Crust and mantle lithospheric structure of the Iberian Peninsula deduced from potential field modeling and thermal analysis

- 3D Lithospheric structure of the Iberian Peninsula and crustal density variations
- The Variscan domain is characterized by a relatively flat Moho and a thin lithosphere.
- The Alpine domain shows a more variable Moho relief and a thicker lithosphere.
- Denser crust in the Iberian Massif and locally in the Pyrenees and Iberian Chain
- Least dense crust in the Betics and in sedimentary basin depocenters

We investigate the lithospheric structure of the Iberian Peninsula and lateral crustal density variations using a three-step approach. First the crustal and mantle lithosphere thicknesses are calculated from joint geoid and elevation modeling combined with thermal analysis further constrained by seismic data. We then compute the 3D gravity effect of the resulting lithospheric structure to separate the measured Bouguer anomaly into its regional and local components. Finally we invert the residual gravity anomalies to highlight lateral average crustal density variations and discuss them in terms of crustal structures. Our results show that for the majority of the study area the crustal thickness does correlate with the regional topography pattern. The highest topography - above 1500 m - shows thicknesses above 44 km with local values up to 48 km. Crustal thicknesses in the range of 36-40 km are obtained in the uplifted Alpine areas while a thinner crust is observed in sedimentary basins and in the Iberian Massif (30 to 35 km) with the exception of SW Iberia region where the crust thins from 30 to 28 km. Thick lithosphere - above 140 km - is found along the Pyrenees, the Cantabrian Mountains, the Iberian Chain and in the Betics while the thinnest lithosphere is found in SW Iberia (90 km). 3D inversion of residual anomalies show that for the majority of the area the average density of the crust is in the range of 2810 ± 10 kg m− 3. The denser crust is found in the NW and SW regions of the Iberian Massif (+ 30 kg m− 3 on average) and locally in the Pyrenees (above + 70 kg m− 3), NW of the Iberian Chain (+ 15 kg m− 3 on average) and in the southern Internal Betics (+ 70 kg m-3). The least dense crust is found in the central and western Betic Chain (− 30 kg m− 3 on average) and in sedimentary basin depocenters.