f Application of Structural Analogs to Enhance Understanding of Tectonically Inverted Settings (Best of AAPG)

Integration of field and subsurface data from the Wessex Basin (UK) and Doseo Basin (Chad) has provided important new insights into petroleum prospectivity in structurally inverted settings. Using these data it has proved possible to refine models of inversion anticline development and recognition criteria for a variety of polyphase deformation scenarios. In the Wessex Basin, structures are exposed that are typically difficult to image seismically, such as the steeply dipping, highly deformed forelimb of inversion anticlines. These regions are particularly important to resolve when mapping trap geometry, field extent, and fault displacement for fault seal analyses. In all cases the inversion anticlines are related one-for-one with early rift faults, regardless of their trend and that relaying normal faults produce en-echelon inversion anticlines. Thus, en-echelon folds do not indicate strike-slip faulting a priori. In addition, maximum inversion is coincident with the center of the fault segment where maximum subsidence occurs during extension. As a result, much can be interpreted about the pre-inversion structure by mapping the inversion anticlines themselves.