## 2 Materials and Methods  
### Study Area  
The study area is located in the northwest of the province of Pontevedra, on the southeastern coast of the Ria of Arosa (Figure 1). This ria is one of the largest and most important in the Ria Bajas, with its northern area belonging to the province of La Coruna and its southern area to the province of Pontevedra. In general, the study area covers approximately 9600 hectares and includes the Galician municipalities of Cambados, El Grove, and La Isla de Arosa, and parts of the municipalities of Sangenjo, Meano, Ribadumia, and Villanueva de Arosa, where a total of 57,358 people reside. Climatologically, it is situated in a continental zone with Mediterranean influences that result in mild and humid average annual conditions [26]. The oceanic effect is the primary influencing factor for the mild temperatures and abundant precipitation. An average annual precipitation of approximately 1455 mm is recorded, with a mean summer temperature of 19.3 \({}^{\circ}\)C and 9 \({}^{\circ}\)C in winter [27]. The southeastern area of the Ria of Arosa is located in the northwest part of the Iberian Massif, specifically within the Galicia-Tras-os-Montes Zone. Geologically, it represents an internal zone of the Variscan orogen and is characterized by being composed of various allochthonous domains overlying a bedrock of Paleozoic metasediments and granitic rocks. More precisely, the study area exhibits distinct lithological domains. The first domain is initially referred to as the Vigo-Pontevedra-Noya complex (\"polymettamorphic graben\" or \"blastomylionic trough\") and more recently referred to as the Malpica-Tui unit. It is a basal unit consisting of metasediments, including orthogneisses and metabasites. The deformation within the unit varies, with a dominance of highly deformed facies where mylonites can be observed. Structurally, it represents an elongated belt that covers almost the entire western part of Galicia. It is laterally bounded in the western part by a shear zone where it contacts the schistoe or autochthonous domain, while in the eastern part, it is in contact with the para-autochthonous domain through a dextral-subvertical tear [28]. The autochthonous domain consists of metasediments and sandstones from the schist-graywacke complex, the mica schists of the \"El Rosal-La Lanzada\" region, and the two-mica alkaline feldspar granite of synkinematic nature from the \"Villagarcia-Cuntis\" region [28]. The western part of Galicia is dominated by a significant amount of granitic magmatism, representing the main typologies studied in the northwestern part of the Iberian Peninsula (Figure 2A). All these granites, in a simplified manner, can be classified according to their synkinematic and postkinematic nature. In the Barbanza Peninsula and on the Isla de Arosa, the postkinematic calc-alkaline granites belonging to the Caldas de Reyes  
Figure 1: Location map of the study area (in red) within the province of Pontevedra in Galicia. pluton are best represented. This pluton exhibits multifacial characteristics ranging from biotite monzogranites to biotite granodiorites, with occasional occurrences of tonalite [29]. In the southeastern part of the study area, synkinematic calc-alkaline granites outcrop. In general, these granites appear as parallel and concordant bands with medium- to low-grade Variscan rocks. They exhibit deformation and local mignatization resulting from regional shear processes equivalent to the D3 evolutionary phase of the Variscan orogen [30]. Geomorphologically, there are numerous well-defined geomorphological units grouped into different morphogenetic systems (Figure 2B). Several Quaternary units can be distinguished, which constitute the morphogenetic deposits of different depositional agents. These units are found overlying the Variscan basement.