Remote sensing applications for marine placer deposit exploration remain limited due to the mineralogical complexity and dynamic coastal processes. This study presents the first medium- to high-level detailed multi-scale remote sensing analysis of placer deposits in the Rías Baixas, NW Spain, focusing on five beaches within the Vigo Estuary. Ten beach samples were analyzed for their heavy mineral (HM) content and spectral signatures, using bromoform separation and FieldSpec 4 spectroradiometer equipment, respectively. The spectral signatures of beach samples with a high HM content were characterized and resampled for the Sentinel-2 application, employing the Spectral Angle Mapper (SAM) algorithm. Field validation and an unmanned aerial vehicle (UAV) survey confirmed surface placer occurrences and the SAM’s results. Santa Marta Beach exhibited significant placer anomalies (up to 30% HM), correlating with low SAM values (minimum value–0.10), indicating high spectral similarity. The SAM-derived anomaly patches aligned with the field observations, demonstrating Sentinel-2’s potential for placer deposit mapping. This work highlights the application of Sentinel-2 in the exploration of placer deposits and the use of a specific spectral range of these deposits in coastal environments. These tools are non-invasive, more environmentally friendly, and sustainable, and can be extrapolated to other regions of the world with similar characteristics.

Marine ferromanganese crusts are metal-rich chemical sediments showing an increasing economic interest as potential mineral resources for strategic and critical metals. Formation of Fe-Mn crusts is linked to a series of different factors that favor or limit their genesis on the seabed. The objective of this work is the search of areas for potential formation of these deposits, using data obtained in the Canary Islands Seamount Province. The study has been carried out based on multi-criteria analysis, using a Geographic Information System (ArcGis 10.5, Spatial Analysis and Statistical tools). For this purpose, it has been created a cartographic model, which considers data related to depth, seabed substrate nature and age, slope and exposure to marine bottom currents. This model has been applied to non-sampled areas, contrasting them with data derived from the analysis of samples taken in different oceanographic surveys, in order to establish the correct conclusions. This work has been carried out using bathymetric and geological data shared by the Geological Survey of Spain (IGME) with the MINDeSEA [1] and EMODnet-Geology [2] European projects.[1] This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 731166.[2] EMODNET-Geology project (EASME/EMFF/2018/1.3.1.8-Lot 1/SI2.811048).

The exploration of coastal placer deposits, often enriched in critical raw materials demanded by industry, is significantly challenged by the dynamic marine environment and by the limited research devoted to developing dedicated exploration methodologies. This study presents the first systematic integration of multi-source geospatial data in the Rías Baixas for placer mineral prediction in the initial exploratory stage of these deposits. The primary objective is to investigate the presence of Titanium (ilmenite, and rutile), Zirconium (zircon), and Rare Earth Element (REE)-bearing minerals (monazite, xenotime, allanite, and garnets) in Rías Baixas (NW Spain). The methodology includes a lithological reclassification and the generalization of coastal types. These features are then integrated with watershed, coastline dynamics, and mineral occurrence data. Validation includes existing semi-quantitative and qualitative mineral identification data, and new field observations of heavy mineral accumulations. This integration allowed us to identify nine potential and ten predictive areas with a high probability of hosting coastal placers. The validation process showed a 79% spatial correlation, confirming a significant heavy mineral accumulation in 15 areas. This work underscores the efficacy of integrated cartography in prioritizing potential and predictive areas during the crucial first stage of mineral exploration. The methodology can be further enhanced by incorporating additional data, such as stream sediment geochemistry and the application of remote sensing techniques.