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Journal ArticleDOI

Palaeoecology of the Aptian Santana Formation (Northeastern Brazil)

01 Oct 1973-Palaeogeography, Palaeoclimatology, Palaeoecology (Elsevier)-Vol. 14, Iss: 2, pp 97-118
TL;DR: In the interior of northeastern Brazil there occurs the Santana Formation of Aptian age, composed lithologically of three members: Crato - an alternation of thin limestones and shales; Ipubi - gypsum; and Romualdo - almost pure limestone as discussed by the authors.
About: This article is published in Palaeogeography, Palaeoclimatology, Palaeoecology.The article was published on 1973-10-01. It has received 72 citations till now. The article focuses on the topics: Santana Formation & Aptian.
Citations
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Journal ArticleDOI
TL;DR: The Araripe Basin comprises four main stratigraphic sequences separated by unconformities: 1. a Paleozoic sequence consisting of the Cariri Formation, 2. a Juro-Neocomian sequence composed of the Brejo Santo Formation, Missao Velha Formation (redefined) and Abaiara Formation, 3. an Aptian-Albian-Cenomanian sequence, and 4. an Exu Formation.
Abstract: The Araripe Basin comprises four main stratigraphic sequences separated by unconformities: 1. a Paleozoic sequence composed of the Cariri Formation; 2. a Juro-Neocomian sequence composed of the Brejo Santo Formation, Missao Velha Formation (redefined) and Abaiara Formation; 3. an Aptian-Albian sequence composed of the Barbalha Formation and Santana Formation; and 4. an Albian-Cenomanian sequence composed of the Exu Formation. The Juro-Neocomian sequence is characterized by horsts and grabens displayed in two sub-basins: Cariri and Serrolândia subbasins. The Aptian-Cenomanian is characterized by sub-horizontal bedding and localized brittle deformation. The events of sedimentation, erosion, and deformation proposed for the sequences above, integrate the Phanerozoic evolution in Northeastern Brazil. The Paleozoic deposits which have, in attempt, been classified as Upper Ordovician/Lower Silurian, have also been interpreted as an extension of the cratonic Parnaiba Basin. The Juro-Neoconian sequence is u» sedimentary response to the mechanical subsidence brought about by the Gondwana rifting processes. The Barbalha and Santana formations comprise a transgressive-regressive cycle characterized by short-lived sea ingression which has deposited an exuberant fossiliferous carbonate concretions level and extensive gypsum beds. The presence of alluvial deposits of Exu Formation, deposited contemporaneously to a global eustatic sea level rising, suggests an epeirogenic uplift early in the Albian-Cenomanian time.

134 citations


Cites background from "Palaeoecology of the Aptian Santana..."

  • ...Mabesoone & Tinoco (1973) constataram que a Formação Exu, na porção oeste da bacia, compõem-se de dois membros com características litológicas diferentes, denominando-os informalmente de membros inferior e superior....

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  • ...O registro fossilífero é abundante, sendo também encontrados conchostráceos, fragmentos vegetais lenhosos carbonizados, além de pequenos peixes (Dastilbe elongatus) e insetos (Mabesoone & Tinoco 1973, Martins 1990)....

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  • ...Além disso, é comum a utilização dos termos em desacordo com a proposta original de Beurlen (1971), tanto que Mabesoone & Tinoco (1973) colocam o nível de folhelhos com concreções carbonáticas fossilíferas dentro do Membro Romualdo, quando pela definição pertenceriam ao Membro Ipubi....

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Journal ArticleDOI
David M. Martill1
01 Jul 1990-Nature
TL;DR: In this article, the authors report the study of striated muscle tissue from a fossil elopomorph fish from the Santana Formation, in which subcellular ultrastructural features are distinguishable.
Abstract: THE Santana Formation (Lower Cretaceous, Aptian/Lower Albian) of Ceara, Brazil, contains many exceptionally preserved fish fossils within carbonate concretions1,2. These concretions formed before compaction of the sediment and nucleated around carcasses of fish killed in mass-mortality events. Some concretions may contain several fish, preserved in three dimensions with fully articulated skeletons1. A few specimens contain calcium phosphate in the form of cryptocrystalline hydroxyapatite. This occurs as coatings on bones and as a replacement of tissues. Samples of mineralized soft tissues can easily be liberated from the concretions by immersion in 10% acetic acid3. Of several mineral phases often preserving soft tissues, calcium phosphate and silica probably offer the greatest resolution of detail4. Fossilized soft tissues are most frequently found in fishes, although in the Santana Formation pterosaur wing membrane5 and the cuticles of arthropods6,7 have been reported. I report here the study of striated muscle tissue from a fossil elopomorph fish8 from this formation, in which subcellular ultrastructural features are distinguishable. The exceptional degree of preservation of the specimen raises interesting questions about the mechanism of fossilization.

120 citations

Journal ArticleDOI
TL;DR: In the case of the Romualdo Member of the Santana Formation Konservat Lagerstatten of north-east Brazil, it was first dated as Cretaceous by Agassiz on the basis of fish fossils obtained by Bavarian explorers Spix and Martius between 1817 and 1820 as discussed by the authors.

106 citations

Journal ArticleDOI
TL;DR: This study brings together new information of the megafossil record of Welwitschia-like plants and also reports of pollen said to be similar to that of WelWitschia from Lower Cretaceous sediments.
Abstract: Welwitschiaceae, a family in the Gnetales, is known today from only one extant species, Welwitschia mirabilis. This species is distributed in the Namibian desert, along the western coast of southern Africa, about 10 km inland from the coast. Very little is known about the fossil record of this family. Lower Cretaceous megafossils of various organs, assigned to Welwitschiaceae, are presented here. These fossils include young stems with paired cotyledons attached (Welwitschiella austroamericana n. gen. et sp.), isolated leaves (Welwitschiophyllum brasiliense n. gen. et sp.), and axes bearing male cones (Welwitschiostrobus murili n. gen. et sp.). They were collected in the Crato Formation, which is dated by palynomorphs and ostracods as Late Aptian (114 to 112 million years ago). These sediments are exposed in the Araripe Basin of northeastern Brazil. This study brings together new information of the megafossil record of Welwitschia-like plants and also reports of pollen said to be similar to that of Welwitschia from Lower Cretaceous sediments.

98 citations


Additional excerpts

  • ...…and Hills, 1961, 1976, 1979; (18) Krutzsch, 1961; (19–25) Lima, 1978a, b, 1979, 1980, 1981, 1982, 1984; (26) Lima and Coelho, 1987; (27) Lima and Perinotto, 1984; (28) Mabesoone and Tinoco, 1973; (29) Müller, 1966; (30) Osborn et al., 1993; (31, 32) Pons, 1983, 1988; (33, 34) Pons et al., 1990,…...

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References
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Journal ArticleDOI
Robert A. Berner1
12 Jan 1968-Science
TL;DR: Bacterial decomposition of butterfish and smelts in small sealed jars containing seawater and other solutions, for periods ranging from 65 to 205 days, results in a large increase in concentrations of dissolved bicarbonate, carbonate, and ammonia (plus volatile amines).
Abstract: Bacterial decomposition of butterfish and smelts in small sealed jars containing seawater and other solutions, for periods ranging from 65 to 205 days, results in a large increase in concentrations of dissolved bicarbonate, carbonate, and ammonia (plus volatile amines). Accompanying this is a rise in pH and the precipitation of Ca(++) ion from solution. The Ca(++) is not precipitated as CaCO(3) but instead as a mixture of calcium fatty acid salts or soaps with from 14 to 18 carbon atoms. This can be explained by the thermodynamic instability of CaCO(3) relative to Ca soaps in the presence of excess free fatty acid. It is suggested that some ancient CaCO(3) concretions, especially those enclosing fossils of soft-bodied organisms, may have formed rapidly after death in the form of natural Ca soap (adipocere) which was later converted to CaCO(3).

230 citations

Journal ArticleDOI
TL;DR: Theoretical aspects of the formation of fossil assemblages are explored for the purpose of obtaining criteria and methods for the reconstruction of circumstances of preservation of shallow-water marine organisms.
Abstract: Theoretical aspects of the formation of fossil assemblages are explored for the purpose of obtaining criteria and methods for the reconstruction of circumstances of preservation of shallow-water marine organisms. Models are developed which represent: (1) a death assemblage preserved under conditions of rapid burial; (2) an assemblage preserved in situ under conditions of gradual accumulation; and (3) an assemblage composed almost entirely of remains transported to the site of burial. The histories represented by the models influence the following features of fossil assemblages: faunal composition, morphologic composition, density, disassociation of hard parts, fragmentation, surface condition of fossils, chemical and mineralogical composition of fossils, orientation, dispersion, and the texture and structure of the sedimentary aggregate. The expressions of these features indicate that biological criteria are more indicative of the mode of accumulation than physical criteria. The stretched-line method of sampling provides a means of obtaining objective and repeatable measures of features of the fossil assemblages in place. It is restricted to sediments in which fossils can be recovered readily. A rank-correlation analysis of 11 samples from the Pleistocene Millerton formation of Tomales Bay, California, is given as an example of a means of evaluating the interrelations of variables measured by the line technique.

169 citations

Journal ArticleDOI
31 Dec 1964-Copeia

117 citations

Journal ArticleDOI
TL;DR: In this paper, a new type of sedimentation balance for grain sizes from 500 to 5 µ has been made by means of a new kind of scale for arithmetic probability paper, and the results have been plotted on arithmetic probability papers to study the phenomena caused by the differentiation of detritus.
Abstract: Mechanical analyses of deposits of various sedimentary environments have been made by means of a new type of sedimentation balance for grain sizes from 500 to 5 µ. The results have been plotted on arithmetic probability paper. Well-sorted sands give on this paper straight lines proving that they have a symmetrical size frequency distribution when an arithmetic grade scale is used. The size frequency distribution of the sand and silt grades of argillaceous sediments commonly is a part of a symmetrical one. The arithmetic probability paper enables us to study the phenomena caused by the differentiation of the transported detritus. Three main types of frequency distribution called R-, S- and T-types occur in sedimentary deposits due to the sorting of the transporting medium. The characteristic features of a sedimentary size frequency distribution are found in the extremes and not in the central half of the distribution. Statistical values based on quartiles, therefore, do not give satisfactory results. The characteristic shape of the extremes of the distributions caused by the differentiating action are frequently blurred by later mixing of material due to variations in the capacity of the transporting medium. Composite frequency distributions, however, are commonly recognized if the results are plotted on the probability paper. As far as analyses by means of the sedimentation balance have been made sedimentary environments can be recognized by the predominance or alternation of certain frequency distributions.

107 citations

MonographDOI
01 Jan 1921

5 citations