Papers by Juan Ramirez Fernandez
Geological Society of America Abstracts with Programs
International Geology Review, 2005
Alkaline magmas along the periphery of Sierra de San Carlos-Cruillas and Sierra de Tamaulipas (Ea... more Alkaline magmas along the periphery of Sierra de San Carlos-Cruillas and Sierra de Tamaulipas (Eastern Alkaline Province, northeast Mexico) contain ultramafic xenoliths. Most of the host rocks are mafic (e.g., basalts, basanites, trachybasalts, phonotephrites), and have geochemical characteristics of nearly primary magmas generated in subcontinental zones (SiO 2 = 42.6-48.4%, MgO = 6.3-11.2%, Mg# = 59.2-69.7). MORB-normalized patterns are similar to those displayed by extensionrelated mafic magmas. This hypothesis is supported by an enrichment in light REE ([La/Yb] N = 10.8-27.1; chondrite-normalized ratios) and the behavior of relatively immobile trace elements. Using a partial melting model for REE, the source for the mafic magmas apparently was in the garnet P-T stability field. On the other hand, peralkaline phonolites and tephriphonolites (SiO 2 = 52.9-54.1%, MgO = 1.5-1.8%, Mg# = 33.1-39.8) also contain mantle xenoliths. These evolved magmas show MORB-normalized multi-element diagrams characterized by enrichment in highly incompatible elements (e.g., Rb, Sr, Ba) and positive anomalies for HFSE. Ultramafic xenoliths are predominantly protogranular spinel-lherzolites as well as harzburgites and rare dunites, websterites, and wherlites. A few samples display transitional and porphyroclastic textures, indicating that the xenoliths were carried to the surface from stable mantle zones with little or no deformation. The mineralogy (olivine + orthopyroxene + clinopyroxene ± spinel) of xenoliths contained in mafic magmas is typical of unaltered mantle nodules. However, small garnet crystals exhibiting disequilibrium textures occur in one sample. The core and rim compositions in olivine range from Fo 90 to Fo 94 , whereas orthopyroxenes are characterized by En 88-93 and clinopyroxenes by En 44-51 Fs 3-10 Wo 43-50. Chromiferous spinels have Mg/(Mg + Fe +2) = 0.76-0.83 and Cr/(Cr + Al) = 0.10-0.25. In comparison to the nodules contained in mafic magmas, mantle xenoliths included in phonolitic liquids show some differences: (1) smaller size (diameter < 1 cm); (2) clinopyroxene is less common (< 5% volume) and spinel is absent; and (3) partial alteration to micaceous minerals. Equilibrium temperatures for mantle xenoliths contained in mafic magmas range from 850 to 1170ºC, as calculated applying different geothermometers, whereas mantle nodules sampled by peralkaline liquids show only lower equilibrium temperatures (<900ºC). A first approximation to equilibrium pressure, based on mineralogical constrains, indicates values from 10 to 25 kbar. Summing up, we consider that the mafic magmas were generated within the spinel-garnet domain of the lithospheric mantle, having little or no interaction with their wall rocks. The ultramafic xenoliths were probably sampled during magma ascent above its source. In contrast, the geochemistry of phonolitic rocks and their altered mantle xenoliths reveal that such magmas cannot be explained by direct mantle melting. The petrogenesis of these peralkaline magmas can be described by a two-step model: (1) partial melting of metasomatized mantle which produced an alkaline magma enriched in LILE and HFSE; and (2) subsequent fractional crystallization of this magma at upper mantle pressures, producing phonolites. While ascending, the peralkaline magmas sampled altered nodules in a shallow level of the subcontinental mantle. The rise and eruption of the mantle-bearing mafic and evolved magmas were facilitated by the post-Laramide extensional regime established during Tertiary time in northeast Mexico.
Late Triassic-Jurassic volcanism from Galeana, NE Mexico 90 and mudstone) have been classified in... more Late Triassic-Jurassic volcanism from Galeana, NE Mexico 90 and mudstone) have been classified into several lithostratigraphic units (Barboza-Gudiño et al., 2010): i) El Alamar Fm. (Late Triassic), mainly outcropping in the Galeana region, and incomplete sections in the Huizachal-Peregrina Anticlinorium; ii) Zacatecas Fm. (Late Triassic), whose exposures are distributed in the Mesa Central province (San Luis Potosí); iii) La Boca Fm. (Early to Middle Jurassic), exposed in the eroded core of the Huizachal-Peregrina Anticlinorium and Aramberri region; iv) Nazas Fm. (Early to Middle Jurassic), outcropping in the northeastern Mesa Central province (San Luis Potosí); and v) La Joya Fm. (Middle Jurassic), with exposures in all localities previously mentioned. Extensive evaporitic sulphate successions including carbonate layers were deposited over the red beds during Callovian-Oxfordian times in the Huizachal-Peregrina Anticlinorium, Aramberri, and Galeana areas, and are termed the Minas Viejas or Olvido Fm. (Fig. 1; Goldhammer, 1999). Kroeger and Stinnesbeck (2003) suggested that these salt deposits represented the first evidence of the marine incursion into Northeastern Mexico. Additionally, a magmatic arc was active from Permian through Jurassic times along the border between the northern (Laurentia) and southern (Gondwana) continental landmasses of Pangea (Torres et al., 1999; Dickinson and Lawton, 2001). Stern and Dickinson (2010) reported that the Permian-Triassic East Mexico arc was active prior to Pangea break-up, whereas the Jurassic Nazas arc was coeval with the continental fragmentation process and the opening of the Gulf of Mexico. However, volcanic and intrusive rocks produced by these arcs are not well exposed. Felsic plutons linked to Permian-Triassic arc have been reported in the Coahuila, Tampico, and Yucatan-Chiapas blocks (Torres et al., 1999; Dickinson and Lawton, 2001; Iriondo and Arvizu, 2009). Bartolini et al. (1999) reported volcanic rocks exposed in the following localities: La Cruz, Aramberri, in Nuevo León; Huizachal, Caballeros, and La Boca Canyons, and Miquihuana, in Tamaulipas; and Real de Catorce, in San Luis Potosí. These extrusive rocks are considered remnants of the Permian-Triassic arc. However, based on U-Pb in zircon dating, Barboza-Gudiño et al. (2008) suggested a Lower Jurassic age for the volcanism previously studied by Bartolini et al.
Geological Society of America Abstracts with Programs
Geological Society of America Abstracts with Programs, 2021
Environmental education is one of the urgent problems of our time. Educational and research activ... more Environmental education is one of the urgent problems of our time. Educational and research activities contribute to the formation of environmental culture of children, the formation of a holistic picture of the world preschooler and the foundations of cultural knowledge of the world around them.
Ciencia UANL, 2004
2004 José Manuel Vasconcelos Fernández / Juan Alonso Ramírez Fernández GEOLOGÍA Y PETROLOGÍA DEL ... more 2004 José Manuel Vasconcelos Fernández / Juan Alonso Ramírez Fernández GEOLOGÍA Y PETROLOGÍA DEL COMPLEJO VOLCÁNICO DE VILLA ALDAMA, TAMAULIPAS. PARTE I: ESTRUCTURAS Y LITOLOGÍA Ciencia UANL, enero-marzo, año/vol. VII, número 001 Universidad ...
Revista mexicana de …, 2000
Ciencia …, 2006
... de los cortes del pozo, para controlar la presión del flui-do, aislar el fluido de la formaci... more ... de los cortes del pozo, para controlar la presión del flui-do, aislar el fluido de la formación rocosa, enfriar y lubricar la barrena y ... Miguel Ángel Arias Gtz., del Servicio Geológico Mexicano (Gerencia Saltillo) y los estudiantes Eduardo González y José Jonathan Jasso, de la FCT ...
Journal of South American Earth Sciences, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Geological Society of America Abstracts with Programs
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Papers by Juan Ramirez Fernandez