Curie Point Depth of the Iberian Peninsula and Surrounding Margins. A Thermal and Tectonic Perspective of its Evolution

Abstract

In this work the thermal structure of the Iberian Peninsula is derived from magnetic data by calculating the bottom of the magnetization, assumed to be the Curie‐point depth (CPD) isotherm, which accounts for the depth at which magnetite becomes paramagnetic (580°C). Comparison of the CPD with crustal thickness maps along with a heat flow map derived from the CPD provides new insights on the lithospheric thermal regime. Within Iberia, the CPD isotherm has thickness in the range of 17 to 29 km. This isotherm is shallow (<18 km) offshore, where the lithosphere is thinner. In continental Iberia, the NW Variscan domain presents a magnetic response that is most probably linked to thickening and later extension processes during the late Variscan Orogeny, which resulted in widespread crustal melting and emplacement of granites (in the Central Iberian Arc). The signature of the CPD at the Gibraltar Arc reveals a geometry consistent with the slab roll‐back geodynamic model that shaped the western Mediterranean. In offshore areas, a broad extension of magnetized upper mantle is found. Serpentinization of the upper mantle, probably triggered in an extensional context, is proposed to account for the magnetic signal. The Atlantic margin presents up to 8 km of serpentinites, which, according to the identification of exhumed mantle, correlates with a hyperextended margin. The Mediterranean also presents generalized serpentinization up to 6 km in the Algerian Basin. Furthermore, a heat flow map and a Moho temperature map derived from the CPD are presented.

Geothermal heat flow in Antarctica: current and future directions

“…2) is thus assumed to be the depth to the bottom of the magnetic source (DBMS) determined from magnetic survey data. The DBMS maps a transition zone, rather than an exact depth (Haggerty, 1978), and can provide information on crustal temperatures at depths not accessible by other means (Andrés et al, 2018;Okubo et al, 1985). Regions found to have a shallower DBMS (and thus an assumed shallower CPD) are expected to have higher average temperature gradients, and, therefore, higher GHF (e.g.…”

“…Regions found to have a shallower DBMS (and thus an assumed shallower CPD) are expected to have higher average temperature gradients, and, therefore, higher GHF (e.g. Aboud et al, 2011;Andrés et al, 2018;Arnaiz-Rodríguez and Orihuela, 2013;Bansal et al, 2013Bansal et al, , 2011Bhattacharyya and Leu, 1975;Guimarães et al, 2013;Li et al, 2017;Obande et al, 2014;Okubo et al, 1985;Ross et al, 2006;Salem et al, 2014;Tanaka et al, 1999;Trifonova et al, 2009).…”

Review article: Geothermal heat flow in Antarctica: current and future directions

“…7 and 2) is thus assumed to be the depth to the bottom of the magnetic source (DBMS) determined from magnetic survey data. The DBMS maps a transition zone, rather than an exact depth (Haggerty, 1978) and can provide information on crustal temperatures at depths not accessible by other means (Andrés et al, 2018;Okubo et al, 1985). Regions found to have a shallower DBMS (and thus an assumed shallower CPD) are expected to have higher average temperature gradients, and, therefore, higher GHF (e.g.…”

Estimation of Depth to Bottom of Magnetic Sources Using Spectral Methods: Application on Iran's Aeromagnetic Data

“…The 3‐D random magnetization model is then Fourier transformed and multiplied by (Pilkington & Todoeschuck, ), where k x , k y , and k z are the wavenumbers in the x , y , and z directions, α is the scaling exponent of magnetization α = β +1 (Maus & Dimri, ). Here we select α=3 for 3‐D sources as commonly used by many (e.g., Andrés et al, ; Bouligand et al, ; Fedi et al, ; Li et al, , ). Subsequently, the modulated wavenumber domain model is inverse transformed into the space domain to obtain the fractal magnetization model.…”