Palynological record of the Paso Flores Formation (Late Triassic) on the southeastern side of the Limay River, Patagonia, Argentina

Ana María Zavattieri¹ and Natalia Mego¹

¹Laboratorio de Paleopalinología, Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales, Centro Científico Tecnológico - Consejo Nacional de Investigaciones Científicas y Técnicas, Casilla de Correo 330, 5500 Mendoza, Argentina. amz@lab.cricyt.edu.ar, nmego@lab.cricyt.edu.ar

Abstract. Well-preserved spore-pollen assemblages from the type locality of the Paso Flores Formation, in the Estancia Paso Flores area, on the southeastern side of the Limay River, northern Patagonia, Argentina, are presented in this contribution. In this area, the Paso Flores Formation is exposed along the boundary between the Río Negro and Neuquén provinces; it consists mainly of conglomerates, sandstones and mudstones and contains remains of the Dicroidium Flora. The facies associations suggest gravelly to sandy braided river systems as the main depositional environments of the lower to middle sections of the unit outcropping in this region. The palynofloral assemblages contain 48 species of bryophytic and pteridophytic spores, 30 species of gymnospermous pollen grains, and chlorophytic algal remains, most of which are illustrated herein. New forms belonging to the genera Cadargasporites, Neoraistrickia, Perotrilites, Verrucosisporites, Equisetosporites, and Steevesipollenites are described. Anapiculatisporites dawsonensis Reiser and Williams, Biretisporites sp. and Thymospora cicatricosa (Balme and Hennelly) Hart are also described and discussed. The miospore assemblages conform to the Ipswich phytogeographic province of the Gondwanan Triassic. Within this province, the Paso Flores assemblages are correlated compositionally and chronostratigraphically with the Craterisporites rotundus Oppel Zone of eastern Australian continental sequences. Thus, a Late Triassic (Late Carnian-Early Norian) age is established for the palynoflora of the lower section of the Paso Flores Formation.

Resumen. Registro palinológico de la Formación Paso Flores (Triásico Superior) sobre la margen sureste del Río Limay, Patagonia, Argentina. En esta constribución se presenta el estudio de asociaciones bien preservadas de esporas y granos de polen hallados en la localidad tipo de la Formación Paso Flores, en el área de la Estancia Paso Flores, margen sureste del Río Limay, norte de Patagonia, Argentina. En esta área, dicha formación está expuesta a lo largo del límite entre las provincias de Río Negro y Neuquén; consiste de conglomerados, areniscas y pelitas y contiene restos de la Flora de Dicroidium. Las asociaciones de facies sugieren sistemas fluviales anastomosados gravosos y arenosos como los principales ambientes de depositación se las secciones inferior a media de la unidad aflorantes en esta región. Las asociaciones palinológicas contienen 48 especies de esporas de briófitas y pteridófitas, 30 especies de granos de polen de gimnospermas y restos de algas clorófitas, la mayoría de las cuales se ilustran en este trabajo. Se describen nuevas formas pertenecientes a los géneros Cadargasporites, Neoraistrickia, Perotrilites, Verrucosisporites, Equisetosporites y Steevesipollenites. También se describen y discuten las especies Anapiculatisporites dawsonensis Reiser and Williams, Biretisporites sp. y Thymospora cicatricosa (Balme and Hennelly) Hart. Las asociaciones de mioesporas conforman la provincia fitogeográfica Ipswich del Triásico de Gondwana. Dentro de esta provincia, las asociaciones de Paso Flores se correlacionan composicional y cronológicamente con la Zona Oppel Craterisporites rotundus de las secuencias continentales del este de Australia. Por lo tanto, se establece una edad triásica superior (Carniano Tardío - Noriano Temprano) para la palinoflora de la sección inferior de la Formación Paso Flores.

Key words. Palynology; Upper Triassic; Paso Flores Formation; Patagonia; Argentina.

Palabras clave. Palinología; Triásico Superior; Formación Paso Flores; Patagonia; Argentina.

Introduction

The Upper Triassic continental sequence of the Paso Flores Formation occurs as scattered outcrops in the southwestern part of Neuquén Province and in the north-northwestern part of the Río Negro Province at the southeastern border of the Neuquina Basin (Legarreta and Gulisano, 1989), northern Patagonia, Argentina (figure 1.1). Various exposures of the Paso Flores Formation were studied by Fossa Mancini (1937) and Frenguelli (1948), and described in more detail by many authors, including Galli (1969), Nullo (1979), González Díaz (1982), and Lapido et al. (1984). Spalletti et al. (1990) described and analyzed sedimentary facies from several Paso Flores outcrops. The most complete succession of the formation is exposed on both sides of the Limay River, along the boundary between the above-mentioned provinces (figure 1.1). Its type section was not formally designated, but is accepted as being on the right side of the Limay River, downstream from the Alicurá Dam and south of the Cerro Mariana, in the area surrounding the now-flooded former Estancia Manantiales de Paso Flores compound (Nullo, 1979, p. 29-30). Here, the base of the Paso Flores Formation is not evident, although it is thought to lie unconformably on magmatic, metamorphic and volcanic rocks of the Paleozoic basement and/or on the Choiyoi volcanic complex (Nullo, 1979). The formation is succeeded unconformably by an Early Jurassic coastal marine siliciclastic sequence known as the Nestares Formation (Zavattieri and Volkheimer, 2001; Zavattieri et al., 2008).

Figure 1. 1, Geological map of the study area in the Paso Flores region (adapted from Nullo, 1979). The arrow indicates the location of the type section of the Paso Flores Formation / mapa geológico del área de estudio en la región de Paso Flores (adaptado de Nullo, 1979). La flecha señala la ubicación de la sección tipo de la Formación Paso Flores; 2, Schematic studied profile showing the palynological sample levels and location of the palynofloral assemblages studied / perfil esquemático estudiado, mostrando los niveles palinológicos muestreados y la ubicación de las asociaciones palinoflorísticas estudiadas.

The outcrops of the Paso Flores Formation on either side of the Limay River (near Paso Flores, more than 3 km east of the Alicurá Dam), and those of the Lomas and Cañadón de Ranquel Huao, have been interpreted as braided river deposits (Jenchen, 2001; Spalletti et al., 1990). The thickest sections, representing alluvial fan deposits and gravelly braided systems, were described by Spalletti et al. (1990) from the Corral de Piedra area in Neuquén Province. All of these above-mentioned outcrops along the Limay River and in the surrounding area represent the lower to middle parts of the Paso Flores Formation. The thinnest section of the formation, indicative of braided- plain, meandering-riverine and lacustrine deposition, crops out at Cañadón de Pancho, near the Collón Curá River (González Díaz, 1982; Ganuza et al., 1995). That section we consider to constitute the formation's upper part.
In the studied section, the Paso Flores Formation is characterized by red to brown-reddish coarse conglomerates, whose supporting clasts comprise volcanic, plutonic and metamorphic rocks, derived from the North Patagonian Massif (Jenchen and Rosenfeld, 2002). These conglomerates and associated massive coarse sandstones (approximately 60 m thick) have been interpreted as sheets and longitudinal braided bars formed by high regime sheetflooding of braided river systems (Jenchen, 2001; Spalletti et al., 1990). Below these very coarse deposits, eight samples of greenish to grey mudstones and siltstones were collected and processed palynologically (figures 1.2) and only two of these provided the well-preserved palynomorphs documented herein.
This paper is the first account of a spore-pollen assemblage from the type locality of the Paso Flores Formation. Two, very brief palynological reports on the formation (i.e., conference abstracts: Zavattieri, 1997; Zavattieri and Volkheimer, 2001), were based on the Cañadón de Pancho locality, in the Collón Curá River valley, southern Neuquén Province. The systematic description of that palynoflora is under study (by AMZ).

Material and methods

The palynological samples were obtained from two grey claystone levels from the lowermost part of the outcropping section in the type locality of the Paso Flores Formation in the ex Estancia Paso Flores area (southeastern side of the Limay River), Río Negro Province, northern Patagonia, Argentina (figure 1.1). The physical and chemical extractions of the palynomorphs were carried out in the Paleopalynology Laboratory of IANIGLA/CCT- CONICET-Mendoza following the standard physico-chemical processing techniques used in this laboratory (Volkheimer and Melendi, 1976). The slides are housed in the Paleopalynological Slide Collection of the above-mentioned institution under numbers 6171 and 6172 prefixed MPLP (Mendoza-Paleopalinoteca-Laboratorio de Paleopalinología). For the microscopic study we used an Olympus BX50 microscope and the photomicrographs were taken with an Olympus digital camera. Coordinates of specimens are denoted by an England Finder (EF) reference.
All the spores and pollen grains taxa identified in this study are alphabetically compiled in a list. Those discussed in the text are indicated in that list with an asterisk. The text fully describes new form-species, commenting on some others. The half-tone illustrations have been grouped according to morphological criteria.

Alphabetical list of identified species and illustration references

Trilete Spores

Anapiculatisporites cooksonae Playford 1965, figures 4.7-8
Anapiculatisporites dawsonensis Reiser and Williams 1969, figure 2.22 (*)
Anapiculatisporites pristidentatus Reiser and Williams 1969, figures 3.5, 9
Anapiculatisporites tereteangulatus (Balme and Hennelly) Playford and Dino 2002, figure 2.19
Annulispora folliculosa (Rogalska) de Jersey 1959, figure 2.15
Annulispora microannulata de Jersey 1962, figure 2.8
Baculatisporites comaumensis (Cookson) Potonié 1956, figure 2.17
Biretisporites sp. 2 (in Zavattieri, 1986), figure 2.5 (*)
Brevitriletes bulliensis (Helby ex de Jersey) de Jersey and Raine 1990, figure 3.10
Cacheutasporites minutus Jain 1968, figure 2.4
Cacheutasporites wielandii Jain 1968, figure 2.3
Cadargasporites reticulatus de Jersey and Paten 1964, figure 3.15
Cadargasporites sp. 1, figures 3.2-3 (*)
Calamospora tener (Leschik) de Jersey 1962, not illustrated
Ceratosporites helidonensis de Jersey 1971a, figure 4.10
Clavatisporites hammenii (Herbst) de Jersey 1971b, figure 4.13
Conbaculatisporites mesozoicus Klaus 1960, figure 4.14
Craterisporites rotundus de Jersey 1970, figures 2.23-24; figure 3.19
Deltoidospora minor (Couper) Pocock 1970, not illustrated
Deltoidospora directa (Balme and Hennelly) Norris 1965, figure 2.1
Densoisporites nejburgii (Schulz) Balme 1970, figure 4.11
Densoisporites psilatus (de Jersey) Raine and de Jersey in Raine et al. 1988, figure 4.12
Dictyophyllidites atraktos Stevens 1981, figures 2.12, 16
Dictyophyllidites mortonii (de Jersey) Playford and Dettmann 1965, figure 2.11
Gleicheniidites senonicus (Ross) Skarby 1964, figure 2.10
Leptolepidites volkheimerii Zavattieri 1986, figure 3.16
Neoraistrickia taylorii Playford and Dettmann 1965, figure 2.21
Neoraistrickia ramosus (Balme and Hennelly) Hart 1960, figure 4.9
Neoraistrickia sp. A, figures 4.3-6 (*)
Osmundacidites diazii Volkheimer 1972, figure 2.13
Osmundacidites wellmanii Couper 1953, figure 2.18
Perotrilites sp., figure 4.21 (*)
Polycingulatisporites mooniensis de Jersey and Paten 1964, figure 2.14
Polypodiisporites mutabilis Balme 1970, figure 4.15
Punctatosporites walkomii de Jersey 1962, figure 4.18
Pustulatisporites blackstonensis de Jersey 1970, figures 3.6-7, 11
Rogalskaisporites cicatricosus (Rogalska) Danzé-Corsin and Laveine 1963, figure 2.9
Rugulatisporites neuquenensis Volkheimer 1972, figure 3.14
Rugulatisporites permixtus Playford in Playford, Rigby and Archibald 1982, figure 3.4
Stereisporites antiquasporites (Wilson and Webster) Dettmann 1963, figure 2.7
Stereisporites psilatus (Ross) Pflug 1953, figure 2.6
Striatella seebergensis Mädler 1964b, figures 2.20; 3.1
Thymospora ipsviciensis (de Jersey) Jain 1968, figures 4.16-17
Thymospora cicatricosa (Balme and Hennelly) Hart 1965, figures 4.19-20 (*)
Todisporites minor Couper 1958, figure 2.2
Uvaesporites verrucosus (de Jersey) Helby in de Jersey 1971b, figures 3.17-18
Verrucosisporites sp. A, figures 3.12-13 (*)
Verrucosisporites sp. 2 (in Zavattieri, 1986), figure 3.8
Verrucosisporites varians Volkheimer 1972, figures 4.1-2

Figure 2. All figures approx. x 700 / todas las figuras aprox. x 700. 1, Deltoidospora directa (Balme and Hennelly) Norris 1965, 6171A: B39/0. 2, Todisporites minor Couper 1958, 6172C: P34/0, median focus / foco medio. 3, Cacheutasporites wielandii Jain 1968, 6172B: M37/2. 4, Cacheutasporites minutus Jain 1968, 6172B: X42/2. 5, Biretisporites sp. 2 (in Zavattieri, 1986), 6171F: C33/3. 6, Stereisporites psilatus (Ross) Pflug 1953, 6172C: Q27/4. 7, Stereisporites antiquasporites (Wilson and Webster) Dettmann 1963, 6171C: B40/4. 8, Annulispora microannulata de Jersey 1962, 6172F: L40/2. 9, Rogalskaisporites cicatricosus (Rogalska) Danzé-Corsin and Laveine 1963, 6172A: R36/2. 10, Gleicheniidites senonicus (Ross) Skarby 1964, 6172B: O34/2. 11, Dictyophyllidites mortonii (de Jersey) Playford and Dettmann 1965, 6172B: N32/0. 12, Dictyophyllidites atraktos Stevens 1981, 6172A: V21/1. 13, Osmundacidites diazii Volkheimer 1972, 6172B: H35/4. 14, Polycingulatisporites mooniensis de Jersey and Paten 1964, 6172C: U30/1, median focus / foco medio. 15, Annulispora folliculosa (Rogalska) de Jersey 1959, 6172 F: P38/0, proximal view / vista proximal. 16, Dictyophyllidites atraktos Stevens 1981, 6172F: Q23/4. 17, Baculatisporites comaumensis (Cookson) Potonié 1956, 6171A: C20/4. 18, Osmundacidites wellmanii Couper 1953, 6171A: Q32/4, equatorial view / vista ecuatorial. 19, Anapiculatisporites tereteangulatus (Balme and Hennelly) Playford and Dino 2002, 6172A: F28/0. 20, Striatella seebergensis Mädler 1964b, 6172C: S23/2, proximal view / vista proximal. 21, Neoraistrickia taylorii Playford and Dettmann 1965, 6171B: M38/0, distal view / vista distal. 22, Anapiculatisporites dawsonensis Reiser and Williams 1969, 6171B: V23/0, proximal view / vista proximal. 23, Craterisporites rotundus de Jersey 1970, 6172E: L40/4, equatorial view / vista ecuatorial. 24, Craterisporites rotundus de Jersey 1970, 6172B: D38/2, distal view / vista distal.

Figure 3. All figures approx. x 700, otherwise as indicated / todas las figuras aprox. x 700, excepto las indicadas. 1, Striatella seebergensis Mädler 1964b, 6172F: M27/0, uncompressed specimen, distal view / ejemplar no comprimido, vista distal. 2, Cadargasporites sp. 1, 6172B: U33/2, median-distal view / vista medio-distal. 3, Cadargasporites sp. 1, 6172B: U33/2, proximal view / vista proximal. 4, Rugulatisporites permixtus Playford in Playford, Rigby and Archibald 1982, 6172C: K38/2. 5, Anapiculatisporites pristidentatus Reiser and Williams 1969, 6171C: C24/4, proximal view / vista proximal. 6, Pustulatisporites blackstonensis de Jersey 1970, 6171B: W28/4, medium-distal view / vista medio-distal. 7, Pustulatisporites blackstonensis de Jersey 1970, 6171B: W28/4, proximal view / vista proximal. 8, Verrucosisporites sp. 2 (in Zavattieri, 1986), 6171B: E21/4. 9, Anapiculatisporites pristidentatus Reiser and Williams 1969, 6171B: M38/0, specimen at lower limit of size range / ejemplar en el límite inferior de rango de tamaños. 10, Brevitriletes bulliensis (Helby ex de Jersey) de Jersey and Raine 1990, 6172B: D41/4. 11, Pustulatisporites blackstonensis de Jersey 1970, 6171E: U23/2. 12, Verrucosisporites sp. A; 6171C: V34/2, x 600, proximal view / vista proximal. 13, Verrucosisporites sp. A, 6172E: O23/4, x 600, median view / vista media. 14, Rugulatisporites neuquenensis Volkheimer 1972, 6171F: Q23/2, median view / vista media. 15, Cadargasporites reticulatus de Jersey and Paten 1964, 6172F: M22/2, proximal view / vista proximal. 16, Leptolepidites volkheimerii Zavattieri 1986, 6172B: H32/0, distal view / vista distal. 17, Uvaesporites verrucosus (de Jersey) Helby in de Jersey 1971b, 6171F: X34/4, x 650; interference contrast illumination, proximal view / iluminación con contraste de interferencia, vista proximal. 18, Uvaesporites verrucosus (de Jersey) Helby in de Jersey 1971b, 6171F: X34/4, x 650, interference contrast illumination, medium-distal view / iluminación con contraste de interferencia, vista medio-distal. 19, Craterisporites rotundus de Jersey 1970, 6172C: F40/3, specimen with dimensions towards the upper limit of the observed size range, oblique-distal view / ejemplar con dimensiones hacia el límite superior del rango de tamaño observado, vista oblicua-distal.

Figure 4. All figures approx. x 700, otherwise as indicated / todas las figuras aprox. x 700, excepto las indicadas. 1, Verrucosisporites varians Volkheimer 1972, 6171F: T39/0. 2, Verrucosisporites varians Volkheimer 1972, 6172C: F31/0. 3, Neoraistrickia sp. A, 6171D: M27/1, proximal view / vista proximal. 4, Neoraistrickia sp. A, 6171D: M27/1, distal view / vista distal. 5, Neoraistrickia sp. A, 6171F: N25/4, showing range of morphological variability / mostrando el rango de variabilidad morfológica. 6, Neoraistrickia sp. A, 6171A: C32/2, showing extreme morphological variability / mostrando extreme de variabilidad morfológica. 7, Anapiculatisporites cooksonae Playford 1965, 6172A: R20/2, distal view / vista distal. 8, Anapiculatisporites cooksonae Playford 1965, 6172A: R20/2, proximal view / vista proximal. 9, Neoraistrickia ramosus (Balme and Hennelly) Hart 1960, 6172A: C24/1. 10, Ceratosporites helidonensis de Jersey 1971a, 6172B: T40/0. 11. Densoisporites nejburgii (Schulz) Balme 1970, 6172A: Q33/4. 12, Densoisporites psilatus (de Jersey) Raine and de Jersey in Raine et al. 1988, 6172 F: E25/0. 13, Clavatisporites hammenii (Herbst) de Jersey 1971b, 6172F: Q36/0, x 650. 14, Conbaculatisporites mesozoicus Klaus 1960, 6172C: M42/1. 15, Polypodiisporites mutabilis Balme, 1970, 6172C: R37/4, showing verruco-rugulate sculpture, closely spaced with narrow interstices interconnected, lower limit of the specie's size range / mostrando escultura verruco-rugulada, estrechamente espaciada con intersticios interconectados, límite inferior del rango de tamaños de la especie. 16, Thymospora ipsviciensis (de Jersey) Jain 1968, 6172C: K35/1. 17, Thymospora ipsviciensis (de Jersey) Jain 1968, 6172C: L40/1. 18, Punctatosporites walkomii de Jersey 1962, 6172B: X31/0. 19, Thymospora cicatricosa (Balme and Hennelly) Hart 1965, 6172E: X25/2, distal view / vista distal. 20, Thymospora cicatricosa (Balme and Hennelly) Hart 1965, 6172E: X25/2, proximal view / vista proximal. 21, Perotrilites sp., 6172E: E41/3, median view / vista media. 22, Playfordiaspora cancellosa (Playford and Dettmann) Maheshwari and Banerji 1975, 6171E: H22/4, x 500. 23, Playfordiaspora cf. crenulata (Wilson) Foster 1979, 6172B: V34/0, x 500.

Pollen grains

Accinctisporites ligatus Leschik 1955, figures 5.16-17
Alisporites australis de Jersey 1962, figure 5.13
Alisporites lowoodensis de Jersey 1963, figure 5.3
Alisporites parvus de Jersey 1962, figure 5.11
Araucariacites fissus Reiser and Williams 1969, figure 6.12
Corollina simplex (Maljavkina) Cornet and Traverse 1975, figures 6.13-14
Cycadopites argentinus Herbst 1965, figure 6.10
Dacrycarpites sp. (in Jain, 1968), figure 5.15
Equisetosporites steevesii (Jansonius) de Jersey 1968, figures 6.11, 15
cf. Equisetosporites sp., figure 6.8 (*)
Falcisporites nuthallensis Balme 1970, figure 5.2
Falcisporites stabilis Balme 1970, not illustrated
Inaperturopollenites intragranulosus (Bharadwaj and Singh) Zavattieri and Rojo 2005, figures 6.3, 16
Klausipollenites decipiens Jansonius 1962, figures 6.4, 6
Klausipollenites staplinii Jansonius 1962, figure 5.7
Minutosaccus acutus Mädler 1964a, figure 5.9
Monosulcites enormis (Jain) Herbst 1970, figure 6.5
Pityosporites scaurus (Nilsson) Schulz 1967, figure 5.1
Platysaccus papilionis Potonié and Klaus 1954, figure 5.12
Platysaccus queenslandi de Jersey 1962, figure 5.14
Playfordiaspora cancellosa (Playford and Dettmann) Maheshwari and Banerji 1975, figure 4.22
Playfordiaspora cf. crenulata (Wilson) Foster 1979, figure 4.23
Podocarpidites cf. multesimus (Bolkhovitina) Pocock 1962, figure 5.4
Protohaploxypinus microcorpus (Schaarschmidt) Clarke 1965, figure 6.2
Steevesipollenites sp., figure 6.7 (*)
Striatopodocarpites rarus (Bharadwaj and Salujha) Balme 1970, figure 6.1
Sulcosaccispora lata de Jersey and Hamilton 1967, figure 5.5
Vitreisporites contectus (de Jersey) de Jersey 1962, figure 5.8
Vitreisporites microsaccus de Jersey 1964, figure 5.6
Vitreisporites subtilis (de Jersey) de Jersey 1962, figure 5.10

Figure 5. All figures approx. x 700, otherwise as indicated / todas las figuras aprox. x 700, excepto las indicadas. 1, Pityosporites scaurus (Nilson) Schulz 1967, 6172F: H29/2. 2, Falcisporites nuthallensis Balme 1970, 6172A: V23/1. 3, Alisporites lowoodensis de Jersey 1963, 6172A: C21/4. 4, Podocarpidites cf. multesimus (Bolkhovitina) Pocock 1962, 6172C: C39/0. 5, Sulcosaccispora lata de Jersey and Hamilton 1967, 6172B: F38/3. 6, Vitreisporites microsaccus de Jersey 1964, 6172B: Q36/4. 7, Klausipollenites staplinii Jansonius 1962, 6172F: K27/3. 8, Vitreisporites contectus (de Jersey) de Jersey 1962, 6172B: E41/0. 9, Minutosaccus acutus Mädler 1964a, 6172F: Q31/1. 10, Vitreisporites subtilis (de Jersey) de Jersey 1962, 6172B: V36/6. 11, Alisporites parvus de Jersey 1962, 6172F: O20/1. 12, Platysaccus papilionis Potonié and Klaus 1954, 6172E: R22/2. 13, Alisporites australis de Jersey 1962, 6172D: F25/0. 14, Platysaccus queenslandi de Jersey 1962, 6172D: L24/3. 15, Dacrycarpites sp. (in Jain, 1968), 6172C: J21/0, x 500. 16, Accinctisporites ligatus Leschik 1955, 6172F: K32/2. 17, Accinctisporites ligatus Leschik 1955, 6172F: C38/4.

Figure 6. All figures approx. x 700, otherwise as indicated / todas las figuras aprox. x 700, excepto las indicadas. 1, Striatopodocarpites rarus (Bharadwaj and Salujha) Balme 1970, 6172C: C26/0. 2, Protohaploxypinus microcorpus (Schaarschmidt) Clarke 1965, 6172D: E20/2. 3, Inaperturopollenites intragranulosus (Bharadwaj and Singh) Zavattieri and Rojo 2005, 6171A: B18/0, x 600. 4, Klausipollenites decipiens Jansonius 1962, 6171A: B21/1. 5, Monosulcites enormis (Jain) Herbst 1970, 6172D: U35/4. 6, Klausipollenites decipiens Jansonius 1962, 6172A: R 24/2. 7, Steevesipollenites sp., 6171A: K23/0. 8, cf. Equisetosporites sp., 6172A: O38/6, median view / vista media. 9, Ovoidites spriggii (Cookson and Dettmann) Zippi 1998, 6172C: U41/2, x 700, half specimen, folded inward / mitad de ejemplar plegado hacia adentro. 10, Cycadopites argentinus Herbst 1965, 6172B: J34/1. 11, Equisetosporites steevesii (Jansonius) de Jersey 1968, 6172F: K31/4, compressed specimen / ejemplar comprimido. 12, Araucariacites fissus Reiser and Williams 1969, 6172C: U31/0, median view / vista media. 13, Corollina simplex (Maljavkina) Cornet and Traverse 1975, 6172F: 39/2, medium- proximal view, showing equatorial thickening, rimula and faintly infrapunctate exine / vista medio-proximal, mostrando engrosamiento ecuatorial, rímula y exina finamente intrapunctuada. 14, Corollina simplex (Maljavkina) Cornet and Traverse 1975, 6172F: 39/2; distal view showing subequatorial circular furrow / vista distal mostrando la endidura circular subecuatorial. 15, Equisetosporites steevesii (Jansonius) de Jersey 1968, 6171E: C28/3. 16, Inaperturopollenites intragranulosus (Bharadwaj and Singh) Zavattieri and Rojo 2005, 6171B: G24/3, x 600. 17, Ovoidites spriggii (Cookson and Dettmann) Zippi 1998, 6172C: O42/1, x 700, half specimen / mitad de ejemplar. 18, Botryococcus sp., 6172B: H40/1, x 500.

Algae

Botryococcus sp., figure 6.18
Ovoidites spriggii (Cookson and Dettmann) Zippi 1998, figures 6.9, 17

Systematics of selected taxa

Bryophytic and Pteridophytic spores

Genus Biretisporites Delcourt and Sprumont emend. Delcourt, Dettmann and Hughes 1963

Type species. Biretisporites potoniaei Delcourt and Sprumont 1955.

Biretisporites sp. 2 (in Zavattieri 1986)
Figure 2.5

Dimensions. Maximum equatorial diameter, 27-32 μm (2 specimens).

Studied material. 6171F: C33/3; 6171D: R32/2 MPLP.

Remarks. Two specimens are regarded as conspecific with those from the Potrerillos Formation (Upper Triassic), Cuyana Basin, recorded as Biretisporites sp. 2 (Zavattieri, 1986). They are characterized by a triangular to subtriangular amb, with straight to convex sides, laesura extending to or almost to the equator and commissures enclosed within exinal thickenings. Exine smooth, 1 to 1.5μm thick. Insufficient specimens are available for formal specific designation. They could not assigned to Dictyophyllidites mortonii (de Jersey) Playford and Dettmann, because "membraneous laesurate lips, together with exinal thickenings about the laesurae" (kyrtomes) are not clearly observed. Among other species recorded from the early Mesozoic of Gondwana, the Paso Flores specimens also share general morphological characters and dimensions with those described as Biretisporites sp. A by de Jersey (1970) from Esk Beds (Middle Triassic) and from Rewan Formation (1972) (Early Triassic). Specimens assigned to B. sp. 2 also agree with the morphological features and dimensions given by McKellar (1974) for B. modestus. Irregular pits and channels on the distal surface of the spores mentioned for B. modestus were not observed in the Paso Flores specimens, otherwise they have a smooth exine. McKellar (1974, p. 4) considered that those characters would be a corrosion state rather than a primary feature and he mentioned that it is not a universal feature of the species. B. sp. A described and illustrated by de Jersey and Raine (1990) differs from specimens here recorded in having subcircular ambs. Probably all mentioned informal species could be form a single species and maybe, there is a continuous gradation in the equatorial shapes from spores with triangular to subcircular ambs.

Genus Anapiculatisporites Potonié and Kremp 1954

Type species (by original designation). Anapiculatisporites isselburgensis Potonié and Kremp 1954.

Anapiculatisporites dawsonensis Reiser and Williams 1969
Figure 2.22

Dimensions. Maximum diameter, 33-42 μm (3 specimens).

Studied material. 6171C: L36/; 6171C: K37/0; 6171B: V23/02 MPLP.

Remarks. The specimens studied coincide with those described and illustrated by Reiser and Williams (1969). In the original description some sculptural elements show confluent bases, although this feature is rare in the material. The Argentinian specimens have also short bacula as sculptural elements, not mentioned in the original diagnosis.

Genus Cadargasporites de Jersey and Paten 1964

Type species. Cadargasporites baculatus de Jersey and Paten 1964.

Cadargasporites sp. 1
Figures 3.2-3

Description. Trilete spore, amb subcircular in polar and lateral view, showing pyramidal aspect in the proximal area. Exine two layered, intexine smooth, thin ca. 0.5 μm thick, clearly detached from the exoexine leaving a clear "cavus" near and around the equator of the spore. Exoexine thicker (3-5 μm thick) distally and equatorially ornamented with small foveolae (0.5-1 μm in diameter and 1 μm deep), densely disposed all over the surface of the spore giving a spongeous aspect and/or a thick irregular reticulum to the spore surface, except in a well defined contact area surrounding the laesura where the exoexine is smooth and thinner. The contact area is large, 1/2 to 2/3 radius of the spore. Trilete mark is raised around which folding of the exoexine gives the appearance of lips; laesurae extend to the margin of the proximal smooth area. Margin of the contact area is marked by abrupt ending of the ornament, thinnings of the exoexine proximally and a low and wavy folding. On the contact area the exoexine is broken, detached and loose, giving an appearance of remaining perine.
Dimensions. Maximum equatorial diameter, 59-60 μm; polar diameter 49-56 μm (2 specimens).

Studied material. 6172B: U33/2; 6172B: V32/0 MPLP.

Remarks. There are only two specimens in the assemblage with a small foveolate sculpture not previously recorded for the genus. Both specimens provide evidence of two-layered and clearly cavate condition of the exine. The presence of a clear thin cavus close and constantly equidistant to the equator on the distal and equatorial regions has never been mentioned for the genus. It is necessary to study additional material to erect a genus new species characterized by small foveolate sculpture.

Genus Neoraistrickia Potonié 1956

For the genus synonymy see Potonié (1970, p.27); de Jersey (1972, p. 7); and Sajjadi and Playford (2002a, p.34).

Type species. Neoraistrickia truncata (Cookson) Potonié 1956 (by original designation).

Discussion. As mentioned by Dettmann (1963, p. 35), Potonié (1956) instituted the genus Neoraistrickia to incorporate trilete, azonate, Mesozoic microspores showing a sculpture pattern composed solely of bacula, having subtriangular amb and reduced proximal sculpture. It is partially a synonym of the genus Cepulina Malyavkina. For this genus we follow de Jersey (1972, p. 7) and McKellar (1974, p. 9) to incorporate spores ornamented distally and equatorially mostly by bacula.

Neoraistrickia sp. A
Figures 4.3-6

Description. Trilete spore; amb convexly subtriangular with rounded apices and sides weakly to strongly convex to subcircular in some specimens. Laesurae more or less straight, extending to, or almost to the equator and usually enclosed within narrow or thick membraneous lips 1 to 2.5 μm thick. Exine difficult to measure because of the density of the ornament in the equator. Proximal exine smooth, thin; proximal area well-defined, radius ca. 0.7 of spore radius. Distally and mainly equatorially strongly ornamented by closely packed and short baculate projections ca. 2 to 4 μm high and mostly 2-3 μm diameter, with rounded and truncated distal extremities, some scarce elements have crenulated tops and look "exploded"; the bacula are mostly conical showing expanded bases with subcircular to usually elongated cross-sections (2-6 μm in maximum diameter), others are columns possessing parallel sides and rounded to quadrangular in cross section. In the equatorial region, where they are more densely disposed, bacula bases sometimes coalesce between two or more joint elements by short and low ridges. The bacula are characteristically irregularly distributed and remain mainly discrete on the distal surface, being spaced between 3 to 5 μm apart.
Dimensions. Equatorial diameter, 41-58 μm (including sculptural projections) (7 specimens).

Studied material. 6171E: F41/1; 6172F: K37/0; 6171A: C32/2; 6171D: M27/1; 6171C: T43/4; 6171F: N25/4; 6171F: T32/4.

Remarks. This species is characterized by a prominent distal and equatorial ornament consisting solely of mostly short and robust baculate projections, with expanded and coalescent bases in the equatorial region where the ornament is remarkably more densely disposed. Size and density of elements on the distal surface vary from specimen to specimen. Among well known species of Neoraistrickia recorded from the early Mesozoic of Gondwana, mainly those described by Reiser and Williams (1969), McKellar (1974), Filatoff (1975) and Sajjadi and Playford (2002a) display the unique and robust baculate ornament and distribution of the elements like in N. sp. A above described.

Genus Perotrilites Erdtman ex Couper emend. Evans 1970

For the genus synonymy, see Sajjadi and Playford, 2002b, p. 114.

Type species. Perotrilites granulatus Couper emend. Evans 1970; by subsequent designation of Couper (1953, p. 31).

Perotrilites sp.
Figure 4.21

Description. Spore zonate, ?alete. Amb triangular with slightly convex sides, strongly denticulate peripherically. Exine two-layered: intexine darker and thicker than the exoexine, thickness difficult to measure; exoexine very thin, transparent, ca. 0.5 μm thick, membranous to finely granular, closely adpressed proximally (and may be distally) to the intexine but expanded equatorially to form a zona of irregular width, irregularity probably due to the compressional state. Exoexine equatorially (and ?distally) ornamented with conate and spinose elements ca. 1-6 μm high, having acute to blunt apices and expanded bases ca. 3-6 μm in diameter, discrete to coalescent.
Dimensions. Overall equatorial diameter, including ornament of the exoexine, 51 μm (1 specimen).

Studied material. 6172E: E41/3 MPLP.

Remarks. The unique specimen recorded herein is compared to, rather than positively identified with, Perotrilites because a trilete mark is not clearly visible, although the specimen does closely resemble the specimens described and figured by Sajjadi and Playford (2002b, p. 11-155; pl. 3, figs. 14-16). Given its preservation a specific attribution to this specimen is doubtful. It would also be assigned to the genus Kraeuselisporites (Leschik) Jansonius due to its spongeous nature of the exine. However, because it's compressional state is difficult to secure that it is a truthful zonotrilete spore.

Genus Verrucosisporites Ibrahim emend. Smith and Butterworth 1967

Type species. Verrucosisporites verrucosus (Ibrahim) Ibrahim 1933.

Verrucosisporites sp. A
Figures 3.12-13

Description. Spores trilete. Amb rounded subtriangular to subcircular. Laesura distinct, straight, 0.5 to 0.7 of spore radius in length, simple, but sometimes bordered by a narrow margo. Exine 1-2 μm thick, sculptured by discrete low rounded verrucae and/or low and rounded conical elements 1-1.5 μm high and 2-3 μm wide at their expanded bases, bases subcircular to elongate in outline. In some specimens the sculpture elements are irregularly distributed leaving space for several similar elements between them. The ornamentation is reduced in size and number on the contact area.
Dimensions. Maximum diameter, 53-87 μm (3 specimens).

Studied material. 6172E: O23/4; 6171C: V34/2; 6172C: A32/3 MPLP.

Remarks. The specimens described are provisionally assigned to the genus Verrucosisporites, although they also could be assigned to the genus Converrucosisporites because of their convexly subtriangular-subcircular amb. The main features of these recorded spores are the distinct simple short laesura, although this is sometimes bordered by a thickness and/or margo, and the type and disposition of the low verrucae- conical ornament that is irregularly and sparsely distributed on the surface of the spore. None of the known species of both mentioned genera display the above mentioned features. More specimens are needed for a reliable assignation.

Monolete spores

Genus Thymospora Wilson and Venkatachala emend. Alpern and Doubinger 1973

Type species (by original designation). Thymospora thiessenii (Kosanke) Wilson and Venkatachala 1963.

For the synonymy and discussion of the genus, see Foster 1979, p. 62.

Thymospora cicatricosa (Balme and Hennelly) Hart 1965
Figures 4.19, 20

For the synonymy of the species, see Foster, 1979, p. 62.

Description. Spore bilateral. Amb circular to ovalsubcircular. Laesura simple, monolete to asymmetrically trilete, often obscured by the sculpture; in trilete specimens the two longer rays extending about three-fourths length of the spore. Exine 2-3 μm thick with sculpture of closely spaced verruco-rugulate, vermiculate and verrucate elements uniformly distributed on distal and equatorial surfaces. Sculptural elements of variable size and shape, commonly bearing 1-3 μm, isolated verrucae of ca. 0.5-2 μm in diameter. Sculpture is reduced or absent on the proximal face.
Dimensions. Maximum equatorial diameter: 36 x 37 μm (1 specimen).

Studied material. 6172E: X25/2 MPLP.

Remarks. Even though just one specimen has been recorded in the Paso Flores Formation, the main morphological characteristics that define the species, such as laevigate proximal face, laesura with triradiate tendency, closely distributed sculpture of the rugulate- verrucate elements on distal and equatorial surfaces allow an accurate assignation. All mentioned morphological characters are clearly distinct from those exhibited by P. ipsviciensis also recorded in this assemblage in greater abundance. P. mutabilis Balme (1970) is closely similar to P. cicatricosa in also having an asymmetric trilete or monolete scar and in its irregular verrucate or rugulate sculpture although it is distributed on both faces and is smaller. P. cicatricosa has been previously recorded in Permian assemblages (see Foster, 1975, 1979), making it the first record of this species in the late Upper Triassic Gondwana strata.

Polyplicate pollen grains

Genus Equisetosporites Daugherty emend. Pocock and Jansonius in Pocock 1964 [1965]

Type species (by original designation). Equisetosporites chinleana Daugherty 1941.

Remarks. The genus Equisetosporites is considered restricted only to Triassic forms similar to the type species of the genus (Muller, 1968; de Jersey, 1968; Balme, 1970, 1995). Balme (1995, p. 212) discussed the botanical affinities for ephedra-like dispersed pollen, variouly assigned to the genera Equisetosporites and/or Ephedripites. He remarked that some workers have suggested that Ephedripites should be regarded as a junior synonym of the Late Triassic genus Equisetosporites Daugherty, but remarked that optical data alone do not provide a clear basis for distinguishing between the two genera and that, without ultrastructural study, the botanical affinities are not definite. De Jersey (1968, p. 20) also pointed out that the name Equisetosporites is misleading, because it is wrongly suggestive of equisetalean affinities. Scott (1960) definitively demonstrated that the type species of Equisetosporites is of ephedraceous affinity. De Lima (1980) has discussed and characterized the morphology and taxonomy of many polyplicate pollen grains (Equisetosporites, Steevesipollenites and Gnetaceaepollenites, among others the most commonly recorded genera in Early Mesozoic strata) on the basis of their most diagnostic features. His interpretations of the generic circumscription of Equisetosporites and Steevesipollenites are followed here.

cf. Equisetosporites sp.
Figure 6.8

Description. Polyplicate? pollen grain; overall outline rounded oval to rounded polygonal. Exine two layered; exoexine thin, transparent, hyaline under optical microscopy, less than 0.5 μm thick, broken and detached from the intexine all over the grain. Intexine thicker and darker, apparently floating free inside the exoexine. Corpus (intexine) with 6? parallel ribs about 2-3 μm wide not tapering toward longitudinal ends, separated by unbranched narrow furrows reaching almost to the longitudinal ends. The ribs may be fused at both extremes of the longitudinal axis, but do not form thickenings there. Both layers are apparently laevigate.
Dimensions. Total length, 59 μm (including broken exoexine); length of intexine, 45 μm; maximum breadth, 44 μm; breadth of intexine, 33 μm (1 specimen).

Studied material. 6172A: O38/6 MPLP.

Remarks. The assignment of this single specimen is provisional, because no similar pollen grains have been described in the available literature. More material is necessary for a confident interpretation.

Genus Steevesipollenites Stover 1964

Type species (by original designation). Steevesipollenites multilineatus Stover 1964.

Steevesipollenites sp.
Figure 6.7

Description. Polyplicate pollen grain; outline broadly fusiform to ellipsoidal with a broad expansion in the middle part of the grain and tapering towards both extremes where two small thickenings of the exoexine of conical shape are located at the ends of the longest axis. Intexine relatively thick; 12 to 14 subparallel ribs (counted in the equatorial region), approx. 1-3 μm wide and separated by 0.5 μm wide grooves, rarely branched.
Dimensions. Total length, 33 μm; length of central body, 26 μm; total breadth, 30 μm (1 specimen).
Studied material. 6171A: K23/0 MPLP.
Remarks. De Lima (1980) characterized the diagnostic features of Steevesipollenites as: "Acolpate pollen of ellipsoidal to fusiform shape, with a variable number of longitudinal ridges alternating with narrower grooves. Exine has two layers. Poles are modified equally". All of these structural features are observed in the sole specimen recorded here and allow assigning it provisionally to the genus Steevesipollenites.

Biostratigraphy and age

A primary objective of the investigation has been to study assemblages distributed through the complete vertical sequence of the Paso Flores Formation. Zavattieri (1997) and Zavattieri and Volkheimer (2001) listed and analyzed the chronostratigraphic distribution of some species of spore-pollen assemblages from the upper third of the Paso Flores Formation, at the Cañadón de Pancho section, near the Collón Curá River, Neuquén Province. They suggested a latest Norian age for that uppermost miospore assemblages, the youngest Triassic palynoflora recorded up to now from Argentinian basins. This investigation reaches now to the lower part of the unit, in the Limay River area. Although unfavorable lithology has reduced the coverage in some parts of the sequences (see Morel et al., 1999, Figs 1-2: Lomas and Cañadón de Ranquel Huao, Estancia Corral de Piedra, north-western side of the Limay River), sufficient knowledge of the palynofloras of the Paso Flores Formation is now available to enable assessment of their stratigraphic and age range significance.
The miospore assemblages recorded herein share spore and pollen taxa with assemblages previously found in the upper part of the unit, at the Cañadón de Pancho locality. Some biostratigraphically significant species recorded by Zavattieri (1997) and Zavattieri and Volkheimer (2001) from that uppermost part of the formation are absent in this lower section of the unit, for example: Converrucosisporites cameronii, Neoraistrickia truncata, Foveogleicheniidites atavus, Foveosporites moretonensis, cf. Retitriletes rosewoodensis, Rugulatisporites nelsonensis, Polycingulatisporites crenulatus, Tuberculatosporites aberdarensis, among others.
The palynological dating of the assemblages here recorded is principally based on the zonations devised by de Jersey (1975), Stevens (1981), McKellar (1982), Helby et al. (1987) and de Jersey and Raine (1990) (figure 7). De Jersey (1975) defined four miospore zones in a continuous sedimentary sequence in southeastern Queensland, eastern Australia, ranging from Middle Triassic to Early Jurassic, characterized by the occurrence of species as zonal markers (cf. FAD/LAD markers). In ascending stratigraphic order they are (see also Helby et al., 1987, Figs. 4-5; de Jersey and Raine, 1990, Figs. 4.3, 4.4):

Duplexisporites problematicus Microflora (uppermost Anisian to lowermost Ladinian)
Craterisporites rotundus Zone (Carnian to lowermost Norian)
Polycingulatisporites crenulatus Zone (uppermost Norian to "Rhaetian")
Ceratosporites helidonensis Subzone ("Rhaetian" to Lower Hettangian)
Trisaccites variabilis Zone (Lower Jurassic)

Figure 7. Stratigraphic distribution and range of selected miospore species recorded in the lower section of the Paso Flores Formation at its type locality, Limay River area, Neuquén Basin and from the Comallo Formation, Rio Negro Province, North Patagonian Massif (Argentina). Comparison of selected stratigraphically significant miospore species of Australasian Upper Triassic palynozones. Principal sources of data: Zavattieri et al. (1984); de Jersey (1975); Stevens (1981); McKellar (1982); Helby et al. (1987); de Jersey and Raine (1990) / distribución estratigráfica y rangos de especies de miosporas seleccionadas registradas en la sección inferior de la Formación Paso Flores, localidadtipo, área del Río Limay, Cuenca Neuquina y de la Formación Comallo, provincia de Río Negro, Macizo Nordpatagónico (Argentina). Comparación de especies de miosporas seleccionadas y estratigráficamente significativas del Triásico Superior de palinofloras de Australasia. Fuente principal de datos: Zavattieri et al. (1984); de Jersey (1975); Stevens (1981); McKellar (1982); Helby et al. (1987); de Jersey y Raine (1990).

As mentioned by McKellar (1982), the presence of D. problematicus (= Striatella seebergensis) in absence of Craterisporites rotundus delimits the D. problematicus Microflora (de Jersey, 1975) of Middle Triassic age. On the other hand, the Late Triassic C. rotundus Zone (de Jersey, 1975) is defined by the first appearance of this species and by the presence of co-occurring species, together with D. problematicus (= Striatella seebergensis) as a common element and the absence of Polycingulatisporites crenulatus. Significant accessory and co-occurring forms in the C. rotundus Zone are shown in figure 7. De Jersey and Raine (1990) defined new miospore zonations for the Triassic to Lower Jurassic of New Zealand and correlated them with Australian zonations previously established. For the Carnian to Early Norian stages they characterized the Annulispora folliculosa Zone and Annulispora microannulata Subzone whose ages were established to be Late Ladinian to Early Norian range, defined by the first appearance of A. folliculosa (Rogalska) and partially correlated with the Craterisporites rotundus Zone (de Jersey, 1975) of eastern Australia (see also de Jersey and Raine, 1990, Fig. 4.3, p. 63). In the A. folliculosa Zone of New Zealand, C. rotundus appears in the base of that zone and extends into higher zones but is much less abundant than A. folliculosa and consequently was not used for the definition of the zone. In the upper part of that zone (earliest Norian) Striatella seebergensis (=Duplexisporites problematicus) and Rogalskaisporites cicatricosus make their first appearance in New Zealand assemblages (de Jersey and Raine, 1990, p.61). These taxa occur in the assemblages studied herein, thus, they may be correlated with the upper segment of the A. folliculosa Zone established for New Zealand palynozones (de Jersey and Raine, 1990, Fig. 4.3, p. 63).
C. rotundus is a quite common element in the studied assemblages of the Paso Flores Formation at its type locality. D. problematicus (= Striatella seebergensis) and R. cicatricosus are less common than C. rotundus and, A. folliculosa and A. microannulata are rare components in these assemblages. Most of the species identified in this study have also been recorded in a region close to the Paso Flores area, in the Comallo Formation, Rio Negro Province, North Patagonian Massif (previously referred as Cerro Puntudo Formation by Zavattieri et al., 1994 and Zavattieri and Batten, 1996) (see Stipanicic and Zavattieri, 2002; Zavattieri and Stipanicic, 2002). The Comallo Formation palynoflora was also assigned a Late Triassic age (equivalent to Carnian-Early Norian of marine sequences) (Zavattieri, 2002) (see figure 7).
No previous records of C. rotundus and co-occurring forms such as Anapiculatisporites pristidentatus, Annulispora folliculosa, A. microannulata, Cadargasporites baculatus, C. reticulatus, Rogalskaisporites cicatricosus, Striatella seebergensis, Uvaesporites verrucosus, Alisporites spp. and rare Corollina (=Classopollis) which are persistent components of the C. rotundus Zone of Australia (de Jersey, 1975; Stevens, 1981; Helby et al., 1987), have been recorded in Triassic palynofloras from Argentinian basins previously. Aratrisporites is also frequently recorded in the Australian C. rotundus Zone. The absence of this pleuromeiacean Lycopsida genus in the studied assemblages may be paleoenvironmentally controlled, presumably because of a specific environmental requirement.
Thus, it is important to mention that it is a quite common element in some leves of the Comallo Formation (Zavattieri et al., 1994).
C. rotundus is a persistent element of the continental Ipswich Microflora assemblages from the Late Triassic of southeastern Queensland (de Jersey, 1975) and it is a relatively rare element in marine environments of the Upper Triassic New Zealand assemblages. De Jersey and Raine (1990, p. 75) suggested that its rarity is a consequence of local paleoecological rather than paleolatitudinal factors.
The younger Australian Polycingulatisporites crenulatus Zone of the Late Triassic (latest Norian sensu de Jersey, 1975 and Stevens, 1981) was defined by the first appearance of this species, as well as first appearances of Retitriletes spp., Podocarpidites ellipticus, Perinopollenites spp., Rewanispora antiquus, Pustulatisporites blackstonensis, Polycingulatisporites densatus, among others. None of these have been recorded in this study (see figure 7), although co-occurring species mentioned as components of the lower part of the P. crenulatus Zone (Stevens, 1981; McKellar, 1982) are present in the studied Paso Flores palynoflora (see figure 7).
In summary, the lowermost part of the Paso Flores Formation at its type locality, outcropping in the Limay River region, is assigned to a middle Late Triassic age (equivalent to Late Carnian - Early Norian of marine sequences) based on the composition of the continental palynological zonations from the Australasian Mesozoic, that have been controlled by marine faunal and palynofloral zonations (Helby et al., 1987; de Jersey and Raine, 1990). The Paso Flores assemblages conform to the Ipswich biogeographic province of Dolby and Balme (1976), situated in southern high latitudes during the Triassic Period.
These age conclusions suggest that the strata at the type locality of the Paso Flores Formation in the Limay River are older than the outcrops of the Cañadón de Pancho, near the Collón Curá River, in Neuquén Province.
Morel et al. (1999) and Spalletti et al. (1990) assigned a late Late Triassic age to the outcropping section of the Paso Flores Formation in the Limay River area on the basis of the plant macrofossil assemblages. They considered this section to be the upper part of the Paso Flores sequence because following Spalletti (1996), they thought that the Nestares Formation lies conformably on the Triassic siliciclastic sequence of the Paso Flores Formation and assumed the Nestares Formation to be of continental origin. However, Zavattieri et al. (2008) have demonstrated that the strata of the latter unit correspond to a marginal marine environment of deposition and have assigned it to the Early Jurassic (Toarcian). Therefore, there is a significant disconformity between both mentioned units that crop out in the Limay area.

Paleoecological significance

The paleoenvironmental interpretation of the Late Triassic Paso Flores Formation in the Limay River region (Paso Flores area) is based upon the paleoecological significance of the recorded plant macrofossil flora, palynoflora and on sedimentary facies analysis. Spalletti et al. (1990) have interpreted the Paso Flores sequence in this area as corresponding to gravelly and sandy braided systems (multichannel and lowsinuosity rivers) with fine-grained deposits developed on the top of the bars and islands of the braided system. The plant macrofossil assemblages from different outcropping sections of the Paso Flores Formation (cf. Spalletti et al., 1990) have been listed and described by, among others, Morel et al. (1999) and Artabe et al. (2001). However, rich and well-preserved spore-pollen suites provide evidence of a more diverse Late Triassic Paso Flores vegetation.
The botanical affinities of the dispersed miospores encountered in the Paso Flores Formation, at its type locality, are presented in figure 8 (cf. Balme, 1995; de Jersey and Raine, 1990; Raine et al., 2006).

Figure 8. Inferred botanical affinities of most of the spore and pollen genera identified in this study. Principal source of information concerning natural relationships of sporae dispersae: Potonié (1962, 1967); Filatoff (1975); de Jersey and Raine (1990); Balme (1995) / Afinidades botánicas inferidas de la mayoría de los géneros de esporas y pollen identificados en este studio. Principal fuente de información referida a las relaciones naturales de las mioesporas dispersas: Potonié (1962, 1967); Filatoff (1975); de Jersey y Raine (1990); Balme (1995).

The palynological assemblages recovered are entirely of terrestrial origin, including spores and pollen grains, together with a minor aquatic component (rare Chlorophytic algae). Gymnospermous disaccate pollen grains constitute an important component of the palynoflora (43 % of the spectrum in sample 6171 and more than 76 % in sample 6172). The gymnosperm forests of the hinterland (allochthonous elements) were characterized by the Podocarpaceae, Araucariaceae, Pteridospermaceae, Caytoniaceae and rare Cheirolepidaceae (Classopollis = Corollina). Pteridophytes (ferns) were also prominent palynofloral components, both qualitatively and quantitatively (approx. 51% in sample 6171 and 19 % in 6172). Ferns included several families that supplied smooth and apiculate spores such as Schizeaceae, Matoniaceae, Dicksoniaceae, Gleicheniaceae, Pteridaceae, Polypodiaceae, and Osmundaceae are well-represented. Less frequent are the equisetaleanlike (arthrophyte) spores (Calamospora). Bryophyta (mosses, hornworts and liverworts) constitute minor components of the studied assemblages. Lycopsida, mainly represented by Selaginellaceae and Lycopodiaceae contributed abundant elements that occupied stream banks or ponds within fluvial plains.

Conclusions

The palynofloral assemblages studied from the lower part of the Paso Flores Formation at its type locality, compositionally resemble those from eastern Australia assigned to the Craterisporites rotundus Oppel Zone of de Jersey (1975) and the lower part of the Polycingulatisporites crenulatus Zone of Helby et al. (1987). Correlation with the New Zealand Annulispora folliculosa Zone of de Jersey and Raine (1990) is consistent with correlation with the C. rotundus Zone of de Jersey (1975). Thus, the Paso Flores Formation assemblages studied herein can be assigned to the middle Late Triassic (equivalent to Late Carnian- Early Norian age range of marine sequences), on the base of the spore-pollen content.
The previously recorded palynoflora from the Comallo Formation, in the Comallo area, northern Río Negro Province, North Patagonian Massif (Zavattieri et al., 1984) is considered equivalent in age to the lower part of the Paso Flores Formation outcropping in the Limay area, based on its similar palynological content.
The uppermost part of the Paso Flores Formation that crops out in the Collón Curá River area (Cañadón de Pancho locality), characterized by pelitic facies of typical lacustrine origin, contains a palynoflora which indicates a latest Triassic age (latest Norian -"Rhaetian"). This represents the youngest Triassic palynofloras known in Argentina.
A considerable diastema separates the lower part of the Late Triassic continental Paso Flores Formation from the Late Toarcian near-coast Nestares Formation (Zavattieri et al., 2008) in the Limay River area. The first marine transgression of the Neuquén Basin is represented by the Late Toarcian Nestares Formation sequence that constitutes, in the area of the Alicurá Dam on the Limay River, the basal stratigraphic unit of the Cuyano Group. The Paso Flores Formation is considered a preliminary continental infilling of the Neuquén Basin (pertaining to the pre-Cuyano).
These palynofloral assemblages of continental origin are related to the Ipswich Microflora (Dolby and Balme, 1976; Zavattieri and Batten, 1996).

Acknowledgements

To the CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas, PIP # 5430/05) for the grant (NM). We are most grateful to J.I. Raine, NGS Science, Lower Hutt, New Zealand, for both critically reviewing and linguistic improving the manuscript as one of the reviewers. We greatly acknowledge to G. Playford, Petrobras / Cenpes, Río de Janeiro, Brazil, for their helpful comments, critical reading and suggestions that enhanced the manuscript as the other journal reviewer. We specially thank to M.E. Soler (IANIGLA-Mendoza, CONICET) for her assistance with English grammar corrections. We are also grateful to W. Volkheimer (IANIGLA-Mendoza, CONICET) for the critical reading on the final version of the manuscript and pertinent comments. The physical and chemical extractions of the samples were performed by A. Moschetti in the paleopalynological laboratory of IANIGLA-Mendoza, CONICET.

References

1. Alpern, B. and Doubinger, J. 1973. Microfossiles organiques du Paléozoïque; 6, Les spores. Les miospores monoletes du Paléozoïque. Paris, Commission Internationale de Microflore du Paléozoïque, Éditions C.N.R.S., 103 pp.        [ Links ]

2. Artabe, A.E., Morel, E.M. and Spalletti, L. A. 2001. Capítulo 10. Paleoecología de las floras triásicas argentinas. In: A.E. Artabe, E.M. Morel and A.B. Zamuner (eds.), El Sistema Triásico en la Argentina: 199-225. Fundación Museo de La Plata "Francisco Pascasio Moreno".        [ Links ]

3. Balme, B.E. 1970. Palynology of Permian and Triassic strata in the Salt Range and Surghar Range, West Pakistan. In: B. Kummel and C. Teichert (eds.), Stratigraphic boundary problems: Permian and Triassic of West Pakistan. University of Kansas, Department of Geology, special publication 4: 306-453.        [ Links ]

4. Balme, B.E. 1995. Fossil in situ spores and pollen grains: an annotated catalogue. Review of Palaeobotany and Palynology 87: 81- 323.        [ Links ]

5. Clarke, R.F.A. 1965. British Permian saccate and monosulcate miospores. Palaeontology 8: 322-354.        [ Links ]

6. Cornet, B. and Traverse, A. 1975. Palynological contributions to the chronology and stratigraphy of the Hartford Basin in Connecticut and Massachusetts. Geoscience and Man 11: 1-33.        [ Links ]

7. Couper, R.A. 1953. Upper Mesozoic and Cainozoic spores and pollen grains from New Zealand. New Zealand Geological Survey, Paleontological Bulletin 22: 1-77.        [ Links ]

8. Couper, R.A. 1958. British Mesozoic microspores and pollen grains. A systematic and stratigraphic study. Palaeontographica Abteilung B 103: 75-179.        [ Links ]

9. Danzé-Corsin, P. and Laveine, J.P. 1963. Microflore. In: P. Briche, P. Danzé-Corsin and J.P. Laveine, Flore infraliassique du Boulonnais. Société Géologique du Nord Mémoire 13: 57-143.        [ Links ]

10. Daugherty, L.J. 1941. The Upper Triassic flora of Arizona. Carnegie Institute of Washington, publications 526: 1-108.        [ Links ]

11. De Jersey, N.J. 1959. Jurassic spores and pollen grains from the Rosewood Coalfield. Queensland Government Mining Journal publication 60: 346-366.        [ Links ]

12. De Jersey, N.J. 1962. Triassic spores and pollen grains from the Ipswich coalfield. Geological Survey of Queensland publication 307: 1-18.        [ Links ]

13. De Jersey, N.J. 1963. Jurassic spores and pollen from the Marburg Sandstone. Geological Survey of Queensland publication 313: 1-18.        [ Links ]

14. De Jersey, N.J. 1964. Triassic spores and pollen from the Bundamba Group. Geological Survey of Queensland publication 321: 1-21.        [ Links ]

15. De Jersey, N.J. 1968. Triassic spores and pollen grains from the Clematis Sandstone. Geological Survey of Queensland publication 338, palaeontological papers 14: 1-44.        [ Links ]

16. De Jersey, N.J. 1970. Triassic miospores from the Blackstone Formation, Aberdare Conglomerate and Raceview Formation. Geological Survey of Queensland publication 348, palaeontological paper 22: 1-41.        [ Links ]

17. De Jersey, N.J. 1971a. Early Jurassic miospores from the Helidon Sandstone. Geological Survey of Queensland publication 351, palaeontological papers 25: 1-46.        [ Links ]

18. De Jersey, N.J. 1971b. Triassic miospores from the Tivoli Formation and Kholo Sub-Group. Geological Survey of Queensland publication 353, palaeontological papers 28: 1-40.        [ Links ]

19. De Jersey, N.J. 1972. Triassic miospores from the Esk Beds. Publications of the Geological Survey of Queensland, palaeontological papers 46: 1-39.        [ Links ]

20. De Jersey, N.J. 1975. Miospore zones in the Lower Mesozoic of southern Queensland. In: K.S.W. Campbell (ed.), Gondwana Geology. Canberra, Australian National University Press 159-172.        [ Links ]

21. De Jersey, N.J. and Hamilton, M. 1967. Triassic spores and pollen grains from the Moolayember Formation. Geological Survey of Queensland publication 336, palaeontological papers 10: 1-61.        [ Links ]

22. De Jersey, N.J. and Paten, R.J. 1964. Jurassic spores and pollen grains from the Surat Basin. Geological Survey of Queensland publication 322: 18 pp.        [ Links ]

23. De Jersey, N.J. and Raine, J.I. 1990. Triassic and earliest Jurassic miospores from the Murihiku Supergroup, New Zealand. New Zealand Geological Survey Paleontological Bulletin 62: 1-164.        [ Links ]

24. Delcourt, A.F., Dettmann, M.E. and Hughes, N.F. 1963. Revision of some Lower Cretaceous microspores from Belgium. Palaeontology 6: 282-292.        [ Links ]

25. Delcourt, A. and Sprumont, G. 1955. Spores et grains de pollen du Wealdien du Hainault. Mémoires de Société Belge de Géologie, de Paléontologie et d'Hydrologie. (Nouvelle série) 5: 73 pp.        [ Links ]

26. De Lima, M.R. 1980. Palinologia da Formação Santana (Cretaceo do nordeste do Brasil. III. Descrição sistematica dos polens da Turma Plicates (Subturma Costates). Ameghiniana 17: 15- 47.        [ Links ]

27. Dettmann, M.E. 1963. Upper Mesozoic microfloras from South- Eastern Australia. Proceedings of the Royal Society of Victoria 77: 1-148.        [ Links ]

28. Dolby, J.H. and Balme, B.E. 1976. Triassic palynology of the Carnarvon Basin, Western Australia. Review of Paleobotany and Palynology 22: 105-168.        [ Links ]

29. Evans, P.R. 1970: Revision of the miospore genera Perotrilites Erdtman ex Couper 1953 and Diaphanospora Balme and Hassell 1962. Australian Bureau of Mineral Resources, Geology and Geophysics, Bulletin 116: 65-82.        [ Links ]

30. Filatoff, J. 1975. Jurassic palynology of the Perth Basin, Western Australia. Palaeontographica Abteilung B 154: 1-113.        [ Links ]

31. Fossa Mancini, E. 1937. La formación continental de Paso Flores en el Limay. Notas Meseo de La Plata 2, Geología 3: 89 pp.        [ Links ]

32. Foster, C.B. 1975. Permian plant microfossils from the Blair Athol Coal Measures, Central Queensland, Australia. Palaeontographica Abteilung B 154: 121-171.        [ Links ]

33. Foster, C.B. 1979. Permian plant microfossils of the Blair Athol Coal Measures, Baralaba Coal Measures, and basal Rewan Formation of Queensland. Geological Survey of Queensland publication 372, palaeontological paper 45: 244 pp.        [ Links ]

34. Frenguelli, J. 1948. Estratigrafía y edad del llamado "Rético" en la Argentina. GAEA 8: 159-309.        [ Links ]

35. Galli, C.A. 1969. Descripción geológica de la Hoja 39c, Piedra del Aguila, Provincia de Neuquén y de Río Negro. Dirección Nacional de Geología y Minería, Boletín 111: 69 pp.        [ Links ]

36. Ganuza, D., Spalletti, L., Morel, E. and Arrondo, O. 1995. Paleofloras y sedimentología de una sucesión lacustre - fluvial del Triásico tardío: La Formación Paso Flores en Cañadón de Pancho, Neuquén, Argentina. Ameghiniana 32: 3-18.        [ Links ]

37. González Díaz, E. F. 1982. Sedimentitas del Triásico superior continental en el valle del Río Collón Curá, entre los arroyos Quemquemtreu y Caleufú, Provincia de Neuquén. Revista de la Asociación Geológica Argentina 37: 214-220.        [ Links ]

38. Hart, G.F. 1960: Microfloral investigation of the Lower Coal Measures (K2); Ketewaka-Mchuchuma Coalfield, Tanganyika. Bulletin of the Geological Survey of Tanganyika 30: 18 pp.        [ Links ]

39. Hart, G.F. 1965. Microflora from the Ketewaca-Mchuchuma Coalfield, Tanganyika. Tanganyika Geological Survey Bulletin 36 [1963]: 1-27.        [ Links ]

40. Helby, R.J., Morgan, R. and Partridge, A.D. 1987. A palynological zonation of the Australian Mesozoic. Memoirs of the Australasian Association of Palaeontologists 4: 141-155.        [ Links ]

41. Herbst, R. 1965. Algunos esporomorfos del Triásico de Argentina. Ameghiniana 4: 141-155.        [ Links ]

42. Herbst, R. 1970. Estudio palinológico de la Cuenca Ischigualasto- Villa Unión (Triásico), provincias de San Juan-La Rioja. I. Introducción. II. Monoaperturados. Ameghiniana 7: 83-97.        [ Links ]

43. Ibrahim, A.C. 1933: Sporenformen des Aegir-horizonts des Ruhr- Reviers. University of Berlin, Konrad Triltsch, Wurzburg: 47 pp.        [ Links ]

44. Jain, R.K. 1968. Middle Triassic pollen grains and spores from Minas de Petróleo Beds of Cacheuta Formation (Upper Gondwana), Argentina. Palaeontographica Abteilung B 122: 1-47.        [ Links ]

45. Jansonius, J. 1962. Palynology of Permian and Triassic sediments, Peace River area, western Canada. Palaeontographica Abteilung B 110: 35-98.        [ Links ]

46. Jenchen, U. 2001. Fazies und Geochemie in kontinentalen Trias- Becken im westlichen Argentinien und in Patagonien (30º-50º S). Münstersche Forschungen zur Geologie und Paläontologie 91: 441.        [ Links ]

47. Jenchen, U. and Rosenfeld, U. 2002. Continental Triassic in Argentina: response to tectonic activity. Journal of South American Earth Sciences 15: 461-479.        [ Links ]

48. Klaus, W. 1960. Sporen der Karnischen Stufe der ostalpinen Trias. Jahrbuch der Geologischen Bundesanstalt 5: 107-184.        [ Links ]

49. Klaus, W., 1960: Sporen der Karnischen Stufe der ostalpinen Trias. Jahrbuch der Geologischen Bundesanstalt 5: 107-184.        [ Links ]

50. Lapido, O.R., Lizuaín, A. and Núñez, E. 1984. La cobertura sedimentaria Mesozoica. In: V. Ramos (ed.), Geología y recursos naturales de la Provincia de Río Negro. Relatorio 9º Congreso Geológico Argentino: pp. 139-162.        [ Links ]

51. Legarreta, L. and Gulisano, C.A. 1989. Análisis estratigráfico secuencial de la Cuenca Neuquina (Triásico superior - Terciario inferior). In: G. Chebli and L. Spalletti (eds.), Cuencas Sedimentarias Argentinas. Serie Correlación Geológica, Universidad Nacional de Tucumán 6: 221-243.        [ Links ]

52. Leschik, G. 1955 [1956]. Die Keuperflora von Neuewelt bei Basel. II. Die Iso- und Mikrosporen. Schweizerische Paläontologische Abhandlungen 72: 1-70.        [ Links ]

53. Mädler, K. 1964a. Die geologische Verbreitung von Sporen und Pollen in der Deutschen Trias. Beihefte zum Geologischen Jahrbuch 65: 1-147.        [ Links ]

54. Mädler, K. 1964b. Bemerkenswerte Sporenformen aus dem Keuper und dem Unteren Lias. Fortschritte Geologischen Rheinland und Westfalen 12: 169-200.        [ Links ]

55. Maheshwari, H.K. and Banerji, J. 1975. Lower Triassic palynomorphs from the Maitur Formation, West Bengal. Palaeontographica, Abteilung B 152: 149-190.        [ Links ]

56. McKellar, J.L. 1974. Jurassic miospores from the upper Evergreen Formation, Hutton Sandstone and basal Injune Creek Group, northeastern Surat Basin. Geological Survey of Queensland publication 361, palaeontological papers 35: 89 pp.        [ Links ]

57. McKellar, J.L. 1982. Palynostratigraphy of samples from GSQ Ipswich 26. Queensland Government Mining Journal 83 (973): 509-523.        [ Links ]

58. Morel, E.M., Ganuza, D.G. and Zúñiga, A. 1999. Revisión paleoflorística de la Formación Paso Flores, Triásico superior de Río Negro y del Neuquén. Revista de la Asociación Geológica Argentina 54: 389-406.        [ Links ]

59. Muller, J. 1968. Palynology of the Pedawan and Plateau Sandstone formations (Cretaceous-Eocene) in Sarawak, Malaysia. Micropaleontology 14: 1-37.        [ Links ]

60. Norris, G. 1965. Triassic and Jurassic miospores and acritarchs from the Beacon and Ferrar Groups, Victoria Land, Antarctica. New Zealand Journal of Geology and Geophysics 8: 236-277.        [ Links ]

61. Nullo, F.E. 1979. Descripción geológica de la Hoja 39c, Paso Flores, Provincia de Río Negro. Boletín Servicio Geológico Nacional 167: 1-70.        [ Links ]

62. Pflug, H.D. 1953. Zur Entstehung und Entwicklung des angiospermiden Pollens in der Erdgeschichte. Palaeontographica Abteilung B 95: 60-171.        [ Links ]

63. Playford, G. 1965. Plant microfossils from Triassic sediments near Poatina, Tasmania. Journal of the Geological Society of Australia 12: 173-210.        [ Links ]

64. Playford, G. and Dettmann, M.E. 1965. Rhaeto-Liassic plant microfossils from the Leigh Creek Coal Measures, South Australia. Senckenbergiana Lethaea 46: 127-181.        [ Links ]

65. Playford, G. and Dino, R. 2002. Permian palynofloral assemblages of the Chaco-Paraná Basin, Argentina: Systematics and stratigraphic significance. Revista Española de Micropaleontología 34: 235-288.        [ Links ]

66. Playford, G., Rigby, J.F. and Archibald, D.C. 1982. A Middle Triassic flora from the Moolayember Formation, Bowen Basin, Queensland. Geological Survey of Queensland publication 380: 1-52.        [ Links ]

67. Pocock, S.A. 1962. Microfloral analysis and age determination of strata at the Jurassic-Cretaceous boundary in the Western Canada Plains. Palaeontographica Abteilung B 111: 1-95.        [ Links ]

68. Pocock, S.A. 1964 [1965]. Pollen and spores of the Chlamydospermidae and Schizaeaceae from Upper Mannville strata of the Saskatoon area of Saskatchewan. Grana palynologica 5: 129-209.        [ Links ]

69. Pocock, S.A.J. 1970. Palynology of the Jurassic sediments of Western Canada. I. Palaeontographica Abteilung B 130: 12-136.        [ Links ]

70. Potonié, R. 1956. Synopsis der Gattungen der Sporae Dispersae. I. Teil: Sporites. Beihefte zum geologischen Jahrbuch 23: 103 pp.        [ Links ]

71. Potonié, R. 1962. Synopsis der Sporae in situ. Die Sporen der fossilen Fruktifikationen (Thallophyta bis Gymnospermophyta) im natürlichen System und im Vergleich mit den Sporae dispersae. Beihefte zum Geologischen Jahrbuch 52: 204 pp.        [ Links ]

72. Potonié, R. 1967. Versuch der Einordnung der fossilen Sporae dispersae in das phylogenetische System der Pflanzenfamilien. I. Teil: Thallophyta bis Gnetales. II. Teil. Angiospermae. Forschungsber. Landesämtern Geologischen Nordrhein. Westfalische 1761: 310 pp.        [ Links ]

73. Potonié, R. 1970. Synopsis der Gattungen der Sporae Dispersae. V Teil: Nachträge zu allen Gruppen (Turmae). Beihefte zum geologischen Jahrbuch 87: 222 pp.        [ Links ]

74. Potonié, R. and Klaus, W. 1954. Einige Sporengattungen des alpinen Salzgebirges. Geologische Jahrbuch 68: 517-546.        [ Links ]

75. Potonié, R. and Kremp, G. 1954. Die Gattungen der paläozoischen Sporae dispersae und ihre Stratigraphie. Geologische Jahrbuch 69: 111-194.        [ Links ]

76. Raine, J.I., de Jersey, N.J. and Ryan, K.G. 1988: Ultrastructure and lycopsid affinity of Densoisporites psilatus (de Jersey) comb. nov. from the Triassic of New Zealand and Queensland. Memoir of the Association of Australasian Palaeontologists 5: 79-88.        [ Links ]

77. Raine, J.I., Mildenhall, D.C. and Kennedy, E.M. 2006. New Zealand fossil spores and pollen: an illustrated catalog. 2^nd ed. GNS Science miscellaneous series no. 4. Web: http://www.gns.cri.nz/what/earthhist/fossils/spore_pollen/catalog/index.htm.        [ Links ]

78. Reiser, R.F. and Williams, A.J. 1969. Palynology of the Lower Jurassic sediments of the northern Surat Basin. Geological Survey of Queensland 399, palaeontological papers 15: 24 pp.        [ Links ]

79. Sajjadi, F. and Playford, G. 2002a. Systematic and stratigraphic palynology of Late Jurassic-earliest Cretaceous strata of the Eromanga Basin, Queensland, Australia: Part one. Palaeontographica Abteilung B 261: 1-97.        [ Links ]

80. Sajjadi, F. and Playford, G. 2002b. Systematic and stratigraphic palynology of Late Jurassic-earliest Cretaceous strata of the Eromanga Basin, Queensland, Australia: Part two. Palaeontographica Abteilung B 261: 99-165.        [ Links ]

81. Schulz, E. 1967. Sporenpaläontologische Untersuchungen rätoliassischer Schichten im Zentralteil des Germanischen Beckens. Paläontologische Abhandlungen, Paläobotanik B 2: 427- 633.        [ Links ]

82. Scott, R.A., 1960: Pollen of Ephedra from the Chinle Formation (Upper Triassic) and the genus Equisetosporites. Micropaleontology 6: 271-276.        [ Links ]

83. Skarby, A. 1964. Revision of Gleicheniidites senonicus Ross. Stockholm Contributions in Geology 11: 59-77.        [ Links ]

84. Smith, A.H.V. and Butterworth, M.A. 1967. Miospores in the coal seams of the Carboniferous of Great Britain. Special Papers in Palaeontology 1: 324 pp.        [ Links ]

85. Spalletti, L.A. 1996. Lower Jurassic anastomosing fluvial deposits from the cratonic margin of an Andean back-arc Basin, Argentina. GeoResearch Forum 1-2: 265-274.        [ Links ]

86. Spalletti, L.A., Arrondo, O.G., Morel, E and Ganuza, D.G. 1990. Los depósitos fluviales de la cuenca Triásica superior en el sector noroeste del Macizo Nordpatagónico. Revista de la Asociación Geológica Argentina 43 [1988]: 544 - 557.        [ Links ]

87. Stevens, J. 1981. Palynology of the Callide Basin, east-central Queensland. University of Queensland papers, Department of Geology 9: 35 pp.        [ Links ]

88. Stipanicic, P.N. and Zavattieri, A. M. 2002. Formación Comallo, prov. de Río Negro. In: P.N. Stipanicic and C.A. Marsicano (eds.): Léxico Estratigráfico de la Argentina, Volumen VIII: Triásico. Asociación Geológica Argentina, Serie "B" (Didáctica y Complementaria) 26: 98-99.        [ Links ]

89. Stover, L.E. 1964. Cretaceous Ephedroid pollen from West Africa. Micropaleontology 10: 145-156.        [ Links ]

90. Volkheimer, W. 1972. Estudio palinológico de un carbón Caloviano de Neuquén y consideraciones sobre los paleoclimas jurásicos de la Argentina. Revista del Museo de La Plata, Paleontología 6: 101-157.        [ Links ]

91. Volkheimer, W. and Melendi, D.L. 1976. Palinomorfos como fósiles guía. Tercera parte: Técnicas de laboratorio palinológico. Revista Minera de Geología y Mineralogía 34: 119-130.        [ Links ]

92. Wilson, L.R. and Venkatachala, B.S. 1963. Thymospora, a new name for Verrucososporites. Oklahoma Geological Notes 23: 75-79.        [ Links ]

93. Zavattieri, A.M. 1986. Estudio palinológico de la Formación Potrerillos (Triásico) en su localidad tipo, Cuenca Cuyana (provincia de Mendoza, Argentina). Parte 1. Esporas triletes y monoletes. Revista Española de Micropaleontología 18: 247-294. Madrid.        [ Links ]

94. Zavattieri, A.M. 1997. Palinoflora de la Formación Paso Flores (Triásico Superior), Cañadón de Pancho, Neuquén. Resultados preliminares. 10º Simposio Argentino de Paleobotánica y Palinología (Mendoza). Resúmenes: 58.        [ Links ]

95. Zavattieri, A.M. 2002. Anexo 4: Microfloras. In: P.N. Stipanicic and C.A. Marsicano (eds.), Léxico Estratigráfico de la Argentina, Volumen 8: Triásico. Asociación Geológica Argentina, Serie "B" (Didáctica y Complementaria) 26: 318-321.        [ Links ]

96. Zavattieri, A.M. and Batten, D.J. 1996. Chapter 20B. Miospores from Argentinian Triassic deposits and their potential for intercontinental correlation. In: J. Jansonius and D.C. McGregor (eds.), Palynology: principles and applications. American Association of Stratigraphic Palynologists Foundation 2: 767-778.        [ Links ]

97. Zavattieri, A.M. and Rojo, L.D. 2005. Estudio microflorístico de las formaciones Potrerillos y Cacheuta (Triásico) en el sur del cerro Cacheuta, Mendoza, Argentina. Parte 2. Ameghiniana 42: 513-534.        [ Links ]

98. Zavattieri, A.M., Rosenfeld, U. and Volkheimer, W. 2008. Palynofacies analysis and sedimentary environment of Early Jurassic coastal sediments at the southern border of the Neuquén Basin, Argentina. Journal of South American Earth Sciences 25: 227-245.        [ Links ]

99. Zavattieri, A.M. and Stipanicic, P.N. 2002. Formación Cerro Puntudo, prov. de Río Negro. En: P.N. Stipanicic and C.A. Marsicano (eds.), Léxico Estratigráfico de la Argentina, Volumen VIII: Triásico. Asociación Geológica Argentina, Serie "B" (Didáctica y Complementaria) 26: 74-75.        [ Links ]

100. Zavattieri, A.M. and Volkheimer, W. 2001. Palynologic and paleoenvironmental characterization of strata near the Triassic- Jurassic boundary in northern Patagonia, Argentina. 34th Annual Meeting of the American Association of Stratigraphic Palynologists, San Antonio (Texas, 2001), Abstracts: 51.        [ Links ]

101. Zavattieri, A.M., Volkheimer, W. and Rosenfeld, U. 1994. Palynology and facies of the Late Triassic of Comallo (Northern Patagonia, Argentina). Zentralblatt für Geologie und Paläontologie, Teil I (1/2): 133-154.        [ Links ]

102. Zippi, P.A. 1998. Freshwater algae from the Mattagami Formation (Albian), Ontario: Paleoecology, botanical affinities, and systematic taxonomy. Micropaleontology 44, Supplement 1: 1-78.        [ Links ]

Recibido: 6 de julio de 2007.
Aceptado: 4 de abril de 2008.