Examinando por Autor "Hidalgo, M. Carmen"

Mostrando 1 - 13 de 13

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, Senen
Accumulated 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.
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, Senen
Accumulated 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.
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. Carmen
This 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).
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, Camilo
The 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.
Estimation of the Pb Content in a Tailings Dam Using a Linear Regression Model Based on the Chargeability and Resistivity Values of the Wastes (La Carolina Mining District, Spain)
(MDPI, 2021-12-21) Mendoza, Rosendo; Martínez, Julián; Hidalgo, M. Carmen; Campos-Suñol, M. José
The study area is located in the old mining district of Linares–La Carolina (southeastern Spain), the largest global producer of lead between 1875 and 1920. The selected environmental liability is the dam of the Federico mine and the waste that was generated during the flotation process. Geophysical techniques were applied along the slope of the dam, specifically ERT and IP. In total, 26 waste samples were taken along the entire slope of the dam, in which a high metal(oid) content was identified, sometimes much higher than the reference levels established by European and regional legislation for contaminated soils. The concentrations of Pb, As, and Ba stood out, with mean values of 4863 mg·kg−1, 89 mg·kg−1, and 794 mg·kg−1, respectively. Univariate and multivariate statistical analysis could characterize the distribution of the contents of the different elements along the slope, defining the associations and dispersion patterns of the metal(oid)s in the interior structure of the mine wastes. With the results of the Pb content (the most abundant metal in mineral paragenesis), a mathematical model was obtained by linear regression that related the variability of this cation with the variation in electrical resistivity and chargeability obtained by geophysical techniques.
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. Carmen
Conservation, 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.
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, Senen
In 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.
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, Kevin
We 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.
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, Rosendo
The 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.
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. José
The 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.
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. José
This 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.
Potentially Toxic Elements (PTEs) Dispersion in Alluvial Deposits from Abandoned Mining Sites
(MDPI, 2024-03-26) Martínez, Julián; Mendoza, Rosendo; De La Torre, María J.; Hidalgo, M. Carmen
In the watersheds of abandoned mining districts, it is common to find remains of former facilities and waste dams on stream banks and slopes—a situation that results in the transport and accumulation of metal(loid)s in alluvial deposits. To analyze this problem, an area of the former mining district of Linares–La Carolina (southern Spain) was selected to evaluate the contents and distributions of Ag, As, Ba, Cu, and Pb as potentially toxic elements (PTEs) found in the mineral paragenesis. Specifically, this study focused on the Siles Stream, which runs through a sector where underground mining for the exploitation of galena veins generated abundant mining wastes, mainly waste rock and tailings. Thirty-four sediment samples from the stream bed of the Siles Stream and two sediment samples from the Guadiel River, of which it is a tributary, were analyzed. Floodplain sediments were sampled in the stream banks at the middle and lower reaches (11 samples), as well as the riverine soils developed at the mouth of the Siles Stream (22 samples). The analyzed samples presented high levels of PTEs, in most cases with values much higher than the generic reference levels established by European and regional legislation for PTEs in soils. In the case of Pb, the main metal mined in this district, contents of up to 27,074 mg kg􀀀1 were observed in the stream bed sediments. Very high concentrations of Pb also appeared in the floodplain sediments, with maximum values in the middle course of the stream, where the concentration reached 43,692 mg kg􀀀1. With respect to the sediments of the Guadiel river bed, the Pb content was 699 mg kg􀀀1 before the confluence with the stream and 2537 mg kg􀀀1 downstream, which clearly reflects the influence of the contributions from the Siles Stream. The enrichment factors (EFs) show that the sediments present a severe to very severe anthropogenic influence for Ag, As, Ba, Cu, and Pb. The geoaccumulation index (Igeo) indicates that the entire basin is extremely polluted by Pb, to which As and Ag are added in the middle course of the stream. The potential ecological risk index (RI) and pollution load index (PLI) based on the contamination factor (CF) suggested that metal loads far exceeded the reference values. Selective chemical extraction methods were used to assess the potential bioavailability of these elements in sediment and soil samples. The results showed high concentrations of Pb in the exchangeable fraction, which poses a significant ecological risk and potential human health risks.
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, Bruna
The 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.

RUJA: Repositorio Institucional de Producción Científica

Examinando por Autor "Hidalgo, M. Carmen"