Seismic stratigraphy and subsidence analysis of the southern Brazilian margin (Campos, Santos and Pelotas basins)

Contreras, J.; Zühlke, Rainer; Bowman, Scott A.; Bechstädt, Thilo

doi:10.1016/j.marpetgeo.2010.06.007

Cited by 126 publications

(102 citation statements)

References 59 publications

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“…The Santos Basin initially formed as a rift basin during the Early Cretaceous as the South Atlantic began to open (Meisling et al, 2001;Modica and Brush, 2004;Karner and Gambôa, 2007;Mohriak et al, 2008;Contreras et al, 2010). A series of graben and half-graben were filled by non-marine strata (Picarras and Itapema formations), which are overlain by shallow-marine carbonates (Barra Velha Formation) (Fig.…”

Section: Geological Settingmentioning

confidence: 99%

Enigmatic structures within salt walls of the Santos Basin—Part 1: Geometry and kinematics from 3D seismic reflection and well data

Jackson¹,

Jackson²,

Hudec³

et al. 2015

Journal of Structural Geology

151

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a b s t r a c tUnderstanding intrasalt structure may elucidate the fundamental kinematics and, ultimately, the mechanics of diapir growth. However, there have been relatively few studies of the internal structure of salt diapirs outside the mining industry because their cores are only partly exposed in the field and poorly imaged on seismic reflection data. This study uses 3D seismic reflection and borehole data from the São Paulo Plateau, Santos Basin, offshore Brazil to document the variability in intrasalt structural style in natural salt diapirs. We document a range of intrasalt structures that record: (i) initial diapir rise; (ii) rise of lower mobile halite through an arched and thinned roof of denser, layered evaporites, and emplacement of an intrasalt sheet or canopy; (iii) formation of synclinal flaps kinematically linked to emplacement of the intrasalt allochthonous bodies; and (iv) diapir squeezing. Most salt walls contain simple internal anticlines. Only a few salt walls contain allochthonous bodies and breakout-related flaps. The latter occur in an area having a density inversion within the autochthonous salt layer, such that upper, anhydrite-rich, layered evaporites are denser than lower, more halite-rich evaporites. We thus interpret that most diapirs rose through simple fold amplification of internal salt stratigraphy but that locally, where a density inversion existed in the autochthonous salt, RayleigheTaylor overturn within the growing diapir resulted in the ascent of less dense evaporites into the diapir crest by breaching of the internal anticline. This resulted in the formation of steep salt-ascension zones or feeders and the emplacement of high-level intrasalt allocthonous sheets underlain by breakout-related flaps. Although regional shortening undoubtedly occurred on the São Paulo Plateau during the Late Cretaceous, we suggest this was only partly responsible for the complex intrasalt deformation. We suggest that, although based on the Santos Basin, our kinematic model may be more generally applicable to other salt-bearing sedimentary basins.

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Section: Geological Settingmentioning

confidence: 99%

Enigmatic structures within salt walls of the Santos Basin—Part 1: Geometry and kinematics from 3D seismic reflection and well data

Jackson¹,

Jackson²,

Hudec³

et al. 2015

Journal of Structural Geology

151

View full text Add to dashboard Cite

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“…Although the Brasilian escarpments were not incised by post-breakup glacial erosion, Neogene sedimentary thicknesses in parts of Pelotas, Santos, and Campos basins range between 0.5 to perhaps more than 2 km (Modica & Brush, 2004;Assumpção et al, 2011;Contreras, 2011). The load is applied atop very thin crust (Mohriak et al, 2010;Assumpção et al, 2011;Zalán et al, 2011;Mohriak & Leroy, 2012).…”

Section: The Model Abroadmentioning

confidence: 99%

Some remarks on the earthquakes of Fennoscandia: A conceptual seismological model drawn from the perspective of hyperextension

Redfield¹,

Osmundsen²

2015

NJG

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To a first order, patterns of Fennoscandia's seismicity reflect the benchmark domain boundaries of its Mesozoic rifted margin. Three distinct belts of earthquakes strike sub-parallel to the generalized line of breakup. The outermost seismic belt (SB1) marks the Taper Break (TB), or the zone of flexural coupling/decoupling between the distal (seaward) and proximal/necking (landward) domains. A coastal belt (SB2) follows the Innermost Limit of Extension, defined as the onset of 39 km-thick crystalline continental crust. An interior belt (SB3) follows the Hinterland Break in Slope, or the landward limit of the Scandinavian rifted margin. Between each belt, large portions of the necking, proximal, and hinterland domains are seismically quiescent. Evaluation of the 'Cumulative Seismic Moment' (CSM w ) per unit area indicates that the release of seismic energy is asymmetric. Although some of Fennoscandia's largest seismic events occur in the dominantly Proterozoic to Archean lithosphere of the eastern craton, 80% of Fennoscandian CSM w maps to the domain boundaries of the western rifted margin. CSM w energy tends to be highest at the TB and decreases system atically towards the continental interior.As proposed by many previous studies, a first-order spatial correlation between Scandinavia's offshore earthquake belt and voluminous, geo logically rapid, sedimentary loading during the Neogene period is evident. However, the presence of thinned, faulted crystalline basement is also a very important factor behind Scandinavia's offshore seismicity. Where the Neogene deposits are at their thickest the underlying crust is dominantly oceanic; CSM w is lower per unit area there than where lesser Plio-Pleistocene loading impacts continental crust that was fully prepared by Mesozoic necking and hyperextension. CSM w data suggest that the 'strength' of the TB and the continental margin's distal domain is significantly less than that of relatively young (ca. 54 Ma) oceanic lithosphere. Our data imply that ridge push does not contribute significantly to Fennoscandia's seismicity. Rather, we find that thin-plate bending stresses stemming from offshore depositional loading conspire with unbuttressed Gravitational Potential Energy (GPE), onshore erosion, and post-glacial isostatic rebound to generate Fennoscandia's earthquakes.We present a conceptual seismological model for Fennoscadia that is consistent with modern hypotheses of extended margin evolution, including post-breakup reactivation by footwall uplift in regions adjacent to sharp crustal taper. Illustrated by simple concepts of elastic thin-plate theory, the model honors our conclusion that Fennoscandian seismicity is principally the product of locally derived stress fields and that far field stress from the oceanic domain is unlikely to penetrate deeply into a hyperextended continental margin. It predicts the locations of the observed seismic belts and seismic gaps with the mathematics of thin-plate bending. It describes how the outer seismic belt will remain localized in the...

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“…Na Bacia de Santos são reconhecidas falhas extensionais lístricas e de alto ângulo que afetam a crosta continental, rochas vulcânicas do Barremiano ao início do Aptiano e depósitos clásticos; domos do sal no talude continental; falhas lístricas, inversas e thrusts geradas pelo sal em sedimentos do Cretáceo Superior e Paleogeno; falhas limitando meio-grábens causados pela fase extensional entre o Hauteriviano e Barremiano Superior (Contreras et al, 2010).…”

Section: Geologia Regionalunclassified

Análise sismoestratigráfica da seção rifte da Bacia de Santos, Brasil

et al. 2015

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Resumo -A Bacia de Santos, apesar de uma das principais bacias atualmente no Brasil exploradas devido à importância do pré-sal, possui pouca informação geológica, como registros de poço, sísmi-ca 3D e sísmica 2D de boa qualidade na seção rifte. O presente trabalho visa à integração da análise sismoestratigráfica e proposição de um modelo de evolução tectonoestratigráfica para a seção rifte da bacia. A análise sismoestratigráfica envolveu a interpretação dos refletores, que é a base da identificação das unidades sismoestratigráficas e a caracterização das sismofácies. Como resultado, foi obtida a definição de 16 unidades sismoestratigráficas e quatro sismofácies (incluindo o sag), e o desenvolvimento das cartas cronoestratigráficas de eventos adaptadas para o contexto sísmico. Com base no ajuste do modelo de padrões de empilhamento para mudanças na atividade tectônica, foram delimitados os tratos de sistemas tectônicos de início de rifte, de alta atividade tectônica, de baixa atividade tectônica e o pós-rifte, representado pelo sag. O desenvolvimento de cada um dos tratos respondeu a variações dos fatores controladores das bacias lacustres, interpretado como o balanço relativo entre as taxas de mudanças do espaço de acomodação gerado pela tectônica e o aporte sedimentar influenciado pelo clima. Palavras-chave: Bacia de Santos, seção rifte, unidades sismoestratigrafia, sismofácies, tratos de sistemas tectônicos.Abstract -Seismic Stratigraphic Analysis in the Rift Section of Santos Basin, Brazil. The Santos Basin, despite its surmount significance due to the pre-salt reservoirs, has limited geological information well-logs, 3D seismic or good quality 2D seismic for the rift section. The present work aims at integrating seismic stratigraphic analysis and proposing a tectonic-stratigraphic evolution model for the rift section of the basin. Seismic stratigraphic analysis involved interpretation of reflectors, which is the base of seismic stratigraphic units identification and seismic facies characterization. The result was the definition of 16 seismic stratigraphic units, four seismic facies (including the sag), and the development of chronostratigraphic charts of events adapted to the seismic context. Based on the adaptation of the stacking patterns to tectonic activity changes model, it was possible to delimit the rift initiation system tract, the high tectonic activity system tract, the low tectonic activity system tract and the post-rift, represented by the sag. The development of each tectonic system tract responded to variations in controlling factors of the lacustrine basin, interpreted as the relative balance between the rate changes in the accommodation space generated by tectonic and sediment supply influenced by climate.

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Seismic stratigraphy and subsidence analysis of the southern Brazilian margin (Campos, Santos and Pelotas basins)

Cited by 126 publications

References 59 publications

Enigmatic structures within salt walls of the Santos Basin—Part 1: Geometry and kinematics from 3D seismic reflection and well data

Enigmatic structures within salt walls of the Santos Basin—Part 1: Geometry and kinematics from 3D seismic reflection and well data

Some remarks on the earthquakes of Fennoscandia: A conceptual seismological model drawn from the perspective of hyperextension

Análise sismoestratigráfica da seção rifte da Bacia de Santos, Brasil

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