How to predict thermal stress in hyperextended margins: Application of a new lithospheric model on the Iberia margin

Abstract

Although passive margins have been explored for decades, they remain frontier zones with commonly little or no data available for calibration of basin models. The thermal history modeling of these margins, critical for maturity assessment, thus strongly relies on the rifting models available in basin-modeling tools. Coupling lithospheric evolution with sedimentation and integrated petroleum system modeling has proven to add value compared with user-defined heat flows applied at the base of sediments. However, classic approaches based on uniform stretching factors are limited in hyperextended margins where more complex models are required. The different basement domains and their structural complexity as well as rock-property evolution through time must be considered. An improved lithospheric model has been developed with this objective. Still coupled with sedimentation, it allows a precise description of the lithosphere’s shape and properties through time. This new model is applied to a two-dimensional cross section located on the Iberia margin. A basin model is built from published data, and focus is on the basement using a conceptual model as input only and using available surface-heat-flow measurements for calibration. Thermal stress and maturity resulting from the margin evolution are analyzed and discussed. Results demonstrate the strength of the approach to build reliable geological reconstruction of the heat flow through time in areas where classic rifting models cannot be applied, from a minimum of data and in a limited time, leaving room for sensitivity analysis to reduce exploration risk.