Temporal and spatial variations in tectonic subsidence in the Iberian Basin (eastern Spain): inferences from automated forward modelling of high-resolution stratigraphy (Permian–Mesozoic)

By subsidence analysis on eighteen surface sections and 6 wells, which cover large part of the Iberian Basin (E Spain) and which are marked by high-resolution stratigraphy of the Permian, Triassic, Jurassic and Cretaceous, we quantify the complex Permian and Mesozoic tectonic subsidence history of the basin. Backstripping analysis of the available high resolution and high surface density of the database allows to quantify spatial and temporal patterns of tectonically driven subsidence to a much higher degree than previous studies. The sections and wells have also been forward modelled with a new ‘automated’ modelling technique, with unlimited number of stretching phases, in order to quantify variations in timing and magnitude of rifting. It is demonstrated that the tectonic subsidence history in the Iberian Basin is characterized by pulsating periods of stretching intermitted by periods of relative tectonic quiescence and thermal subsidence. The number of stretching phases appears to be much larger than found by earlier studies, showing a close match with stretching phases found in other parts of the Iberian Peninsula and allowing a clear correlation with discrete phases in the opening of the Tethys and Atlantic

The Arctic lithosphere: Thermo-mechanical structure and effective elastic thickness

For the first time, lithospheric temperatures, strength, and effective elastic thickness (Te) distributions are estimated for the Arctic region north of 68°. To this aim, we use ArcCRUST, a recent model of the Arctic crust, which includes the thickness and density of the crust and sediments, the boundaries between the continental and oceanic crust, and the age of the oceanic lithosphere. We estimate the temperature variations in the continental lithosphere assuming steady-state conditions, for a constant surface heat flow of 50 mWm−2 and 62 mWm−2 for the onshore and offshore regions, respectively. In the oceanic domain, the temperature variations are estimated adopting a global depth and heat flow model. We discuss the robustness of the results by comparing the new thermal field with temperatures obtained from inversion of a regional seismic velocity model. The results are used as input for estimating integrated strength and Te, assuming a mafic crustal rheology. Our models predict a sharp transition between cratonic areas, characterized by high strength and Te, and tectonically active areas with a weaker lithosphere, corresponding to the continental shelves and the oceanic spreading ridges. The significant lateral change in our modeled strength and Te at the edges of Greenland and Canadian Arctic and along the active mid-ocean ridge in the NE Atlantic corresponds to increased observed seismic activity

The Arctic lithosphere: Thermo-mechanical structure and effective elastic thickness

For the first time, lithospheric temperatures, strength, and effective elastic thickness (Te) distributions are estimated for the Arctic region north of 68°. To this aim, we use ArcCRUST, a recent model of the Arctic crust, which includes the thickness and density of the crust and sediments, the boundaries between the continental and oceanic crust, and the age of the oceanic lithosphere. We estimate the temperature variations in the continental lithosphere assuming steady-state conditions, for a constant surface heat flow of 50 mWm−2 and 62 mWm−2 for the onshore and offshore regions, respectively. In the oceanic domain, the temperature variations are estimated adopting a global depth and heat flow model. We discuss the robustness of the results by comparing the new thermal field with temperatures obtained from inversion of a regional seismic velocity model. The results are used as input for estimating integrated strength and Te, assuming a mafic crustal rheology. Our models predict a sharp transition between cratonic areas, characterized by high strength and Te, and tectonically active areas with a weaker lithosphere, corresponding to the continental shelves and the oceanic spreading ridges. The significant lateral change in our modeled strength and Te at the edges of Greenland and Canadian Arctic and along the active mid-ocean ridge in the NE Atlantic corresponds to increased observed seismic activity