Pirabas Formation Research Articles

The Pirabas Formation (Early Miocene from Brazil) and the Tropical Western Central Atlantic Subprovince

The Neogene Tropical Western Central Atlantic-South American faunal assemblage from the Pirabas Formation (Early Miocene) has specific and unique features, which distinguishes it from the rest of the Proto-Caribbean Subprovince in diversity, paleoceanographic condition and ecosystems. Principal component analysis (PCA) distinguished three groups of localities with similar faunas (Group A: Ilha de Fortaleza, Colônia Pedro Teixeira and Praia de Fortalezinha; Group B: Estação Agronômica, Ilha de Marajó, Turiacu, Baixo Parnaíba, Aricuru and Salinópolis; Group C: Capanema B-17 Mine) and five different depositional facies (surf zone, beach, lagoons, tidal channel and tidal delta), in agreement with previous geological studies showing heterogeneous paleoenvironments among the outcrops. These heterogeneous lithostratigraphic sequences suggest different members, and may be related to different ages along the Pirabas sequence. The Neogene Northwestern Atlantic Subprovince is erected to encompass this entire geographical area.

New remains of a gavialoid crocodilian from the late Oligocene−early Miocene of the Pirabas Formation, Brazil

New specimens of gavialoids collected from the Pirabas Formation, Brazil, provide additional information about the evolutionary evolution of Gavialoidea during the late Oligocene−early Miocene. We describe a specimen that has a more gracile symphyseal mandible than any other South American gavialoid. This fossil represents an unusually diverse radiation of gavialoids that were probably ecologically differentiated from each other by size and dietary specialization. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163, S132–S139.

The Genera Haplocytheridea Stephenson, 1936 and Cytheridea Bosquet, 1852 (Subphylum Crustacea, Class Ostracoda) from the Early Miocene Pirabas Formation, Brazil

The genera Haplocytheridea and Cytheridea have Tethyan origins and a wide paleobiogeographic and stratigraphic distribution, ranging from the Cretaceous to Recent. Both of them have been recorded in northern South America, but only Cytheridea has been found in the northern Cretaceous basins of Brazil. The genus Haplocytheridea is recorded, for the first time, in the Early Miocene deposits of the Pirabas Formation of northern Brazil, from a 20 m-thick succession of carbonate and argillaceous rocks deposited in lagoonal and restricted platform environments. Among the ten Haplocytheridea species identified, four are new: H. variopunctata n. sp., H. sandbergi n. sp., H. pirabasensis n. sp . and H. sinuosa n . sp . In addition, three new species of Cytheridea are also described: C. coimbrai n. sp., C. pirabasensis n. sp. and C. purperae n. sp. The highest frequencies and abundances of both genera, in the studied section, are thought to be associated with nearshore to brackish water settings.

Estudio de los foraminíferos de la Formación Pirabas (Mioceno Inferior), estado de Pará, Brasil y su correlación con faunas del Caribe

Las variaciones verticales en el contenido de las asociaciones de foraminíferos, detectadas por medio de estudios cuantitativos y cualitativos, permitieron el reconocimiento de ocho biofacies en la Formación Pirabas, correspondientes a los subambientes de plataforma somera y lagunar. Los sedimentos fueron depositadosen las áreas lagunares en función de las variaciones en la profundidad y la salinidad.La presencia de los foraminíferos planctónicos confirma la edad Mioceno Inferior para la Formación Pirabas. El registro de Globorotalia kugleri Bolli y Globigerinoides primordius Blow & Banner en la base y Globigerinoides altiaperturus Bolli y Globigerinoides trilobus trilobus (Reuss) en el tope del afloramiento puede ser co-rrelacionado con las Zonas Bioestratigráficas Internacionales N4 y N5 de Blow (1969)

Considerações filogenéticas e biogeografia histórica dos malacostráceos (decápodes e isópodes) cenozóicos do Brasil

This work deals the analysis of the Historical Biogeography of the brazilian cenozoic paleocarcinofauna, recorded in the Maria Farinha, Tremembé and Pirabas formations. This taxa has affinity with the tethian carcinofaunas and modern aspect. The paleobiogeographic setting allows to situate their biological events of the origin, dispersional and irradiation trends in the tethian, south high latitude and amphitropical origins. The majority of the brazilian carcinofauna has affinity with the tethian faune, that migrate in two seaways, west and east. The phylogenetic relationships suggest appearence of the Thalassinoidea group from the Caridea infraordo. The Retroplumidae family (genus Costacopluma) recorded at Maria Farinha Formation is directed related with the cenozoic ocypodid (i.e. genus Uca at Pirabas Formation, living in the same ecological niches and environmental tolerances. Also, the morphological similarities between Xanthoidea and Portunoidea in the Paleocene, suggest monophyletic relationships with Goneplacidae and Hexapodidae. The detailed phylogenetic studies in Goneplacidae family reveals that Glyphithyreus genus is related with Eucratopsinae subfamily.

Shark teeth from Pirabas Formation (Lower Miocene), northeastern Amazonia, Brazil

The shark fauna (Chondrichthyes: Elasmobranchii) of Pirabas Formation is one of the most representative and diversified of the Neogene of South America. This fauna is associated with the early Miocene transgression resulting from the global sea level rise. In this paper, the composition of the Pirabas shark fauna is re-evaluated based on new fossil findings. The occurrence of the following taxa is confirmed: Carcharhinus sp.1, Carcharhinus sp.2, Carcharhinuscf. macloti, Carcharhinus priscus, Galeocerdo sp., Sphyrna cf. media, Hemipristis serra, Carcharodon subauriculatus, Isurus sp., Ginglymostoma sp., Nebrius obliquus.

Shark teeth from Pirabas Formation (Lower Miocene), northeastern Amazonia, Brazil

Shark teeth from Pirabas Formation (Lower Miocene), northeastern Amazonia, Brazil

Novos registros de crustáceos decápodes do Cenozóico (Paleoceno e Mioceno Inferior) do Brasil

The crustacean decapods Calappilia brooksi Ross & Scolaro, 1964 and Arenaeus cribarius (Lamarck, 1818) are recognized in the Castelo ecofacies of the Pirabas Formation (Lower Miocene), Para State, and the species Dardanus fucosus Biffar & Provenzano, 1972, D. insignis (Saussure, 1858) e Glyphityreus sturgeoni Feldmann et al ., 1998 in the Maria Farinha Formation (Paleocene), Pernambuco State, Brazil. Calappilia brooksi and Glyphithyreus sturgeoni were registered in Williston and Castle Hayne formations, Eocene of Florida and North Carolina (USA), respectively. In the first time are recognized as fossils the species Arenaeus cribarians, Dardanus fucosus Biffar & Provenzano, 1972 and D. insignis (Saussure, 1858), registered in the recent american continent.

Chondrichthyan fauna from the Pirabas Formation, Miocene of Northern Brazil, with comments on paleobiogeography

The chondrichthyan fauna from the Pirabas Formation is redescribed.Only thirteen nominal taxa are considered valid. From these taxa, ten were reassigned to extant taxa (Carcharhinus sorrah, Carcharhinus perezii,Galeocerdo cuvier, Rhizoprionodon lalandii, Sphyrna sp., Hemipristis elongatus, Carcharodon carcharias, Isurus oxyrinchus, Nebrius ferrugineus, and indeterminate Myliobatidae), confirming the Neogene age of this formation. This elasmofauna is compared with other Caribbean and African Tertiary faunas.

New Decapods from the Navidad Formation (Miocene) of Chile

Abstract A new Miocene decapod fauna is described from the Navidad Formation of coastal Chile. The fauna includes five callianassoid taxa, none of which is preserved sufficiently to identify to species level. New species include Calappilia? chilensis, Hepatus spinimarginatus, Proterocarcinus navidad, Pilumnus cucaoensis, and Pinnixa navidadensis. A possible rhizopine member of the Pilumnidae Samouelle, 1819, is described. Trichopeltarion levis Casadio et al., 2004, previously known from the late Oligocene of western Argentina, was also recovered from these rocks. Calappa circularis Beurlen, from the lower Miocene Pirabas Formation in Brazil, is herein referred to Calappilia. This report greatly increases the known number of fossil decapods from Chile and sets the stage for paleobiogeographic comparison of the decapod faunas of Chile and Argentina.

Tectonics and paleogeography of the Marajó Basin, northern Brazil

The Marajó Basin area presents geologic and geomorphologic features chiefly due to the Mesozoic extension and post-Miocene neotectonics. The extension event with an Early and a Late Cretaceous phases originated four sub-basins that constitutes the Marajó Basin, with a thick continental clastic sequence showing marine influence. NW and NNW normal faults and NE and ENE strike-slip faults controlled the basin geometry. The extension, related to the Equatorial Atlantic opening, propagated into the continent along crustal weakness zones of the Precambrian Tumucumaque, Amapá and Araguaia orogenic belts. The neotectonic event is a strike-slip regime which developed transtensional basins filled in by Upper Tertiary shallow marine (Pirabas Formation) and transitional sequences (Barreiras Group), followed by Quaternary fluvial deposits and transitional sequences derived from the Amazon and Tocantins rivers and the Marajoara estuary. The current landscape has a typical estuarine morphology. The coast morphology presents sea-cliffs on transitional Upper Tertiary sequences, while inwards dominate hills sustained by Mid-Pleistocene lateritic crust, with a flat erosive surface at 70 m. In the eastern Marajó Island several generations of paleochannels associated with fluvial-estuarine sequences are recognized, while a fluvial-marine plain is widespread on its western side.

SISTEMÁTICA E TAFONOMIA DOS CRUSTÁCEOS DECÁPODES DA ECOFÁCIES CAPANEMA DA FORMAÇÃO PIRABAS (MIOCENO INFERIOR), ESTADO DO PARÁ

The systematic study of the decapod crustaceans of the Capanema ecofacies of the Pirabas formation (Lower Miocene), sampled in the B-17 deposit of the Cimentos do Brasil S/ACIBRASA, Capanema district, NE Para State, has confirmed the occurence of the Calappa circularis Beurlen, Acanthocarpus obscurus (Rathbun), Portunus haitensis Rathbun, Callinectes reticulatus Rathbun and Scylla costata Rathbun species. Also recognized are Portunus atecuicitilis Vega et al. , P. spinimanus Latreille, Necronectes tajinensis Vega et al. and Tetraxanthus rathbunae Chace, for the first time in Pirabas formation, and one undetermined species, Callinectes sp.1. The taphonomic study reveals that the fossiliferous concentration was formed by the only event, and that your burial occured in situ . The biostratinomic features suggest depositional environment with high energy during the burial event. The brachyura majority was buried after their death- normal position, although 45% represents specimens surprised by burial- escape position. The presence of the young and adults decapod suggest a event of high mortality, that implies in catastrophic event.

Ocorrência de Uma nova espécie de Escleractíneo (Coelenterata) na Formação Pirabas (Eomioceno), Estado do Pará

Caryophyllia (Acanthocyathus) fernandesi n.sp .occuring in the Capanema and Castelo ecofacies of Pirabas formation (Eomiocene), in NE Para state, is described. This new species is characterized by strong costae and large costal spines, best developed on costae along the longer calicular axis.

PROSPECÇÃO DE ÁGUA SUBTERRÂNEA NA REGIÃO DE BELÉM (PA) ATRAVÉS DE PERFILAGEM GEOFÍSICA DE POÇO E ELETRORRESISTIVIDADE

Today, about 46% of potable water consumed in Belem region comes underground. This shows the importance of this source inspite of abundance of surface water in this region (existence of rivers, riverlets, streams and even a bay). Present of enormous quantity of groundwater in Barreiras and the Pirabas formation sediments contribute this alternative water resource. In this context, we demonstrate the need to investigate these resources with the intention to exploit them optimally. Therefore, two geophysical methods are used in an integrated from: Vertical Electric Soundings (VES) and Geophysical Well Logging, employing gamma rays, spontaneous potential (SP) and electric resistance. Aquifers of two environments are discerned. The first up to about 160 m of depth whit predominantly sandy bodies in the from second is constituted of extensive sandy packages along with clay lenses extending from 160 m to about 285 m depth. The superior portion can be explored economically the relativity small water supplies like condominiums, while for greater demand such as the public supply for the town, the lows part could be explored it provides a higher discharge and a good quality water as the deeper aquifers as well protect against pollution’s.

OCORRÊNCIA DA FORMAÇÃO PIRABAS (MIOCENO INFERIOR) NA BACIA DE BARREIRINHAS, MARANHÃO

A new outcrop of the Pirabas Formation was found in the right bank of the igarape Marciano, 3.5 km south of Caete, county of Pinheiro da Cruz. Field observations and examination of the collected samples lead the authors to describe a new geologic setting of the formation, inside the Barreirinhas basin. Moreover, the fossil content includes specimens of genus Orthaulax, a gastropod considered as a good index-fossil lor a great number of Lower Miocene formations of the Caribbean Province. A special kind of pyrite was found, probably biogenic, resulting from metasomatic processes affecting calcium carbonates.

Ocorrências de Foraminíferos Fósseis no Brasil

São descritos pela primeira vez alguns foraminiferos fósseis do Brasil. O artigo inicia com um breve apanhado das informações pré¬ vias sobre ocorrências de foraminiferos fósseis do Brasil. Discute-se material com foraminiferos procedente de Caraparú, Estado do Pará, provavelmente referivel à formação Pirabas de idade miocenica. Não foram atingidas, porém, determinações sistemáticas. Segue-se a descrição de alguns foraminiferos do Paleozoico Superior, procedentes do Rio Parauarí (formação Itaituba). dentre os quais foram genericamente reconhecidos Endothyra e Plectogyra. São considerados, então, foraminiferos cretácicos vindos do Rio Gramane, Estado de Paraiba do Norte e Ponta dos Barcos, Estado de Sergipe. Detem-se o autor mais demoradamente sobre fósseis coletados na Ponta de Pirabas (formação P irabas), cuja idade é considerada miocenica. Descreve: Quinqueloculina sp. a, Q. sp. b., Q. sp. c, Pytgo sp. a, P. sp. b., Peneroplis sp., Discovbis? sp.., “Rotalia ’ sp., Gyroidina? sp., Eponides sp., Nonion sp. a, N . sp. b