Reverse magnetic anomaly controlled by Permian igneous rocks in the Iberian chain

• Published in: Geologica acta Vol. 12; no. 3; pp. 193 - 208
• Main Authors: Calvin, P, Casas, A.M, Villalain, J.J, Tierz, P
• Format: Journal Article
• Language: English
• Published: Geologica Acta 2014; Institut de Ciències de la Terra "Jaume Almera"; Universitat de Barcelona (UB), Geociències Barcelona (Geo3BCN), Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDAEA), Universitat Autònoma de Barcelona (UAB)
• Subjects: 2.5D modelling; Early Permian; Geomagnetism; Geophysical research; Iberian Chain; Kiaman; Magnetic properties; Paleomagnetic properties; Reverse magnetic anomaly; Rocks, Igneous; Spain
• ISSN: 1695-6133; 1696-5728
• DOI: 10.1344/GeologicaActa2014.12.3.2

Two important reverse dipolar magnetic anomalies in the Iberian Chain (Spain) are located over Permian igneous rocks. A detailed study of one of them, the Loscos magnetic anomaly, where the geological structure is well constrained, reveals that the source of the anomaly must be a reverse remanent magnetisation carried by igneous rocks, acquired during the period of the Kiaman reverse magnetic superchron. Magnetic and gravimetric detailed survey (with 50 new gravimetric measurements and 8 main magnetic profiles -six of them N-S and the rest E-Wwith a total length of 40km), together with a study of the petrophysical characteristics of igneous materials, data processing and interpretation (upward continuation, 2.5D modelling, etc.) allowed to characterize qualitatively the anomaly and its source. Two overlapping anomalies with different wavelength were identified, indicating the presence of a shallower strongly altered igneous body with heterogeneous magnetic properties, and a deeper, large igneous body, responsible for the main, long-wavelength anomaly. KEYWORDS Reverse magnetic anomaly. Kiaman. Early Permian. 2.5D modelling. Paleomagnetic properties. Iberian Chain.