Post-Variscan evolution of the lithosphere in the area of the European Cenozoic Rift System
conference paper
The European Cenozoic Rift System (ECRIS) transects Variscan basement, Permo-Carboniferous troughs and Late Permian to Mesozoic series, deposited in thermal sag basins, which are exposed on rift-related arches. We have analysed processes governing the transformation of the orogenically destabilized Variscan lithosphere into end-Cretaceous stabilized cratonic lithosphere, prior to its renewed Cenozoic rift-related destabilization. In the ECRIS area, crustal and lithospheric thicknesses at present are in the range of 24-35 km and 60-120 km, respectively. The Variscan orogen was characterized at the time of its end-Westphalian consolidation by 45-60 km deep crustal roots, marking major sutures. During the Stephanian-Early Permian wrench-induced collapse of the Variscan orogen, subducted lithospheric slabs were detached, causing upwelling of the asthenosphere, thermal thinning and/or partial delamination of the lithospheric mantle, and regional uplift. By mid-Permian times, the crust was thinned to 28-35 km owing to its regional erosional unroofing, localized mechanical stretching and the interaction of mantle-derived melts with its basal parts. By mid-Permian times, when the temperature of the asthenosphere returned to ambient levels, thermal subsidence of the lithosphere commenced, controlling development of a system of Late Permian and Mesozoic intracratonic basins. These experienced repeated minor subsidence accelerations, related to the build-up of far-field stresses, which did not involve renewed lithospheric destabilization. Modelling of observed subsidence curves indicates that during the mid-Permian lithospheric thicknesses ranged in the ECRIS area between 40 and 80 km, but had increased by the end of the Cretaceous to 100-120 km. Cenozoic rifting and mantle-plume activity caused renewed lithospheric thinning. © The Geological Society of London 2006.
Topics
TNO Identifier
239690
ISSN
04354052
ISBN
1862392129
9781862392120
9781862392120
Publisher
Geological Society
Source title
Geological Society Memoir
Editor(s)
Gee D.G.
Stephenson R.A.
Stephenson R.A.
Place of publication
London
Pages
97-112
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