Autonomous (Non-Plate-Tectonic) Geodynamics of the Pyrenees

Abstract

The tectonic structure, seismicity, and modern geodynamics of the roughly EW-trending Pyrenees are considered based on the literature data. Geological evidence suggests that the structure of this mountain system is dominated by scaly overthrusts partially shifting into tectonic covers and conjugated folds. A lower width of the Pyrenees in the near-NS direction, across the strike, which was expected in the context of the plate-tectonic concept due to compression resulting from the convergence of the Eurasian Plate in the north and the African and Iberian lithospheric plates in the south, has not been confirmed by the geodetic data. GPS measurements reveal a higher width of the Pyrenees, also established by the seismological data based on the interpretation of the earthquake foci sets. Thus, there is a clear contradiction between the results obtained, on the one hand, by geological methods and, on the other hand, by geodetic and seismological surveys. This contradiction is proposed to be eliminated by invoking the previously developed ideas of the volume expansion of stratified rocks and the expansion of the corresponding parts of the Earth’s crust as a result of the inflow of additional mineral material with deep fluids rising from the lower crust/upper mantle.