Examinando por Autor "Sandoval, Senen"
Mostrando 1 - 6 de 6
- 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 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.