2026-10-30T01:04:57Zhttps://riubu.ubu.es/oai/requestoai:riubu.ubu.es:10259/60952021-12-16T11:41:35Zcom_10259.4_2560com_10259_5086com_10259_2604col_10259.4_2561
Repositorio Institucional de la Universidad de Burgos
author
Ayarza, Puy
author
Villalaín Santamaria, Juan José
author
Martínez Catalán, José R.
author
Álvarez Lobato, Fernando
author
Durán Oreja, Manuela
author
Calvín Ballester, Pablo
author
Recio, Clemente
author
Suárez Barrios, Mercedes
author
Gómez Martín, Elena
2021-11-04T10:59:34Z
2021-11-04T10:59:34Z
2021-03
0278-7407
http://hdl.handle.net/10259/6095
10.1029/2020TC006120
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.
eng
aeromagnetic anomaly
Central Iberian Arc
extensional tectonics
Iberian Massif
Kiaman superchron
magnetic S-Type granitoids
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
info:eu-repo/semantics/article
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URL
https://riubu.ubu.es/bitstream/10259/6095/3/Ayarza-tectonics_2021.pdf
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Ayarza-tectonics_2021.pdf