RT info:eu-repo/semantics/article
T1 Characterizing the Source of the Eastern Galicia Magnetic Anomaly (NW Spain): The Role of Extension in the Origin of Magnetization at the Central Iberian Arc
A1 Ayarza, Puy
A1 Villalaín Santamaria, Juan José
A1 Martínez Catalán, José R.
A1 Álvarez Lobato, Fernando
A1 Durán Oreja, Manuela
A1 Calvín Ballester, Pablo
A1 Recio, Clemente
A1 Suárez Barrios, Mercedes
A1 Gómez Martín, Elena
K1 aeromagnetic anomaly
K1 Central Iberian Arc
K1 extensional tectonics
K1 Iberian Massif
K1 Kiaman superchron
K1 magnetic S-Type granitoids
K1 Geología
K1 Geology
K1 Magnetismo
K1 Magnetism
AB The Eastern Galicia Magnetic Anomaly is the best studied anomaly of the Central Iberian Arc. This is due to its location, on the Lugo-Sanabria gneiss dome, and to the fact that its source rocks crop out in the Xistral Tectonic Window. Multiple studies of this anomaly have been carried out, but still, new results keep on shedding light on its understanding. This paper presents the first results on rock magnetic analyses, natural remanent magnetization, anisotropy of the magnetic susceptibility, X-ray diffraction, and stable isotopes geochemistry carried out on the source rocks of this anomaly. Results suggest that magnetization responds to the increase in oxygen fugacity underwent by rocks affected by late Variscan (330-300 Ma) extensional tectonics. Extensional detachments were the pathways that allowed the entrance of fluids that led to syntectonic crystallization of magnetite and hematite in metasediments and inhomogeneous S-Type granitoids derived from their partial melting. Accordingly, magnetization is not linked to lithologies, but to extensional structures developed in the late Carboniferous/earliest Permian, during the Kiaman reverse superchron. Systematic reverse magnetic remanence exhibited by hematite-bearing samples confirms the age of the magnetization and adds complexity to the interpretation of the anomaly. Understanding the EGMA contributes to the interpretation of other anomalies existing in the CIA, also located on thermal domes. The observed extension-related magnetization probably affected most of the NW Iberian Massif, thus hindering the study of previous tectonics by paleomagnetic techniques. This work aims to provide new hints to interpret magnetic anomalies located in extensional tectonic contexts worldwide.
PB American Geophysical Union (AGU)
SN 0278-7407
YR 2021
FD 2021-03
LK http://hdl.handle.net/10259/6095
UL http://hdl.handle.net/10259/6095
LA eng
NO Projects SA065P17 and BU235P18, funded by the Regional Castilla-León Government, (2) Salamanca University through different lines of funding related to its support to research groups program, (3) projects CGL2016-78560-P and CGL2016-77560 of the Spanish Ministry of Economy, Industry and Competitiveness, and (4) project PID2019-108753GB-C21/AECI/10.13039/501100011033 of the Agencia Estatal de Investigación.
DS Repositorio Institucional de la Universidad de Burgos
RD 02-may-2024