Platô do Ceará: uma plataforma carbonática isolada e afogada da Margem Equatorial brasileira
Studies about the Brazilian Equatorial Margin (BEM) have always been concentrated in the continental shelf, supported by oil and gas industry. Deep-waters are vast, unknown and economically unexplored. In this way, there is a great data lack of the BEM's deep portion. Ceará Plateau (CeP) is...
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| Formato: | Dissertação |
| Idioma: | por |
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/26274 |
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| Resumo: | Studies about the Brazilian Equatorial Margin (BEM) have always been concentrated
in the continental shelf, supported by oil and gas industry. Deep-waters are vast,
unknown and economically unexplored. In this way, there is a great data lack of the
BEM's deep portion. Ceará Plateau (CeP) is a seamount and a significant feature of
BEM, located 100 km offshore Fortaleza (Brazil) and east of Fortaleza High. Its origin
supposed to be volcanic based in its steep flanks and collected samples (olivine basalt)
in others surrounding seamounts. Its top is average 280 m depth and the coverage is
limestone enriched with phosphorite (up to 18%). The aim of this work is to define CeP
evolution as an isolated carbonatic platform and then its demise. We used 2D
multichannel seismic reflection data associated with lithology and biostratigraphy of
exploratory wells. In the seismic profiles, the shape and pattern of reflectors
termination was interpreted, as well as their external and internal sequences geometry.
In the seismic profiles, seven seismic patterns and four seismic sequences were
recognized on the volcanic CeP top. Our results indicate that during the
Rupelian/Chattian transition, the substrate was in the photic zone and partially
emerged, leading to the development of carbonate wedges on the flanks. The
development has become progradational (Chattian-Burdigalian) and then
aggradational (Burdigalian/ Tortonian). Carbonate production ceased during the
Tortonian, probably when the Antarctic ice sheet began to melt. Tectonics, subsidence
and eustatic changes on a global and regional scale acted as control factors in the
platform growth. This platform can be used as a model for the stratigraphic
development of adjacent BEM seamounts. |
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