Arcabouço crustal profundo da parte centro-norte da margem de Angola
Palavras-chave:
arcabouço crustal, sísmica profunda de reflexão, modelagem gravimétrica, modelo de ruptura continental, margem passiva, manto exumado, AngolaResumo
A aquisição e interpretação de novos dados sísmicos tem possibilitado melhor visualização das porções mais profundas de margens passivas, permitindo melhor imageamento e compreensão da zona de transição entre as crostas continental e oceânica. Como resultado disto, os clássicos modelos de ruptura e breakup continental têm sido revisados e aperfeiçoados para se obter um modelo coerente com os dados existentes. Neste trabalho, a interpretação de seções sísmicas de imageamento profundo obtidas pela ION-GXT, integrada à modelagem gravimétrica, possibilitou a identificação dos limites crustais na região centro-norte da margem de Angola, nas bacias de Kwanza e Baixo Congo, com a definição de quatro domínios crustais: Proximal (formado pela crosta continental estirada); domínio de Estrangulamento, onde há um rápido afinamento da crosta continental; Distal (formado pela crosta continental hiperestirada e manto continental exumado); e Oceânico (formado por crosta oceânica). Com base na análise da interpretação sísmica, associada a mapas de anomalia gravimétrica e geológico de Angola, foram identificadas duas áreas com características distintas. Uma delas, ao norte, abaixo da Bacia do Baixo Congo, com o domínio crustal distal extenso, com poucos altos do embasamento afetando a seção pré-sal bastante espessa. Esta área está relacionada a um embasamento composto por rochas do Cinturão Oeste do Congo e margens cratônicas retrabalhadas. A outra área, ao sul, abaixo da Bacia de Kwanza, possui o domínio crustal distal menos extenso, com diversos altos do embasamento afetando a seção pré-sal, mais delgada. Esta área está relacionada a um embasamento formado pelo Cráton de Angola e rochas do Escudo Central.
Referências
ASLANIAN, D.; MOULIN, M.; OLIVET, J.-L.; UNTERNEHR, P.; MATIAS, L.; BACHE, F.; RABINEAU, M.; NOUZÉ, H.; KLINGELHOEFER, F.; CONTRUCCI, I.; LABAILS, C. Brazilian and African passive margins of the Central Segment of the South Atlantic Ocean: kinematic constraints. Tectonophysics, Amsterdam, v. 468, n. 1-4, p. 98-112, Apr. 2009.
BEAUMONT, C.; KEEN, C. E.; BOUTILIER, R. On the evolution of rifted continental margins: comparison of models and observations for the Nova Scotia margin. Geophysical Journal of the Royal Astronomical Society, Oxford, v. 70, n. 3, p. 667-715, Sept. 1982.
BLAICH, O. A.; TSIKALAS, F.; FALEIDE, J. I. North-eastern Brazilian margin: regional tectonic evolution based on integrated analysis of seismic reflection and potential field data and modeling. Tectonophysics, Amsterdam, v. 458, n. 1-4, p. 51-67, Oct. 2008.
BOILLOT, G.; GRIMAUD, S.; MAUFFRET, A.; MOU-GENOT, D.; KORNPROBST, J.; MERGOIL-DANIEL, J.; TORRENT, G. Oceancontinent boundary off the Iberia margin: a serpentinite diapir west of the Galicia Bank. Earth and Planetary Science Let-ters, Amsterdam, v. 48, n. 1, p. 23-34, June 1980.
BOILLOT, G.; RECQ, M.; WINTERER, E. L.; MEYER, A. W.; APPLEGATE, J.; BALTUCK, M.; BERGEN, J. A.; COMAS, M. C.; DAVIES, T. A.; DUNHAM, K.; EVANS, C. A.; GIRARDEAU, J.; GOLDBERG, G.; HAGGERTY, J.; JANSA, L. F.; JOHNSON, J. A.; KASAHARA, J.; LOREAU, J. P.; LUNA-SIERRA, E.; MOULLADE, M.; OGG, J.; SARTI, M.; THUROW, J.; WILLIAMSON, M. Tectonic denudation of the upper mantle along passive margins: a model based on drilling results (ODP leg 103, western Galicia mar-gin, Spain). Tectonophysics, Amsterdam, v. 132, n. 4, p. 335-342, Jan. 1987.
BULHÕES, E. M.; AMORIM, W. N. Princípio da SismoCamada elementar e sua aplicação à técnica Volume de Amplitudes (tecVA). In: CONGRESSO INTERNACIONAL DA SOCIEDADE BRASILEIRA DE GEOFÍSICA, 9., 2006, Salvador. Anais... Salvador: SBGf, 2006.
CARMICHAEL, R. S. Practical handbook of physical properties of rocks and minerals. Boca Raton: CRC Press, 1988.
CARVALHO, H. Geologia de Angola. Lisboa: Instituto de Investigação Científica Tropical, 1981. 4 f. Escala 1:1.000.000.
CARVALHO, H.; TASSINARI, C.; ALVES, P. H.; GUI-MARÃES, F.; SIMÕES, M. C. Geochronological review of the Precambrian in western Angola: links with Brazil. Journal of African Earth Sciences, Oxford, v. 31, n. 2, p. 383-402, Aug. 2000.
CONTRUCCI, I.; MATIAS, L.; MOULIN, M.; GÉLI, L.; KLINGELHOFER, F.; NOUZÉ, H.; ASLANIAN, D.; OLIVET, J.-L.; RÉHAULT, J.-P.; SIBUET, J.-C. Deep structure of the West African continental margin (Congo, Zaïre, Angola), between 5oS and 8oS, from reflection/refraction seismic and gravity data. Geophysical Journal International, Oxford, v. 158, n. 2, p. 529-553, 2004.
COWIE, L.; ANGELO, R. M.; KUSZNIR, N.; MANATSCHAL, G.; HORN, B. Structure of the ocean–continent transition, location of the continent–ocean boundary and magmatic type of the northern Angolan margin from integrated quantitative analysis of deep seismic reflection and gravity anomaly data. In: CERALDI, T. S.; HODGKINSON, R. A.; BACKE, G. (Ed.). Petroleum Geoscience of the West Africa Margin. London: The Geological Society, 2016. (Special Publications, 438).
COSTA, J. L.; SCHIRMER, T. W.; LAWS, B. R. Lower Congo Basin, deep-water exploration province, offshore West Africa. In: DOWNEY, M. W.; THREET, J. C. MORGAN, W. A. (Ed.) Petroleum provinces of the twenty-first century. Tulsa: American Association of Petroleum Geologists, 2001. p. 517-530. (Memoir, 74).
DUVAL, B.; CRAMEZ, C.; JACKSON, M. P. A. Rafts tectonics in the Kwanza Basin, Angola. Marine Petroleum Geology, Guildford, v. 9, p. 389-404, Aug. 1992.
JACKSON, M. P. A.; HUDEC, M. R.; HEGARTY, K. A. The great West African Tertiary coastal uplift: fact or fiction? a perspective from the Angolan divergent margin. Tectonics, Washington, v. 24, n. 6, Dec. 2005.
KARNER, G. D.; DRISCOLL, N. W. Tectonic and stratigraphic development of the West African and eastern Brazilian Margins: insights from quantitative basin modelling. In: CAMERON, N. R.; BATE, R. H.; CLURE, V. S. (Ed.). The oil and gas habitats of the South Atlantic. London: The Geological Society, 1999. p. 11-40. (Special Publications, 153).
LAVIER, L. L.; MANATSCHAL, G. A mechanism to thin the continental lithosphere at magmapoor margins. Nature, London, v. 440, n. 7.082, p. 324-328, Mar. 2006.
LENTINI, M. R.; FRASER, S. I.; SUMNER, H. S.; DAVIES, R. J. Geodynamics of the central South Atlantic conjugate margins: implications for hydrocarbon potential. Petroleum Geoscience, Bath, v. 16, n. 3, p. 217-229, Aug. 2010.
LISTER, G. S.; ETHERIDGE, M. A.; SYMONDS, P. A. Detachment faulting and the evolution of passive continental margins. Geology, Boulder, v. 14, n. 3, p. 246-250, Mar. 1986.
MARTON, L. G.; TARI, G. C.; LEHMANN, C. T. Evolution of the Angolan Passive Margin, West Africa, with emphasis on Post-Salt Structural Styles. In: MOHRIAK, W. U.; TALWANI, M. (Ed.). Atlantic Rifts and Continental Margins. Washington: American Geophysical Union, 2000. p. 129-149. (Geophysical monograph series, 115).
MARZOLI, A.; MELLUSO, L.; MORRA, V.; RENNE, P. R.; SGROSSO, I.; D’ ANTONIO, M.; DUARTE MORAIS, L.; MORAIS, E. A. A.; RICCI, G. Geochronology and petrology of Cretaceous basaltic magmatism in the Kwanza Basin (western Angola) and relationships with the Parana-Etendeka continental flood basalt province. Journal of Geodynamics, Oxford, v. 28, n. 4-5, p. 341-356, Nov./Dec. 1999.
MCKENZIE, D. P. Some remarks on the development of sedimentary basins. Earth and Planetary Science Letters, Amsterdam, v. 40, n. 1, p. 25-32, June 1978.
MOULIN, M. Etude géologique et géophysique des marges continentales passives: exemple du Zaïre et de l’Angola. 2003. 360 f. Thesis (PhD) - Uni-versity de Bretagne Occodentale, Brest, 2003. 2 v.
MOULIN, M.; ASLANIAN, D.; OLIVET, J.-L.; CONTRUCCI, I.; MATIAS, L.; GELI, L.; KLINGELHOFER, F.; NOUZE, H.; REHAULT, J.-P.; UNTERNEHR, P. Geological constraints on the evolution of the Angolan margin based on reflection and refraction seismic data (ZaıAngo project). Geophysical Journal International, Oxford, v. 162, n. 2, p. 793-810, Sept. 2005.
PÉRON-PINVIDIC, G.; MANATSCHAL, G. The final rifting evolution at deep magmapoor passive margins from Iberia-Newfoundland: a new point of view. International Journal of Earth Sciences, New York, v. 98, n. 7, p. 1581-1597, 2009.
PÉRON-PINVIDIC, G.; MANATASCHAL, G.; OSMUN-DSEN, P. T. Structural comparison of archetypal Atlantic rifted margins: a review of observations and concepts. Marine Petroleum Geology, v. 43, p. 21-47, May. 2013.
PÉRON-PINVIDIC, G.; MANATASCHAL, G.; MASINI, E.; SUTRA, E.; FLAMENT, J. M., HAUPERT, I.; UN-TERNEHR, P. Unravelling the along-strike variability of the Angola-Gabon rifted margin: a mapping approach. In: SABATO CERALDI, T.; HODGKINSON, R. A.; BACKE, G. (Ed.). Petroleum Geoscience of the West Africa Margin. London: The Geological Society, 2015. (Special Publications, 438).
RESTON, T. J. The opening of the central segment of the South Atlantic: symmetry and the extension discrepancy. Petroleum Geoscience, Bath, v. 16, n. 3, p. 199-206, Aug. 2010.
ROYDEN, L.; KEEN, C. E. Rifting processes and thermal evolution of the continental margin of eastern Canada determined from subsidence curves. Earth and Planetary Science Letters, Amsterdam, v. 51, n. 2, p. 343-361, Dec. 1980.
SANDWELL, D. T.; SMITH, W. H. F. Global marine gravity from retracked Geosat and ERS-1 altimetry: ridge segmentation versus spreading rate. Journal of Geophysical Research, Washington, v. 114, n. B01, Jan. 2009.
SHARP, I.; MESSANGER, G.; SWART, R.; MARSH, J.; GINDRE, L.; PUIGDEFABREGAS, C.; VERWER, K.; FERREIRA, H.; SNIDERO, M.; MACHADO, V.; HOLTAR, E.; DONGALA, M.; JERRAM, D.; BLANC, E.; GRÖGER, E.; SCOTT, M.; FREITAG, U.; LAPPO-NI, F.; VERGES, J.; HUNT, D.; ZELLER, M.; MAR-TIN, J-D.; MORAGAS, M.; CRUZ, I.; BAQUES, V.; CASCIELLO, E.; WENNBERG, O-P.; WARREN, J. Tectono-stratigraphic evolution of the onshore Namibe-Benguela-Kwanza Basins, Angola - implications for margin evolution models. In: CONFERENCE RIFTS - CATCHING THE WAVE, 3., 2016, London. Abstracts… London: The Geological Society, 2016. p. 123-124.
SUTRA, E.; MANATSCHAL, G.; MOHN, G.; UNTER-NEHR, P. Quantification and restoration of extensional deformation along the Western Iberia and Newfoundland rifted margins. Geochemistry, Geophysics, Geosystems, v. 14, n. 8, p. 2575-2597, Aug. 2013.
TUCHOLKE, B. E.; SIBUET, J.-C.; KLAUS, A.; ARNA-BOLDI, M.; DELIUS, H.; ENGSTRÖM, A. V.; GAL-BRUN, B.; GARDIN, S.; HISCOTT, R. N.; KARNER, G. D.; LADNER, B. C., LECKIE, R. M.; LEE, C.-S.; MANATSCHAL, G., MARSAGLIA, K. M.; PLETSCH, T. K.; PROSS, J.; ROBERTSON, A. H. F.; SAWYER, D. S.; SAWYER, D. E.; SHILLINGTON, D.; SHIRAI, M.; SHRYANE, T.; STANT, S. A.; TAKATA, H.; UR-QUHART, E.; WILSON, C.; ZHAO, X. Initial reports. Proceedings of the ocean drilling program, Texas, v. 210, Oct. 2004.
UNTERNEHR, P.; PÉRON-PINVIDIC, G.; MANATS-CHAL, G. Hyper-extended crust in the South Atlantic: in search of a model. Petroleum Geoscience, Bath, v. 16, n. 3, p. 207-215, 2010.
WERNICKE, B. Low-angle normal faults in the Basin and Range province: nappe tectonics in an extending orogen. Nature, London, v. 291, n. 5817, p. 645-648, May 1981.
WERNICKE, B. Uniform-sense normal simple shear of the continental lithosphere. Canadian Journal of Earth Sciences, Ottawa, v. 22, n. 1, p. 108-125, 1985.
WHITMARSH, R. B.; MANATSCHAL, G.; MINSHULL, T. A. Evolution of magma-poor continental margins from rifting to seafloor spreading. Nature, London, v. 413, n. 6852, p.150-154, Sept. 2001.
WILSON, P. G.; TURNER, J. P.; WESTBROOK, G. K. Structural architecture of the ocean-continent boundary at an oblique transform margin through deep-imaging seismic interpretation and gravit y modeling: Equatorial Guinea, West Africa. Tecto-nophysics, Amsterdam, v. 374, n. 1-2, p. 19-40, Oct. 2003.
ZALÁN, P. V.; SEVERINO, M. C. G.; OLIVEIRA, J. A. B.; MAGNAVITA, L. P.; MOHRIAK, W. U.; GONTIJO, R. C.; VIANA, A. R.; SZATMARI, P. Stretching and thinning of the upper lithosphere and continental-oceanic crustal transition in southeastern Brazil. In: AAPG INTERNATIONAL CONFERENCE AND EXHIBITION, 2009, Rio de Janeiro. Abstracts…Tulsa: American Association of Petroleum Geologists Bulletin, 2009.
ZALÁN, P. V.; SEVERINO, M. C. G.; RIGOTI, C.; MAGNAVITA, L. P.; OLIVEIRA, J. A. B., VIANA, A. R. An entirely new 3D-view of the crustal and mantle structure of a ruptured South Atlantic passive margin – Santos, Campos and Espírito Santo Basins, Brazil. In: AAPG ANNUAL CONVENTION AND EXHIBITION, 2011a, Houston. Abstracts… Tulsa: American Association of Petroleum Geolo-gists Bulletin, 2011a.
ZALÁN, P. V.; SEVERINO, M. C. G.; MAGNAVITA, L. P.; RIGOTI, C.; OLIVEIRA, J. A. B.; VIANA, A. R. Crustal architecture and evolution of rift during the breakup of Gondwana in Southeastern Brazil - Santos, Campos and Espírito Santo Basins. In: SYMPOSIUM GONDWANA, 14., 2011b, Armação de Búzios. Abstracts… Rio de Janeiro: Gondwana Research, 2011b.
