Passive Margins: Tectonics, Sedimentation and Magmatism
CONTAINS OPEN ACCESS

This volume has evolved from papers written in memory of Professor David Roberts. They summarize the key findings of recent research on passive margins, from tectonics, bathymetry, stratigraphy and sedimentation, structural evolution and magmatism. Papers include analyses of the central and southern Atlantic margins of South America and Africa, papers on magmatism and extension in the NE Brazilian margin and on the Cote de Ivoire margin, rift architectures of the NW Red Sea margin, tectonics of the eastern Mediterranean margin, salt tectonics of passive margins of the Gulf of Mexico and Brazil, and papers on the NW Shelf margin of Australia. The volume provides readers with new insights into the complexities of passive margin systems that are in reality, not so passive.
‘Ductile v. Brittle’ – Alternative structural interpretations for the Niger Delta Available to Purchase
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Published:May 09, 2020
Abstract
A wealth of subsurface information gathered from over 60 years of hydrocarbon exploration offshore Nigeria provides a reference study area on the interaction between sedimentation, structure and overpressure in a large delta system. The current geological paradigm is that structuration and synkinematic sedimentation is governed by shale mobility from the deeper parts of the delta. This concept is largely the result of interpretations derived from vintage seismic data and insufficient calibration of the deeper parts of the delta. Long-cable seismic data are providing new insights into this interpretation conundrum. A first-order problem, which is of particular interest here, relates to the linkage between the extensional structures updip with the compressional structures downdip. The translational zone between extension and compression is key to unravelling the nature of this link and any associated structural material balance discrepancies. The primary focus of the current paper is to interrogate seismic data and to provide alternative interpretations to the accepted paradigm. Two end-member interpretations of the Niger Delta regional seismic dip lines – referred to here as the ‘ductile model’ and the ‘brittle model’ – are presented. Aside from their internal geometrical dissimilarities, these interpretations suggest fundamentally different kinematic and geomechanical models. The latter may offer a wider scope for deep – largely neglected – hydrocarbon exploration targets. Ultimately, these ideas could provide the conceptual framework that, in conjunction with improved seismic efforts, could lead to rejuvenated exploration portfolios.
- Africa
- brittle deformation
- brittleness
- Campos Basin
- contraction
- deformation
- deltaic environment
- dip
- ductile deformation
- ductility
- extension
- geophysical methods
- geophysical profiles
- geophysical surveys
- kinematics
- mobility
- models
- Niger Delta
- Nigeria
- overpressure
- petroleum
- petroleum exploration
- potential deposits
- regional
- sedimentation
- seismic methods
- seismic profiles
- strike
- structural analysis
- surveys
- variations
- West Africa