Variscan Plutonism in the Geodynamic Evolution of the Central Iberian Zone of Portugal: Castelo Branco Pluton as Another Piece of the Puzzle

• Type: Article in International Scientific Journal
• Date: 2025

Authors

Cruz, C (Author) Other; Sant'Ovaia, H (Author) Other; H. C. B. Martins (Author) FCUP; Antunes, IMHR (Author) Other; Rocha, A (Author) Other; Noronha, F (Author) Other

Journal

Title: Geosciences

Vol. 15

Final page: 72

ISSN: 2076-3263

Publisher: MDPI

Indexing

ISI Web of Knowledge - 0 Citations

Scopus - 0 Citations

Other information

Authenticus ID: P-018-1XB

DOI: 10.3390/geosciences15020072

Abstract (EN): A multidisciplinary analysis of the Pennsylvanian Castelo Branco pluton of Central Iberian Zone (Iberian Variscan belt) was made, focusing on its magnetic behavior and fabric, microstructures, microfractures, and radiometric and gravimetric anomalies. The findings reveal that the Castelo Branco pluton is an ilmenite-type granite, characterized by low magnetic susceptibility values. The petrographic observations and high-temperature solid-state deformation indicate that pluton was emplaced during the latest compression phase (D3) of the Variscan tectonic regime. Magnetic fabric and gravimetric data show that the Castelo Brano pluton has a flat-shaped geometry with a depth of approximately 2-3 km, a feeding zone corresponding to NE-SW-trending regional faults, and that its fabric is oriented parallel to the NW-SE-trending regional foliation of the host rocks. The concentric magnetic foliation in the Alcains granite suggests an earlier ascent and emplacement compared to the Rio de Moinhos and S. Miguel da Acha granites, with Alcains demonstrating a laccolithic shape indicative of significant upward force. The ascent pathways of the different granites seem to have occurred along pre-existing NE-SW faults. The Castelo Branco pluton displays zoned nesting, with fluid inclusion planes indicating NNE-SSW to NE-SW and ENE-WSW trends in biotite-rich granites, and NNE-SSW to NE-SW and ESE-WNW trends in two-mica granites. Structural alignments in the study area show both NE-SW and NW-SE trends. The NE-SW faults and thrust faults are supported by residual gravimetric anomaly data, and NW-SE alignments are evident in magnetic fabric and regional folded structures. These findings enhance our understanding of the geodynamic processes influencing the Variscan plutonism in the Central Iberian Zone, positioning the Castelo Branco pluton as a key component in this geological puzzle.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 29