The thermal evolution in sedimentary basins above Iarge shear zones and detachments

The objective of the project is to develop quantitative models for the thermal histories of basins formed in hanging-walls of large crustal shear zones. We combine field data with numerical models to study and quantify the heat sources and heat transport mechanisms in such basins. The field analogues used in the project are the low-grade metamorphic Devonian supra-detachment basins formed in the hanging-wall of the large-scale extensional detachment zone between Nordfjord and Sognefjorden in western Norway. This large-magnitude extensional shear zone has a heave in the order of 60 to 100 km, and juxtaposes the Devonian basins in its hanging wall with high-grade metamorphic rocks in its footwall.

We have applied the field- and laboratory studies to constrain the basin's peak temperature conditions and to study fractures networks. Raman micro-spectroscopy on carbonaceous material is employed as a geo-thermometer in this study.

New numerical codes are developed to accurately model the thermal evolution of supra-detachment basins by: a) considering the kinematic evolution of the geotherms in extensional detachment systems given the subsidence and exhumation rates of the hanging-wall and footwall units; b) estimating the shear heating contribution associated with the localized rock deformation in the shear zone of the detachment and in contact with the basal part of the basins; c) developing numerical codes to quantify the amount of heat transported by fluid-flow in the system considering the layering and the sedimentary architecture of the basins.