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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Brazilian Deep Water Fold Belts: Tectonic Drivers and
Structural Styles of Potential Traps
By
David
D. J. Stewart1
1Shell International E&P, Inc.
2Amerada Hess
Deep water fold belts in the emerging and frontier basins in Brazil are structurally quite different than those more explored Santos, Campos, and Espirito Santo basins (the Southern Salt basin). One key difference is the nature of the mobile substrate. In the deep water fold belts of the Equatorial Margin and extreme northeast Brazil, little salt exists in the deep water continental margin, although shallow water salt is penetrated in the Potiguar and Sergipe-Alagoas basins. As a result, mobile shales, sometimes overpressured, provide the base of the decollement(s). Structural imprints from breakup of the North and South Atlantic provided strong contrasts in structural fabric of the continental margin separating fold belts into two generic sectors: 1) southern sector from Cumuruxitiba to Parnaiba- Pernambuco basins, where roughly east-west rifting occurred, and 2) northern sector along the Equatorial Margin from the Ceara to the Foz do Amazonas basin, where North Atlantic oblique rifting initiated Berriasian rifts and later drifting. Some limited parts of the Equatorial Margin also have Triassic rifts, akin to eastern North America. Fold belts and their contiguous listric-faulted nearshore structural zones will be dissected from the south to the north, from the Cumuruxitiba to the Foz do Amazonas basins.
Major tectonic drivers and structural controls for formation of these fold belts will be discussed relative to the general stratigraphic section in shallow and deep water. In addition to Campanian uplift, Middle Eocene and Late Middle Miocene Andean orogenies have triggered fold belt formation. The lack of significant exploration in these deep water fold belts points to potential in high-risk and potentially high-reward structural segments.
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