Person:
Fernández Barrenechea, José María

First Name

José María

Last Name

Fernández Barrenechea

URI

https://hdl.handle.net/20.500.14352/75219

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Geológicas

Department

Mineralogía y Petrología

Area

Cristalografía y Mineralogía

Identifiers

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Now showing 1 - 10 of 27

Fluid composition and reactions of graphite precipitation in the volcanic-Hosted deposit at Borrowdale (NW England): evidence from fluid inclusions
(Macla, 2008) Ortega Menor, Lorena; Luque del Villar, Francisco Javier; Fernández Barrenechea, José María; Millward, David; Beyssac, Olivier; Hizenga, Jan Marten; Rodas, Magdalena
Cambios mineralógicos en una bentonita tras 7,6 años de tratamiento termo-hidráulico
(Macla, 2008) Gómez Espina, Roberto; Villar Galicia, María Victoria; Fernández Barrenechea, José María; Luque del Villar, Francisco Javier; Cuevas Rodríguez , Jaime
Natural fluid-deposited graphite: mineralogical characteristics and mechanisms of formation
(American journal of science, 1998) Luque del Villar, Francisco Javier; Pasteris, Jill D.; Wopenka, Brigitte; Rodas, Magdalena; Fernández Barrenechea, José María
This paper focuses on the similarities and differences between metamorphic graphite (formed in situ from organic matter) and fluid-deposited graphite. We discuss the formation of fluid-deposited graphite in terms of the source of carbon, the characteristics of the C-bearing fluids (the C-O-H system), the mechanisms of carbon mobilization, and the mechanisms of carbon precipitation. New and existing analytical data are compiled on the physical and chemical characteristics of fluid-deposited graphite olitained by the following techniques: optical microscopy, differential ilierrilal analysis, thermogravimetry, X-ray diffraction, Raman spectroscopy, and stable isotope mass spectrometry. Our discussions focus on major, that is, volumetrically significant, worldwide concentrations of graphite
The graphite deposit at Borrowdale (UK): A catastrophic mineralizing event associated with Ordovician magmatism
(Geochimica et cosmochimica acta, 2010) Ortega Menor, Lorena; Millward, David; Luque del Villar, Francisco Javier; Fernández Barrenechea, José María; Beyssac, Olivier; Huizenga, Jan-Marten; Rodas, Magdalena; Clarke, S.M.
The volcanic-hosted graphite deposit at Borrowdale in Cumbria, UK, was formed through precipitation from C–O–H fluids. The δ13C data indicate that carbon was incorporated into the mineralizing fluids by assimilation of carbonaceous metapelites of the Skiddaw Group by andesite magmas of the Borrowdale Volcanic Group. The graphite mineralization occurred as the fluids migrated upwards through normal conjugate fractures forming the main subvertical pipe-like bodies. The mineralizing fluids evolved from CO2–CH4–H2O mixtures (XCO2 = 0.6–0.8) to CH4–H2O mixtures. Coevally with graphite deposition, the andesite and dioritic wall rocks adjacent to the veins were intensely hydrothermally altered to a propylitic assemblage. The initial graphite precipitation was probably triggered by the earliest hydration reactions in the volcanic host rocks. During the main mineralization stage, graphite precipitated along the pipe-like bodies due to CO2 → C + O2. This agrees with the isotopic data which indicate that the first graphite morphologies crystallizing from the fluid (cryptocrystalline aggregates) are isotopically lighter than those crystallizing later (flakes). Late chlorite–graphite veins were formed from CH4-enriched fluids following the reaction CH4+O2 → C + 2H2O, producing the successive precipitation of isotopically lighter graphite morphologies. Thus, as mineralization proceeded, water-generating reactions were involved in graphite precipitation, further favouring the propylitic alteration. The structural features of the pipe-like mineralized bodies as well as the isotopic homogeneity of graphite suggest that the mineralization occurred in a very short period of time.
Graphite morphologies in the volcanic-hosted deposits at Borrowdale (NW England, UK): preliminary raman and SIMS data
(Macla, 2008) Fernández Barrenechea, José María; Luque del Villar, Francisco Javier; Ortega Menor, Lorena; Rodas, Magdalena; Millward, David; Beyssac, Olivier
Mineralogy and Microstructure of Lightweight Aggregates Produced from Washing Aggregate Sludge and Fly Ash
(Macla, 2010) González-Corrochano, Beatriz; Alonso Azcárate, Jacinto; Rodas, Magdalena; Luque del Villar, Francisco Javier; Fernández Barrenechea, José María
Palaeogeographical significance of clay mineral assemblages in the Permian and Triassic sediments of the SE Iberian Ranges, eastern Spain
(Palaeogeography, palaeoclimatology, palaeoecology, 1997) Alonso Azcárate, Jacinto; Arche, Alfredo; Fernández Barrenechea, José María; López Gómez, José; Luque del Villar, Francisco Javier; Rodas, Magdalena
The evolution of the palaeogeography of the SE Iberian Basin during the Permian and Triassic represents a general evolution from continental to marine environments. It has been recently studied from the sedimentological, stratigraphical, tectonic and palaeontological points of view. In spite of these results, many aspects of this palaeogeography are still a matter of discussion. In this study, clay mineralogy analysis complements previous studies representing a new aspect for understanding the evolution of the sedimentary environment and the palaeogeography of the Iberian Basin during the periods in question and thus of the palaeogeography and the location of the major high areas in the westernmost border of the Tethys sea. In spite of late diagenetic transformations the original clay mineral associations of the Permian-Triassic sediments of the SE Iberian Ranges can be reconstructed. Seventy-seven samples of siliciclastic and carbonate sediments of these ages have been studied (SEM and XRD), revealing six new aspects that help to precise the palaeogeographical interpretation of the area: (1) Two major mineral assemblages have been found: illite+ kaolinite +pyrophyllite in the continental facies and illite + chlorite + vermiculite + mixed-layer clays in the marine facies. (2) The Mg-rich clay minerals are here considered to be of marine origin. (3) Active phases of basin boundary faults are marked in the sediments by the presence of pyrophyllite, derived directly from the Palaeozoic metamorphic basement. (4) Unconformities separating major depositional sequences also separate formations with different clay mineralogy. (5) Different groups of clay minerals can be separated clearly coinciding with the different palaeogeographical stages also distinguished in the westernmost border of the Tethys sea. (6) The clay mineral associations back up the data of a previous hypothesis of a humid climate for the end of the Permian in the study area just prior to the first incursion of the Tethys sea.
Graphite morphologies from the Borrowdale deposit (NW England, UK): Raman and SIMS data
(Contributions to mineralogy and petrology, 2009) Fernández Barrenechea, José María; Luque del Villar, Francisco Javier; Millward, David; Ortega Menor, Lorena; Beyssac, Olivier; Rodas, Magdalena
Graphite in the Borrowdale (Cumbria, UK) deposit occurs as large masses within mineralized pipe-like bodies, in late graphite–chlorite veins, and disseminated through the volcanic host rocks. This occurrence shows the greatest variety of crystalline graphite morphologies recognized to date from a single deposit. These morphologies described herein include flakes, cryptocrystalline and spherulitic aggregates, and dish-like forms. Colloform textures, displayed by many of the cryptocrystalline aggregates, are reported here for the first time from any graphite deposit worldwide. Textural relationships indicate that spherulitic aggregates and colloform graphite formed earlier than flaky crystals. This sequence of crystallization is in agreement with the precipitation of graphite from fluids with progressively decreasing supersaturation. The structural characterization carried out by means of Raman spectroscopy shows that, with the exception of colloform graphite around silicate grains and pyrite within the host rocks, all graphite morphologies display very high crystallinity. The microscale SIMS study reveals light stable carbon isotope ratios for graphite (δ13C = -34.5 to -30.2%), which are compatible with the assimilation of carbon-bearing metapelites in the Borrowdale Volcanic Group magmas. Within the main mineralized breccia pipelike bodies, the isotopic signatures (with cryptocrystalline graphite being lighter than flaky graphite) are consistent with the composition and evolution of the mineralizing fluids inferred from fluid inclusion data which indicate a progressive loss of CO2. Late graphite–chlorite veins contain isotopically heavier spherulitic graphite than flaky graphite. This agrees with CH4-enriched fluids at this stage of the mineralizing event, resulting in the successive precipitation of isotopically heavier graphite morphologies. The isotopic variations of the different graphite morphologies can be attributed therefore, to changes in the speciation of carbon in the fluids coupled with concomitant changes in the XH2O during precipitation of graphite and associated hydrous minerals (mainly epidote and chlorite).
Key factors controlling massive graphite deposition in volcanic settings: an example of a self-organized critical system
(Journal of the Geological Society, 2012) Luque del Villar, Francisco Javier; Ortega Menor, Lorena; Fernández Barrenechea, José María; Huizenga, Jan-Marten; Millward, David
Massive graphite deposition resulting in volumetrically large occurrences in volcanic environments is usually hindered by the low carbon contents of magmas and by the degassing processes occurring during and after magma emplacement. In spite of this, two graphite deposits are known worldwide associated with volcanic settings, at Borrowdale, UK, and Huelma, Spain. As inferred from the Borrowdale deposit, graphite mineralization resulted from the complex interaction of several factors, so it can be considered as an example of self-organized critical systems. These factors, in turn, could be used as potential guides for exploration. The key factors influencing graphite mineralization in volcanic settings are as follows: (1) an unusually high carbon content of the magmas, as a result of the assimilation of carbonaceous metasedimentary rocks; (2) the absence of significant degassing, related to the presence of sub-volcanic rocks or hypabyssal intrusions, acting as barriers to flow; (3) the exsolution of a carbon-bearing aqueous fluid phase; (4) the local structural heterogeneity (represented at Borrowdale by the deep-seated Burtness Comb Fault); (5) the structural control on the deposits, implying an overpressured, fluid-rich regime favouring a focused fluid flow; (6) the temperature changes associated with fluid flow and hydration reactions, resulting in carbon supersaturation in the fluid, and leading to disequilibrium in the system. This disequilibrium is regarded as the driving force for massive graphite precipitation through irreversible mass-transfer reactions. Therefore, the formation of volcanic-hosted graphite deposits can be explained in terms of a self-organized critical system.
Microstructure and mineralogy of lightweight aggregates produced from washing aggregate sludge, fly ash and used motor oil
(Cement & concrete composites, 2010) González Corrochano, B.; Alonso Azcárate, Jacinto; Rodas, Magdalena; Luque del Villar, Francisco Javier; Fernández Barrenechea, José María
The microstructures and mineralogical compositions of lightweight aggregates (LWAs) manufactured with washing aggregate sludge (WS), fly ash (FA) and used motor oil (UMO) have been studied. Most LWAs with WS and FA exhibited an external layer and a glassy core with isolated pores. LWAs with WS and UMO did not present external shells or signs of bloating. Iron oxides, within the external layer, and pyrrhotite, in the inner glass, were observed. The mineralogical analyses revealed the neo-formation of plagioclase and pyroxene, along with minor gehlenite. Some relationships could be established: (i) the presence of larger pores is related to a decrease in the dry particle density values, (ii) when the LWA lacks the external layer, the water absorption values were dependent on the size and amount of each type of pore (open or closed), and (iii) the neo-formation of Ca-plagioclase and the consumption of quartz improved the compressive strength values.