301 research outputs found
Rasgos generales de los skarns y mineralizaciones asociadas del Sistema Central español
[Resumen] La existencia en el Sistema Central Español de gran variedad de mineralizaciones ligadas a skarns permite discriminarlas en base al protalito, profundidad de emplazamiento y composición del granito asociado.Estas variables definen las condiciones fisicoqu!micas de la alteración metasomitica y por lo tanto, la paragJnesis de la ganga Y mineralización.[Abstract] The ecurrence in the Spanish Central 5ystem of a great variety of ore shewings related te skarns allew te discriminate them in basis to the original rack petrology, deepness and composition of related granite. Those parameters characterize the physicochemical conditions of metasomatic alteration, gangue minerelogu and ore campositio
The Aguablanca Ni–(Cu) sulfide deposit, SW Spain: geologic and geochemical controls and the relationship with a midcrustal layered mafic complex
The Aguablanca Ni–(Cu) sulfide deposit is
hosted by a breccia pipe within a gabbro–diorite pluton.
The deposit probably formed due to the disruption of a
partially crystallized layered mafic complex at about 12–
19 km depth and the subsequent emplacement of melts and
breccias at shallow levels (<2 km). The ore-hosting breccias
are interpreted as fragments of an ultramafic cumulate,
which were transported to the near surface along with a
molten sulfide melt. Phlogopite Ar–Ar ages are 341–
332 Ma in the breccia pipe, and 338–334 Ma in the layered
mafic complex, and are similar to recently reported U–Pb
ages of the host Aguablanca Stock and other nearby calcalkaline
metaluminous intrusions (ca. 350–330 Ma). Ore
deposition resulted from the combination of two critical
factors, the emplacement of a layered mafic complex deep
in the continental crust and the development of small
dilational structures along transcrustal strike-slip faults that
triggered the forceful intrusion of magmas to shallow
levels. The emplacement of basaltic magmas in the lower
middle crust was accompanied by major interaction with
the host rocks, immiscibility of a sulfide melt, and the
formation of a magma chamber with ultramafic cumulates
and sulfide melt at the bottom and a vertically zoned mafic
to intermediate magmas above. Dismembered bodies of
mafic/ultramafic rocks thought to be parts of the complex
crop out about 50 km southwest of the deposit in a
tectonically uplifted block (Cortegana Igneous Complex,
Aracena Massif). Reactivation of Variscan structures that
merged at the depth of the mafic complex led to sequential
extraction of melts, cumulates, and sulfide magma. Lithogeochemistry
and Sr and Nd isotope data of the Aguablanca
Stock reflect the mixing from two distinct reservoirs, i.e.,
an evolved siliciclastic middle-upper continental crust and a
primitive tholeiitic melt. Crustal contamination in the deep
magma chamber was so intense that orthopyroxene
replaced olivine as the main mineral phase controlling the early fractional crystallization of the melt. Geochemical
evidence includes enrichment in SiO2 and incompatible
elements, and Sr and Nd isotope compositions (87Sr/86Sri
0.708–0.710; 143Nd/144Ndi 0.512–0.513). However, rocks
of the Cortegana Igneous Complex have low initial
87Sr/86Sr and high initial 143Nd/144Nd values suggesting
contamination by lower crustal rocks. Comparison of the
geochemical and geological features of igneous rocks in the
Aguablanca deposit and the Cortegana Igneous Complex
indicates that, although probably part of the same magmatic
system, they are rather different and the rocks of the
Cortegana Igneous Complex were not the direct source of
the Aguablanca deposit. Crust–magma interaction was a
complex process, and the generation of orebodies was
controlled by local but highly variable factors. The model
for the formation of the Aguablanca deposit presented in
this study implies that dense sulfide melts can effectively
travel long distances through the continental crust and that
dilational zones within compressional belts can effectively
focus such melt transport into shallow environments
Reflection Seismic Imaging for Mineral Exploration in the Sotiel-Coronada Area, Southwest Spain
Near Surface Geoscience Conference & Exhibition Online 2020This work explores the first results of the seismic data acquired in the Sotiel-Coronada mine
as part of the SIT4ME (Seismic Imaging Techniques for Mineral Exploration) project. In this
experiment, a multi-source seismic data-set was acquired at the end of 2018 in the Sotiel-
Coronada area of the Iberian Pyrite Belt (IPB) (southwest Spain). In the seismic experiment
presented, 653 seismic receivers were deployed distributed in a pseudo 3D grid and six
crooked lines across the study area. The sensors recorded c. 900 vibration points produced
by a 32 Tn vibrotruck.
Here, we present the stack results of the 2D seismic sections. Data from over 100 wells have
been incorporating to aid in the structural interpretation. The preliminary interpretation reveals
the complexity of this highly faulted ore-bearing area. Correlations between well log data
information and 2D seismic profiles, suggest the location of a potentially mineralized area. The
SIT4ME project has been funded by EIT Raw Materials (17024)
The carbonate-hosted Zn-Pb deposits of NW Spain: stratabound and discordant deposits relates to the variscan deformation
The carbonate Vegadeo Fm (Lower-Middle Cambrian, NW Spain) hosts abundant Zn-Pb mineralization. Minor stratiform ore showings occur in mineralogically and geochemically undisturbed limestones of the Lower Member. They are interpreted as related to diagenetic processes, with sulfur derived from the abiogenic reduction of sulfates interbedded in the carbonates and lead leached from the nearby detrital rocks. The major mineralization, stratabound deposits in the Upper Vegadeo Fm and discordant replacements (Rubiales-type), occurs inrelationship with pervasive epigenetic silicification and minor hydrothermal breccias. They are interpreted as of Late Variscan age. Here, the mineralization seems to be formed by reaction of the hosting carbonates with low-saline (<7 wt% NaCI eq.) water-rich fluids that circulated along major lithologic contacts or extensional faults. Isotopic composition of the hydrotherrnal fluids falls within the field of low-grade metamorphic or basinal waters ( δ180=-l.0 to +6.3 ‰; δD=-43 to -3l ‰). The ore-fonning process occurred at temperatures between 150 and 250ºC and at low fluid pressures (<500 b). Lead isotopes suggest tha_t most of the base metals were derived from the hydrothermal remobilization of the diagenetic ores in a "lead-frozen" system. Sorne of the sulfur appears to have had the same source, but there was also a significant input from biogenically -reduced sulfur from the endosing sbales. These Variscan ores have many of the descriptive features of carbonate-hosted deposits, but the fluid compositions, P-T conditions of formation, and tectonic setting were fundamentally different. They can be interpreted as equivalent to MVT deposits, but formed in the intemal zones of orogenic belts
Integration of SAR and passive seismic data for monitoring mining activities (Minas Riotinto, SW Iberia)
[EN]This presentation describes how the subsidence in a mining area can be tracked down from INSAR data and passive seismic dat
Modified magnetic anisotropy at LaCoO_(3)/La_(0.7)Sr_(0.3)MnO_(3) interfaces
Controlling magnetic anisotropy is an important objective towards engineering novel magnetic device concepts in oxide electronics. In thin film manganites, magnetic anisotropy is weak and it is primarily determined by the substrate, through induced structural distortions resulting from epitaxial mismatch strain. On the other hand, in cobaltites, with a stronger spin orbit interaction, magnetic anisotropy is typically much stronger. In this paper, we show that interfacing La0.7Sr0.3MnO3 (LSMO) with an ultrathin LaCoO3 (LCO) layer drastically modifies the magnetic anisotropy of the manganite, making it independent of the substrate and closer to the magnetic isotropy characterizing its rhombohedral structure. Ferromagnetic resonance measurements evidence a tendency of manganite magnetic moments to point out-of-plane suggesting non collinear magnetic interactions at the interface. These results may be of interest for the design of oxide interfaces with tailored magnetic structures for new oxide devices
Mitochondrial Toxicogenomics for Antiretroviral Management: HIV Post-exposure Prophylaxis in Uninfected Patients
Background: Mitochondrial genome has been used across multiple fields in research, diagnosis, and toxicogenomics. Several compounds damage mitochondrial DNA (mtDNA), including biological and therapeutic agents like the human immunodeficiency virus (HIV) but also its antiretroviral treatment, leading to adverse clinical manifestations. HIV-infected and treated patients may show impaired mitochondrial and metabolic profile, but specific contribution of viral or treatment toxicity remains elusive. The evaluation of HIV consequences without treatment interference has been performed in naïve (non-treated) patients, but assessment of treatment toxicity without viral interference is usually restricted to in vitro assays. Objective: The objective of the present study is to determine whether antiretroviral treatment without HIV interference can lead to mtDNA disturbances. We studied clinical, mitochondrial, and metabolic toxicity in non-infected healthy patients who received HIV post-exposure prophylaxis (PEP) to prevent further infection. We assessed two different PEP regimens according to their composition to ascertain if they were the cause of tolerability issues and derived toxicity. Methods: We analyzed reasons for PEP discontinuation and main secondary effects of treatment withdrawal, mtDNA content from peripheral blood mononuclear cells and metabolic profile, before and after 28 days of PEP, in 23 patients classified depending on PEP composition: one protease inhibitor (PI) plus Zidovudine/Lamivudine (PI plus AZT + 3TC; n = 9) or PI plus Tenofovir/Emtricitabine (PI plus TDF + FTC; n = 14). Results: Zidovudine-containing-regimens showed an increased risk for drug discontinuation (RR = 9.33; 95% CI = 1.34-65.23) due to adverse effects of medication related to gastrointestinal complications. In the absence of metabolic disturbances, 4-week PEP containing PI plus AZT + 3TC led to higher mitochondrial toxicity (−17.9 ± 25.8 decrease in mtDNA/nDNA levels) than PI plus TDF + FTC (which increased by 43.2 ± 24.3 units mtDNA/nDNA; p < 0.05 between groups). MtDNA changes showed a significant and negative correlation with baseline alanine transaminase levels (p < 0.05), suggesting that a proper hepatic function may protect from antiretroviral toxicity. Conclusions: In absence of HIV infection, preventive short antiretroviral treatment can cause secondary effects responsible for treatment discontinuation and subclinical mitochondrial damage, especially pyrimidine analogs such as AZT, which still rank as the alternative option and first choice in certain cohorts for PEP. Forthcoming efforts should be focused on launching new strategies with safer clinical and mitotoxic profile
SIT4ME: Multidisciplinary techniques for mining exploration in Sotiel (SW-Spain).
X Congreso Geológico de España, 5-7 Julio 2021, Vitoria - GasteizLa necesidad de satisfacer la creciente demanda de materia prima de forma segura, sostenible y a bajo coste, es la principal motivación del proyecto SIT4ME, financiado por el programa EIT-Raw Materials. El objetivo principal de SIT4ME es desarrollar una metodologÃa efectiva y eficiente para la exploración de recursos minerales mediante métodos sÃsmicos. Este proyecto se centra en la adquisición, procesado e interpretación de datos sÃsmicos (fuente activa y pasiva) en un entorno real: Sotiel-Coronada, ubicada al SO de la Faja PirÃtica Ibérica. Estos datos permitirán obtener imágenes de las principales estructuras y de los niveles mineralizados a profundidades de entre 300-500 m. El procesado de los datos sÃsmicos 2D incluye correcciones estáticas, deconvolución, ecualización de la amplitud, filtro de frecuencia y análisis de velocidad. La correlación entre las imágenes sÃsmicas, la geologÃa de superficie y los sondeos existentes ha permitido identificar las principales estructuras. Los resultados muestran buena reflectividad hasta los 2000 ms two-way traveltime (TWT), con estructuras buzando al norte. En la zona central del perfil se identifica una zona de alta reflectividad de 385 m de longitud a 130 ms TWT, correspondiente a un nivel mineralizado. En el futuro se incluirán procesos de migración pre-stack, procesado sÃsmico de los datos en 3D y tomografÃa de primeras llegadas para obtener un modelo robusto incrementando la probabilidad de éxito en la exploración.The need to satisfy the increasing demand for raw materials in a safe, sustainable and cost-effective manner, is the main motivation of the SIT4ME project, financed by the EIT-Raw Materials program. The main objective of SIT4ME is to develop an
effective and efficient methodology to apply seismic techniques in the search of mineral resources. This project focuses on the acquisition, processing and interpretation of seismic data (controlled and natural sources) in a real environment: Sotiel-Coronada,
located at the SW of the Iberian Pyrite Belt. These data will allow us to obtain images of the principal structures and mineralized levels at depths of 300-500 m. The 2D seismic data process flow includes static corrections, deconvolution,
amplitude equalization, frequency filters and velocity analysis. The correlation between seismic images, surface geology and existing drill cores allowed identifying the main deep structures. The results show good, north-dipping reflectivity up to
2000 ms TWT. A high reflectivity zone, c. 380m long, exists in the center of the profile at 130 ms TWT, related to one of the mineralized areas. Future work will include the pre-stack depth migration, processing of 3D seismic data and first arrivals
tomography to obtain a robust model that increases the probability of success in the exploration
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