Torrential rainfall regimes, among others, are the origin of accelerated soil erosion. The Spanish southeastern Mediterranean region is characterised by an arid climate regime affected by extreme erosion episodes with an important loss of sediments. Soil erosion effects are even more noticeable in areas where soil has been anthropically degraded, as in the mining district of Sierra Minera de Cartagena. The present research focuses on monitoring and mapping the changes in the sediment distribution of iron oxides and hydroxyl (OH−) bearing minerals caused by a cold drop known in Spanish as 'DANA' in September 2019 on the Rambla del Beal. This short rambla is fed by sediments from its drainage basin and by mining residues, irrigating a wide agricultural area. When discharges overflow the rambla channel, residues spread over its floodplain and reach the ecological protected coastal lagoon Mar Menor. The objective of the study was mapping the mineral distribution of the mining materials eroded from the source areas and sedimented in Rambla del Beal during a DANA. The study was carried out using a pre‐ and a post‐DANA image from the Sentinel‐2 satellite. After masking vegetation, urban areas and water bodies, different band ratios (B4/B3, B11/B12, B8A/B6) and a Spectral Angle Mapper (SAM) classification were applied. Sediment deposits were identified in wider areas after the DANA. Iron oxides increased their extension by 11.08% in the central area (B3/B4 with R2 of 0.84) and hydroxyl‐bearing minerals increased by 8.95% in the Rambla del Beal's headwaters (B11/B12 with R2 of 0.71). The SAM classification (with a 0.1 rad threshold and an overall accuracy of 87.33%) allowed the differentiation and classification of two ferric iron oxides (haematite and goethite) and one iron hydrous sulphate mineral (jarosite). Additionally, band ratio images were spatially overlaid with the soil land uses map layer of the cadastre in order to plot the land uses most affected by the transported sediments during the DANA. These results highlighted agricultural land as the areas (land uses) most affected by iron oxides deposition, as oxidation processes occur more rapidly in these areas. However, grassland and scrubland were the areas with the highest content of hydroxyl‐bearing minerals, as water is accumulated in these places, which favours hydrolysis reactions. Highlights Torrential events can relocate large volumes of contaminated sediments from former mining areas. Sentinel‐2 allows monitoring mine waste iron‐sulphate changes caused by weathering alteration. Spatial mineralogical pattern in sediments is controlled by geomorphology and flood dynamics. The proposed digital image analysis allows mapping short‐term evolution of mine waste sediments.

This paper presents detailed mineralogical results together with a geochemical characterization for a sequence of six natural soil profiles. Bedrock samples (R series) and overlying soil samples (S series) were characterized. The soil profiles are distributed in a series of Paleozoic lithological units from lower Ordovician to upper Carboniferous in age (Iberian Massif, NW Iberia). The lithological influence on mineral properties and geochemical composition and, how different weathering may be occurring under very similar temperate and acidic conditions, have been studied. Field observations together with laboratory analyses were indicative of differential weathering. So, a series of selected chemical indices and relations were applied to clarify this assumption. The mineralogy was analysed by Scanning electron microscopy (SEM-EDS), X-ray diffraction (XRD) of rock powder and soil oriented aggregates. X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectroscopy (ICP-MS) were applied to analyse chemical composition. The first results showed how major elements, SiO2, Al2O3 and Fe2O3, slightly enriched in the soil profiles, are consistent with the dominant mineralogy: quartz, chlorite, muscovite and/or illite, together with kaolinite and albite. The bases K2O, Na2O, CaO and MgO are also coherent with mineral composition and experience little variation, but are gradually removed in the profiles. The mobility of major elements leads to a general loss of bases and, in general, a slight enrichment in silica and sesquioxides. SiO2 is enriched, firstly accumulated in soils and partially depleted by dissolution as colloidal form. Al2O3 in some soils is slightly less than in former rocks, so other physical processes are expected to take place, involving clay removal with consequent aluminium depletion too. A special emphasis has been given to albite coexisting with kaolinite, firstly supposed to be directly inherited from parent substrates when present, but finally the chemical index PIA shows it was mainly due to mineral alteration of plagioclases. The best correlations to explain the albite alteration and kaolinitization progress were obtained with chemical indices PIA, CIW, CIA and Al2O3/Na2O ratio. This together with mineralogical signatures, suggest that kaolinite is the result of gradual dissolution due to the acid hydrolysis of albite in such acidic environments, which may also be attributed to the organic matter influence.

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<p>High spatial resolution data recorded by the AHS (<em>Airborne Hyperspectral Scanner</em>) imaging system is evaluated for mapping the mineral composition of low relief landforms. The study area is located in the Cenozoic Tagus sedimentary basin (Central Iberian Peninsula) in geological units made of clay (smectites), evaporitic (gyspsum, anhydrite) and carbonate rocks (limestones and dolostones). The study is based on the spectral response of key minerals such as calcite, gypsum and both Mg and Al-bearing clays in order to map their presence in the flat and gently sloping surfaces of the area located between the Tagus, Tajuña and Jarama rivers. Two mapping techniques were used: image band ratios to enhance diagnostic mineral absorption features and the SAM (<em>Spectral Angle Mapper</em>) algorithm. Both methods show a good discrimination of the above referred minerals, being the best mapped gypsum. For the validation of the results, spectroscopic field and laboratory measurements were used together with the geological map of the study area and conventional aerial photointerpretation, providing the spatial distribution of Landforms mapping units and their differentiated mineral composition grouped in three main domains.</p><p><strong>Acknowledgements:</strong> this research is supported by FEDER/Spanish Ministry of Science and Innovation-<em>Agencia Estatal de Investigación</em>) research project ISGEOMIN-ESP2017-89045-R and HYPOPROCKS (PDC2021-121352-100) by MCIN/AEI/10.13039/501100011033 and the European Union “NextGenerationEU”/PRTR</p>