Basin modeling meets rift analysis - A numerical modeling study from the Jeanne d'Arc basin, offshore Newfoundland, Canada

摘要

The Jeanne d'Arc basin, on the Grand Banks offshore Newfoundland, is a confined, failed-rift basin. Its initial development and burial history were controlled by crustal stretching and thinning. This study provides a detailed analysis of the heat flow-, tectonic subsidence-, stretching factor-, maturation- and temperature history, based on 44 1D models- and one full 4D (space and time) model. In basin models, the heat flow history is usually calculated from vitrinite reflectance (%VRr) data. However, this causes uncertainties and reflects only the periods of sedimentation, which where penetrated by wells. Therefore, other methods should be used to reconstruct the early heat flow history not recorded by sediments. In this study, a discontinuous, pure-shear stretching model, including radioactive heat production, reflecting the timing and magnitude of stretching factors of crust and lithospheric mantle was applied to a 4D numerical model for the Jeanne d'Arc basin. It is the first time that this new technique is shown on a real-case scenario and it gives new insights into the regional geodynamics. Results show that to understand the thermal evolution of the Jeanne d'Arc sedimentary basin completely, it is crucial to consider the Triassic rift system. This first rift generated the structural framework of the basin where most of the sediments were deposited. The second extension, in the Cretaceous, represents most likely an ultra-slow extension phase with a heat-impulse too weak to leave any thermal record. This study demonstrates that the entire evolution of the Jeanne d'Arc basin can be reconstructed assuming just one single Triassic thermal rift. Additionally, it shows the effects of a lateral heat transfer on the determination of stretching factors and thus on tectonic subsidence and the resulting heat flow history.