The rotation of Spain: Palaeomagnetic evidence from the Spanish meseta

Abstract

The magnetic properties of 39 oriented samples of Triassic siltstones and of 43 oriented samples of Silurian andesites and basalts from the Spanish Meseta were investigated.

After a.c. magnetic field demagnetization up to 3,000 Oe, peak value, and after correction for the dip of the geological strata the Triassic samples revealed a characteristic direction of magnetization with an average declination (D) of 359.5° and an inclination (I) of 23°. One group of samples of Silurian volcanic rocks from the province of Guadalajara had, after a.c. magnetic field demagnetization and correction for the dip, a characteristic direction of magnetization with an average declination of 159°C and an inclination of 18.5°; another group from the province of Ciudad Real had, after a.c. magnetic field demagnetization and after correction for the dip, a characteristic direction of magnetization with an average declination of 130.5° and an inclination of 22.5°.

The palaeomagnetic pole position derived from the Triassic rocks is situated at 63°N 177.5°E, and the pole positions of the first and second group of Silurian samples are situated at 35.5°N 157°W and 21°N 132°W, respectively.

The divergency between these results and the already known data for Triassic and Silurian from stable (extra-Alpine) Europe highly supports a counterclockwise rotation of Spain.