Carnets de Géologie [Notebooks on Geology] - Letter 2013/05 (CG2013_L05)

Paleotropical pollen grains from the Neuquén Group, , Argentina

1 Patricia VALLATI

Abstract: This paper discusses the presence of elater-bearing pollen grains and other characteristic paleotropical palynomorphs in the mid to Late Neuquén Group at the El Zampal locality, south of Mendoza Province, Argentina. The elaterates characterize the equatorial paleofloristic province in the -. The species Elateroplicites africaensis is present in the pollen assemblage recovered from the lower section of the Huincul Formation, a basal unit of the studied Neuquén Group. It represents the first record of elater- bearing pollen grains in Argentina and marks their southernmost extension. Other conspicuous paleo- tropical elements recorded in different lithostratigraphic units of the Neuquén Group include gymno- spermous polyplicate pollen grains and angiosperm pollen, including two species of the periporate pol- len genus Cretacaeiporites and the triporate pollen species Confossia vulgaris. The paleobiogeographic and biostratigraphic significance of the paleotropical sporomorph record in the Cretaceous palynofloras of the Neuquén Group at El Zampal is herein discussed. Key Words: Paleotropical palynomorphs; mid and ; Neuquén Group; Patagonia; Ar- gentina.

Citation: VALLATI P. (2013).- Paleotropical pollen grains from the Neuquén Group, Patagonia, Argenti- na.- Carnets de Géologie [Notebooks on Geology], Brest, Letter 2013/05 (CG2013_L05), p. 273-279. Résumé : Grains de pollen paléo-tropicaux dans le groupe de Neuquén, Patagonie, Argenti- ne.- Cette note discute la présence de grains de pollen à élatères et d'autres palynomorphes paléo-tro- picaux caractéristiques dans le Groupe de Neuquén d'âge Crétacé moyen à supérieur de la localité d'El Zampal au Sud de la Province de Mendoza en Argentine. Au cours de l'intervalle Albien-Cénomanien, les élatèrates caractérisent la province paléofloristique équatoriale. L'espèce Elateroplicites africaensis est présente dans l'association de pollen extraite de la partie inférieure de la Formation Huincul, à la base du Groupe de Neuquén. C'est la première fois que des grains de pollen à élatères sont découverts en Argentine et cela correspond aussi à leur occurrence la plus méridionale. D'autres éléments paléo-tropicaux incontestables sont présents dans différentes unités lithostratigraphiques du Groupe de Neuquén : ce sont, par exemple, des grains de pollen polypli- cates de gymnospermes et des grains d'angiospermes, incluant deux espèces à grains périporés du genre Cretacaeisporites, ainsi que l'espèce Confossia vulgaris à grains triporés. La signification paléo- géographique et biostratigraphique de l'association de sporomorphes crétacés paléo-tropicaux extraite du Groupe de Neuquén à El Zampal est discutée. Mots-Clefs : Palynomorphes paléo-tropicaux ; Crétacé moyen et supérieur ; Groupe de Neuquén ; Pa- tagonie ; Argentine. Introduction locality, the purple of the Candele- ros Formation and the base of the Huincul For- This contribution focuses on the paleotropi- mation are not exposed (Fig. IIA). The Neuquén cal pollen recovered from different lithostrati- Group includes terrestrial post-orogenic depo- graphic units of the Neuquén Group at the El sits related to the main Miranic Orogeny (also Zampal section (approximately 36°32' S, known in the literature as the Patagonidic Oro- 69°39' W), 115 km to the south of Malargüe, geny) (STIPANICIC & RODRIGO, 1969; LEANZA, southern Mendoza Province (Fig. I). At this 2010).

1 Laboratorio de Bioestratigrafía, UNPSJB, Ciudad Universitaria, 9000, Comodoro Rivadavia, Chubut (Argentina) [email protected] Manuscript online since August 2, 2013 [Scientific and language editor: Robert W. SCOTT; copy editor: Bruno GRANIER]

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W Figure I: Location map of the El Zampal section in the Neuquén Basin.

Rich remains of dinosaurs and other reptiles 2006, 2010). Typical paleotropical constituents have been recovered from various levels of the such as Elateroplicites africaensis, Cretacaeipo- Neuquén Group (see compilations by LEANZA et rites polygonalis, Cretacaeiporites scabratus al., 2004). Taking into account the micropa- and Confossia vulgaris were recorded in diffe- leontological record, calcareous microfossil as- rent stratigraphic units of the Neuquén Group semblages including charophytes and ostracods (VALLATI, 2006, 2010, this contribution) (see have contributed to the chronology of these Fig. II). continental beds (MUSACCHIO, 2000, 2006, Paleotropical pollen grains have been repor- 2010). ted from other Cretaceous palynofloras in Ar- Previous palynological studies of the Neu- gentina, which also include endemic austral ta- quén Group have yielded angiosperm pollen xa, suggesting a mixed character for these as- assemblages comprised of diversified pollen semblages (PRÁMPARO, 1990; VALLATI, 2002, types. These include the Fraxinoipollenites 2006, 2010; BARREDA & ARCHANGELSKY, 2006). fragilis assemblage (?Albian-Cenomanian) in In this contribution, the paleobiogeographic, the upper section of the Huincul Formation, the paleoecological and biostratigraphic significance Cretacaeiporites polygonalis level in the Cerro of the Cretaceous tropical pollen grains in Lisandro Formation (Cenomanian) and the Northern Patagonia is discussed, taking into ac- Confossia vulgaris-Cretacaeiporites scabratus count their restricted distribution in the Equato- assemblage (-?) in the rial Region (HERNGREEN et al., 1996). Bajo de la Carpa Formation (VALLATI, 2002,

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Figure II: Schematic section of the Neuquén Group at El Zampal (modified from ULIANA & MUSACCHIO, 1978). A: lower levels of the unit, B: upper levels of the unit. Paleotropical representatives in green mudstone beds yielded well preserved palynomorphs including the elater-bearing Northern Patagonia pollen grain Elateroplicites africaensis and a sin- 1. Elater-bearing pollen grains gle specimen identified as Galeacornea? sp. (Fig. III, 8). The study of additional material is The elaterate group includes several taxa of necessary in order to corroborate the presence enigmatic pollen grains with protuberances of this last mentioned taxon in Patagonia. from the Albian-Cenomanian Elaterates provin- ce, originally restricted to northern South Ame- 1.1. Botanical affinity rica and northern Africa (HERNGREEN & CHLONOVA, In spite of the fact that the elater-bearing 1981; HERNGREEN et al., 1996). The protuberan- pollen grains have been intensely studied, their ces that characterize this otherwise heteroge- botanical affinity remains a matter of discussion neous group of pollen grains, are only superfi- among specialists. The morphological cha- cially compared to the elaters of the spores of racteristics of these grains are unknown from extinct calamitaceans and of Equisetum, the extant pollen grains and up to now in situ speci- unique extant genus representing the Spheno- mens have not been found. A probable ephe- phyta. droid affinity for the elaterates has been propo- The conspicuous tropical pollen grains, sed by different authors (DINO et al., 1999; reported here, were mainly recovered from the SCHRANK, 2001). The elaterates are, otherwise, Huincul Formation in the lower section of the suggested to have been a group of extinct unit (Fig. IIA, Section I). This section includes plants with sophisticated mechanisms of polli- massive grey and yellowish brown sandstones, nation, which developed and diversified in the interbedded with mudstones, siltstones and paleotropics. purple sandstones. Within this interval, the dark

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1.2. Biostratigraphic and paleoecologi- 2.1. Botanical affinity cal aspects HERNGREEN (1974) suggested that the species The elater-bearing grains have a restricted Cretacaeiporites scabratus had an affinity with stratigraphic distribution. They appeared in the the genera Trimenia, Thalictrum and Alisma. Lower Albian sediments of the low latitude re- BOLTENHAGEN (1975) also noted the similarity of gion, diversified, became numerically important some species of Cretacaeiporites with pollen of in the Upper Albian-Cenomanian stratigraphic the family Caryophyllaceae. More recently, FRIIS interval and disappeared at the top of the Ceno- et al. (2011) considered the presence of Creta- manian during the rapid diversification and rise caeiporites scabratus in the mid to Upper Creta- to dominance of the angiosperms (HERNGREEN & ceous of Brazil and Africa, as the oldest poten- DUENAS JIMENEZ, 1990; HERNGREEN et al., 1996). tial record of the Trimenaceae. Elateroplicites, in particular, is restricted to the 2.2. Biostratigraphic interest Middle Albian-Cenomanian interval (HERNGREEN Cretacaeiporites scabratus is distributed in et al., 1996). The record of elater-bearing the Albian-Campanian of Brazil (see VALLATI, grains supports the previously suggested ?Al- 2010) and the Upper Albian-Santonian of bian-Cenomanian age for the Huincul palynoflo- northern Africa (M.S. MAHMOUD & A.E. MAHMOUD, ra at El Zampal (VALLATI, 2006). 2007). Cretacacaeiporites polygonalis is a con- The paleotropical Elaterates Province repre- spicuous element in paleotropical Middle Albian- sents warm arid or semi-arid conditions (HERN- Early Cenomanian assemblages of Brazil, África GREEN et al., 1996; ZOBAA et al., 2013). The pre- and Perú and decreases in abundance in the sence of Elateroplicites at the latitude of Upper Cenomanian, when the triporates are Northern Patagonia suggests the southward mi- first recorded. gration of favorable conditions for the expan- 3. Triporate pollen grains sion of the elater-bearing grains. Its restricted stratigraphic distribution in the lower section of Confossia vulgaris is a triporate pollen grain the Huincul Formation at El Zampal should be of uncertain botanical affinity. It represents a analyzed considering the probable fluctuating pollen probably endemic to South America and environmental conditions related to the main is present in the Patagonian Austral and Neu- Miranic Orogeny. These tectonic movements quén basins (STOUGH, 1968; PÖTHE DE BALDIS, were responsible for changing the regional slo- 1995; VALLATI, 2010) and in different Brazilian pe from the Pacific to the Atlantic, and cones- marginal basins, where it is distributed in the quent physiographic changes. In this sense, it Santonian-Middle Campanian stratigraphic is stressed that the Fraxinoipollenites fragilis interval (REGALI et al., 1974; REGALI, 1989). assemblage, previously recognized in the upper section of the unit (Fig. IIA, Section II), which is dominated by angiosperm pollen grains and has few Classopollis and polyplicate grains, sug- X Figure III: Paleotropical grains recognized in dif- ferent units of the Neuquén Group at El Zampal. In gests a humid climate (VALLATI, 2006). parenthesis slide numbers and coordinates in the mi- 2. Periporate pollen grains croscope. Scale bars = 10 μm. The genus Cretacaeiporites includes Creta- 1. Elateroplicites africaensis (CR.P.CV 536 3 19/110) ceous spherical periporate pollen grains with a 2. Elateroplicites africaensis (CR.P.CV 536 2 23/100) characteristic scabrate pore membrane. 3. Elateroplicites africaensis (CR.P.CV 536 1 3/87) Previous palynological studies of the Neu- 4. Elateroplicites africaensis (CR.P.CV 536 1 20/90) 5. Elateroplicites africaensis (CR.P.CV 536 F quén Group have highlighted the presence of 3.5/103) this pollen type (VALLATI, 2006, 2010). Cretacei- 6. Elateroplicites africaensis (CR.P.CV 536 1 20/96) porites polygonalis was reported from the Cerro 7. Loose elaters (CR.P.CV 536 4 23/97) Lisandro Formation characterizing a palynologi- 8. Galeacornea ? sp (CR.P.CV 536 1 11/86) cal level (VALLATI, 2006). Cretacaeiporites sca- 9. Cretacaeiporites scabratus (CR.P.CV 241 And bratus was, in turn, reported from the Santo- 6/109) nian-?Campanian Confossia vulgaris-Cretacei- 10. Cretacaeiporites scabratus (CR.P.CV 543M porites scabratus assemblage in the younger 15/108) Bajo de la Carpa Formation, in the upper levels 11. Cretacaeiporites scabratus (CR.P.CV 543B 12/95) 12. Cretacaeiporites polygonalis (CR.P.CV 863 N2 of the Neuquén Group (VALLATI, 2010). In the 10/112.5) present contribution, the species C. scabratus is 13. Cretacaeiporites polygonalis (CR.P.CV 863a also reported from the upper section of the 10/108.5) Huincul Formation (Fig. IIA, Section II). 14. Confossia vulgaris (CR.P.CV 543L 17/98) These records from the Neuquén Group sug- 15. Confossia vulgaris (CR.P.CV 54EZ3O 17/90) 16. Confossia vulgaris (CR.P.CV 543L 10/91) gest that the periporate pollen type was well 17. Equisetosporites sp. (CR.P.CV 536 5 23/94) diversified by the mid to Upper Cretaceous of 18. Equisetosporites sp. (CR.P.CV 536 6 15/105) Northern Patagonia. 19. Equisetosporites sp. ( CR.P.CV 536 3 21/95) 20. Equisetosporites sp. ( CR.P.CV 536 1 25/96)

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This angiosperm marker pollen characterizes The record of Elateroplicites africaensis in the palynomorph assemblage Confossia vulga- the Huincul Formation supports the ?Albian- ris-Cretacaeiporites scabratus (Santonian-?Early Cenomanian age previously suggested for the Campanian) recovered from the Bajo de la Car- Fraxinoipollenites fragilis assemblage recogni- pa Formation in the upper levels of the Neu- zed in the upper section of the unit (VALLATI, quén Group at El Zampal (Fig. IIB). 2002, 2006). 4. Polyplicate pollen grains Acknowledgements Cretaceous assemblages of the Equatorial Region are characterized by the common distri- This article is dedicated to the memory of bution of gymnospermous pollen with straight Professor Eduardo Aldo MUSACCHIO, who has permanently supported me in the development or twisted ribs (HERNGREEN et al., 1996). of palynological studies during the many years Although not abundant, this pollen type is shared in the Laboratory of Biostratigraphy at well diversified in palynological assemblages at the Universidad Nacional de la Patagonia San different levels of the Neuquén Group. In parti- Juan BOSCO (UNPSJB), Comodoro Rivadavia. cular, the liver-red colored siltstones and clay- stones of the Cerro Lisandro Formation and the I would like to thank two anonymous revie- Bajo de la Carpa Formation include several spe- wers for their careful reading and helpful com- cies of the genera Equisetosporites, Steevesi- ments that helped to improve the original pollenites, Gnetaceaepollenites and Singhia manuscript. (VALLATI, 2006, 2010). Bibliographic references New reports of polyplicate pollen grains are BARREDA V. & ARCHANGELSKY S. (2006).- The sou- herein presented for the same samples inclu- thernmost record of tropical pollen grains in ding elaterates in the lower section of the Huin- the mid-Cretaceous of Patagonia, Argenti- cul Formation. Among others, Equisetosporites na.- Cretaceous Research, London, vol. 27, cf. evidens and some specimens with irregular n° 6, p. 778-787. and sinuous twisted ridges, included as Equise- BOLTENHAGEN E. (1975).- Pollen périporé du tosporites spp. are recognized (Fig. III, 17-20). Crétacé Supérieur du Gabon.- Revue de Equisetosporites irregularis (HERNGREEN, 1973) Micropaléontologie, Paris, vol. 17, n° 17, p. LIMA, 1980 (Syn.: Ephedripites irregularis HERN- 164-170. GREEN, 1973), represented in the -Ceno- DINO R., POCKNALL D.T. & DETTMANN M.E. (1999).- manian stratigraphic interval in northeastern Morphology and ultrastructure of elater-bea- Brazilian basins and Africa, is a tropical species ring pollen from the Albian to Cenomanian of with twisted ribs and great morphological varia- Brazil and Ecuador: implications for botanical bility. The Patagonian specimens have thinner affinity.- Review of Palaeobotany and Paly- and more irregular ridges. nology, Amsterdam, vol. 105, n° 3-4, p. Conclusions 201–235. FRIIS E.M., CRANE R. & PEDERSEN K.R. (2011).- Distinctive paleotropical pollen taxa (Elatero- Early flowers and angiosperm evolution.- plicites africaensis, Cretacaeiporites spp., Con- Cambridge University Press, 596 p. fossia vulgaris, polyplicate pollen grains) have HERNGREEN G.F.W. (1974).- Palynology of been identified in the Neuquén Group at El Albian-Cenomanian strata of borehole 1-QS- Zampal, south of Mendoza Province. 1-MA, State of Maranhão, Brazil.- Pollen et The occurrence of these conspicuous paleo- Spores, Paris, vol. 15, n° 3-4, p. 514-555. tropical pollen grains in mid to Late Cretaceous HERNGREEN G.F.W. & CHLONOVA A.F. (1981).- Patagonian palynofloras suggests the southward Cretaceous microfloral provinces.- Pollen et migration of warm climatic conditions during Spores, Paris, vol. 23, n° 3-4, p. 441-555. this chronostratigraphic interval. HERNGREEN G.F.W. & DUENAS JIMENEZ H. (1990).- These pollen types represent significant Dating of the Cretaceous Formation, palynological markers for the entirely terrestrial and the relationship with the red beds of the Neuquén Group. Albian-Cenomanian African-South American microfloral province.- Review of Paleobotany The presence of the paleotropical species and Palynology, Amsterdam, vol. 66, n° 3-4, Cretacaeiporites polygonalis, Cretacaeiporites p. 349-359. scabratus and Elateroplicites africaensis in diffe- HERNGREEN G.F.W, KEDVES M., ROVNINA L.V. & rent units of this group is unique in Argentina. SMIRNOVA S.B. (1996).- Cretaceous palyno- The occurrence of elater-bearing pollen spe- floral provinces: a review. In: JANSONIUS J. & cies in the Huincul Formation represents the MC GREGOR D.C. (eds.), Palynology: princi- southernmost known report of this pollen type. ples and applications.- AASP (American Its restricted presence in the lower section of Association of Stratigraphic Palynologists) the unit may be indicative of specific (drier?) Foundation, Dallas, vol. 3, p. 1157-1188. environmental conditions.

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LEANZA H.A. (2010).- Las principales discordan- Association of Stratigraphic Palynologists) cias del Mesozoico de la Cuenca Neuquina Foundation, Dallas, p. 201-210. según observaciones de superficie.- Revista STOUGH J.B. (1968).- Palynomorphs from South del Museo Argentino de Ciencias Naturales, America. Part 1. New Late Cretaceous Buenos Aires, (n.s.), vol. 11, n° 2, p. 145- palynomorphs from southern South Ame- 184. rica.- The University of Kansas Paleontologi- LEANZA H.A., APESTEGUÍA S., NOVAS F.E. & DE LA cal Contribution Papers, Lawrence, vol. 32, FUENTE M.E. (2004).- Cretaceous terrestrial p. 1-8. beds from the Neuquén Basin (Argentina) ULIANA M.A. & MUSACCHIO E.A. (1978).- Microfó- and their tetrapod assemblages.- Cretaceous siles calcáreos no marinos del Cretácico Su- Research, London, vol. 25, n° 1, p. 61-87. perior en el Zampal, Provincia de Mendoza. MAHMOUD M.S. & MAHMOUD A.E. (2007).- Palyno- Argentina.- Ameghiniana, Buenos Aires, vol. logy of some Cretaceous mudstones from 15, n° 1-2, p. 111-135 southeast Aswan, Egypt: significance to re- VALLATI P. (2002).- Biostratigraphy of Creta- gional stratigraphy.- Journal of African Earth ceous non-marine sequences in Patagonia. Sciences, Oxford, vol. 47, p. 1–8 In: European Meeting on the Paleontology MUSACCHIO E.A. (2000).- Biostratigraphy and and Stratigraphy of Latin America, 3, 2002.- biogeography of Cretaceous Charophyta Expanded Abstracts, Toulouse, p. 124-127. from South America.- Cretaceous Research, VALLATI P. (2006).- Las primeras angiospermas London, vol. 21, n° 2-3, p. 211-220. en el Cretácico de la Cuenca Neuquina (cen- MUSACCHIO E.A. ( 2006).- Charophyta del Cretá- tro-oeste de Argentina): aspectos geológicos cico tardío y el Paleoceno del centro oeste de relacionados.- Revista Brasileira de Paleonto- Argentina.- Revista Brasileira de Paleontolo- logía, Porto Alegre, vol. 9, n° 1, p. 83-92. gía, Porto Alegre, vol. 9, n° 1, p. 93-100. VALLATI P. (2010).- Asociaciones palinológicas MUSACCHIO E.S. (2010).- Upper Cretaceous con angiospermas en el Cretácico Superior Lychnothamnus, Nitella y Tolypella (Charo- de la Cuenca Neuquina, Argentina.- Revista phyta) from Zampal, Argentina.- Cretaceous Brasilera de Paleontología, Porto Alegre, vol. Research, London, vol. 31, n° 5, p. 461-472. 13, n° 2, p. 143-158. PÖTHE DE BALDIS E.D. (1995).- Santonian micro- ZOBAA M.K., EL BEIALY S.Y., EL-SHEIKH H.A. & EL flora of Rio Guanaco Formation (continental BESHTAWY M.K. (2013).- –Cretaceous facies) from Rio Turbio profile, Santa Cruz palynomorphs, palynofacies, and petroleum Province, Argentine. In: South Atlantic potential of the Sharib-1X and Ghoroud-1X Mesozoic Correlations (IGCP Project n° 381), wells, north Western Desert, Egypt.- Journal 2, 1995.- Abstracts, Rio de Janeiro, p. 20. of African Earth Sciences, Oxford, vol. 78, p. PRÁMPARO M.B. (1990).- Palynostratigraphy of 51–65. the Lower Cretaceous of the San Luis Basin, Appendix Argentina. Its place in the Lower Cretaceous flora provinces pattern.- Neues Jahrbuch für List of species illustrated or mentioned in the Geologie und Paläontologie, Abhandlungen, text Stuttgart, Band 181, p. 255–266. Gymnosperm pollen grains REGALI M.S.P. (1989).- Evolução da paleoflora • Equisetosporites sp. (Fig. III, 17-20) no Cretáceo das margens equatorial e nord- este do Brasil.- Revista da Escola de Minas, • Equisetosporites irregularis (HERNGREEN, Ouro Preto, vol. 42, n° 4, p. 17-33. 1973) LIMA, 1980 (Syn.: Ephedripites REGALI M.S.P., UESUGUI N. & SANTOS A.S. irregularis HERNGREEN, 1973) (1974).- Palinologia dos sedimentos meso- • Equisetosporites cf. evidens (BOLKHOVITI- cenozóicos do Brasil (I).- Boletim Técnico NA) LIMA, 1980 Petrobrás, Rio de Janeiro, vol. 17, n° 3, p. • Elateroplicites africaensis HERNGREEN, 177-191. 1973 (Fig. III, 1-6) STIPANICIC P.N. & RODRIGO F. (1969).- El diastro- • Galeacornea? sp. (Fig. III, 8) fismo eo- y mesocretácico en Argentina y Chile, con referencias a los movimientos Angiosperm pollen grains jurásicos de la Patagonia.- Actas de las • Confossia vulgaris STOUGH, 1968 (Fig. Cuartas Jornadas Geológicas Argentinas, III, 14-16) Mendoza, tomo 2, p. 337-352. • Cretacaeiporites polygonalis (JARDINÉ & SCHRANK E. (2001).- Paleoecological aspects of MAGLOIRE) HERNGREEN, 1974 (Fig. III, 12- Afropolis/Elaterates peaks (Albian-Cenoma- 13) nian pollen) in the Cretaceous of Northern Sudan and Egypt. In: GOODMAN D.K., & • Cretacaeiporites scabratus (JARDINÉ & CLARKE R.T. (eds.), Proceedings of the IX MAGLOIRE) HERNGREEN, 1974 (Fig. III, 9- International Palynological Congress, Hou- 11) ston, Texas, U.S.A., 1996.- AASP (American • Fraxinoipollenites fragilis BURGER, 1993

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