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Just How Uncertain is Our Interpretation of Deep Seismic Reflection Data From Passive Margins, and Does it Matter: A Case Study From the Argentina Margin

Abstract

The Argentinian Passive Margin provides an exceptional example of a volcanic passive margin that has been a focus, along with much of the South Atlantic, for hydrocarbon exploration and understanding the crustal architecture will be essential for exploration success. Recently acquired, well imaged, seismic reflection data is used to constrain the margin architecture. These new data provide significant improvements in imaging throughout the oceanic and continental lithosphere that enables us to interpret lower and mid crustal reflectivity, the continental and oceanic moho, seaward dipping reflections and oceanic crust domains. Despite this high quality imaging uncertainty still remains in both the interpretation of the data as well as the geophysical properties of the margin, including the extent of lower crustal magmatic bodies, the geometry of break-up volcanics and Seaward Dipping Reflection emplacement. Constraining these interpretations have a fundamental control in our understanding of the processes involved in continental rifting and break up. Interpretation of previous data, as well as existing models of the margin, do not account for such uncertainty in the interpretations. In this study we present multiple seismic-structural interpretations for data that are geometrically valid. We then use a number of techniques, including kinematic restorations, gravity modelling, backstripping and subsidence analysis to test the validity of each of the models. By addressing the uncertainty inherent in any sub-surface data we can better constrain the suite of likely scenarios. This enables us not only to understand the evolution of, hence process involved in, lithospheric stretching, it also allows us to discuss how these uncertainty will influence the risking of future exploration in such frontier areas.