Examinando por Autor "Rey, Javier"
Mostrando 1 - 14 de 14
- Resultados por página
- Opciones de ordenación
Ítem Assessment of Tailings Ponds by a Combination of Electrical (ERT and IP) and Hydrochemical Techniques (Linares, Southern Spain)(SPRINGER LINK, 2020-09-01) Rey, Javier; Martínez, Julián; Hidalgo, M. Carmen; Mendoza, Rosendo; Sandoval, SenenAccumulated mine waste in certain locations in the abandoned mining district of Linares-La Carolina (southern Spain) contain high levels of metals. Therefore, in recent years, many of these tailings ponds have been restored and sealed. This study assessed the efficacy of two geophysical techniques, electrical resistivity tomography (ERT) and induced polarisation (IP), combined with hydrochemical studies, as tools to image the effectiveness of the encapsulation. In the bedrock, ERT profiles distinguished a surficial layer of moderate-low resistivity values (below 80 Ω m), associated with alluvial sands or altered granite, and a deeper zone of high resistivity (up to 1000 Ω m) related to unaltered granite basement. Lateral changes in resistivity were identified inside the upper layer and downstream of the tailings pond. The IP profiles detected local anomalies in the chargeability values (up to 8 mV/V), unusual in granitic rocks. The locations with high chargeability also had low resistivity, which typically indicates the percolation of mining leachates in the underlying altered granites. Integration of geological and geochemical information confirmed this interpretation. This work verified that the combined use of ERT and IP methods were effective for monitoring ancient tailings ponds and for assessing tailings encapsulation.Ítem Assessment of tailings ponds by means of a combination of electrical (ERT and IP) and hydrochemical techniques (Linares, southern Spain).(Springer, 2021) Rey, Javier; Martínez, Julián; Hidalgo, M. Carmen; Mendoza, Rosendo; Sandoval, SenenAccumulated mine waste in certain locations in the abandoned mining district of Linares-La Carolina (southern Spain) contain high levels of metals. Therefore, in recent years, many of these tailings ponds have been restored and sealed. This study assessed the efficacy of two geophysical techniques, electrical resistivity tomography (ERT) and induced polarisation (IP), combined with hydrochemical studies, as tools to image the effectiveness of the encapsulation. In the bedrock, ERT profiles distinguished a surficial layer of moderate-low resistivity values (below 80 Ω m), associated with alluvial sands or altered granite, and a deeper zone of high resistivity (up to 1000 Ω m) related to unaltered granite basement. Lateral changes in resistivity were identified inside the upper layer and downstream of the tailings pond. The IP profiles detected local anomalies in the chargeability values (up to 8 mV/V), unusual in granitic rocks. The locations with high chargeability also had low resistivity, which typically indicates the percolation of mining leachates in the underlying altered granites. Integration of geological and geochemical information confirmed this interpretation. This work verified that the combined use of ERT and IP methods were effective for monitoring ancient tailings ponds and for assessing tailings encapsulation.Ítem Characterization of Tailings Dams by Electrical Geophysical Methods (ERT, IP): Federico Mine (La Carolina, Southeastern Spain)(MDPI, 2021-01-31) Martínez, Julián; Mendoza, Rosendo; Rey, Javier; Sandoval, Senen; Hidalgo, M. CarmenThis work analyzed the effectiveness of two electrical geophysical methods in characte-rizing tailings dams. A large flotation cell used for sludge thickening in the concentration plant of the Federico Mine (closed in 1985) within the old mining district of La Carolina (southeastern Spain) was selected for this research. In addition to the direct information provided by the geology of the study area and the surface exposure of the waste deposits, information regarding the construction of this mining structure was available, which helped in the interpretations of the geophysical survey data. In this study, two geophysical surveying methods were used simultaneously: Electrical resistivity tomography (ERT) and induced polarization (IP). Six profiles were acquired, processed, and interpreted. The length of the profiles allowed the obtaining of data reaching maximum investigation depths ranging between 7 and 65 m. These profiles provided information for a detailed analysis of the internal characteristics of the deposited materials. The lateral and vertical observed variations are linked to different degrees of moisture content. The study also defines the geometry of the top of the bedrock and the tectonics that affect the pouring/dumping hole. Old flotation sludge has resistivity values that range between 1 and 100 Ωm (i.e., wet waste 1–30 Ωm, dry waste 30–100 Ωm), while phyllites in the rocky substrate have resistivities larger than 200 Ωm and can even reach va-lues greater than 1000 Ωm. Between the waste and unaltered phyllites, there is a supergene alteration zone (weathering) with resistivity values between 100 and 200 Ωm. The IP method was used to detect the presence of metals in the accumulated waste in the pond by analyzing the presence of large chargeability anomalies. Anomalies were detected in four of the profiles, which ranged from low (i.e., between 0 and 8 mV/V) to medium (i.e., between 8 and 18 mV/V) and high values (i.e., 18 and >30 mV/V).Ítem Combining geophysical methods (DC, IP, TDEM and GPR) to characterise mining waste in the Linares-La Carolina district (southern Spain)(ELSEVIER, 2022-09-07) Rey, Javier; Mendoza, Rosendo; Martínez, Julián; Hidalgo, M. Carmen; Flores, CamiloThe accumulation of waste materials in old, abandoned mining districts without prior sealing of the substrate currently poses a significant risk of contamination to soils and surrounding waters. Some of these mining dams have undergone a reclamation and sealing process in recent years to alleviate this problem. The current study is an analysis of the effectiveness of using different geophysical techniques for characterising these structures and monitoring the isolation performed. This study was carried out in the old mining district of Linares-La Carolina (southern Spain). The following techniques were investigated in this study: direct current (DC) resistivity, induced polarization (IP), ground-penetrating radar (GPR) and the time domain electromagnetic method (TDEM). Combining DC and IP made it possible to characterise the internal structure of the abandoned mining dams, whereby the geometry of these deposits was determined and the corresponding potential risks were assessed. In addition, percolation zones of mining leachates were detected that indicate defects in the sealing stage. TDEM was a good complementary technique for calculating the depth of the bedrock on which the mining dam is located. GPR could only be used to investigate shallow depths at all of the antenna frequencies used (100, 250 and 500 MHz) but was useful for obtained detailed information about the last stages of filling and characterising the encapsulation performed during sealing.Ítem Geological and Mining Heritage as a Driver of Development: The NE Sector of the Linares-La Carolina District (Southeastern Spain)(MDPI, 2022-02-06) Mendoza, Rosendo; Rey, Javier; Martínez, Julián; Hidalgo, M. CarmenConservation, rehabilitation and post-valuation of the facilities of old mining districts is considered a valid strategy to revitalize these areas. In this study, the northeastern sector of the Linares-La Carolina mining district was analyzed, integrating geological information with mining to assess its value. The characteristics of the three most emblematic veins (consisting of galena, sphalerite, chalcopyrite, pyrite, quartz, ankerite and calcite) were analyzed, namely El Guindo, Federico and El Sinapismo. In this study, each mining exploitation was evaluated according to their geological context. Currently, old mining operations can only be visited from drainage galleries or from some exploration galleries. However, some of the old mining shafts could be adapted for visitation. On the surface, the remains of the most important extraction shafts and part of the associated facilities are still visible. One can also visit old tailings dumps with a high contents of heavy metals associated with ore concentration plants. The contaminating potential of these wastes is being monitored thanks to control piezometers and sensors installed at different depths within the tailings ponds, which assist in controlling evolution in the latter years. Different localities of special interest from geological, mining and mineralogical points of view are indicated. Therefore, the guided tour described in this work is attractive for tourism and educational purposes.Ítem Geophysical characterisation of geologic features with mining implications from ERT, TDEM and seismic reflection (Mining District of Linares-La Carolina, Spain)(ELSEVIER, 2021-11-15) Mendoza, Rosendo; Rey, Javier; Martínez, Julián; Hidalgo, M. Carmen; Sandoval, SenenIn this study, the effectiveness of different geophysical techniques is analysed in relation to the imaging of geological structures with mining interest. To achieve this goal, the old district of Linares-La Carolina (Southeast Spain) is chosen due to the presence of dense swarm of mineralised dykes, primarily consisting of galena (PbS). In particular, the western boundary of the mining district is studied. At this westernmost area the veins lose their continuity due to regional fractures which resulted in the abandoning of the extracting labours. Direct information from both the surface geology and several boreholes are used as ground-truth calibration and verification for the geophysical tools used in this study. The seismic response is characterised by high-amplitude reflectors, generally at the base of the sedimentary cover. The seismic profiles suggest lateral changes in the thickness and the existence of fractures affecting the sedimentary cover and/or the top of the acoustic basement. However, this technique has proved ineffective when studying the Palaeozoic substrate, precisely at those areas where the veins are hosted. Electrical resistivity tomography (ERT) studies suggest fractures and lateral changes in the facies, in both the sedimentary cover and the Palaeozoic basement. The basement shows phyllites in the granite intrusion, which are crucial for the elastic properties of the hosting rock and therefore indicate areas prone to further mineralisation. Time-domain electromagnetic (TDEM) data, which is an excellent complement to the two previous techniques, have also been collected. Data have been taken with different configurations and varying measurement parameters at each sounding station. This approach has made it possible to compare the effectiveness benefits and drawbacks of the different methods.Ítem Geophysical Characterization of Aquifers in Southeast Spain Using ERT, TDEM, and Vertical Seismic Reflection(MDPI, 2020-10-21) Rey, Javier; Martínez, Julián; Mendoza, Rosendo; Sandoval, Senen; Vladimir, Tarasov; Kaminsky, Alex; Hidalgo, M. Carmen; Morales, KevinWe assess the effectiveness of complementary geophysical techniques to characterize a Jurassic dolomite confined aquifer at Loma de Ubeda, Spain. This aquifer, which is penetrated by wells in the 100–600-m depth range, is confined by Triassic clays (bottom) and Miocene marls (top). The Jurassic dolomite is characterized by prominent seismic reflectors of high amplitude. Thus, it is readily differentiated from the low-amplitude reflectors of the confining clay-rich Triassic and Miocene materials. Electrical resistivity tomography (ERT) allowed us to detail the characteristics of the aquifer up to a maximum depth of 220 m. Lateral changes in facies and small faults have been identified using ERT. Time-domain electromagnetic (TDEM) is an excellent complement to the two above-mentioned techniques in order to widen the analyzed depth range. We acquire TDEM data with different configurations at multiple study sites while simultaneously varying measurement parameters. In doing so and by comparing the effectiveness of these different configurations, we expand the use of TDEM for aquifer characterization.Ítem Geophysical Prospecting Using ERT and IP Techniques to Locate Galena Veins(MDPI, 2019-12-06) Martínez, Julián; Rey, Javier; Sandoval, Senen; Hidalgo, M. Carmen; Mendoza, RosendoThe aim of this study is to prove the effectiveness of two electrical geophysical prospecting techniques, namely electrical resistivity tomography (ERT) and induced polarization (IP), in locating thin vein structures of metal sulphides embedded in Palaeozoic materials underlying a sedimentary cover. For this purpose, a Quaternary basin known as La Garza was selected, located in the mining district of Linares-La Carolina (Southern Spain). Galena (PbS) veins appear abundantly throughout this area, hosted in the Palaeozoic granitic bedrock. The studied veins show thicknesses from 0.5 to 2.0 m, and most present a vertical planar distribution. The veins lose their continuity below the sedimentary cover due to normal fractures that control the subsidence of the basin. During the 1980s, geophysical research campaigns were carried out in La Garza using vertical electrical sounding and failed in detecting the hidden veins. For this reason, to carry out this study, a closed regular mesh was designed, composed by eight ERT and IP profiles, with variable lengths between 315 and 411 metres. An electrode spacing between 5 and 7 metres was selected, thus allowing the granite bedrock to be reached without significantly reducing the resolution capabilities of the method. Even though ERT and IP are well-known geophysical techniques for mapping ore deposits, this is a case study that shows the advantages of the simultaneous use of both techniques (ERT and IP), over their individual application. ERT allows for reconstructing the morphology of the basin and the fractures that control it due to high-resistivity contrast between the overlying sedimentary cover and the underlaying granitic basement. However, it cannot provide any insights about their degree of mineralization. At this point, it is the IP technique that makes it possible to differentiate which are the mineralized structures. Some of these fractures produce high (above 50 mV/V) and moderate (below 50 mV/V) chargeability values, suggesting the existence of several unexploited metal veins. Furthermore, the derived models enable researchers to analyse the morphology of this sedimentary basin controlled by normal faults.Ítem GPR and Magnetic Techniques to Locate Ancient Mining Galleries (Linares, Southeast Spain)(Hindawi, 2023-08-30) Mendoza, Rosendo; Marinho, Bruna; Rey, JavierOld mining districts have created numerous subsurface cavities, often at shallow depths. The resulting subsidence risk is a major territorial planning problem, especially when these holes are in urban expansion areas. Ground-penetrating radar (GPR) and magnetic techniques can help to detect and to characterise these shallow mining structures based on the strong contrast of electromagnetic and magnetic properties (dielectric constant and magnetic susceptibility) between the rock and the backfill of cavities. In the present study, these techniques were used to locate old mining cavities near the city of Linares, located south of Spain and connected to the area’s old mining district. GPR and magnetometry (total magnetic field and vertical magnetic gradient) were performed on a grid in one of the most important veins in the sector. By comparing both working methods, the vein structure within the granite can be detected. On the one hand, the magnetic prospecting technique (magnetic anomalies) has allowed us to detect when the vein is covered by metallic elements of natural or anthropogenic origin. On the other hand, strong reflections and hyperbolic events associated in GPR profiles confirm the presence of cavities related to old mining operations. Shallow magnetic anomalies not associated to GPR variations are related to the slag present in the study area (detected in the outcrop) or to unexploited vein mineralizations.Ítem Ground-Penetrating Radar Study of Progradational Units in Holocene Coastal Plains: Carchuna Beach (SE Spain)(MDPI, 2020-07-19) Rey, Javier; Martínez, Julián; Hidalgo, M. Carmen; Mendoza, Rosendo; Campos-Suñol, M. JoséThe internal geometries of progradational units on the coastal plain in southeastern Spain (Carchuna Beach, Granada) since the maximum Holocene marine transgression (ca. 7000 cal BP) have been analysed using ground-penetrating radar (GPR). Radargram analysis shows the presence of sedimentary structures consistent with the progradation of coastal plains, interpreted as laminations associated with the foreset and topset. Laterally, five middle scale progradational units (H2, H3, H4, H5 and H6) are identified. Each of these units can be grouped into two major units. The general trend towards progradation is interrupted at the boundary of the units. Minor scale units (prograding wedges), deposited at topographically lower areas, are detected in GPR profiles. The radargrams also show channel erosional surfaces and sigmoidal landward dipping reflections interpreted as washover channel deposits, with the erosion and transference of sediments between the beach and the back-ridge domain. Furthermore, the saturation of coastline sediments with saltwater rapidly attenuates the GPR signal. Thus, the GPR is also a good tool to detect saltwater intrusions in shallow aquifers.Ítem Metal(loid)s Transport in Hydrographic Networks of Mining Basins: The Case of the La Carolina Mining District (Southeast Spain)(MDPI, 2020-09-28) Mendoza, Rosendo; Martínez, Julián; Rey, Javier; Hidalgo, M. Carmen; Campos-Suñol, M. JoséThis study analyses the distribution of the total metal(loid)s content accumulated in the sediments of the Grande River, the most important river course that runs through the old mining district of La Carolina (Jaén, Spain), whose waters are collected in an urban supply reservoir. In total, 102 sediments samples were taken along the river, 51 in the live-bed channel and another 51 in the floodplain. The samples analysed have high metal(loid)s content, sometimes much higher than the reference levels established by European and regional legislation for soils, especially Pb, As and Ba, with average values of 5452 mg/kg, 116 mg/kg and 2622 mg/kg, respectively. The statistical analysis of the values obtained allows the distribution of the contents of the different elements along the river to be characterized and the associations and dispersion patterns in the sediments of the metal(loid)s coming from the environmental liabilities of the numerous dumpsites and tailings dams generated by mining activity to be defined. In both cases, the high metal(loid)s content identified as well as the resulting values of various environmental indices (the enrichment factor, contamination factor, geoaccumulation index, potential ecological risk index and pollution load index), confirmed that the sediment samples were moderately to highly contaminated over extensive areas of the basin studied, with the greatest intensity and extent in the floodplain sediments.Ítem Oxidation Dynamics and Composition of the Flotation Plant Derived Tailing Impoundment Aquisgrana (Spain)(Springer, 2019) Rojas, Diego; Hidalgo, M. Carmen; Kohfahl, Claus; Rey, Javier; Martínez, Julián; Benavente, JoséÍtem Processing GPR Surveys in Civil Engineering to Locate Buried Structures in Highly Conductive Subsoils(MDPI, 2023-08-14) Mendoza-Vílchez, Rosendo; Araque-Pérez, Carlos; Marinho, Bruna; Rey, Javier; Hidalgo-Estévez, María CarmenMany studies have illustrated the great benefit of ground-penetrating radar (GPR) in civil engineering. However, in some cases, this geophysical survey method does not produce the desired results due to the electromagnetic characteristics of the subsoil. This study presents the results obtained in two locations near Linares (southern Spain), evaluating the detection of structures buried in conductive host materials (0.02 S/m in site 1 and 0.015 S/m in site 2) characterized by strong signal attenuation. Accounting for the study depth, which was 1.5 m, a 500 MHz shielded GPR antenna was used at both sites. At the first site, a controlled experiment was planned, and it consisted of burying three linear elements. An iron pipe, a PVC pipe, and a series of precast blocks were buried at a depth of 0.5 m in a subsoil composed of highly conductive clayey facies. To eliminate additional multiples caused by other superficial structures and increasing the high-frequency content, the predictive deconvolution flow was applied. In the 3D processing, the cover surfaces technique was used. Once the acquired GPR signals was analyzed and the optimal processing flow established, a second site in which different infrastructures in a conductive host medium formed by marly facies was explored. The 2D flow and 3D processing applied in this work allows to detect and see the continuity of some structures not visible for the default processing.Ítem Testing the Efficacy of Indirect Methods on Characterization of Sedimentary Basins by Correlation of Direct Data and Geophysical Techniques(MDPI, 2024) Rey, Javier; Mendoza, Rosendo; Hidalgo, M. Carmen; Marinho, BrunaThe information obtained from direct data (geological mapping and boreholes) and indirect techniques (reflection seismology, time-domain electromagnetics and magnetometry) is combined to analyse the northern limit of the Bailén basin (southeastern Spain). This Triassic–Neogene basin is confined by a graben-type structure, limited by two normal faults in the SW–NE direction (the Baños de la Encina-La Carolina fault and Guarromán fault). The movement of these faults was complex, with different pulses occurring over time. Therefore, the subsidence of the basin and the sedimentary filling of the graben were different, giving rise to lateral changes in the facies and thicknesses. This study focuses on the Baños de la Encina fault, chosen as the experimental site to analyse the effectiveness and accuracy of these geophysical techniques to reveal the basement structure and geometry. Seismic reflection allows to detect two faults that caused the subsidence of the eastern sector of the graben. The TDEM method made it possible to calculate the depth of the Palaeozoic basement, as well as reveal the presence of the two aforementioned faults. Magnetic total field data highlight variations in the basement depth that can be used to infer previously unknown fractures, in this case, in the NW–SE direction.