Dynamics Of Passive Margins

This work reviews the mechanism of rifting with a focus on pre-existing tectonic weaknesses in pre-rift and/or basement rocks, i.e., on tectonic inheritance. The passive margins that are studied in this book are the Norwegian Continental Shelf, the Eastern North America and the East and West Indian Continental Margins. The continental rifts that have been analysed are the East African Rift System, the Brazilian Continental Rift Systems and the European Cenozoic Rift System. It states how rifts and passive margins serve as valuable locations for hydrocarbon exploration. Tectonic inheritance/heritage examines the influence of pre-existing/pre-rift elements on the geometry, genesis and propagation of rift-related faults. Such elements include anisotropies in the shallow crustal levels, as well as the rheology of the lithosphere. Inheritance greatly influences the architecture of rifted passive margins including the attitude of faults and geometry of horsts, (half-) grabens, transfer zones etc. Inheritance is also a determining factor in the width of rifts and rift shoulder topography.

This is a comprehensive synthesis of state-of-the-art information on vitally important hydrocarbon habitats for advanced geology students and researchers, exploration geoscientists, and petroleum managers.

The papers and research results presented here have been prepared as part of the Integrated Basin Studies project. This project had the objective of studying the lithospheric and upper crustal processes governing the formation and evolution of extensional and foreland basins and to decipher the role of tectonics, sea level and sedimentary processes in the filling of such basins. The Dynamics of the Norwegian Margin module focused on the rifted sedimentary basins of the northern North Sea and off Mid-Norway. This prolific hydrocarbon province has an extensive industry and scientific database and offers a unique opportunity to study fundamental earth processes, from failed rifting to crustal breakup and accretion of oceanic crust. A set of new models for basin formation and filling has been derived, including linking of sedimentary basin faulting to lower crustal deformation, signature and variability of syn-rift infill, correlation of mineralogy to seismic signature, nature and characteristics of volcanic margin formation and distribution of present-day stress field.

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.

The volume reviews current knowledge of transform margins and addresses fundamental questions for future research. Furthermore, the articles look at principal factors that influence the dynamics, kinematics and thermal regimes of continental break-up at transform margins and cover geophysics (bathymetry, seismic, gravity and magnetic studies), structural geology, sedimentology, geochemistry, plate reconstruction and thermo-mechanical numerical modelling.