The Volcanic Outer High of Campos Rifted Margin in Southeast Brazil: The structure and formation of SEMA

Michelle Cunha Graça, Natasha Santos Gomes Stanton, Andres Ceasar Gordon


The SEMA (South East Magnetic Anomaly) is a high amplitude magnetic lineament in the most distal part of the Campos Rifted Margin in Southeast Brazil. It runs continuously from south to north along 85 km reaching 500 nT in deep waters. The aim of this paper is to investigate the structure, stratigraphy and nature of the SEMA, and to discuss its significance for the evolution of the margin. Based on seismic, magnetic and gravity analysis, we interpret the SEMA as a volcanic outer high. Its formation was prior to the salt migration oceanwards, probably earlier to the breakup, constraining a time-relative formation in the Late Aptian - Early Albian. It is bounded by a basinward dipping, large-scale fault that created a huge depocenter continentwards. The Volcanic Outer High of the SEMA marks the transition to a distinct tectonostratigraphic compartment and salt domain, characterized by intense halokinesis, significant thinning and modification of the pre-salt sequences, and increasing presence of volcanic and intrusive rocks. It forms a long volcanic ridge in the external boundary of the Campos Rifted Margin, which may have influenced the paleo-circulation. Moreover, its understanding could provide new insights into the breakup process.


Southeast Magnetic Anomaly; magmatism; pre-salt; Brazilian margin; breakup; Campos basin.

Full Text:



Alvarez, P., A.C. Araújo, N. Stanton, J.P. Oliveira, R. Ferro, M. Lemma, I. Nascimento, and L. Borghi, 2021, Crustal Features and Transfer Zone of Campos Basin: A Review and Evaluation: Conference Proceedings, Second EAGE Conference on Pre-Salt Reservoir, September 2021, 1-5, doi: 10.3997/2214-4609.202183022

Araujo, M.N., M. Perez-Gussinye, and I. Mushaldev, 2022, Oceanward rift migration during formation of Santos-Benguela ultra-wide rifted margin: Geological Society, London, Special Publications, 524, SP524-2021-123, doi: 10.1144/SP524-2021-123

Blakely, R.J., 1996, Potential theory in gravity and magnetic applications: Cambridge University Press, Cambridge, 441 pp.

Chang, H.K., R.O. Kowsmann, A.M.F. Figueiredo, and A.A. Bender, 1992, Tectonics and stratigraphy of the East Brazil Rift system: an overview, in ZIEGLER P.A. (Ed.). Geodynamics of Rifting, volume II, Case History Studies on Rifts: North and South America and Africa: Tectonophysics, 213, 97-138, doi: 10.1016/B978-0-444-89912-5.50032-6

Faw, J., R. White, and D. Allinson, 2017, New regional 3D framework delivers fresh insights into complex petroleum systems: World Oil, September, p. 35-38.

Karner, G.D., C. Johnson, J. Shoffner, M. Lawson, M. Sullivan, J. Sitgreaves, J. McHarge, J. Stewart, and P. Figueredo, 2021, Tectono-magmatic development of the Santos and Campos basins, offshore Brazil, in Mello, M.R., P.O. Yilmaz, and B.J. Katz, Eds., The supergiant Lower Cretaceous pre-salt petroleum systems of the Santos Basin, Brazil: AAPG Memoir, 124, 215-256, doi: 10.1306/13722321MSB.9.1853

Lavier, L.L., W.R. Buck, and A.N.B Poliakov, 1999, Self-consistent rolling-hinge model for the evolution of large-offset low-angle normal faults: Geology, 27, 12, 1127-1130, doi: 10.1130/0091-7613(1999)027<1127:SCRHMF>2.3.CO;2

Magnavita L.P., N.M. Dehler, P.V. Zalan, M.V. Sant'anna, M.C.G. Severino, L.C. Gomes, A.J. Santana, I.S. Vieira, C.A. Rigoti, A.E.C.M. Souza, and J.R.C. Menezes, 2012, Kinematics of the Cretaceous rift along the Eastern Brazilian Margin: implications for petroleum exploration: 34th International Geological Congress, Brisbane, Australia, 5-10 August, 2012.

Mizusaki, A.M.P., R. Petriniz, G. Bellieni, P. Comin-Chiaramonti, J. Dias, A. De Min, and E.M. Piccirillo, 1992, Basalt magmatism along the passive continental margin of SE Brazil (Campos basin): Contrib. Mineral Petrol., 111, 143-160, doi: 10.1007/BF00348948

Mohriak, W.U., A. Gordon, and M.R. Mello, 2021, Origin and Petroleum System of the Cabo Frio High between the Santos and Campos Basins: Reviewed Integration of Structural and Paleogeographic Reconstruction with the Oil and Gas Systems: The Supergiant Lower Cretaceous Pre-Salt Petroleum Systems of the Santos Basin, Brazil, AAPG Special Volumes, Memoir 124, Chapter 11, 273-324, doi: 10.1306/13722323MSB.11.1853

Norton, I.A., D.T. Carruthers, and M.H. Hudec, 2016, Rift to drift transition in the South Atlantic salt basins: A new flavor of oceanic crust: Geology, 44, 1, 55-58, doi: 10.1130/G37265.1

Oreiro, S.G., J.A. Cupertino, P. Szatmari, and A. Thomas-Filho, 2008, Influence of pre-salt alignments in post-Aptian magmatism in the Cabo Frio high and its surroundings, Santos and Campos basins, SE Brazil: An example of non-plume-related magmatism: J. South Am. Earth Sci., 25, 1, 116-131, doi: 10.1016/j.jsames.2007.08.006

Raposo, M.I.B., M. Ernesto, and P.R. Renne, 1998, Paleomagnetism and 40Ar/39Ar dating of the early Cretaceous Florianópolis dike swarm (Santa Catarina Island), Southern Brazil: Phys. Earth Plan. Int., 108, 275-290, doi: 10.1016/S0031-9201(98)00102-2

Stanton, N., R.S. Schmitt, A. Galdeano, M. Maia, and M. Mane, 2010, Crustal structure of the southeastern Brazilian Margin from aeromagnetic data: new kinematic constraints: Tectonophysics, 490, 15-27, doi: 10.1016/j.tecto.2010.04.008

Stanton, N., N. Kusznir, A. Gordon, and R.S. Schmitt, 2019, Architecture and Tectono-magmatic Evolution of the Campos Rifted Margin: Control of OCT Structure by Basement Inheritance: Marine and Petroleum Geology, 100, 43-59, doi: 10.1016/j.marpetgeo.2018.10.043

Szatmari, P., and E.J. Milani, 2016, Tectonic control of the oil-rich large igneous-carbonate-salt province of the South Atlantic rift: Mar. Petrol. Geo., 77, 567-596, doi: 10.1016/j.marpetgeo.2016.06.004

Winter, W.R., R.J. Jahnert, and A.B. França, 2007, Bacia de Campos, in Milani, E.J., H.D. Rangel, G.V. Bueno, J.M. Stica, W.R. Winter, J.M. Caixeta, and O.C. Pessoa Neto, Eds., Cartas Estratigráficas: Bol. Geoc. Petrobras, Rio de Janeiro, 15, 511-529.


Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.

>> Brazilian Journal of Geophysics - BrJG (online version): ISSN 2764-8044
a partir do v.37n.4 (2019) até o presente

Revista Brasileira de Geofísica - RBGf (online version): ISSN 1809-4511
v.15n.1 (1997) até v.37n.3 (2019)

Revista Brasileira de Geofísica - RBGf (printed version): ISSN 0102-261X
v.1n.1 (1982) até v.33n.1 (2015)


Brazilian Journal of Geophysics - BrJG
Sociedade Brasileira de Geofísica - SBGf
Av. Rio Branco 156 sala 2509
Rio de Janeiro, RJ, Brazil
Phone/Fax: +55 21 2533-0064


Creative Commons