Benthonic Foraminifera from the Lower - Middle Jurassic transition of the central sector of the Lusitanian Basin: the Zambujal de Alcaria section
Keywords:
foraminifera, Lower – Middle Jurassic, Zambujal de Alcaria, Lusitanian Basin, biostratigraphy, paleoecologyAbstract
The present work describes the benthonic fora-minifera assemblages recorded in the Upper Toarcian (Aalensis Biozone) – Lower Aalenian (Opalinum Biozone) – Middle Aalenian (Bradfordensis Biozone) from the Zambujal de Alcaria Section (Central Sector of the Lusitanian Basin, Portugal). Over the studied stratigraphic range, 20 samples, from which 5.291 foraminifera were obtained, which have enabled the determination of the foraminiferal assemblages composition, as well as the analysis of their evolution.
From the taxonomic point of view, 5 suborders, 13 families, 25 genera and 57 species were recognized; the most abundant specimens in the assemblages belong to the Lagenina Suborder, Vaginulinidae Family, Lenticulina genera and Lenticulina toarcense Payard species.
From the biostratigraphic point of view, the presence of Astacolus dorbignyi (Roemer), allows the correlation of the section with other biostrati-graphic scales based in foraminifera, established for the northern hemisphere. The analysis of the species present in each association and their evolu-tion along the section, enable the differentiation of four groups of species and highlight the presence of some key events, recognized by the first or last occurrence of some species or by the increase of the relative abundance of one species.
The quantitative analysis of the benthonic fora-minifera assemblages enabled the evaluation of their diversity, as well as their evolution over the studied stratigraphic range. The resulting values, based on the application of several diversity indices, indicate that the assemblages are, in general, scarce, but relatively diverse.
From the paleoecological point of view, the fora-minifera assemblages registered along the Zambujal de Alcaria Section would occupy zones of the marine platform, with normal salinity and well-oxygenated. The foraminifera would have had benthonic, infaunal and epifaunal modes of life. All the studied assemblages are characteristic of the boreal realm and are typical of Jurassic carbonate platforms.
References
AZERÊDO, A. C. Formalização da litostratigrafia do Jurássico Inferior e Médio do Maciço Calcário Estremenho, Bacia Lusitânica. Comunicações Geológicas, Instituto Nacional de Engenharia, Tecnologia e Inovação, Lisboa, v. 94, p. 29-51, 2007.
AZERÊDO, A. C.; DUARTE, L. V.; HENRIQUES, M. H.; MANUPPELLA, G. Da dinâmica continental no Triásico aos mares do Jurássico Inferior e Médio. Cadernos de Geologia de Portugal, Instituto Geológico e Mineiro, Lisboa, 2003. 43 p.
BARBIERI, F. Micropaleontologia del Lias e Dogger del pozzo Ragusa 1 (Sicilia). Rivista Italiana di Paleontologia e Stratigrafia, v. 70, n. 4, p. 709-830, 1964.
BARTENSTEIN, H.; BRAND, E. Mikro-paläontologische Unter suchungen zur Stratigraphie des nordwest-deutschen Lias und Doggers. 1937. 224 p. (Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft, v. 439).
BEERBOWER, J. R.; JORDAN, D. Application of infor-mation theory to paleontologic problems: I Taxonomic diversity . Journal of Paleontology, v. 43, n. 5, p. 1184-1198, 1969.
BOUTAKIOUT, M. Les foraminifères du Jurassique des Rides sud-rifaines et des régions voisines (Maroc). Lyon: Villeurbanne, Centre des sciences de la terre, Université Claude Bernard. Documents des Laboratoires de Géologie de Lyon, v. 112, p. 1-247, 1990.
CANALES, M. L. Foraminíferos del Aaleniense en la Cuenca Vasco-Cantábrica. 1998. 759 f. Tesis (Doctoral) – Universidad Complutense de Madrid, Departamento de Paleontología, Madrid, 1998.
CANALES, M. L. Los foraminíferos del Aaleniense (Jurásico Médio) en la Cuenca Vasco-Cantábrica (N de España). Revista Española de Micropaleontología, v. 33, n. 3, p. 253-438, 2001.
CANALES, M. L.; HENRIQUES, M. H. Análisis Cuantitativo de los Foraminíferos del Aaleniense (Jurásico Médio) de la Sección de Murtinheira (Cabo Mondego, W de Portugal). Consideraciones Paleoecológicas: In: CARVALHO, I. S.; CASSAB. R. C. T.; SCHWANKE, C.; CARVALHO, M. A.; FERNANDES, A. C. S.; RODRIGUES, M. A. C.; CARVALHO, M. S. S.; ARAI, M.; OLIVEIRA, M. E. Q.(Eds.) Paleontologia: cenários de vida. Interciência, 2007. v. 2, p. 382-393.
CANALES, M. L.; HENRIQUES, M. H. Foraminifera from the Aalenian and the Bajocian GSSP (Middle Jurassic) of Murtinheira section (Cabo Mondego, West Portugal): biostratigraphy and paleoenvironmental implications. Marine Micropaleontology, v. 67, n. 1-2, p. 155-179, 2008.
INSTITUTO GEOLÓGICO DE PORTUGAL (Lisboa). Carta Geológica de Portugal. Escala 1:500.000. Serviços Geológicos de Portugal, 1992. 2 f. Lisboa.
COPESTAKE, P.; JOHNSON, B. The Hettangian to Toarcian. In: JENKINS, D. G.; MURRAY, J. W. (Eds.) Stratigraphical Atlas of Fossil Foraminifera. 2 ed. Ellis Horwood Limited, Chichester, p. 129-188, 1989. (British Micropaleontological Society Series).
COPESTAKE, P.; JOHNSON, B. Lower Jurassic (Hettangian-Toarcian) Foraminifera from the Mochras Borehole, North Wales (UK) and their application to a worldwide biozonation. In: OERTLI, H. J. (Ed.) Elf Aquitaine, Esso REP and Total CFP. BENTHOS’83, INTERNATIONAL SYMPOSIUM ON BENTHIC FORAMINIFERA, 2., 1983. Pau and Bordeaux, 1984. p. 183-184.
GRADSTEIN, F. M. Jurassic Grand Banks foraminifera. Journal of Foraminiferal Research, v. 8, n. 2, p. 97-109, 1978.
GRIGELIS, A.; NORLING, E. Jurassic geology and foraminiferal faunas in the NW part of the East European Platform: a Lithuanian-Swedish geotraverse study. Geological Survey of Sweden, 1999, 101 p.
HALLAM, A. Faunal realms and facies in the Jurassic. Palaeontology, v. 12, n. 1, p. 1-18, 1969.
HAMMER, O.; HARPER, D. A. T. Paleontological Data Analysis. Oxford: Blackwell Publishing, 2006. 351 p.
HAYNES, J. R. Foraminifera. London: Macmillan, 1981. 433 p.
HENRIQUES, M. H. Aalenian of the Zambujal de Alcaria section (Central Lusitanian Basin, Portugal): advances in Jurassic research. In: INTERNATIONAL SYMPOSIUM ON THE JURASSIC SYSTEM, 5., Vancouver, 1998. Proceedings… Canada: Trans Tech Publications, Zurich, v. 6, p. 85-94, 2000.
JOHNSON, B. Ecological ranges of selected Toarcian and Domerian (Jurassic) foraminiferal species from Wales. In: INTERNATIONAL SYMPOSIUM ON BENTHONIC FORAMINIFERA OF CONTINENTAL MARGINS, 1., 1975. Halifax, 1975. Maritime Sediments Special Publication, 1976. v. 1, p. 545-556.
KULLBERG, J. C. Evolução Tectónica Mesozóica da Bacia Lusitaniana. 2000. 280 f. Tese (Doutorado) – Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia, Portugal, 2000.
KULLBERG, J. C.; ROCHA, R. B.; SOARES, A. F.; REY, J.; TERRINHA, P.; CALLAPEZ, P.; MARTINS, L. A Bacia Lusitaniana: estratigrafia, paleogeografia e tectônica. In: DIAS, R., ARAÚJO, A., TERRINHA, P.; KULLBERG, J. C. (Ed.). Geologia de Portugal no contexto da Ibéria. Évora: Universidade Évora, 2006. p. 317-368.
LOEBLICH, A. R.; TAPPAN, H. Foraminifera genera and their classification. New York: Van Nostrand Reinhold Company, v. 2, 1988, 970 p.
MANUPPELLA, G.; ANTUNES, A. T.; ALMEIDA, C. A. C.; AZERÊDO, A. C.; BARBOSA, B.; CARDOSO, J. L.; CRISPIM, J. A.; DUARTE, L. V.; HENRIQUES, M. H.; MARTINS, L. T.; RAMALHO, M. M.; SANTOS, V.; TERRINHA, P. Carta Geológica de Portugal. Notícia Explicativa da Folha 27-A (Vila Nova de Ourém). Escala 1:50.000. 2 ed. Lisboa: Instituto Geológico e Mineiro, 2000. 156 p.
MIRA, F. J. Foraminíferos del Lías margoso de las Cordilleras Béticas. Zona Subbética. 1986. 242 f. Tesis (Doctoral) – Universidad de Granada, Departamento de Estratigrafía y Paleontología, España, 1986.
MURRAY, J. W. Syndepositional Dissolution of Calcareous Foraminifera in Modern Shallow-water Sediments. Marine Micropaleontology, v. 15, n. 1-2, p. 117-121, 1989.
MURRAY, J. W. Ecology and Paleoecology of Ben-thic Foraminifera. New York: John Wiley, 1991. 397 p.
NORLING, E. Jurassic stratigraphy and foraminifera of Western Scania, southern Sweden. Sveriges Geologiska Undersökning, v. 47, p. 1-120, 1972.
OHMERT, W. Erdgeschichtliche Bedeutung der Schichtenfolge bei Wittnau. Informationen der Geologisches Landesamt Baden-Württemberg, v. 8, p. 7-42, 1996.
OHMERT, W., PRAUSS, M., WEISS, M. The Toarcian-Aalenian boundary at Wittnau (Oberrhein area, south west Germany), a possible boundary stratotype for the Aalenian. In: MORTON, N. (Eds.) (Proceed-ings of) Conference on Aalenian and Bajocians Stratigraphy, Isle of Skye. Scotland: Birbeck College, University of London, p. 7-31, Apr. 1991.
PENA DOS REIS, R.; CORROCHANO, A.; BERNARDES, C.; CUNHA, P. P.; DINIS, J. L. O Meso-Cenozóico da mar-gem atlântica portuguesa. In: CONGRESSO GEOLÓGICO DE ESPAÑA, 3.; CONGRESSO LATIONOAMERICANO DE GEOLOGIA, 8., 1992. Guias de las excursiones geológicas. Espanha: Universidad de Salamanca, 1992. p. 115-138.
RASMUSSEN, E. S.; LOMHOLT, S.; ANDERSEN, C.; VEJBAEK, O. V. Aspects of the structural evolution of the Lusitanian Basin in Portugal and the shelf and slope area offshore Portugal. Tectonophysics, v. 300, n. 1-4, p. 199-225, Dec. 1998.
RIBEIRO, A.; ANTUNES, M. T.; FERREIRA, M. P.; ROCHA, R. B.; SOARES, A. F.; ZBYSZEWSKI, G.; MOITINHO DE ALMEIDA, F. M.; CARVALHO, D.; MONTEIRO, J. H. Introduction à la géologie géné-rale du Portugal. Portugal: Serviços Geológicos de Portugal, 1979. 114 p.
SCHEIBNEROVÁ, V. On the discovery of Microfauna in the Opalinus Beds (Klippen Belt, West Carpathians). Mitteilungen der Bayerischen Staatssammlung. Paläontologie und Historische Geolgie, v. 8, p. 51-65, 1968.
SOARES, A. F.; ROCHA, R. B.; ELMI, S.; HENRIQUES, M. H.; MOUTERDE, R.; ALMERAS, Y.; RUGET, C.; MARQUES, J.; DUARTE, L. V.; CARAPITO, M. C.; KULLBERG, J. Le sous-bassin nord-lusitanien (Portugal) du Trias au Jurassique moyen: histoire d’un rift avorté. C. R. Académie Science Paris, série 2, v. 317, p. 1659-1666, 1993.
TYSZKA, J. Paleoenvironmental implications from ich-nological and microfaunal analyses of Bajocian Spotty Carbonates, Pieniny Klippen Belt, Polish Carpathians. Palaios, v. 9, n. 2, p. 175-187, 1994a.
TYSZKA, J. Response of Middle Jurassic benthic fo-raminiferal morphogroups to dysoxic/anoxic condi-tions in the Pieniny Klippen Basin, Polish Carpathians. Palaeogeography Palaeoclimatology Palaeo-ecoly, v. 110, n. 1-2, p. 55-81, July 1994b.
TYSZKA, J. Foraminiferal Biozonation of the Early and Middle Jurassic in the Pieniny Klippen Belt (Carpathians). Bulletin of the Polish Academy of Sciences, Ear th Sciences, v. 47, n. 1, p. 27-46, 1999.
TYSZKA, J. Microfossil assemblages as bathymetric indicators of the Toarcian/Aalenian Fleckenmergel- facies in the Carpathian Pieniny Klippen Belt. Geologica Carpathica, v. 52, n. 3, p. 147-158, 2001.
WERNLI, R.; SEPTFONTAINE, M. Micropaléontologie comparée du Dogger du Jura méridional (France) et des Préalpes Médianes Plastiques romandes (Suisse). Eclogae geologicae Helvetiae, v. 64, n. 3, p. 437-458, 1971.
WILSON, R. C. L. A reconnaissance study of Upper Jurassic sediments of the Lusitanian Basin. Ciências da Terra (UNL), n. 5, p. 53-85, 1979.
WILSON, R. C. L. Mesozoic development of the Lusitanian Basin, Por tugal. Revist a de la Sociedad Geológica de España, v. 1, n. 3-4, p. 393-407, 1988.
WILSON, R. C. L.; HISCOTT, R. N.; WILLIS, M. G.; GRADSTEIN, F. M. The Lusitanian Basin of West Central Portugal: Mesozoic and Tertiary Tectonic, Stratigraphic, and Subsidence History. In: TANKARD, A. J.; BALKWILL, H. (Eds.) Extensional tectonics and stratigraphy of the North Atlantic margins. Tulsa: AAPG, 1989. p. 341-361. (AAPG Memoir, 46).
