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An?lise estrutural da deforma??o cenoz?ica na Bacia de Cumuruxatiba (BA)Ferreira, Talles Souza 03 September 2010 (has links)
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Previous issue date: 2010-09-03 / The Cumuruxatiba basin is located at the southern coast State of Bahia in
northeastern of Brazil. This basin was formed in distensional context, with rifting
and subsequent thermal phase during Neocomian to late Cretaceous. At Cenozoic
ages, the Abrolhos magmatism occurs in the basin with peaks during the
Paleocene and Eocene. In this period, there was a kinematic inversion in the
basin represented by folds related to reverse faults. Structural restoration of
regional 2D seismic sections revealed that most of the deformation was
concentrated at the beginning of the Cenozoic time with the peak at the Lower
Eocene. The post-Eocene is marked by a decrease of strain rate to the present.
The 3D structural modeling revealed a fold belt (trending EW to NE-SW)
accommodating the deformation between the Royal Charlotte and Sulphur
Minerva volcanic highs. The volcanic eruptions have caused a differential
overburden on the borders of the basin. This acted as the trigger for halokinesis,
as demonstrated by physical modeling in literature. Consequently, the
deformation tends to be higher in the edges of the basin. The volcanic rocks
occur mainly as concordant structures (sills) in the syn-tectonic sediment
deposition showing a concomitant deformation.
The isopach maps and diagrams of axis orientation of deformation
revealed that most of the folds were activated and reactivated at different times
during the Cenozoic. The folds exhibit diverse kinematic patterns over time as
response to behavior of adjacent volcanic highs. These interpretations allied with
information on the petroleum system of the basin are important in mapping the
prospects for hydrocarbons / A Bacia de Cumuruxatiba est? localizada no extremo sul da costa do
Estado da Bahia, no Nordeste do Brasil. Esta bacia foi formada em ambiente
distensional, com rifteamento e posterior fase termal durante o Neocomiano at?
final do Cret?ceo. Durante o Cenoz?ico ocorre o magmatismo de Abrolhos na
bacia com picos durante o Paleoceno e Eoceno. Neste per?odo ocorre uma
invers?o cinem?tica na bacia representada por dobras relacionadas a falhas
reversas. Restaura??es estruturais regionais de se??es s?smicas 2D, revelaram
que a maior parte da deforma??o est? concentrada no inicio do Cenoz?ico com o
pico no Eoceno Inferior. O per?odo p?s-Eoceno ? marcado pela diminui??o da
taxa de deforma??o at? o presente.
A modelagem estrutural 3D revelou uma frente de dobras (de orienta??o
E-W variando para NE-SW) acomodando a deforma??o entre os altos vulc?nicos
de Royal Charlotte e Sulphur Minerva. Os derrames vulc?nicos causaram uma
sobrecarga diferencial nas bordas da bacia que serviu de gatilho para atua??o da
halocinese, como j? demonstrado em modelagens f?sicas na literatura.
Consequentemente, a deforma??o tende a ser maior na bordas da bacia. As
rochas vulc?nicas ocorrem principalmente como estruturas concordantes (sills)
nos sedimentos sin-tect?nicos revelando uma deposi??o concomitante ?
deforma??o.
O estudo dos mapas de is?pacas e diagramas com orienta??o do eixo de
deforma??o revelaram que maior parte das dobras foram ativadas e reativadas em
diferentes per?odos durante o Cenoz?ico. As dobras apresentam padr?es
cinem?ticos variados ao longo do tempo que refletem a atua??o diferencial dos
altos vulc?nicos adjacentes. Estas interpreta??es aliadas a informa??es sobre os
sistemas petrol?feros da bacia s?o importantes no mapeamento dos prospectos
para hidrocarbonetos
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