Oceanografia Ambiental
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Programa de Pós-Graduação em Oceanografia Ambiental
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Navegando Oceanografia Ambiental por Autor "Amado Filho, Gilberto Menezes"
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- ItemAnálise da composição e estrutura interna de rodolitos da Cadeia Vitória-Trindade(Universidade Federal do Espírito Santo, 2018-06-19) Menandro, Tarcila Franco; Amado Filho, Gilberto Menezes; https://orcid.org/0000-0002-6053-4915; http://lattes.cnpq.br/5734763044971419; Bastos, Alex Cardoso; https://orcid.org/0000-0002-1272-1134; http://lattes.cnpq.br/2951081353357019; https://orcid.org/0000-0003-1783-2607; http://lattes.cnpq.br/6958042160031234; Quaresma, Valéria da Silva; https://orcid.org/0000-0002-7470-6642; http://lattes.cnpq.br/9423011006200936; Pereira Filho, Guilherme Henrique; https://orcid.org/0000-0001-6078-2241; http://lattes.cnpq.br/1211745530577271; Brasileiro, Poliana Silva; https://orcid.org/0000-0001-5520-8907; http://lattes.cnpq.br/3652663799345776; Bahia, Ricardo da Gama; https://orcid.org/0000-0003-3274-8008; http://lattes.cnpq.br/3076005225100928Rodoliths are nodules composed mainly of calcareous algae and other subordinate encrusting organisms (SEO), formed by subsequent overlapping processes of incrustations. The rhodoliths of the Vitória-Trindade Seamount Chain presented as main builders the calcareous algae (genera Sporolithon, Mesophyllum, Lithothamnion, Hydrolithon and Titanoderma) and peyssonneliaceae (genus Peyssonnelia). The main groups of SEO were encrusting foraminifers (Homotrema rubrum, agglutinated foraminifera or encrusting foraminifera), bryozoans, serpulids and cirripids. In rhodoliths where the bioerosion is very high, obliteration of the morphological characters of calcareous algae occurs, and identification at the species level is impossible, making it difficult to characterize the environment since this must be done at the species level. The study of the composition of SEO is an alternative to the study of the algal assemblage in environments with high bioerosion index. The analysis of the composition of SEO was distinct between the seamount and the insular platform indicating local differences in these environments that would be influencing the establishment of organisms. The ichno-assemblage of the Vitória-Trindade Seamount Chain was composed of microperforations and macroperforations of the Entobia type (associated with perforating sponges); Gastrochaenolites (associated with bivalves) and Trypanites (associated with polychaetes and sipunculus worms). The study of the ichno-assemblage identified an environment with low sedimentation rate and low hydrodynamics that allowed the development for long uninterrupted period of bioerosion. The formation of empty spaces by the bioerosion process allows the deposition of sediment that can trap benthic macroforaminifera. In Jaseur the genus Amphistegina was more frequent in both collection sites and in Trindade it was the genus Archaias that presented greater contribution. The large number of perforations due to the intense bioerosion could lead to the collapse of the nodules; however, large rhodoliths were observed (larger diameters with a mean of 17.8 ± 3.8cm for Jaseur 74m, 15.92 ± 2.14cm for Jaseur 66m and of 11.74 ± 1.40cm for Trindade 65m). The filling material of the perforations of the rhodoliths internal structure presented a sedimentary texture and was lithified; integrating the rigid structure inside the nodules. The lithification due to the growth of carbonaceous cement crystals in the empty pores in the internal structure is fundamental for the maintenance of nodule integrity. The lithification of the filling sediment creates new rigid structures within the older inner structure and these become susceptible to new infestations of perforating organisms. The repetition of the processes of perforation, filling, cementation and new perforations replaces the original internal structure (composed mainly by encrusting organisms) by the structure resulting from the repetition of processes (composed of bioclasts and lithified sediment). The present study identified the importance of the integrated study of all components of the internal structure of rhodoliths as the best way to understand the dynamics involved in the development of nodules and as a tool to obtaining solid environmental indicators
- ItemRegistro geológico holocênico de recifes submersos na plataforma de Abrolhos(Universidade Federal do Espírito Santo, 2015-05-28) Vieira, Laura Silveira; Webster, Jody; Bastos, Alex Cardoso; Moura, Rodrigo Leão de; Amado Filho, Gilberto MenezesCoral Reef systems are common features throughout many modern tropical coastal zone and the evidence of their occurrence during different sea levels have been studied worldwide. The Abrolhos Shelf (Brazil) encompasses the most important coral reef system in the South Atlantic showing high levels of endemism, low diversity and unique growth (locally known as “chapeirões”). The reef system along the shelf is characterized by shallow reef arcs parallel to the coast, and “give-up” reefs throughout the north-central and southern shelf. The main objective of this study is to investigate the geological record showing the Late Holocene evolution of two submerged pinnacles in the Abrolhos Shelf. Herein, two submerged pinnacles were drilledwith their tops at 4 and 15 m below sea level, called "Shallow Water Reef" (SW) and "Deep Water Reef" (DW). A total of eight cores were collected. Vertical (top down) and horizontal (perpendicular to the pinnacle wall) cores were recovered, ranging from 0.70 to 2.03 m in length. Significant coralgal framework was observed in the cores (corals such species as Mussismilia harttii., Millepora sp., Siderastrea sp., Porites sp., Favia sp. and Madracis sp.; and coralline algae such species as Hydrolithon sp., Lithophyllum kotschyanum, Lithophyllum sp., Amphiroa sp., Mesophyllum erubescens and Sporolithon episporum). However, we found that by far the most abundant framebuilding component were Schizoporellidae bryozoans. Extensive encrusting bryozoans were identified in all cores comprising between 15 - 52,9% of 2D areas. Bryozoans were most representative in the "DW" cores. Paradoxically, the poor spatial competition of encrusting bryozoans must be the explanation for the bryozoan dominance in the "DW" cores, which hermatypic corals can not develop. Radiocarbon dates indicate that the "DW" reef is older than the "SW" reef as well as higher reef accumulation rates occur in the past thousand years is in the "SW" reef. The results show that the both reefs have been developed in a shallow shelf environment (<30 meters depth)
- ItemSedimentação da plataforma continental do Espírito Santo : do aporte terrígeno à ocorrência de fundos recifais(Universidade Federal do Espírito Santo, 2017-02-24) Vieira, Fernanda Vedoato; Bastos, Alex Cardoso; Baptista Neto, José Antônio; Amado Filho, Gilberto MenezesShort and long term processes, such as biological activity, sediment transport, hydrodynamic conditions, relative sea level variation, sedimentary input and pre-existing geology, determine the continental shelf morphology. The study area of this research is the continental shelf of the Brazilian east coast. Its platform presents a variation in its width, being of 240 km in the region of Abrolhos to 50 km in its remainder, accompanied by two distinct sedimentary regimes along the platform, the accommodation and supply regime. Associated with those factors, the coastal region is characterized by the presence of Barrier Formation Traps, Crystalline Basement and Quaternary Coastal Plains. These units are distributed in different forms along the coast. The acquired data had the objective to investigate how the long term processes influence the occurrence and distribution of the heterogeneous funds along the platform. The results showed four different reef structures, isolated type 1 and 2 reefs, concretions / crusts, paleovalleys bioconstructions, and an extensive rhodoliths funds throughout the study area. Mud deposits were restricted to the mouth of the Doce river, extending toward the north of the platform. The remainder of the platform is composed of carbonate sediments and terrigenous sand to the north. In the region southern of the Doce river the platform presented a carbonate domain with significant changes in its morphology, with the presence of paleovalleys, irregular structures associated with hardbottoms. For the region to the north, the platform presents a more homogenous morphology, with the presence of the delta of the Doce river and a widening of the platform in the region of Abrolhos. Thus, the geomorphology evolution of the platform was related to the long term processes, and these processes differentiated the faciology of the platform.