Magdalena Lime- ted and poorly sorted. Bioclastic wackesrone is most stone (Pennsylvanian) and an unconformably overlying abundant and contains a diverse biota, including frag- sequence termed Hueco Limestone. According to King ments derived from bivalves, brachiopods, gastropods, (1942), the Hueco Limestone includes all beds above the echinoderms, bryozoans, ostracods, fusulinids, smaller unconformity at the top of the Magdalena Limesrone, foraminifers, rare brachiopod spines, trilobite fragments up to the highest occurrence of Pseudosctrtzuagerina and and Spirorbis. Among the calcareous algae, recrystallized associated fossils. phylloid algal fragments are most abundant; Epimasto- In the Robledo Mounrains, Thompson (1954) pora, ?Antbracoporella and Eflugelia are subordinate. recorded an early Volfcampian fusulinid fauna contain- Locally, bioclasts, particularly shell fragments, are ing species of Dwnbarinella (now Leptotriticites) and a microbially encrusted and contain a few sessile species of Psewdofuswlina (now Stewartina, a dainellid foraminifers, forming small oncoids (oncoidal wacke- taxon) from limestones he referred to the Bursum For- stone). Micritic intraclasts are ràre. The matrix is mation, which are underlain by limestones of what he micrite, and frequently pelmicrite with abundant small termed the Fresnal (: Madera) Group and overlain by peioids forming bioclastic peloidal wackestone. Hueco Limestone. Jordan (1975) divided the Hueco Fusulinid wackestone composed of abundant Limestone of the Robledo Mountains into four sub- fusulinid tests and some orher bioclasts is rare. Algal units: two limestone subunits below the Abo tongue wackestone occurs in the upper part of the section and (lower and middle member), red beds of the Abo is composed of abundant large, completely recrystal- tongue, and Hueco Limestone above the Abo tongue lized fragments of phylloid algae, which are embedded in (upper member). Lucas et al. (1998 4 b) revised the a micritic and pelmicritic matrix. Osrracods, bryozoans stratigraphy of the Hueco Limestone by raising the and smaller foraminifers are rare in this microfacies. Hueco to group status and renaming the members of Peloidal wackestone, locally grading into grain- Jordan (1975) as Shalem Colony Formarion, Communi- stone, is recognized in the middle part of the secrion. ty Pit Formation, Robledo Mountains Formation, and This microfacies contains abundant calcivertellid Apache Dam Formation from base to top (see also foraminifers, some ostracods and a few larger shell frag- Cook et aL. 1998). The total thickness of the Hueco ments, a pelmicritic matrix and microspar cement, and Microfacies and microfossik from South-Central Neu Mexico
Shalem Colony Formation, Hueco Group
Section A su*pr*" Robledo Mountains . RM50 Section B Samples RM ?? R$ 21 F|ii îg iì[1 18
RM J6 tr tr g. g, RM 15
o- o- R[.]| 14 Rt\4 13 Rt,4 12 v, u lrJ UJ o- 3 'RM39 o : FMSi o- 3 z z o : l- F
R[,| B RM7 Rt"f 6 = = ú. u. o o lr lr
z z o o TT--l Massive and thìck bedded J limestone o o ffi Bedded timestone o u ffi Wavy bedded limestone ffi Nodularlimestone E Laminated limestone = IJJ IJI lHl Algal limeslone FI;r:l ,. . J RM3 r:l:-1 Algal óounostone- RM2 ffi ooid grainstone :c Bioturbation a o ffi carbonate nodules Crossbedded sandstone @ Carbonate conglomerate
Madera _ll
Group I
Fig. 3 - Measured stratigraphic sections through the lower part (sectìon A) and upper part (section B) of the Shalem Colony Formation (Hueco Group) at Robledo Peak (location see Fig. 1). K. Krainer D. Vachard €z S. G. Lucas
locally a few siliciclastic grains. This microfacies is fossil constituents. interbedded with boundsrone composed of irregular Grainstones are poorly sorted, nonlaminated, and crusts formed of cyanobacteria, peimicrite, sparry calcite cemented by sparry calcite. Constituents are micritic and a few bioclasts. intraclasts, shell debris, algal fragments, ostracods, a few Grainstones are subordinate in the secrion, pas- tuberitinid foraminifers and Spirorbis. Micrite envelopes sing into wackestone as well as packstone. Bioclastic occur around intraclasts and bioclasts. Locally, thin grainstone is poorly sorted and cemented by sparry cal- coatings and layers of cyanobacteria forming bindstone cite, and contains a biota similar ro that of the bioclastic are present. wackestones (Pi. 1, fig. 1). A few micritic intraclasts are Oolitic grainstone is well sorted, indistinctly bed- present, too. Many of the bioclasts and intraclasts are ded and composed of single ooids formed of large nuclei surrounded by micrite envelopes, and some are encrust- and relatively thin cortices (Pl. 1, fig.7). Average grain ed by cyanobacterra and sessile foraminifers. Locally, the size of the ooìds is 0.2 mm. The nuclei of most ooids are matrix contains abundant small peloids and some recrystallized fossil fragments; in some ooids, rhe cor- micrite, forming a bioclastic peloidal grainstone. tices display radial structures. A few shell fragments are In the upper part of the section, at the base of the presenr. massive algai limestone (biostrome), boundsrones Above a 2.5-m-thick covered interval, bedded gray formed of algal crusts are developed (P1. 1, fig. 6). The limestones are exposed. The lowermost bed is an oolitic algal crusts consist of Archaeolithopbyllum lamelloswrrt, limestone, overlain by fossiliferous limestones com- Archaeolithoporella, some other a1gae, and calcivertellid posed of algal wackestone and bioclastic foraminifers. Between these algal laminae there is an grainstone/packsrone. inhomogenous micritic matrix containing fragments of Algal wackestone is composed of large, in most molluscs, bryozoans, echinoderms, ostracods and abun- cases, completely recrystallized fragments of phylloid dant smaller foraminifers. Individual crusts are uD ro algae, which are embedded in a micritic and pelmicritic, several cm thick. bioturbated matrix. ln addirion, diverse shell fragmenrs, ostracods, gastropods, trilobite fragmenrs, smaller Section B (Upper Shalem Colony Formation): Sec- foraminifers and rare fusulinids are presenr. tion B (Fig. 3) is located about 5OO m wesr of section A Bioclastic grainstone/packstone contains large (western Robledo Peak). The measured secrion is 54.5 m amounts of smaller foramiiiifers, parricularly calcivertel- thick and starts above a massive limestone cliff. The lid forms. Other bioclasts include shell fragmenrs, ostra- lower 26 m are composed of war,y and nodular, gray cods, echinoderms, bryozoans and trilobite fragments. micritic limestone, laminated and partly bioturbated A few detrital quanz grains are present. gray limestone, and indistinctly bedded to massive gray The uppermost 19.5 m of section B consist of limestone, composed of wackestone, packstone and gray, bedded, micritic limestone with varying bed thick- grainstone. Bioclastic wackestone contains a diverse ness (from a few cm up to 1.4 m),laminated and partly biota, small peloids and micrire, and locally grades into bioturbated limestone, nodular limestone, thin oolitic packstone. Some bioclasts display micrite envelopes. In limestone beds and a 1.2 m thick interval of crossbed- peloidal packstones a few ostracod shells are rhe only ded, pebbly sandstone composed of siliciclastic grains
PLATE 1
Thin section photomicrographs of characteristic microfacies tvpes of the Shalem Colony Formation at Robledo Mountain. Plane polarized light, widthofFig. 1-Fig.'1 :6mm,wìdthofFig.5-Fig.7:4.3mm.ForpositìonofthesamplesinthesectionseeFig.3.
Fio I - Grainstone, poorly sorted, containing abundant calcìvertellid foraminifers and peloids, subordinate gastropods, osrracods and echin- oderms and micritic intraclasts. Shalem Colony Formation, Section A, sample RM 50. Fio ) - Fusulinid wackestone composed of abundant fusulinid tests (Triticites), subordinate are echinoderms, smaller foraminìfers and ostracods. The matrix consisrs of micrìte. Shalem Colony Formation, Section A, sample RM 28. flg. J - Grainstone composed of abundant peloids, calcivertellid foraminifers and calcite cemenr. Shalem Colony Formation, Section B, sam- ple RM 22. Fig. 4 - Algal wackestone/packstone composed of abundant fragments oÍ Epìmastopora. Some recrystallized phylloid algae also occur. The matrix is micrite. Shalem Colony Formation, Section B, sample RM 9. - Grainstone/packstone composed of abundant micritic intraclasts with dark gray micrite envelopes and rare bioclasts (ostracods). Shalem Colony Formation, Sectìon B, sample RM l/. Fig. 6 - Algal boundstone formed of algal crusts (Archaeolitbophyllum lamellosum) and rare calcivertellìd foraminifers. Shalem Colony For- mation, Section A, sample RM 45. - Oolitic grainstone, well sorted, cemented by sparry calcite. Some ooids are micritized. Shalem Colony Formatìon, Section B, sam- ple RM 5. Pl. 1 Microfacies and microfossils from South-Central Nett Mexico 10 K. Krainer, D. Vachard & S. G. Lucas cemented by calcite. The limestones of this unit are and display thin, dark gray micrite envelopes. Bioclasts composed of different microfacies, particularly wacke- are rare, and are mostly ostracod shells and a few other stone, packstone and grainstone, and rarely of bound- shell fragments. Some ooids are present. This microfa- stone. cies is indistinctly bedded, with alternating coarser and Bioclastic wackestone, 1oca1ly grading into fÌoat- finer grained layers. stone, is poorly sorted and contains a diverse fossil Fine-grained, bioturbated peloidal grainstone assemblage composed of large, recrystallized fragments composed mostly of peloids and smaller foraminifers derived from brachiopods, bivalves, gastropods, echino- (mostly sessile calcivertellid forms), ostracod shells and derm remains, broken fragments of recrystallized phyl- a few other shel1 fragments rarely occurs. A few micri- loid algae, locally abundant small fragments of Epi- tic intraclasts are present, too. mastopora alpina and another species of Epimastopora, The boundstone is composed of encrusting layers ostracods, echinoderm spines, trilobite fragments, and of cyanobacteria with a hemispheroidal growth form. many smaller foraminifers (mostly calcivertellids). Between the crusts, pelsparitic sediment is present. The Many bioclasts are encrusted by cyanobacteria and boundstone is overlain by a grainstone composed of Palaeonubecularia, forming oncoid-like clasts. The reworked crusts and peloids that are cemented by cal- matrix consists of pelmicrite; locally, some calcite cite. cement is present. The sandstone horizon consists of medium- and Algal wackestone is poorly sorted and consists of very coarse-grained, mixed siliciclastic and carbonate abundant fragments of Epimastopora, and subordinately sandstone. Both sandstone types are composed of car- of recrystallized phylloid alga1 plates, echinoderm bonate clasts (micritic intraclasts), ooids and bioclasts remains, gastropods, fusulinids, ostracods, smaller (shell fragments, echinoderm remains, rare algal frag- foraminifers, and brachiopod fragments (P1. 1, fig. a). ments, fusulinids and smaller foraminifers). Siiiciclastic Packstone consists of abundant shell fragments, grains are abundant polycrystalline quartz, including gastropods, calcareous algae (rare Epimastopord), some stretched metamorphic quartz grains; monocry- bryozoans, ostracods, smaller foraminifers and fusuli- stalline quartz, sedimentary chert and rare detrital nids, abundant rounded, recrystailized and micritic feldspars are subordinate. Siliciclastic grains are suban- lithoclasts (intraclasts) with dark gray micrite envelopes, gular to subrounded. The sandstone is indistinctly bed- calcire cement, and a micritic matrix. ded, moderately sorted and cemented by calcite; diage- Different rypes of grainstone have been reco- netic chert/microquartz cement is present. gnized (Pl. 1, figs. 1, 3, 5). One type is poorly sorted and composed of recrystallized ooids, micritic intra- clasts, a few detrital qLrartz grains (mono- and polycrys- Facies of the Robledo Mountains Formation and lower talline quartz) and abundant bioclasts, including shell Apache Dam Formation near Picacho Peak fragments, phylloid algae, Epimastopora (rare), echino- derms, gastropods, fusulinids, ostracods, echinoid The Robledo Mountains Formation is 125 m thick spines, and bryozoans. The matrix is composed of spar- and consists of limestones that are cyclically interbed- ry calcite cement, and locally of micrite and pelmicrite. ded with siliciclastic sediments. The limestone facies of Many clasts display micritic envelopes. this formation was described in detail by Krainer 8c Oncolitic grainstone is also poorly sorted and Lucas (1995); a detailed description of the clastic facies consists of abundant oncoids (mostly 1 - 4 mm in diam- is presented by Mack and James (1986), and a summary eter) . The nuclei are formed of bioclasts, which are is given by Lucas et al. (1998a, b). encrusted by cyanobacteria. According to Krainer & Lucas (1995),limestones Bioclasts are shell fragments, echinoderms, ga- of the Robledo Mountains Formation are mostly com- stropods, smaller foraminifers, ostracods, and bry- posed of different types of wackestone and packstone ozoans (almost all are encrusted to form oncoids). A (ostracodal wackestone/packstone, foraminiferal wacke- few small detrital quartz grrins are present.;nd rare. stone/packstone, bioclastic wackestone/packstone), larger sedimentary chert fragments have also been subordinate mudstone, bioclastic mudstone, grainstone obser-ved. (foraminiferal and bioclastic grainstone) and rare bind- Indistinctly bedded grainstone composed of alter- stone. nating thin layers rich in bioclasts (cemented by calcite Limestones dominated by smaller foraminifers spar), peloids or smaller foraminifers (mostly calcivertel- and ostracods are more abundant in the lower part, lids and some tuberitinids) also occur (P1. 1, fig. 1). whereas limestones containing a more diverse fossil Intraclast grainstone/packstone, moderately to assemblage are predominant in the middle and upper poorly sorted, cemented by calcite spar, and locally con- parts. This reflects a trend from a shallow shelf environ- taining some micrite, is present (P1. 1, fig. 5). Most ment with restricted circulation and, locally, a probable lithoclasts are micritic to microsparitic in composition brackish water environment in the lower part to more Microfacies and mìcrofossils from South-Central Neu.t Mexico 11
' lrr, .1c33 { , Laborcita lWV$l$ I I\, Canyon \o. \
.fc3? /,,, ,
.Lc3i I, |\, , :i8rs I l .LC 30 I
iaÀllvvr^I' l .LC2s \ I .LC !9 'Lc 27 I t, .1c26 l, , .LC 48 .LC 25 ór/s *7 r6 ^ z # qF o z .LC 5 .!9 { :18 î * Fig. 4 - Measured stratigraphic section through the Laborcita Formation at Laborcita Canyon (type section; location see Fig. 1). \2 K. Krainer, D. Vacbard & S. G. Lucas open marine conditions with normal salinity in the mid- Laborcita Formation is wholly Wolfcampian in age. dle and upper parts of the formation. Siliciclastic red Rasbury et al. (tlls) estimated the Pennsyivan- beds contain extensive invertebrate and vertebrate trace ian-Permian and Carboniferous-Permian boundaries fossils, particularly tetrapod footprints, and represent a within the Laborcita Formation of the Sacramento tidal flat environment (Lucas et al. 1.995,1998b). The Mountains by U-Pb-dating of paleosols from the overlying Apache Dam Formation is composed of shal- underlying Holder Formation (Goldstein 1988, 1991) low marine shelf limestones and siltstones. and using classical linear least-squares fitting of sample IX/e studied thin sections from limestones of the age versus cycle number. They determined the Pennsyl- Robledo Mountains Formation and lower part of the vanian-Permian boundary àt302 -r 2.4Ma and the Car- Apache Dam Formation (sections A, B, and C of Lucas boniferous-Permian boundary at 301 -r 2 Ma. Rasbury et aI. 1995, 1,998ro; Krainer and Lucas 1995). Sample et al. (1998) state that there is biostratigraphic control numbers in this paper refer to the sections of Krainer & on the position of the boundaries, but they did not men- Lucas (1995). tion on which biostratigraphic zonation their estima- tions are based. Laborcita Formation The Laborcita Formation at Laborcita Canyon (approximately 130 m thick according to our measure- The term Laborcita Formation was established by ments; Fig. a) and Fresnal Canyon (thickness of the Otté (1959) for sedimentary rocks composed largely of measured section 106 m; Fig. 5) is composed of alter- gray and red mudstone, gray limestone, sandstone and nating carbonate and siliciciastic lithotypes. These litho- conglomerate. The Laborcita Formation is exposed in types are arranged to form cycles recognrzable in the the northern Sacramento Mountains, between the lower part of both sections. underlying Holder Formation and overlying red beds of An ideal cycle begins with a conglomerate at the the Abo Formation. At the type locality, the thickness is base, grades upward into alternating sandstone, siltstone 146 m according to Otté (1959). The boundary between and shale, and culminates in thin- and thick-bedded fos- the Laborcita and Abo formations is drawn at the top of siliferous limestone, indicating a deepening upward the highest marine limestone of the Laborcita Forma- trend (transgressive cycles). Grainstone on top of some tion. limestones, overlain by greenish-gray shale, indicates the The different lithotypes of the Laborcita Forma- beginning of a regressioriàl event, although shallowing tion are arranged to form alternating cycles of limestone upward (regressive) cycles are rare and very thin. Most and siliciclastic sedimentary rocks (Fig. +). Otté (1959) cycles are composed of shale with intercalated sandstone pointed out that these lithologies change abruptly late- and siltstone, overlain by thin, waD/ to nodular bedded rally and do not extend over long distances. limestone, and thicker limestone beds on top. The Laborcita Formation is interpreted to consist Conglomerates are polymict, poorly sorted, clast of cyclic sequences of terrestrial to transitional marine supported and in most cases contain subrounded to siliciclastics and shallow marine carbonates that were rounded carbonate clasts, including reworked algal and deposited on a narrow shelf between the Orogrande fusulinid limestones, and siliciclastic grains, particularly basin to the west and the Pedernal landmass to the east pebbles of red jasper. At Fresnal Canyon, individual during Early Permian time (Otté 1959; Delgado 1977; conglomerate layers form up to 2.5 m thick, laterally Fly 1986). Particularly well studied are the algal reefs thinning channel fills that are incised up to 2 m deep into (mounds), which occur in the middle member of the the underlying strata. At Laborcita Canyon, congiome- Laborcita Formation (Otté Er Parks 1963; Cys & Mazul- rate layers are thinner and not so deeply incised, and fre- 1o 1977; Parks 1977; Mazullo & Cys 1929; Cross & quently larger pebbles are floating in sandy, carbonate Klosterman 1981; Bowsher 1986; Mazullo 1988). Like cemented matrix. In the upper part, a poorly sorted, the Bursum Formation, the Laborcita Formation, which angular to subangular conglomerate layer with a maxi- is composed of carbonate and clastic rocks, represents a mum clast size of 10 cm is present. Coarse-grained, transitional facies between the dominantly carbonate locally pebbly sandstones form thicker units, particular- and marine strata of the underlying Holder Formation ly in the upper part of the sections, and appear as mas- and the terrestrial red beds of the overlying Abo Forma- sive to indistinctly laminated or crossbedded ledges tion. associated with conglomerates. Fine-grained sandstone The lower part of the Laborcita Formation at the and siltstone occur as thin beds intercalated in shale, and type locality was considered late Virgilian in age by Otté are massive or horizontally laminated; crossbedding and (1959). He drew the base of the Voifcampian at the base current ripples are rare. of the first limestone bed containing the fusulinid Shale and silty shale intervals are mostiy covered Schwagerina (probably Thompsonites), which is about 26 at Laborcita Canyon, but well exposed along the road m above the base of the formation. Steiner & \filliams cut at Fresnal Canyon. The rock color is either gray to (1968) restudied the fusulinid fauna, concluding that the greenish gray or reddish to pink. Locally, fossils occur in Microfacies and microfossils from South-Central Neza Mexico 13 Fresnal Ganyon z : F z E : ú. F o lJ- : u o : ll- () ú, o : o (J É, J o m J Fig. 5 - Measured stratigraphic section through the Laborcita Formation at Fresnal Canyon (location see Fig. 1). 14 K. Krainer, D. Vachard & S. G. Lucas greenish-gray shales. Claracrwsta, and Eflwgelia to form oncoids up to several In the field, the following lithotypes of limestone cm in diameter (oncoid wackestone), which are not are recognized: observed in the Shalem Colony Formation. Bioclastic (a) Thin-bedded limestone with even to wavy bed- wackestone may grade into phylloid algal wackestone, ding, bed thickness mostly 5 - 10 cm, and frequently fusulinid wackestone and foraminiferal wackestone/grain- with thin shale partings. These limestones are composed stone. of different types of wackestones and packstones; grain- As in the Shalem Colony Formation, the most stones àre rare. The dominant microfacies is bioclastic abundant bioclasts in algal wackestone/packstone are wackestone/packstone; subordinate are algdr wacke- broken fragments of phylloid algae (mostly Ewgonopbyl- stone, foraminiferal wackestone, fusulinid wackestone, lwm); also, locally, the dasycladaceans Antbracoporella oncoid vrackestone, bioclastic mudstone, peloid/oncoid and subordinate Epimastopora are present (P1. 2, figs. 1, grainstone and grainstone/packstone. 2). Phylloid algal plates are frequently aligned parallel to (b) Thin-bedded limestones with waD/ to nodular the bedding and rarely found in growth position. bedding, bed thickness mostly 5 - 20 cm and shale part- Foraminiferal wackestones/packstones are com- ings. The most frequent microfacies type is bioclastic posed of abundant smaller foraminifers, mostly cal- wackestone; subordinate are bioclastic packstone/grain- civertellids, and other bioclasts (P1. 2, fig. 6). stone and fusuiinid wackestone. Fusulinid wackestone is characterized by a rela- (c) Thick-bedded limestone with bed thickness > tively high taxonomic diversity compared to the other 20 cm and up rc 125 cm thick. Common microfacies microfacies of the Laborcita Formation (P1. 2, fig. a); types are bioclastic wackestone/grainstone and algal locally, fusulinid packstone occurs (Pl. 2, fig. 3). wackestone; other observed microfacies are fusulinid Ooid wackestones are composed of well sorted, wackestone, ooid wackestone and ooid/oncoid grain, grain supported, locally matrix-supported ooids, mostly stone. A.2 - A3 mm in diameter. A few bioclasts, mostly echi- (d) At Fresnal Canyon, a thin carbonate bed noderm fragments, are present. occurs in a red silty shale unit that is of pedogenic ori- Oncoid wackestones/packstones contain elongate gir. small oncoids, poorly sorted and iocally densely packed, and some bioclasts (ostracods, echinoderm fragments, small gastropods) that arè'embedded in a marrix com- Limestone Microfacies posed of peloidal micrite and small amounts of calcite In general, Laborcita Limestone microfacies are cement. Oncoids are mostly 1-4 mm long, and the nuclei very similar to those of the Shalem Colony Formation. are commonly formed by bivalve shell fragments. A few Bioclastic wackestones/packstones are characterrzed by angular to subangular detrital qlrartz grains are scattered a relatively high diverse biota (Pl. 2, fig. 5).In some throughout the rock. This facies, which is not observed wackestones, bioclasts are frequently encrusted by in the Shalem Colony Formation, sharply overlies a fine- cyanobacteria (Girvanella), calcivertellids and rare grained, quartz-rich sandstone. Arcbaeolithophyllwm lamellosum, Palaeonwbecwlaria, Bioclastic mudstone is rare and consisrs of a gray, PLATE 2 Thin section photomicrographs of characteristic microfacies types of the Laborcita Formation at Laborcita Canyon and Fresnal Canyon. Plane polarizeci light, *idth of Fig. I - Fig. + : 6 mm. width of Fig.5 . Fig.7 :4.3 mm. I-or porition rhe ìn rhe (Laborci- of 'ample' sccrion see Fig.4 ta Canyon) and Fig. 5 (Fresnal Canyon). Fig. 1 - Algal wackestone with abundant recrystallìzed fragments of phylloìd algae (.Eugonoplryllum) and a few ostracods, embedded in dark gray micrite. Fresnal Canyon, sample FC 19. Fig. 2 - Bioclastic packstone composed of recrystallized phylloid algae, shell debris, ostracods and brachiopod spìnes. Many bioclasts drs- play micrite envelopes. The matrix consists of calcite cement. Fresnal Canyon, sample FC 4. Fig. 3 - Fusulìnid packstone showing densely packed fusulinid tests (Triticites) with pressure solution xt their contacts. Some gray micriric matrix is present. Laborcita Canyon, sample LC 11. Fig. 4 - Fusulinid wackestone containing abundant fusulinid texs (hiticites) embedded in recrystallized micritic matrix. Fresnal Canyon, sample FC 6 ( E:-rr5.J D:^-r---:^ - -^r-estone containing shell debris, echinoderms, algal fragments, gastropods, one trilobite fragment and ostracods, floar- ing ìn gray micrite. Fresnal Canyon, sample FC 15. Ei- A - F^'"-;-;f^-"1 ryackestone with abundant calcivertellid foraminifers, subordinate shell debris, small gastropods, ostracods, some peloids, recrystallized micrite and some calcite cement. Laborcita Canyon, sample LC 29. Fìg. Z - \X/ell sorted sandstone composed of subangular to rounded grains. Siliciclastic grains are mostly monocrystalline qtrarrz. Abundant gray - dark gray micritic carbonate grains are also present. A few bioclasts occur. Laborcita Canyon, sample LC 26. Pl.2 MicroJacies and microfossik from South-Central Neu, Mexico 15 16 K. Krainer, D. Vachard G S. G. Lucas homogeneous to inhomogeneous (bioturbated) micrite The dominant siliciclastic grain type is quartz, with only a few peloids and rarely small bioclasts such as mostly monocrystalline, and subordinately polycrys- ostracods, small shell fragments, and a few foraminifers talline. Locally, qtrarrz grains display authigenlc over- and echinoderm ossicles. Mudstone is composed of gray growths. Less abundanr are opsque grains and chert micrite containing a few caliche peloids/ooids and a fèw grains, which rarely display ghost structures of radiola- ostracoos. rians, spicules and very rare ostracod shells, indicating a Grainstones are represented by coarse-grained sedimentary origin. Very rarely, detrital feldspars, altered oncoid grainstone layers alternating with fine-grained and partly replaced by calcite, phyllitic grains and detri- layers composed dominantly of ooids. Ooid grainstone tal micas occur. Most sandstones contain abundant layers and peloid/oncoid grainstone are composed of recrystallized micritic carbonate grains (up to about fine-grained laminae with mostly peloids and some smali 40%), and some contain small bioclasts such as shell oncoids and coarse-grained laminae with mostly oncoids fragments, echinoderms and fusulinids. Sandstones are and larger peloids. frequently cemented by sparry calcite replacing qLtartz) From outcrops north of Laborcita Canyon, F1y feldspar and chert grains. Locally, recrystallized micrite (1985) described foreset-bedded sandy grainstones, (microsparite) is present. blue-green algal dismicrites, digitate algal stromatolites Like the sandstones, the fine-grained conglomerates and phylloid algal bindstones, but those facies have not are mixed siliciclastic-carbonate in composition and been recognized in sections examined for this study. poorly sorted. Siliciclastic grains are mostly represented by subangular qtrartz grains; subordinate are rounded, sedimentary chert grains. Detrital feldspars areyery rare. Sedimentary petrology of siliciclastics Different types of rounded carbonate clasts are present Siltstones are mixed carbonate - siliciclastic - bio- in high amounts. Fine-grained conglomerates contain clastic in composition with varying amounts of silici- abundant bioclasts, particuiarly broken fusulinid tests, clastic grains (5 - 30%) and bioclasts. Carbonate grain shell fragments, echinoderms, rare bryozoans and Epi- types are mostly dark brownish and gray micritic intra- mdstopora. The matrix consists of blocky calcite cement. clasts that may display dark micrite envelopes. Rarely, peloids are present. Siliciclastic grains are dominantly Depositional environment monocrystalline quartz, wi.th subordinate polycrys- talline detrital quartz. Detrital chert grains, micas and The Hueco Limestone has been generally consi- feldspars, the latter more or less altered and replaced by dered as a good example of an open sheif marine car- calcite, are less abundant. bonate facies (\filson & Jordan 1983). According to Bioclasts are present in all studied siltstone sam- Wahlman & King QAA4, the Lower Flueco Member ples in small amounts, including ostracods, echinoderm (Shalem Colony Formation) is composed of predomi- fragments, recrystallized shell fragments, locally large nantly offshore, normal marine, shallou' shelf deposits recrystallized phylloid algal plates, broken fusulinid with a general shallowing upward trend from a normal tests, smaller foraminifers (calcivertellids, Syzrania, Ear- marine shelf environment in the lower part to mostly landia) and unidentifiable recrystallized bioclasts. In inner shelf, shallow water, restricted marine carbonates i. tLo r,-^o" one sample, a few large shell fragments, mostly derived ^.rt from gastropods, are present. Some of these fragments Limestones of both the Shalem Colony Formation are encrusted by Palaeonubecularia and cyanobacteria, and the Laborcita Formation actually display a number forming oncoids with diameters up to several cm across. of features that according to Vilson & Jordan (1983) are Siltstones are moderately to well sorted, and in diagnostic of an open, well oxygenated shelf environ- some samples poor sorting was observed. The metrix is ment with mostly normal marine salinity, and below the mostly micrite or pelmicrite, although siltstones normal wave base, but above storm wave base: cemented by microsparite also are present. la) Limestones of both formations are character- Sandstones are composed of mixed siliciclastic and izedby irregular bedding with bedding thicknesses rang- carbonate grain types. Only one sample was determined ing from less than 20 cm thick to thick bedded and mas- to be a pure quartz arenite. Angular to subrounded sand sive limestones, locally including algal mounds grains dominate, but in some medium and coarse- (biostromes). watT bedding with thin shale partings is grained sandstones the sand grains are rounded to well common, locally grading into nodular limestone. rounded. Most sandstones are moderately sorted, (b) Muddn frequently bioturbated carbonate tex- although poorly and well sorted sandstones occur as tures predominate with normal marine bioclastic wacke- well (P1. 2, fig.7). Lamination has not been observed in stone and packstone forming the bulk of the limestones, thin section. Commonly, siliciclastic grains are more representing the SMF-Type 9 and 10 of \íilson (1975). abundant than carbonate lithoclasts, and small amounts (c) Presence of different types of grainstones, re- of bioclasts are present in all studied samples. presenting sMF-Type 1.1,1.2, 13, and 15 of vilson (1975), Microfacies and mícrofossik from South-Central Neu; Mexico t7 is indicative of a high-energy shoal environment. is composed of abundant siliciclastic sedimentary rocks, (d) Biota of hìgh taxonomic diversity and inclu- including shale, sandstone and conglomerate, alternating ding a normal marine fauna (stenohaline forms) such as with fossiliferous limestones. Siliciclastic rocks are very brachiopods, bryozoans, crinoids, echinoids, fusulinids, rare in the Shalem Colony Formation. some smaller foraminifers and trilobites. (b) The Laborcita Formation is characterizedby (e) Presence of calcareous algae, particularly phyl- pronounced mixed siliciclastic-carbonate cycles, parti- loid algae, and subordinate dasycladaceans and other cularly in the lower part. Such cycles are absent in the algae, points to deposition within the photic zone with Shalem Colony Formation. maximum water depths of a few tens of meters. Otté (1959) noted that in the lower part of the The limestones contain bioclastic remains of all Laborcita Formation limestones and shales form cycles ma;'or late Paleozoic biotic groups: shell fragments (bra- (cyclothems), that suggest increasing water depth du- chiopods, bivalves, gastropods), echinoderms, bryozoans, ring deposition. He stated that each cycle represenrs one calcareous algae (phylloid algae, Epimastopora, rare complete transgression and regression. He also reported Archaeolithoporella, Anthracoporella, and Eflugelia), that the lower part of the Laborcita Formation was fusulinids, smaller foraminifers (mostly calcivertellid deposited mostly under normal marine conditions, and forms), ostracods, Twbiphytes, rare serpulids and trilo- that towards the southeast and east the facies changes bite fragments. from marine to dominantiy nonmarine facies. He inter- The phylloid algai wackesrones thar occur on rop preted all red conglomerates, sandstones and mudstones of algal boundstones in the upper part of secrion A show as terrestrial deposits, and gray and green mudstone some similarities to the phylloid algal mounds ("Scorpi- locally containing abundant fossils as well as the lime- on Mounds") of the Laborcita reef complex of the stones as marine. Fly (1986) interpreted the clastic se- northern Sacramento Mountains. diments in the Coyote Canyon area as fan delta All carbonate microfacies types that Wilson deposits, alternating with shallow marine limestones. (1975) regarded as typical of late Paleozoic shelf and Carr (1983) investigated a several meter thick clastic, shelf margin limestones are presenr in the investigated coarsening upward sequence in the lower part of the sections, although they occur with some variation. Laborcita Forrnarion, which he interpreted to have Low-energy sediments indicating a restricted shelf formed by progradation of a delraic lote. Carr (1983) environment with reduced water circulation are rare and stated that late Virgilian - early \flolfcampian sandstones represented by mudstone and bioturbated bioclastic of the northern Sacramento Mountains show evidence mudstone containing a restricted fauna with a relatively of both marine and fluvial influences on deposition. large number of organisms such as ostracods and certain Ve interpret the thick, coarse-grain.à .o.rglorn.- species of smaller foraminifers (Laborcita Formation), rates of the Fresnal Canyon section, which are deeply and low-diversity intraclast/peloidal grainstone, which is incised in the underlying srrata, as fluvial channel-fill locally laminated (Shalem Colony Formation). deposits. Conglomerates in the Laborcita Canyon sec- According to Fly (1985), carbonare deposition of tion, which are thinner, fine-grained and not deeply Laborcita the Formation was concenrrated in shallow incised, contain diverse bioclasts clearly indicating a water marine embayments between fan-delta platforms. shallow marine, nearshore depositional environment. Terrigenous clastic sediments migrated towards these All investigated sandstones and siltstones also contain emDayments. marine fossils, pointing to a shallow marine origin. This The sandstone interval of section B of the Shalem is also the case for the greenish-gray shales in which fos- Colony Formarion, which contains various fossil frag- sils are found locally. Pink and reddish colored shales ments, is also of shallow marine origin, and was proba- may indicate terrestrial conditions of a coastal plain. bly deposited during a relative sea-level lowstand with Generally, clastic sediments of the Laborcita Formation increased siliciclastic influx in an upper shoreface envi- were deposited during relative sea-level lowstands and ronment. The red marly shales conraining limestone strong clastic influx. Fossiliferous limestones accumu- nodules in section A, display pedogenic features indica- lated during relative sea-level highstands lacking silici- ting subaerial exposure during relative sea-level low- clastic influx. stands. A general shallowing upward trend within the Otté (1959) noted that many of the strata extend two investigated sections has not been observed. laterally only a few hundred meters and lense out or la- Although the limestones of both the Shalem terally grade into a different lithofacies. According to Colony Formation and Laborcita Formation are more or Otté (1959),Pray (1961), and Kottlowski (1963), rhere less equivalent and accumulated in a very similar shelf is evidence of tectonic acriviry in the norrhern Sacra- environment, the successions differ significantly, parti- mento Mountains during the early \Tolfcampian, indi- cularly in the following two points: cating that the formation of cycles within the Laborcita (a) The Laborcita Formation, which was deposi- Formation was strongly influenced by tectonic acriviry, ted on the narrow easrern shelf of the Orogrande Basin, and that glacioeustatic sea-level changes driven by the 18 K. Krainer, D. Vachard G S. G. Lucas Gondwana glaciation played only a minor role (see also E 1975, Ec 1988). cycles and E E Wilson Wilson Jordan Lack of Table 1: rarity of siliciclastic sediments within the Shalem Algae, algal? microproblematica and algospongia l Colony Formation may indicate that the Robledo Shelf margin of the Orogrande Basin was tèc- on the western Ortuilclla so. I lPl. 5. fis. 1 8) tonically more stable than the Laborcita Shelf on the )ttnnelln sn ? lPl R liq Ortunetla so.3 fPL 8. fie. 29) eastern margin during early Wolfcampian time. Anthtr aDorella \D.,fu ó;1,r Pia. l9)0 tPL l- fis.28 Mizzia ct. carnutd Kochansky Devìdé & Herak, 1960 lPl. 7. tis. 10) Gvronorello s. aPl 7 fis Epinastopora alpina (Kochansky-Devidé & Herak, 1960) Paleontology (smaller foraminifers, pseudoalgae and sensr (rrlik lSTR lPl 5 fis 7-8 l0 l7 lgì EDima.rtÒDora so- lPl. 5. fic. 3,1) algae) Paraepimastopora ex gr. kansasensis (Johnson, 1946) Roux. 1989 lPl.4. fie.30) Pvudaentna:ronora.n lPl.4. fis. 17. Pl.6. fiq..21 The smaller foraminifers have been identified dasvclad indet. (P1.5. fis.26) Eu{onoDhtllunt (Pl. l. tiq. ll according to the criteria of Cushman & Waters 1928; Neoanchicodìum catenotrlet Endo, 195,1 6. fis.31: Pl.7.1ie. l2i Pl. 8. fie.19) Morozova 1.949; Lipina 1949; Reitlinger 1950; Henbest lPl. 1963; Zolotova & Baryshnikov 1980; Baryshnikov et al. Algal? micronroblematica Nas taci tes res iculosa Maslov, 1929 1982;Daxrydov 1986; Groves & Wahlman 1997; Altiner 1P1.3. fis. 13: PI.5. fis. l: not Pl. 6. fis. 8 & Savini 1.997;Pinard & Mamet 1998; Groves & Board- Prcblematicilm een. 1 lPl.5. iìc. 10. 13 15) 2001a, b. ElÌetnerella fl)sn iPl 5 ic | | man 1.999; Groves 2000; Vachard Er Krainer Tuhiphvtes sp. (Pl. 6. fis.'/) Additional references for the algospongia are presented Alsosponcia by Massa & Vachard 1979; Yachard 1980; Vachard & Eflugelíajohnsoní (Flùgel, i966) Vachard in Massa & Vachard, I 979 lPl. 3. fis.9. 17.37: Pl.5- fis. 20- 23-25: Pl. 6. fis. l3r Pl.7. fis. l7) Montenat 1981; Groves 1983; Vachard et al. 1989; for Clom.riltro.aîpnÒí,1p( rHomann l9T2lVachard lgROaPì 3 fis lVostocites: Groves 1983; Perret et aI. 1994 and for Epi- ( la,aîil"Ia,rlrnistralr Vdchard. lq80 lPl.8. lic mastopora by Pia 1937 and Kochansky 8. Herak 1960. nal Canyon and Laborcita Canyon yielded a fossil Fossil assemblages assemblage that in general corresponds with the Auernig Formation, Carnizza Formation and Lower Pseu- All determined fossils (algae, algal? microprob- doschwagerina Limestone'of the Carnic Alps (Vachard lematica, algospongia and smaller foraminifers) are list- Krainer 2A01a, i.e., Orenburgian/early ed in Tables 1-4 with references to the figures on the & b), to the Asselian, the sensu Dar'ydov. The lower plates (Pl. 3-8). or "Bursumian" parts of these sections (especially levels LC 18 and FC Smaller foraminifers of the Holder Formation 24-25) are very similar to the Auernig Formation of the (Virgilian) indicate a Gzhelian age. In Yucca Mound at Dry Canyon, a small association contains elements known from the latest Moscovian/ early Kasimovian: 1950, (?) ìì Brwnsiella cf. densa Reitlinger, Glomospiroides a >.1 E a sp. (= ?Plwmmerinella), hemtgordiopsiid indet., and Table 2: \t> ! ! Syzrania pulchra Kireeva, 1958. At Laborcita Canyon, c Smaller foraminifers c the Holder Formation contains at its top the character- Eaîilherítina reitltilgerdc (Mikhluklo Maclay. 1958) istic fossil Pseudovidalina sp. (= Raphconilia sp.), a aPl I fis I lR 27 30 ill Eorlohdio sn (Pl 1 11Ì 1q Pl N fio 11 ?71 genus that appears in the Gzhelian (Groves 1,997, fig. 1; q5lììll'l I 1io lq P 4 tio 41 44\ Groves tr Wahlman 1997, fig.4-5). A Gzhelian age is Endothfrc exgr. bownari Phillips, 1846 emend. Brady. 1876 con- (énc" ahinr lq65 lPl 4 ffo ìl tsl also confirmed by unpublished fusulinids and Endothrrd ex gt. prisca Rauzer Chemousova & Reitlinger odonts (Wahlman, written comm.). inRauzer-Chemousovaetal.. l936lPl.3.fis ll: Pl 4 fis 24 Limestones in the Scorpion Mound, intercalated Lndothvanelu exs n;nun (WdLers. l9)7, {Pl h fiJ | ì Endothrranelh so rPì :l fiq :l5r in the Laborcita Formation northeast of Tularosa, con- Brd.llina coùpressa Morozova, 19,19 l= ?,8. (l) arcticd Pìnard & Mamet, rooeì rDr < tain 1,,{ostocites z,esicwlosa Maslov, 1929, a charophyte Bradyina lucrla Morozova. 1949 (Pl. 3. fis. 14.20. 26. 31: Pl. 4. fie. 521 Rradrina sD. (P1.3. fis.34) gyrogonite, Eflwgelia johnsoni (Flùgel, 1966) Vachard in Globivalrulina bulloides lBradv. t876). lP1. 7. fis. 3. 9. 15. 19. 22) GIabiyull ulina sD. lPl. 3. fie. l6) Massa Er Vachard, 1979; Eotwberitina reitlingerae Glabìwlrulína spp. (Pl. 6, fi9. 18. 22-23,28-29, 32: I Pl. E- fis. Ì-2. l l-12. 15-161 (Mikhlukho-Maclay, 1958), Quasilitwotuba (?) sp., Ptlaeotertulatia.o {Pl I fip llr PI 8 fio )a) geyeri (Schwellien, (= Endothyra ex gr. prisca Rauzer-Chernousova Ea Deckerclld 1898) D. laheeí Cushman & Waters. 1928 scnsu Vachard & Krainer 2001 al rPl 3 fie I 6 ??-?4ì Reitlinger in Rauzer-Chernousova et al., 1936, Tctratarir sn lPl I fip 20ì l?lrotaxt. \bn lPl I Trc lA Pl Vert,illeina cf. bradyi (Spandel, 1,901), Nodosinelloides PÒlvtdrir lohppi C,r(hm^n & Wàtè^ lg?8 lPl 4 fio I l7 ?t c[. aequiampla (Zo\otova in Zolotova & Baryshnikov, PseudovidaLìna spp. (PI 4, fi9.5-10, 19-20,23,26-28. 131-33. 36 39. 41.45 47. 58. Pl. 5. fis. 28Ì 1980), N. cf. longissima (Suleimanov, 1949), and N. &a//./1a sD. lPl- 6. fic. lil Pseudorcichelina ex n lano.tùtt lT.even 1970\ lPl 7 fiq ?l 40ì nets cbaj ew i (Cherdyntse v, 1.9 1. 4) . Eotchuhertella sD lPl 5 fip 27ì Limestones in the Laborcita Formation at Fres- Sîhubeilelld sp. lPi. 5, fic. 33) Microfacies and microfossils from South Central Nert, Mexico t9 Carnic Alps, with Pseudovidalinll spp. and lt{odosinel- FF Ioides potíez,skayae. "i. Table 3: :u The Fresnal Canyon section yields Antbracoporel- la spectabilis Pia, 1.920, Ewgonophyllwm, Litostroma (?) Smaller Foraminifers Flt Miliolida Blj ,te ''Chnattra .p.(Pl sp., Claracrusta catenoides (Homann, 1972) Vachard, J.fiB.2c,P 4.tìq )t.Pt 5.te I a 'Clùn,aptra" stp. \.Pl 7, fg 24, :7, 30, l8) 1980, Eflugelia johnsoni (Flùgel, 1966) Massa 8c Vachard, rafnùsptrd so (rl. ). !e. ly) B,utt't tto cl d, a, / Rciriinger. lq)0 LPI ì. tig rl 1.979, Eotuberitina reitlingerae (Mikhlukho-Mac1ay, nP4lRo.dtu\ ha4toil; r-.r.hm.n & warers. l9_28 rPl.5 fiÈ t0l H.'ntgo,dtut sî\tunberr,', (Ho$rÈin. l805)(Pl. b. fie. l 1958) , Spireitlina conspeoa (Reitlinger, 1950) , End.othyra nentgurdLus sp. J (Pl 6, îre. 26) nènLgordlu\ sp.4 (P J, !a. J4) sp., Endothyranella sp., Bradyina lucid.a Morozova, nemtgtrùtils ( l ip ) (8t. E, îre j-b) hemr{ordropsrid uìdet. (Pl..j. fip. )l 1.949, Bradyina sp., Tbtrataxis spp., Polytaxis laheei ( rl, in'ilrtta,p rpt <. ìg. tt^. et.ffi Lùt,tvettct!a (sensu sh cro) sD (Pl. 7. fic. 2 | Cushman & Waters, 1928, Globivalaulina sp., Palaeotex- tularia sp., Deckerella A,nmareùella (= C-d1ctr€flrla ) sp. lPt. 4, fiq. I ll geyeri (Schellwien, 1898) (: D. rstilù,i\?rmtpùreua sp. | (pL O, rU.1l-12) laheei Cushman & 1928 Vaters, sensu Vachard & Krain- fseuJol emiputelt4 sA ) (Pl. 8. f)p. 1,8\ er, 2001a), Pseudovidalina spp., Ammo,uertella inz,ersa t\'ta, a\h"Ptulati0 Iurr Reitìineer. lo.0.P. 1, liC. l2l \tua.,t,tuotuba {'ì \p. /Pì l. lld -: ll.4. fig ìsl (Schellwien, 1898), A. sp., Palaeonwbecwlaria otùra,pil 'LtL\ \:),a ( Plùnn"tttîlla)lpl J.]ip. I flwxa ) sp. (Pl. 6, fis. 34) Reitlinger, 195O, "Glomospira" sp., Syzrania spp., N o d o s in e I I o i d e s n ets ch aj eu i (Cher dynts ev, 1 9 1 4), and 11. af[. potievskayae Mamet & Pinard, 1996. ronda (Lipina, 1949), Geinitzina postcarbonica Span- 1901, The Laborcira Canyon secrion yields PsewdoEi- del, and Langella (?) cf. minima Baryshnikov in Zolotova Baryshnikov, 1980. mastoPoftr sp., Paraepimastopora ex gr. kansasensis (lohn- & son, 1946) Roux, 1989, Spireitlina conspecttt (Reitlinger, The Robledo Mountains Formation of section C contains: EJlugelia johnsoni 1950), Quasilituotwba (?) rp., Endothyra ex gr. boramani (Flùgel, 1966) Massa & Vachard, 1979, Phillips, 1846 emend. Brady, 1826 sensu China, 1965, E. Earlandia sp., Globiaalz,ulina bwlloides ex gr. prisca Ratzer-Chernousova & Reitlinger in (Brady, 1876), Pseudoreichelina ex gr. darvasica (Leven, 197A), Ammooertella inaersa (Schellwien, 1898), "Glo- Rauzer-Chernous ova et aI., 19 3 6, B rady in a lw c i da Mor o - mospiratt spp., zova, 1949, Polytaxìs laheei Cushman & Vaters, 1928, llodosinelloides potie,uskayae Mamet 8r Pinard, 1.996, Geinitzina postcarbonica PseudorLidalina spp., "Glomospira" sp., Syzrania spp., Spandel, 1901, G. (?) rp., and Fronclicularia (?) spp. Protonodosaria praecwrsor (Rauzer-Chernousova, 1 949) , The uppermosr parr of the Robledo Mountains N o d o s in e I I o i d e s n ets ch aj eu i (Cher dy nts ev, 1 9 1 4), and l/. potievsbayae Mamet 8t Pinard, 1.996. Formation and lower Apache Dam Formation (section Small oncoids of the the Shalem Colony Forma- B) yield: Ortonella sp. 2, O. sp. 3, lrleoanchicodium tion at Robledo Peak are principally composed of caten o i d e s Endo, 1 9 5 4, C lara crw sta calam i strata Va chard, Ellesmerella (?) rp., Ortonella sp. I, Epimastopora alpina 1.98A, Earlandia sp., Palaeotextularia sp., Tbtrataxis sp., (Kochansky-Devidé & Herak, 1960), E. sp., dasycladale Globiaaalowlina spp., Psewdovermiporella sp. 3, Hemigordius indet., l,{ostocites oesiculosa Maslov, 1929, Eflugelia john- (?) sp. 5, Syzrania sp., Tezaqwina aff. cliowli sozi (Flúgel, 1966) Massa & Vachard, 1979, Tubipbytes sp., Problemdticum gen. 1, Spireitlina cf. rclemor,,ensis t-l, ì- , (Reitlingea 196l), Endothyranella ex gr. minuta (Waters, Table lù :: 4: l( t- :l; 1927), Bradyina compressaMorozova, 0 1,949 l: ? B. (?) Smaller foraminifers 01 ti arctica Pinard & Mamet, 1,998f , Eoschwbertella sp., Scbw- Lagenida íq Sran,u nintna Srepano\r, lqaT tPl. o. fi: 4) bertella sp., Pseudovidalina sp., Cornuspira sp., "Glomo- ,zranta put, hra Krree\d. la5E (Pl. l. lle.4l J)zranta \p (Pl. E. tie 28) spira" sp., Hemigordiws barboni Cushman 8c Warers, ryzldald spp. (P1.3, fig.2ì,33; PÌ.4, fie. 14, 16,34) 1928, H. schlwmbergerl S\zraniid inder. lPl.8- fis. l8ì (Howchin, 1895), Calcitornella T":aqt,nr , lit uli \ dchard In Vacnard toE rìc "fl. & Monlen"r. I r Pl. !. 25 r sp., Syzrania minima Stepanova, 1997, Veroilleina sp. 2, fenilleind sp. 2 (Pl. 5. frp. 2 l lcnilleina sa I lPl.8. fis.2l N o do s in e ll o i d.e s n e ts ch aj ero i (Cher dynts ev, 1 9 1 4), and N. l\aaostneilotdes netschdl€u (Uherdyntsev, l9l4) (Pl.3, fig. l2; potieoskayae Mamet k Pinard, 1.996. Pl. 4, fì9. 3, 40, 49-50, 55; Pt. 5, fi9. t; pt. 6, fig. 9-10) Nodosulelloides potiersfta.Ìrde Mamet & Pinard, 1996 p1. The Robledo Mountains Formarion (section A) (P1.,4, fiS. 4, 29, 43, 48, 5 1, 51, 57?. 58: 5, fig. 4-6, 9?, 3 1; yields Neoanchicodiwm Pl.6, fig. 19-20; Pl.7, fie. 1.1,26.28.31-33.35.37r pl. 8. fiq. t7 catenoides Endo, 1954, Pseu- Notlosinelloides cf. aequtunplú (Zolotova in Zolotova & Baryshnjkov, 1980) doepimastopora sp., Gyroporella sp., cf. (Pl. l. fie. t0) Mizzia cornuta rouost4.ltntde\ cr. langt$tna (5-tc,man0v! tq4u) (pt. J, lts. J) yad.,ti^ landa ( a4q) -. Kochansky-Devidé & Herak, 1960, Eflwgelia johnsoni llrtdc\ "ll. rprna, . tp lìq. 5) t\ùdosLneilotde\ sp. (PL. u, hg. q) (Flùgel, 1966) Massa & Vachard, 1979, Globipalawlina t rot.noh:ana rry.rtlr.o/ (RdJrer.-hemúuso\a. 1949) apl.4. na 54 5hl Langela (?) cf. mínind Baryshnikov in Zolotova & Baryshnikov, 1980 bulloid.es (Brady, 1876), G. spp., Staffella sp., (Pl.7, fig. 8, 13) úeLnnztna pastcarbontcd Spandel, l9ul Ammooertella inversa (Schellwien, 1898), Calcivertella (Pl. 6, fts. 14-1'7.25.27r Pl. 7. fie. 4. 6. 34. t6. 39) (sensu Geiniîzina sp. I (Pl. E. fie. 10) stricto) sp., Psewdovermiporella sp. 1, P sp. 2, ceinit:ina fi.2 (Pl. 8. fis. 14) Hemigord.ius sp. 3, H. sp. Neodiscws sp., 6eta:t,tno t: t'p. \Pl'. îtp. 25) 4, (?) Frondicularia (?) spp. (Pl. 7. fis. 16. 20-21) Nodosinelloides potievskayae Mamet & Pinard, 1996, N. Iltchrphtoia sp. (t,l 8 Ug. 26) 20 K. Krainer D. Vachard & S. G. Lucas PLATE 3 Microfossils from Yucca Mound (Holder Formation), Scorpion Mound and Fresnal Canyon (Laborcita Formation) (New Mexico). For the position of thc samplcs FC lFresnal Canyon) ìn the scction see Fig. 5. Fig. 1 - GLomospiroides (?) sp. Subaxial section. Yucca Mound. Holder Forn-ration. Virgilian (Gzhelian). SampleY 1. x 78. Fìg. 2 - Hemigordiid indet. Oblique section. Yucca Mound. Holder Fonnation. Virgilian (Gzhelian). Samplc Y 3. x 28. Fig. 3 - Brunsiella cf. densa Reitlinger, 1950. Subaxial section. Yucca Mound. Holder Formation. Virgilian (Gzhelian). Samplc Y 3. x 28. Fig. a - Syzrania pulchra Kireeva, 1958. Axial section. Yucca Mound. Holder Formation. Vìrgiìian (Gzhelian). Sample Y 3. x 78. Fig.5 - NodosinelJoides cÍ. longissima (Suleimanor', 1949). Longitudinal sectìon. Scorpion Mound. Laborcita Formation. Early \lolf- campian (Orenburgian). Sample SM. x 78. Fig. 6 - Vert,illeina cÍ. bradyi (Spandel, l901). Scorpion Mound. Laborcita Formation. Early \Wolfcampian (Orenburgian). Sample SM. x 78. Fig. Z - Quasílitwotwba (?) sp. Scorpion Mound. Laborcita Formation. Early Volfcampian (Orcnburgian). Sample SM. x 78. Fig. 8, 18, 27,3A - Eotuberitina reìtlingerae (Mikhlukho-Maclay, 1958). Four axial sections. Laborcìte Formation. Early Wolfcampian (Oren- burgian). Fig.8 - Scorpion Mound Sample SM. x 78. Fig. 18,27,30 - Fresnal Canyon. Fig. 18 - Sample FC 6. x 28. Fig.2/ - Sam- ple FC 12. x 32. Fig. 30 - Sample FC 13. x 78. Frg.9,17,37 - Eflwgelia johnsoni (Flltgel,1966) Massa & Vachard, 1979.Fig.9 - Longitudinal broken section. Scorpion Mound. Laborcita For- mation. Early\ffolfcampian (Orenburgian/Asselian). Sample SM 1. x 32. Fig. 1/ - Longitudinal scction partly filled with micrite (compare with Fig. 9). Fresnal Canyon. Laborcìta Formation. Early'Wolfcampian (Orenburgian). Sample FC 3. x 78. Fig.37 - Longitud:inal secrion. This type of preservation partly fìlled (comp:rre wìth Fig. 9, 17). Fresnal Canyon. Laborcita Formation. Early Iil/olfcampian (Orenburgian). Samplc FC 15. x 78. Fig. 1O - Nodosinelloides cÍ. aequiampla (Zolorova in Zolotova Ee Baryshnikov, 1980). Longitudinal sectìon. Scorpìon Mound. Laborcrta Formation. Early rVolfcampian (Orenburgian). Sample SM. x 1'{0. Fig. 1 1 - Endothyra ex gr. prisca Rauzer-Chernousova & Reitlinger in Rauzer Chernousova et al., 1936. Axial section. Scorpion Mound. Laborcita Formation. Early \X/olfcampian (Orenburgian). Samplc SM. x 78. Fig. 12 - Nodosìnelloides netscbajeui (Cherdyntsev, 191.1). Longitudinal section. Scorpion Mound'.Laborcita Formatìon. Early Volf- campian (Orenburgian). Sample SM. x /8. Fig. 13 - Nostocites resicwlosa Maslov, 1929. Scorpion Mound. Laborcita Form;rtion. Early Wolfcampian (Orenburgìan). Samplc SM 1. r 78. l'ig. 1a, 20, 26,31 - Bradyina lucidaMorozova,7949. Fresnal Canyon. Laborcita Formation. Early \flolfcampian (Orenburgian). x 32. Fig. 1'l - Subaxial section. Sample FCl. Fig. 2O - Subtransverse section. Sample FC 7.Fig.26 - tansverse section. Sample FC 1. Fig. 31 - Transverse section (right) with various sections of Palaeotextularla sp. (left), Eotwberitina and Ewgonophyl/zn (center). Sample FC 13. Fig. 15 - Ammor-,ertella inversa (Scbellwien, 1898). Sublongitudinal section. Fresnal Canyon. Laborcita Formation. Early \Volfcampi:r (Orcnburgian). Sample FC 6. x 32. Fig. 16,22-21 - Deckerella ge;r,erl (Schcllwien, i898) (: D. laheei Cushman & \il/atcrs, 1928 sensu Vachard & Krainer,20O1a). Fresnal Canyon. Laborcita Formation. EarlyrVolfcampian (Orenburgian). x 32. Fig. 16 - Oblique section. Sample FC7. Fig.22 - Subaxial section. Sample FC 10. Fig. 23 - Subaxial sectìon. Sample FC 7.Frg.24 - Axial section. Sample FC 12. Fig. 19 - Spireitlina conspecta (Reitlinger, 1950). Transverse section. Fresnal Canyon. Laborcita Formation. Early \Wolfcampian (Orenbur- gìan). Sample FC 6. x 28. Fig. 21, 33 - Syzrania spp. Th'o subaxial sections. Fresnal Canyon. Laborcita Formation. Early lVolfcampian (Orenburgian). Fìg. 2l- Srmple FC 1, xZ8. Fig.33 - Sample FC 14. x140. Fig.25 - Litostroma (?) sp. Longitudinal scction incrusted by a tolypamminid (l). Fresnal Canyon. Laborcita Formation. Early \il/olf- campian (Orenburgian). Sample FC 10. x 32. -Wolfcampian Fig.28 - Anthracoporella spectabilis Pia, ú2a. Transverse section. Fresnal Canyon. Laborcita Formation. Early (Orenbur- gian). Sample FC 11. x 15. Fig.29 - "Glomospira" sp. Subaxial section. Fresnal Canyon. Laborcita Formation. Early Wolfcampian (Orenburgian). Sample FC 12. x78. Fìg.32 - CLaracrusta catenoides (Homann, 1972)Yachard, 1980. Longitudinal section. Fresnal Canyon. Laborcita Formation. EarlyrWolf- campian (Orenburgian). Sample FC 13. x32. Fig. 34 - Bradyina sp. Subaxial section. Fresnal Canyon. Laborcita Formation. Early \Wolfcampian (Orcnburgian). Sample FC 13. x 15. Fig. 35 - Endothyranella sp. Subaxial section. Fresnal Canyon. Laborcìta Formation. Early Volfcampian (Orenburgian). Sample FC 14. x /8. Fig. 36 - Globixalt,wlina sp. Subaxial section. Fresnal Canyon. Laborcita Formation. Early Volfcampian (Orenburgìan). Sample FC 14. x 78. Fig.38 - Tetraaxis sp. Axial section ìn life position. Fresnal Canyon. Laborcita Formation. Early\Wolfcampian (Orenburgian). Sample FC 15. x 28. Pì. 3 Microfacìes and. mícrofossils from South-Central Neu^ Mexico z1 /\"/-4, ffi' JHù w. -ft s,, tJt\ 22 K. Krainer, D. Vachard & S. G. Lucas PLATE 4 Fossil assemblages of the Laborcìta Formation at Fresnal Canyon (continued) and Laborcita Canyon (New Mexico). For position of the sam- ples in the sections see Fig. 4 (Laborcita Canyon, samples LC) and Fig. 5 (Fresnal Canyon, samples FC). -Frg. i, 17, 22 - PoLytaxis laheeì Ctshman &'Waters, 1928. Three subaxial sections. Laborcita Formation. Early \folfcampian (Orenburgian). x 32. Fig. 1 - Fresnal Canyon. Sample FC 22. Fig. 17 - Encrusting a Psewdoepimastopora rha,Ilùs. Laborcita Canyon. Sample LC 2. Fig. ' 22 - Laborcita Canyon. Sample LC 9. Frg.2 - Tbtrataxis sp. Subaxial section. Fresnal Canyon. Laborcita Formation. Early \folfcampian (Orenburgian). Sample FC 22. x 32. Fig. 3, 40, 49-5A,55 - Nodosinelloides netscbajeui (Cherdyntsev, 1914). Five longitudinal sections. Laborcita Formation. Early \flolfcampran (Orenburgian). x 78. Fig. J - Fresnal Canyon. Sample FC 18. Fig.40, 49-5A,55 - Laborcita Canyon. Fig.40 - Sample LC 18. Fig. 49-50 - Sample LC 44. Fig. 55 - LC 43. Fig. 4, 29,43, 48, 51, 53, 571 - Nod.osinelloid.es potieoskayae Mamet Er Prnard, 7996. Seven longitudinal sections. Laborcita Formation. Early \Wolfcampìan (Orenburgian). x 28. Fig. 4 - Fresnal Canyon. Sample FC 19.Fig.29, 43,48,51,53,57? - Laborcita Canyon. Fig. 29 - Sample LC 15. Fig. 44,48,53 - Sample LC 18. Fig.51 - LC 19.Ftg.57? -LC44. Fig. 5-10, 19-2A, n,26-28,31-33,36-39,41.,45-17,58 - Psewdovid.altna spp. for several morphotypes of P recta (Pottevskaya, 1962)]. Twenty six axial and subaxial sections. Laborcita Formation. Early Sfolfcampian (Orenburgian). x 28. Fig. 5-10 - Fresnal Canyon; the other ones: Laborcita Canyon. Fig. 5 - Sampìe FC 15. Fig.6 - Sample FC 20. Fig. 7-8 - Sample FC 22. Fig.9 - Sample FC 24. Fig. 10 - Sample FC 25.Laborcita Canyon: Fig. 19 - Sample LC 4.Ftg.20 - Sample LC 8. Fig.23 - Sample LC 9. Fig.26-27 - Sample LC 10. Fig. 28 - Sample LC 13. Fig. 31-33, 36-39, 41, 45-47,58 - Sample LC 18. Fig. 58 shows the characteristic association of Pseudoti- d.alina recta wirh Nod.osinelloides potier.'skayae, specimen also reproduced in Fig. 48. Fig. 11 - Ammotertella (= Calcioertella) sp. Sublongitudinal section. Fresnal Canyon. Laborcita Formation. Early \Wolfcampian (Orenbur- gian). Sample FC 27 . x 78. Fig. 12 - Palaeonubecularia fluxa Reitlinger, 1950. Transverse sections of tubules encrusting a bivalve shell. Fresnal Canyon. Laborcita For- mation. Early\folfcampian (Orenburgian). Sample FC 24. x 32. Fig. 13 - Litostroma (?) sp. Longitudinal section. Fresnal Canyon. Laborcìta Formation. Early Wolfcampian (Orenburgian). Sample FC 22. x )l- Ftg. 14, "16, 34 - Syzrania spp. Laborcita Formation. Early lVolfcampian (Orenburgian). Three subaxial sections. Fig. 14 - Fresnal Canyon. Sam- ple FC 19. x /8. Fig. 16,34. Laborcita Canyon. Fig. i6 - Sample LC 2. x /8. Fig.34 - Sample LC 18. x 32. Fig. 15 - Charophyte gyrogonite. Sublongitudinal section. Fresnal Canyon. Laborcita Formation. Early \Wolfcampian (Orenburgian). Sam- ple FC 31. x 28. Fig. 18,25 - Endotbyra ex gr. bozumani Phillips, 1846 emend. Brady 18/6 sensu China, 1965. Laborcita Canyon. Laborcita Formation. Earlv \ffolfcampian (Orenburgìan). x 32. Frg. l8 - Transverse section. Sample LC 3. Fig.25 - Axial section. Sample LC 9. Ftg. 21 - "Glomospira" sp. Subaxial section. Laborcita Canyon. Laborcita Formatìon. Early lVolfcampian (Orenburgian). Sample LC 9. x 32. Fig. 24 - Endotbyra ex gr. prisca Rauzer-Chernousova t{ Reitlinger in Rauzer-Chernousova et al., 7936. Axial section. Laborcita Canyon. Laborcita Formation. Early \folfcampian (Orenburgian). Sample LC 9. x 28. Fig.30 - Paraepimastopora ex gr. kansasensis (Johnson, 1946) Roux, 1989. Longitudìnal section. Laborcita Canyon. Laborcita Formation. Early \Wolfcampian (Orenburgian). Sample LC 15. x 15. Fig. 35 - Quasilituotwba (?) sp. - Subaxial section. Laborcita Canyon. Laborcita Formation. Early \flolfcampian (Orenburgian). Sample LC 77. x 32. \Wolfcampian Fig. 42, 44 - Spireitlina conspecta (Reitlinger, 1950) . Laborcita Canyon. Laborcita Formation. Early (Orenburgian) . Sample LC 1 8. x 78. Fig.42 - Tranverse oblique section.Fig.44 - Subtransverse section. Fig. 52 - Bradyina lwcida Morozova, 1.949. Subaxial section. Laborcita Canyon. Laborcita Formation. Early \il/olfcampian (Orenburgian.l. Sample LC 18. x 32. Fìg. 54,56 - Protonodosarid prdecursor (Rauzer-Chernousova, 1949). Two subaxial sections. Laborcita Canyon. Laborcita Formation. Earìv lVolfcampian (Orenburgian). Sample LC 44. x 78. Microfacies and microfossik from South-Central New Mexico ZJ H?=;$ffi* $* à.!t ffi-' s 6 z LB YS s 10 a',t9 w* K ffi$ 6% #* W 'ff; i:'='r, lg 4ò &ru $s z"J ffi K!r, 2s ryffi K,'. W..$6 *' 35úi' 36 , 33 w^- 'ro 37 .&ffi vffiwm,44% $ Y*' *i 419trffi,4s*ffiff -; No' W Y, É*r /-\ffi : Wq't. t'*,q- 11 K. Krainer, D. Vachard ù S. G. Lucas PLATE 5 Fossil assemblages of the Shalem Colonl' Formation (Hueco Group) at Robledo Peak (New Mexico). For the position of the samples in the sec- tion see Fig. 3. Fig. 1 - Nodosinelloides netschajeui (Cherdyntsev, 1914). Longitudinal section. Robledo Mountains. Shalem Colony Formation. Early-mid- ' dle rWolfcampian (Orenburgìan/Asselian). Sample RM 5. x 78. Fig. 2 - Wrvilleina sp. 2. Sublongitudinal section. Robledo Mountains. Shalem Colony l'ormation. Early-middle \Wolfcampian (Orenbur- gian/Asselian). Sample RM 6. x 78. Fig. 3 - Nostocites resiculosa Maslov, 1929. Sublongitudìnal section. Robledo Mountains. Shalem Colony Formation. Early-middle Wolf- campian (Orenburgian/Asselian). Sample RM 6. x 32. Fig. 4-6, 9?,31 - Nodosinelloides potierLskayaeMamet & Pinard, 1996. Four longitudinal sectìons. Robledo Mountains. Shalem Colony Formation. Early-middle \Wolfcampian (Orenburgian/Asselian). x 28. Fig. 4 - Sample RM Z. Fig. 5-6 -Sample RM 8. Fig. 9? - Sample RM 14. Fig. 31 - Sample RM 31. Fig. /-8' 10,17,19 - Epimastopora alpina (Kochansky Er Herak, 1960) sensu Kulik, 19l8. Several sublongitudinal sections. Robledo Mountains. lVolfcampian Shalem Colony Formatìon. Early-middle (Orenburgian/Asselian). Fig. Z-8 - Sample RM 9. x 15. Fig. 1O - Sample RM 13 (bottom) with"Problematicwm gen. 1" (top). x 32. Fig. 17 - Sample RM 15. r 32. Fig. 19 - Sample RM 23. x 78. Fig. 11 - Oncoid ol ElLesmerella (?) tp. (: "Osagia" sensu lato). Longitudinal section. Robledo Mountains. Shalem Colony Formation. Early- middle lil/olfcampian (Orenburgian/Asselian). Sample RM 11. x 32. Fig. 12 - Calcitornella (?) sp. Subtransyerse section. Robledo Mountaìns. Shalem Colony Formation. Early-middle $folfcampian (Orenbur- gian/Asselian). Sample RM 9. x 32. Fio I ì-l6 - D.^hl.-'tì.i.n gen. 1. Various sections of an encrusting carbonate microproblematicum. Robledo Mountains. Shalem Colony For- mation. Early-middle \flolfcampian (Orenburgian/Asselian) . Sample RM 14. x 32. Fig. 16' 21. - Spireitlina cf. tohmotensis (Reitlinger, 1961). Two axial oblique sections. Robledo Mountains. Shalem Colony Formation. Early-mìd- dle \ilolfcampian (Orenburgian/Asselian). x 32. Fig. 16 - Sample RM 19. Fig. 21 - Sample RM 25. F'ig. 18 - Ortonella sp. 1. Longitudinal section. Robledo Mountains. Shalem Colony Formation. Early-middle $folfcampian (Orenbur- gianlAsselian). Sample RM 16. x 15. Fig. 20,23-25 - Eflwgelia jobnsozl (Flùgel, 1966) Massa & Vachard, i9l9. Robledo Mountains. Shalem Colony Formation. Early-middle lVolf- campian (Orenburgian/ Asselian). Fig.20 - Oblique section convergingwith Fourstonella or Sacheia. Sample RM 23.x78. Fig.23- 25 - Three oblique sections. Sample RM 25. r 32. Fig.22 - "Glomospira" sp. or young Palaeonubecularia sp. Sublongitudinal section. Robledo Mountains. Shalem Colony Formation. Early- middle \folfcampian (Orenburgian/Asselian). Sample RM 24. x 32. Fig.26 - Dasyclad indet. Longitudinal section. Robledo Mountains. Shalem Colony Formation. Early-middle Wolfcampian (Orenbur- gian/Asselìan). Sample RM 25.x32. Fig.27 - Eoschubertella sp. Axial section. Robledo Mountains. Shalem Colony l'ormation. Early-middle \Wolfcampian (Orenburgian/Asselian). Sample RM 28. x78. Fig. 28 - Pseudovidalina sp. Subaxìrl section. Robledo Mountains. Shalem Colony Formation. Early-middle rVolfcampran (Orenburgian/Asselian). Sample RM 29. x 78. Fìg.29 - Cornuspira sp. Transverse section. Roblcdo Mountains. Shalem Colony Formation. Early-middle \folfcampran (Orenburgian/Asselian). Sample RM 31. x 78. Fìg. 30 - Hemígordius harltoni Cushman & \laters, 1928. Subaxial section. Robledo Mountains. Shalem Colony Formatìon. Early-middle '$Tolfcampian (Orenburgian/ Asselian). Samplc RM JI. x78. Fig.32 - Brad.yina compressa Morozova, 1949 l: I B (7'1 arctica Pinard and Mamet, 1998]. Axial section. Robledo Mountains. Shalem Colony -Wolfcampian Formation. Early-middle (Orenburgian/Asselìan). Sample RM 28. x32. Fig. 33 - Scbubertella sp. Subaxial section. Robledo Mountains. Shalem Colony Formation. Early-middle \Wolfcampìan (Orenburgian/Asselian). Sample RM 28. x 78. Fig. 34 - Epìmastopora sp. Longitudinal section. Robledo Mountains. Shalem Colony Formation. Early-middle 1ùfolfcampian (Orenbur- gian/Asselian). Sample RM 28. x 15. Pl. 5 Microfacies and 25 $ry&i{liì tr 1$&j 'ski f"{fi\ 3n!l : *,\ i{rt..,w, ?i 't4# w x:pl !":'..i.. & w 28. @. 16 K. Krainer, D. Vacbard & S. G. Lucas PLATE o Fossil assemblages of the Shalem Colony Formation (samples RM, see Fig. 3) at Robledo Peak (continued) and the Robledo Mountaìns Forma- tion (samples A from Section A of Krainer & Lucas 1995), Hueco Group (New Mexico). Fig. 1 - Endothyranella ex sr. minuta (\il/aters, 1927). Axral sectìon. Robledo Mountains. Shalem Colony Formation. Early-middle \Wolf- campian (Orenburgian/ Asselian). Sample RM 31. x 78. Fig.2,6 - Bradyina comPressa Morozor.a, 1949. Two complementary sections. Robledo Mountains. Shalem Colony Formation. Early-middle 'Wolfcampian (Orenburgian/Asselìan). x 32. Fìg. 2 - Subtrrnsversc secrjon. Sample RM 21. Fig.6 - Axial section. Sample RM 46. Fig.3 - Hemigordius schlwmbergeri (Howchin, 1895). Axial section. Robledo Mountains. Shalem Colony Formation. Early-mìddle 1X/olf- campian (Orenburgian/ Asselian). Sample RM 37. x 78. Fig. 4 - Syzrania minima Stepanova, 1997. Axial section. Robledo Mountains. Shalem Colony Formation. Early-middle Wolfcampian (Oren- burgian/Asselian). Sample RM 44. x 140. Fig. 5 - Calcitornella sp. Axial section. Robledo Mountains. Shalem Colony Formation. Early-mìddle \folfcampian (Orenburgìan/Asselian). Sample RM 37. x 32. Fig.7 - Tubiphytes sp., Ì/hose morphology is intermediate between tolypamminìd foraminifers and "true" Tubìpbytes. Subaxial secrion. Rob- ledo Mountains. Shalem Colony Formation. Earlv-middle rVolfcampian (Orenburgian/Asselìan). Sample RM 35. x 32. Fig. 8 - Hinge of a kirkbyid ostracod (,not Nostocites rLesiculosa). Tangential secrion. Robledo Mountains. Shalem Colony Formation. Early- middle \flolfcampian (Orenburgian/Asselian). Sample RM 47. x78. Fig. 9-10 - Nodosinelloides netschajeu,i (Cherdyntser', 1914).Two longitudinal sections. Robledo Mountains. Shalem Colony Formation. Early- middle lVolfcampian (Orenburgian/Asselian). Sample RM ,18. x 78. Fig. 11-1.2 - Psewdooermiporella sp.1 (by its deep pits this species differs from Hedraìtes). Robledo Mountains (Section A). Robledo Mountaìns Formation. Volfcampian (Sakmarian). x 28. Fig. 11 - Atypical section, maybe À,lendipsia. Sample A 6c.Fig. 12 -'Iypical oblique sec- tìon. Sample A 6e. Fig. 13 - EJlwgelia johnsozi (Flùgel, 1966) Massa & Vachard, 1919. Oblìque section filled with micrite. Robledo Mountains (Section A). Rob- ledo Mountains Formation. Volfcampian (Sakmarian). Sample A 8c x 78. Fig. 14-12, 25,27 - Geinitzinapostcarbonica Spandel, 1901. Robledo Mountains (Section A). Robledo Mountains !'ormation. \folfcampian (Sak- marian). x /8. Fig. 14 -16 - Three sagittal sections. Sample A 8d. Fìg. 1Z - Frontal typical section. Sample A 8d. Fig. 25 - Sagittal sec- tion. Sample A 9. Fig. 27 - Oblique secrion. Sample A 9. Fìg. 18,22-23,28-29,32 - Globroabulina spp. Roblcdo Mountains (Section A). Robledo Mountains l-ormation. lVolfcampian (Sakmarian). Fig. 1 8 - Subaxial section. Sample A 8e. x 32. Fìg. 22 - Subtransverse section. Sample A 9. x 78. Fig. 23, 28-29 - Three subtransverse sec- tions. Sample A 9. x 32. Fig. 32 - Subaxial section. Sample A 12. x 78. Fig. 19-20 - Nodosinelloides Potietskayde Mamet & Pinard, 1996. Two axial scctions. Roblcdo Mountains (Section A). Robledo Mountains For- matìon. \lolfcampian (Sakmarian). Sample A 9. x 78. Fig.21 - PseudoepìmastoPord sp. Longitudinal sectìon. Robledo Mountaìns (Section A). Robledo Mountains Formatìon. Wolfcampian (Sak- marian). Sample A 9. x 32. Fig.24 - Neodiscus (?) sp. Axial section. Robledo Mountains (Section A). Robledo Mountains Fornation. Y/olfcampian (Sakmarian). Sam- pleA9.x32. Fig. 26 - Hemigordius sp. 3. Axial section. Robledo Mountains (Section A). Robledo Mountains Formation. lVolfcampian (Sakmarian). Sam- pleAg.x/8. Fig. 30 - Ammooertella inversa (Schellwien, 1898). Sublongitudinal section. Robledo Mountains (Section A). Robledo Mountains Formation. lVolfcampian (Sakmarian). Sample A L2. x 78. Fig. 31 - Neoancbícodium catenoides Endo, 1954. Various sections. Robledo Mountains (section A). Robledo Mountains Formatìon. 'Wolf- campian (Sakmarian). Sample A 9. r 32. Fig. 33 - Stffilla sp. Subaxial section. Robledo Mountains (Section A). Robledo Mountains Formation. \Wolfcampian (Sakmarian). Sample A 12. x 15. Fig.34 - Hemìgordius sp. 4. Subaxial sectìon. Robledo Mountains (Section A). Robledo Mountains Formation. $folfcampian (Sakmarian). Sample A 12.x78. Pl. 6 Microfacies and microfossils from South-Central New Mexico 27 ffi H. ffi ffi *-trj 'llil''' w v { .". :ry'i...' i.$.è* S'*i &r .,,...i },fr {&,,r j|-&l'l-15 #* w $$il r8 19 Tíf**n ,i""1: w ,,.:*'?:]" 23 i{.-".',",4 ::rt ,: 1!:'*:{ W6 '!,'::$ *.{ .r rì !.,. -i 1,1 25 dse", j f.,:"e .ai" fol'..ì, .'- ,. ' .$.,' .',:1 r . ,slx*t,*,., ,33 28 K. Krainer, D. Vacbard & S. G. Lucas PLATE 7 Fossil assemblages of the Robledo Mountains Formation (samples A refer to Section A and samples C to Section C of Krainer & Lucas 1995), Hueco Group (New Mexico). Frg. I, 7 - Pseudooermiporella sp.2. Robledo Mountains (Section A). Robledo Mountains Formation. Wolfcampian (Sakmarian). x 32. Fig. 1 - Axial-tangential scction. Sample A 12.Fìg.7 - Longitudinal scction with "innermost tubes". Sample A 13. Ftg.2 - Calcirertella (sensu stricto) sp. Robledo Mountaìns (Section A). Robledo Mountains Formatìon. \X/olfcan-rpian (Sakmar:ian). Sam- pleA12.x32. Fig. 3, 9, 15, 19,22 - Globioaloulina bulloides (Brady, 1sZ6). Robledo Mountains (Sections A and C). Robledo Mountains Formation. \folf- campian(Sakmarian/earlyArtinskian).x32.Fig.3-Transversesection.SampleAl3.Fig.g-Axial secrion.SampleAl,lc.Fig. 15- Transverse section. Sàmple A 14c. Fig. 19 - tansverse section. Sample C 19f. Fìg. 22 - Subtr"rnsverse secrion. Sample C 25. Fig.'1,6, 34,36,39 - Geinitzinapostcarbonica Spandel, 1901. Robledo Mountains (Sections A and C). Robledo Mountains Formation. -il/olf- campian(Sakmarian/earlyArtìnskian).x/8.Fìg.4-Frontalsection.SampleAll.Fig.6-Frontalsection.SampleAlS.Fig.3l- Sagittal section. Sample C 35b. Fig. 36, 39 - Two almost frontal secrions. Sample C 35c. Fig' 5 - Nodosínelloides afÍ. ronda (Lipina, 19a9). Subaxìal section. Robledo Mountains (Section A). Robledo Mountains Formation. \lolf- campian (Sakmarian). Sample A 13. x 78. Fig. 8, 13 - LangelLa (?) cf . minìma Baryshnikov in Zolotova tr Baryshnikov, 1980. Two axial sections. - Robledo Mountains (Section A). Rob- ledo Mountains Formation. Middle \Wolfcampian (Asselian/Sakmarian). x 78, Fig. 8 - Sample A 13, Fig. 13 - Sample A i4b. Fig. 10 - Mizzia cÎ. cornuta Kochansky-Devidé Er Herak, 1960. Transverse sectìon. Robledo Mountains (Section A). Robledo Mountains Formation. \folfcampian (Sakmarian). Sample A 14b. x 32. Fig. 11 - Gyroporella sp. Oblique section. Robledo Mountains (Section A). Robledo Mountains Formation. \Wolfcampian (Sakmarian). Sam- pleA14b.x32. Fig. 12 - Neoanchicodium catenoides Endo, 1954. Longitudinal section. Robledo Mountaìns (Section A). Robledo Mountains Formation. \Wolfcampian (Sakmarian). Sample A 1'fb. x 32. Frg. 14,26,28,31-33,35,37 - Nodosinelloides potìevskal,aeManet & Pinard, 1996. Nìne axial sections. Robledo Mountains (Sections A and C). Robledo Mountains Formation. \X/olfcampian (Sakmarian/earlv Artinskian). x 78. Fig. 14 - Sample A 14e. Fig. 26 - Sample C 29. Fig. 28,31-32 - Sample C 35a. Fig. 33, 35 - Sample C 35b. Fig. 37 - C 35c. Fig. 16,2a-21 - Frondicukria (?) spp. Three subaxial sections. Roblcdo Mountains (Sectìon C). Robledo Mountaìns Formation. \Wolfcampian (Sakmarian). x 28. Fig. 16 - Sample C 1. Fig. 2A - 21 - Sample C 19f. Fig' 17 - Eflugelia johnsozl (Flùgel, 1966) Massa & Vachard, 1929. Longitudinal section. Robledo Mountains (Section C). Robledo Mountains Formation. \folfcampian (Sakmarian). Sample C l9c. x 78. Fig. 18 -Ammooertella lzzersa (Schellwien, 1898). Longitudinal section. Robledo Mountains (Section C). Robledo Mounrains Formation. \Wolfcampian (S;rkmarìan). Sample C 16d. x 78. Fig. 23, 40 - Pseudoreicbelind ex gr. dar",asica (Leven, 19lO). Robledo Mountains (Section C). Robledo Mountaìns Formation. Wolfcampian (early Artinskian). x 32. Fig. 2J - Subtransverse section Sample C 26. Fig. 4O - Axial section. Sample C 35c. Fig. 24' 27,30,38 - "Glomospird" spp. Four subaxìal to oblique sections. Robledo Mountains (Scction C). Robledo Mountains Formation. \folf- campian(earlyArtinskian).Fig.24-SampleC26.x78.Fig.27-SampleC30.x78.Fig.30-SampleC35a.x78.Fìg.38-Sample \- J)C. X Jl. Fig. 25 - Geinitzina (?) sp. Longitudinal section. Robledo Mountains (Sectìon C). Robledo Mountaìns Formation. Wolfcampian (early Artrn- skian). Sample C 28 x 28. Fig.29 - Earlandia sp. Subaxial section. Robledo Mountains (Section C). Robledo Mountains Formation. \X/olfcampian (early Artinskian). SampleCl5ax28 Pl.7 Microfacies and microfossils from South-Central Neu- Mexìco 29 i',*P ':ktiS:r" 1t*t .,,.jr't1.1\ ' & iì - b,,,," I. t"'.fr,.;l '! '.;**i{.,; 'i'.l, , t,t{'e$ r1'td'i .!. .:. '1,3| 'Yir. ,'., 1,', t: *,:o1.'4:rr,, .',}. .,];Wl,q : ;l rr::l ,l- "f, "r '''#:': ' wl: f& qr" .é{_ ..i:ì:]? -'t::l à .t'? ,:ll à {' dT:'*' * lil,li 6nd ".n "r* i:r!li {:,:,1i U* 14 *i i':.p "x ;& ,r& '$ !t :: u .' w b.,{ki t6 i.'.. w. ,J '& ffi F fi.', | !--l' fl. 'l 'il!6,.'l : -, ,.i: f , - r ..,:i l,'.i #,rl:,...3 ..,,i r "*. .. i; I # Ft ' i 'i 'ir $. ,: {36t \' .5.t g *" 32 : l,,l :i:: w JU "?{ r*i':r",, l' ''ri', ,,iÍ:i, l&. :,i: t'....-,...... 1"*,{, ' j{' ,t Sr::ri'$rliii!i", u\ qwi5iiiili rla ,{l{ '# *\ 't' !i,*i', ,;'l 1i: {'s 3 !.,,,g1i h- l,* lb :' n-w1!, 1 ,;; #,: ';;.s 4a 3g 30 K. Krainer, D. Vachard & S. G. Lucas PLATE 8 Fossil asscmbÌages of the Robledo Mountains Formation (samples B 3a, b, c) and lower Apache Dam Formation (samples B 8, 11, 13, 17) (Sec- tion B of Krainer Er Lucas 1995), Hueco Group (New Mexico). Fig. 1-2, 11-12, 15-1r6 - Globivah:ulina spp. Roblcdo Mountains (Section B). Robledo Mountains Formation. rilolfcampian (early Artìnskian). Fig. 1-2 - Two subaxìal sections. Sample B 3a. x 78. Fig. 11 - Transverse section. Sample B 3b. x 78. Fig. 12 - Subaxial section. Sample B 3b.x32.Fig.15-Subtransversesection.SampleB8.x28.Fig.l6-Subaxialsection.SampleBS.xTS. Fig.3-6 - Hemìgordius (?) sp. 5. Robledo Mountains (Section B). Robledo Mountains Formation. Volfcampian (early Artinskian). Various sections. Sample B 3a. x 78. Fìg. 7-8 - Pseudorermìporella sp.3. Two longitudinal sections. Robledo Mountains (Section B). Robledo Mountains Formation. \X/olfcampian (early Artinskian). Sample B 3a. x /8. Fig.9 - Nodosinelloid'es sp. Longitudinal section. Robledo Mountains (Sectìon B). Robledo Mountains Formation. lVolfcampian (early Artinskian). Sample B 3a. x 28. Fig' 1O - Geinitzina sp. 1. Longitudinal section. Robledo Mountains (Section B). Roblcdo Mountains Formation. \lolfcampian (early Artin- skian). Sample B 3a. x /8. Fig. 13,27 - Earlandia sp. Two subaxial sections. Robledo Mountains (Sectìon B). Robledo Mountains Formation. Wolfcampian (early Artin- skian). x /8. Fig. 13 - Sample B 3b. Fig. 22 - Sample B 17. Fig. 14 - Ceinitzina sp. 2. Longitudinal section. Robledo Mountains (Section B). Robledo Mountains Formation. \Wolfcampian (early Artin- skian). Sample B 3c. x 78. Fig. 17 - N odosinelloìdes potie?shayae Mamet Er Pinard, 1 996. Axial section. Robledo Mountains (section B). Robledo Mountains Formation. \Wolfcampian (early Artinskian). Sample B 8. x 28. Fio q"""'i;'l _ _b 1R'" - ì''1". Subaxial section. Robledo Mountains (Section B). Robledo Mountains F'ormation. \Wolfcampian (early Artinskian). SamplcB 77.x32. Fig. 19 - Neoanchicodiwm catenoides Endo, 1954. Longitudinal section. Robledo Mountains (Section B). Robledo Mountains Formation. Wolfcampian (early Artinskian). Sample B 8. x 32. Fig. 20 - Tetrataxis sp. Subaxial section. Robledo Mountains (Section B). Robledo Mountains Formation. lVolfcampian (Artinskian). Sample B 13. x 28. Fig.21 - Ortonella sp.2. Longitudinal section. Robledo Mountains (Section B). Robledo Mountains Formation. Wolfcampian (earlyArtin- skian). Sample B 11. x 32. Fig.22 - Clarauusta calamistrata Vachard, 1980. Longitudinal section. Robledo Mountains (Section B). Robledo Mountains Formation..il/olf- campìan (Artinskian). Sample B 13. x 32. Fig.23 - Verrilleina sp. 3. Sublongitudinal section. Robledo Mountains (Section B). Robledo Mountains Formation. \X/olfcampian (Artin- skian). Sample B 13. x 78. Frg.21 - Palaeotextularla sp. Subaxial section. Robledo Mountains (Section B). Robledo Mountains Formation. \X/olfcampian (Artinskian). Sample B 17.x78. Ftg.25 - Tezaqwina aff. cliouli Vachard in Montenat & Vachard, 1981. Oblique secrion. Robledo Mountains (Section B). Robledo Mountains Formation. \il/olfcampian (Artinskian). Sample B 1,7. x 32. Fig.26 - Pachyphloia sp. Axial scction. Robledo Mountains (Section B). Robledo Mountains Formatìon. rVolfcampian (Artinskian). Sample B 13. x 28. Fig.28 - Syzrania sp. Subaxial section. Robledo Mountains (Section B). Robledo Mountains Formation. sfolfcampian (Artinskian). Sample B 17. x 32. Fig.29 - Ortonella sp.3. Longitudinal section. Robledo Mountains (Section B). Robledo Mountains Formation. \folfcampian (Artinskian). S:mpleB ll.x78. Pl. 8 Microfacies and microfc,ssils from South-Central Neu; Mexico 31 w w e{ s a s:,*:@ .'* \ q'^'':&i'''"1'-'*ffi;."1 ".*KJ- !d & ,ss ffi * rsl4'-é 9r'll: rli ;-. :; liil'ie'ff if! ] 7 ,; ,'*j/ p{l à,;i :' ,' S1.,# I 'j' -'.Fl :,iil"' 2& JZ K. Krainer, D. Vachard & S. G. Lucas Vachard in Vachard & Montenat, 1981, syzraniid indet., assemblage that is very similar to thar of the Auernig Wrr.,illeina sp. 3, Nodosinelloides potievskayae Mamet & Formation of the Carnic Alps. The Shalem Colony For- Pinard, 1996, l{. sp., Geinitzina sp. 1, G. sp. 2., and mation (Hueco Group) of the Robledo Mountains is Pachypbloia sp. more or less coeval, and may represent only the upper part of the "Bursumian" (Orenburgian) and Asselian. Biostratigraphy The foraminiferal assemblage of the Robledo Moun- tains Formation (section A) is late Asselian/Sakmarian Although the smaller foraminiferal assemblages in age and comparable with the Grenzland Formation of the Laborcita Formation and Hueco Group are poor and Upper Pseudoschwagerina Limestone of the Carnic when compared to contemporaneous successions in the Alps. The Robledo Mountains Formation of section C Carnic Alps, they allow a relatively precise and easy is clearly early Artinskian in age due ro rhe biostrati- correlation because they are less endemic than the graphic value of the staffelloid Psewdoreicbelina ex gr. fusulinids, whose markers are, for instance in the Oren- d.aroasica. It corresponds to the ma;'or part of the burgian, respectively restricted to North America (Lep- Trogkofel Group of the Carnic Alps. The uppermost totriticites) or some parts of the Paleotethys (Bosby- Robledo Mountains Formation and lower Apache Dam tauella). Formation of section B is poorly dated but is probably The assemblages of smaller foraminifers of the equivalent to the the middle-late Artinskian (upper part Laborcita Formation and Hueco Group are very similar of Trogkofel Group) (Fig. Z). to those recently reported from the upper Auernig These data add support to the hypothesis of Group and Rattendorf Group of the Carnic Alps (Aus- Davydov (1996) concerning the correlations of the tria/Italy) by Vachard 8c Krainer (2aah, b). Biostrati- North American stages with stages from the Urals and graphy of the Auernig and Rattendorf Groups is well further contribute to the correlation of the New Me- established on the basis of fusulinids (e.g. Forke et al. xican formations with those of the Carnic Alps. Only 1998; Kahler & Krainer 1993; Krainer & Davydov 1998; the stratigraphic gap of the middle Asselian, supposed Davydov & Krainer 1999). by Davydov (1996) and Krainer Et Davydov (1998), Based on the assemblages of smaller foraminifers, respectively, in North America and in the Carnic Alps, the Holder Formation is of Gzhelian age at Laborcita is not confirmed here. Finally, we correlate the "Bur- Canyon but the foraminifers are nor age diagnostic at sumian" with the Orenburgian, and the Wolfcampian Dry Canyon (Yucca Mound). The Laborcita Formation with the Asselian, Sakmarian and Artinskian. is typically Orenburgian in age at Laborcita and Fresnal The Laborcita Formation at Laborcita Canyon Canyons, charactertzed by the occurrence of exhibits a complete "Bursumian" section and may be Noclosinelloides potier.,sleayae, .^{. netschajeze,i and more complete than that of the Bursum stratotype Psewdooidalina. spp. The assemblage of the Shalem (Lucas & Vilde 2000), especially for identifying the Colony Formation at Robledo Peak is less diverse and position of the Carboniferous/Permian boundary in probably corresponds to the Asselian. Typical Sakmari- North America. The microfauna o{ the Robledo an assemblages with Geinitzina and Pseudot,ermiporella Mountains Formation (section B) is also important for appea,r in the Robledo Mountains Formation of section the correlation with the early Artinskian, because of A. The Robledo Mountains Formation of section C is the presence oî Psewdoreicbelina ex gr. daroastca. early Artinskian in age, as indicated by Psewdoreicbelina Compared to the late Paleozoic succession ex gr. daraasica. Section B, comprising rhe uppermosr (Auernig and Rattendorf Group) of the Carnic Alps, Robledo Mountains Fomation and lower Apache Dam significant differences exist concerning the bioric con- Formation, is probably late Artinskian in age, but clear stituents of limestones, particularly calcareous algae evidence is lacking. Therefore, the correlations of and smaller foraminifers. In limestones of the Auernig Davydov (1996) are confirmed (see stratigraphic and Rattendorf Group, calcareous algae are the most scheme, Fig. 2). frequent biotic constituent throughout the sequence, occurring in high diversity. In the Carnic Alps, algal Conclusions wackestone is by far the most abundant microfacies. The most abundant algae are Antltracoporella The uppermost part of the Holder Formation at spectabilis, Archaeolithopbyllum missowriense, Epi- Laborcita Canyon is of Gzheliaî age due to the pre- mastopora, and Tubipbytes/Archaeolithoporella in the sence of Psewdoaidalina (: Rapbconilia). The uppermost part. All those taxa are ràre in the Laborci- foraminiferal assemblage of the Holder Formation ar ta and Flueco limestones. Mounds in the Carnic Alps Dry Canyon (Yucca Mound) is less characreristic, con- are composed dominantly of Anthracoporella (Krainer taining Glomospiroid,es and Brunsiella. The Laborcita 1995; Forke et al. 1998; Samankassou 1998) or Tubi- Formation at Fresnal Canyon and Laborcita Canyon phytes/Archaeolitboporella (Flùgel 1981), whereas in exhibits in its lower part an Orenburgian foraminiferai the Laborcita Formation and Hueco Group, phylloid Microfacies and microfossils from Soutb-Central Nell, Mexico 33 algae are the dominant mound-building organisms. allow relatively precise and easy correlations between Smaller foraminifers are also more abundant and New Mexico and Europe (Carnic Alps). display a higher taxonomic diversity in late Paleozoic Acknouledgments. We thank Barry S. Kues and Peter K. Reser limestones of the Carnic Alps (Vachard Krainer & (Albuquerque) for assistance in the field, and Felix Heller (lnns- 20a1.a, b). Although lower diversit;r, smaller in the bruck) for preparing thin sections. \fe are grateful to John R. Groves foraminifers are less endemic than the fusulinids and and Gregory P Wahlman for their commenrs and suggestions. 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