--> Abstract: New Concepts in Salt Tectonics of Brazil's Campos Basin, by P. Szatmari, L. S. Demercian, D. F. Coelho, and P. R. Cobbold; #90987 (1993).

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SZATMARI, PETER, L. S. DEMERCIAN, D. F. COELHO, Petrobas Research Center, Rio de Janeiro, Brazil; P. R. COBBOLD, Universite de Rennes, Rennes, France

ABSTRACT: New Concepts in Salt Tectonics of Brazil's Campos Basin

Two decades of intense petroleum exploration in Brazil's technologically most advanced Campos basin has furnished excellent data that permit 3-dimensional study of salt flow structures and mechanisms in both shallow and deep water. Salt tectonics is almost wholly controlled by the slope of the sea floor, with the dip of the salt bed itself having only minor effect. Downslope flow creates extensional structures where the sea floor slope steepens and compressional structures where the slope decreases oceanwards. There is strain also along strike, as downslope movement results in divergent salt flow from promontories and from below deltas, and convergent flow into bathymetric embayments. Well defined strike slip structures, both convergent and divergent, develop between overburden flakes rafted at different rates over the flowing salt. Some of these strike slip faults cut across the entire basin.

The seaward edge of the salt is formed by one or more oceanward rising salt nappes which flow over sediments originally deposited beyond the seaward limit of the salt. Sedimentation and nappe advance are simultaneous. The advancing salt nappe caries the entire post-salt sedimentary sequence; the same sequence is repeated below, and is cut off discordantly by, the diachronous base of the nappe. Both the salt and post-salt sequence of the nappe wedge out oceanward to an erosional edge beyond which strata are undisturbed by salt flow.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.