Paleocene calcareous nannofossils biostratigraphy from the Sergipe Sub-basin, northeastern Brazil: Implications for this depositional environment

This study reports the first known occurrence of the Ediacaran fauna in northeastern Brazil (at Pacujá Municipality, northwestern state of Ceará) and presents preliminary interpretations of its significance. Regional correlation indicates that the fossils originated in the Jaibaras Basin and that they may represent a new geological system. The depositional environment can be attributed to a fluviomarine system. Nine Ediacaran species can be identified, including members of pandemic groups (e.g., Charniodiscus arboreus Glaessner, 1959; ?Charniodiscus concentricus Ford, 1958; Cyclomedusa davidi Sprigg, 1947; Ediacaria flindersi Sprigg, 1947; and Medusinites asteroides Sprigg, 1949) and endemic groups (e.g., Kimberella quadrata Glaessner & Wade, 1966; Palaeophragmodictya reticulata Gehling & Rigby, 1996; Parvancorina minchami Glaessner, 1958; and Pectinifrons abyssalis Bamforth, Narbonne, Anderson, 2008). Three ichnogenera are also present: Arenicolites Salter, 1857; Palaeophycus Hall, 1987; and Planolites Nicholson, 1873. The relative age of the deposits is between ?Ediacaran and Cambrian, and the fauna resembles the White Sea Assemblage. The bioturbation presents typical unbranched Ediacaran ichnogenera with little depth in the substrate. This previously unknown occurrence of the Ediacaran fauna reinforces the importance of the state of Ceará to Brazilian and global palaeontology.

Download Full-text

Towards an integrated stratigraphy of the Gramame Formation (Maastrichtian), CIPASA quarry, Pernambuco-Paraíba Basin, NE Brazil

Anuário do Instituto de Geociências - UFRJ ◽

10.11137/2006_1_81-94 ◽

2006 ◽

Vol 29 (1) ◽

pp. 81-94

Author(s):

Francisco Henrique de Oliveira Lima ◽

Eduardo A. M Koutsoukos

Keyword(s):

Order Type ◽

Passive Margin ◽

Northeastern Brazil ◽

Calcareous Nannofossils ◽

Calcareous Nannofossil ◽

Warm Climate ◽

Third Order ◽

Transgressive System Tract ◽

System Tract ◽

Integrated Stratigraphy

This study presents the integrated biostratigraphic (calcareous nannofossils and foraminifera), petrographic, geochemical and ichnological analyzes of the Gramame Formation (Maastrichtian) at the CIPASA Quarry section, in the Pernambuco-Paraíba Basin, northeastern Brazil. A high resolution calcareous nannofossil biostratigraphic study has been carried out, allowing to subdivide the studied section into three subzones of Maastrichtian age: CC25A, CC25B, and CC25C. Each biostratigraphic unit was further characterized by petrographic, geochemical and ichnological parameters. During the Maastrichtian the area was characterized by a dry and warm climate with low influx of terrigenous sediments. These conditions were fundamental to the widespread development of a carbonate ramp system in an outer neritic to bathyal setting, with deposition of alternating calcareous mudstones and argillaceous mudstones of the Gramame Formation. The Gramame Formation belongs to the transgressive system tract of second-order type, characteristic of a Passive Margin Sequence. The studied section consists of part of a third order deposicional cycle, which is arranged in a transgressive systems tract and a highstand systems tract. The lowstand systems tract was not characterized.

Download Full-text

Spectroscopic Analysis of a Theropod Dinosaur (Reptilia, Archosauria) from the Ipubi Formation, Araripe Basin, Northeastern Brazil

Journal of Spectroscopy ◽

10.1155/2013/437439 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 7

Author(s):

João Hermínio da Silva ◽

Francisco Eduardo de Sousa Filho ◽

Antônio Álamo Feitosa Saraiva ◽

Nádia Amanda Andrade ◽

Bartolomeu Cruz Viana ◽

...

Keyword(s):

Depositional Environment ◽

Spectroscopic Analysis ◽

Sedimentary Basin ◽

Northeastern Brazil ◽

Partial Substitution ◽

X Ray Diffraction ◽

Energy Dispersion Spectroscopy ◽

Theropod Dinosaur ◽

X Ray ◽

Stone Matrix

The Araripe Sedimentary Basin is known by the excellence of its fossils, regarding the preservation, diversity, and quantity. Here, we present a spectroscopic analysis using several experimental techniques (X-ray energy dispersion spectroscopy, Fourier-transform infrared spectroscopy) as well as X-ray diffraction and thermogravimetric analysis applied in small fragments of bones from the posterior members of a theropod dinosaur. The results agree regarding the different composition of the stone matrix and the fossilized bone, indicating a partial substitution of the material by elements present in the depositional environment. However, differently from what is believed to occur, there is evidence that pyritization is not the only mechanism of fossilization for a specimen of Ipubi formation, but calcification, additionally, plays an important role in the fossil production of this Formation.

Download Full-text