Geogaceta -- Nº 20-3, (1996)

Permanent URI for this collectionhttps://hdl.handle.net/10272/12228

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Zeolites in hydromagmatic volcanoes. A case study of montaña Escachada (Tenerife)
(Sociedad Geológica de España, 1996) Notario del Pino, J. S.; Rodríguez Losada, J. A.; Queralt Mitjans, I.; García Hernández, J. E.
The different types of zeolites occurring in the hydromagmatic volcano called Montana Escachada or Montana Pelada (Southern Tenerife), have been studied. The instrumental techniques of study include X-ray diffraction, scanning electron microscopy, X-ray fluorescence and microprobe analysis. Phillipsite and analcime were detected in amounts inversely proportional from the basis (more phillipsite) to the top (more analcime) of the volcano. A selective enrichment of the phillipsite in potassium and of the analcime in sodium was also observed. The abundance and the genesis of these zeolites are related to the eruptive mechanism and the physico-chemical conditions of the zone. Their formation is, in high degree, irrespective of the composition of the parent magma
Vitrófims básales en flujos piroclásticos de composición riolítica: el caso de la unidad de Nuraxi (Sulcis, SE de la isla de Cerdeña, Italia)
(Sociedad Geológica de España, 1996) Gimeno, Domingo; Assorgia, A.; Díaz, N.; Segura, C.
The bottom of the Nuraxi unit (Assorgia et a/., 7 990) has a vitrophiric character and the unit shows clear evidences of reomorphic flow during cooling. Both characteristics are present in other acid pyroclastic units of the upper section of the pyroclastic pile of Sulcis mainland, SW Sardinia, and elsewhere in the case of high temperature-deposited pyroclastic flows with high total alkali contents. A detailed mesoand microscopic study of Nuraxi vitrophire shows: 7/ a black and jointed bottom vitrophire (some 40 cm thick) depleted in phenocrysts, with resorbed feldspars; the mesostase reached the sphaerulitic stage of devitrification and shows relicts of an eutaxitic texture. 2/a transitional grey vitrophire, with several degree of ramdom distributed vesiculation, evidence of fair eutaxitic texture and developed vesiculation. 3/a sharp horizontal line of color modification that represents the transit towards a flow banded highly macroscopically vesicled reomorphic pyroclastic deposit (Nuraxi unit). The vitrophire overlies a red paleosoil and a 30 cm-thick crystal-rich deposit. All or most of these characteristics could be preserved and recognized in an ancient deposit
Tipología del plutón de Campanario-La Haba: implicaciones petrogenéticas
(Sociedad Geológica de España, 1996) Alonso Olazabal, Ainhoa; Aranguren, A.; Carracedo Sánchez, Manuel; Larrea Bilbao, F. J.
The Campanario-La Haba pluton is located in the suothern part of the Central-Iberian Zone. It is a coarse-grained 5 type granitoid with cordierite. Typologicaly, this pluton is a peraluminous granitoid , CCA type. Mineralogy and petrologycally, the Campanario-La Haba pluton is closer to the Central Extremadura Bath olith ( Cabeza de Araya type) than to the granitic unit of the Los Pedrodres Batholith (Sta. Eufemia, El Guijo, Cerro Mogabar, Cardeña)
Termobarometría núcleo-borde en granates con zonado difusíonal: El ejemplo del Domo Gneísico del Tormes, NO de Salamanca
(Sociedad Geológica de España, 1996) Escuder Viruete, Javier; Indares, A.; Arenas, R.
Metapelites and add orthogneisses from the Lower Unit of the Tormes Gneissic Dome, NW Salamanca, contain high-grade mineral assemblages with characteristics diffusional zoned garnets, The P-T path deduced for this unit from combined studies based on TWEEQU thermobarometry in core-rim garnets, retrograde reaction analysis and mineral zoning, shows an important isothermal decompression of several kilobars. This decompression is the record of the tectonic exhumation of the unit, caused by a D2 extenslonal event related with the collapse of the previously thickened Variscan crust
Stratigraphic and Paleogeographic Reconstuction of Mount Arcuentu-Funtanazza Tertiary Succession (Central-Western Sardinia, Italy)
(Sociedad Geológica de España, 1996) Carena, S.; Ricci, S.; Chiesa, S.; Vezzoli, L.
The stratigraphic, sedimentologic and geometric reconstruction of the Tertiary volcano-sedimentary succession cropping out in the Mt Arcuentu-Funtanazza area (Central-Western Sardinia, Italy) has allowed us to recognize three phases of its sedimentary and volcanic evolution.The succession starts with continental conglomerates and lava flows, followed by a sequence of interbedded subaqueous sediments and distal pyroclastic flow deposits. Volcaniclastic breccias, mostly reworked, form the succession upper part.The Mt Arcuentu-Funtanazza area represents a transitional zone between volcanic sources and sedimentary basins, the latter being mainly carbonade (with sediment source probably in the west) during the second phase, and terrigenous (with a north-eastern sediment source) during the third
Soil gas 222Rn, He, and 220Rn/222Rn ratios at Cañadas caldera, Tenerife, Canary Islands, Spain
(Sociedad Geológica de España, 1996) Hernández, P. A.; Reimer, G. M.; Álvarez, C. E.; Pérez, N. M.; Wakita, H.
Soil gas 222Rn distribution suggest a close relationship with volcanic-geothermal features in and around Cañadas caldera according to both 1992 and 1995 soil gas suiveys. Three transects were selected for soil gas 222Rn, He and 22°Rnp22Rn ratio measurements. Significant spatial variations were observed along those transects wich were designed to intersect fracture zones in the study area. Relatively high emission levels of 222Rn and He as well as relatively high 220Rn/222Rn ratios seem to be related to signific ant diffuse degassing of deep-seated gases along these fracture systems
Soil volatile B and NH3 distribution prior the 1994 eruption at Rabaul caldera, Papua New Guinea
(Sociedad Geológica de España, 1996) Salazar, J. M.; Pérez, N. M.; McKee, C. O.; Saint Ours, P. de; Talai, B.
Soil volatile B and NH3 distribution in and around Rabaul caldera were evaluated by statistical graphical methods in order to investigate the distribution pattern of these volatile components prior the 1994 eruption of Tavurvur and Vulcan volcanoes. A very clear relationship was found between anomalous soil volatile B and this 1994 recent eruptive activity, but it was not observed from the analysis of the soil volatile NH3 distribution pattern
Silicificaciones de calizas oolíticas del Dogger en el Subbético Interno oriental: ¿silcretas freáticas?
(Sociedad Geológica de España, 1996) Bustillo Revuelta, María Ángeles; Rey Arrans, Javier; Delgado, A.; Ruiz Ortiz, Pedro Alejandro
Cherts occurring in oolitic limestones of the Dogger in the Internal Subbetic, are studied for the first time. Two genetic hypothesis are considered from the interpretation of the stratigraphic, petrological and geochemical data. The one first considers that the silicification took place in relation with continental groundwater, in the Middle to Late Jurassic transition, forming silcretes. The second one, shows the silicification as generated from marine waters in diagenetic environments at relatively higher temperatures, during Late Jurassic-Early Cretaceous times
Rocas Ornamentales del Oriente de la Isla de Cuba
(Sociedad Geológica de España, 1996) Heredia Noriega, M.; Sosa Diaz, J.
After several years of continuos geological working, a wide view of the perspectives ornamental rocks in Oriente area of Cuba is presented. For each outcrop, its geographical location, degree of geological knowledge, real and estimate potentialites, and their field, can be obtained; this, however, is not a final view because geological research is open to continue
Rocas granitoides calcoalcalinas altas en potasio en la Zona Centroibérica: el área Garlitos-El Borracho
(Sociedad Geológica de España, 1996) Donaire Romero, Teodosio; Pascual Martínez, Emilio; Higueras, Pablo L.; Morata Céspedes, Diego
New petrographic and chemical data on the Garlitos pluton and other associated igneous rocks in the Almadén area have shown a high-K calc-alkaline character and clear simiarities with other calc-alkaline granitoids, in particular the lithotypes dominant in the Los Pedroches batholith. Similarities include petrographical, mineralogical and chemical features, as well as a number of metamorphic xenoliths, suggesting that igneous rocks were generated from similar sources and emplaced through similar crustal segments.
Relationship between magnetite chemistry and magnetic susceptibility of igneous rocks: Implications for sedimentary provenance studies
(Sociedad Geológica de España, 1996) Martínez Monasterio, E.
A direct relationship between magnetite chemistry and rock magnetic susceptibility has been found. Electron probe microanalysis of titanomagnetites from various igneous rocks has shown them to be enriched in either the ulvospinel phase (Fe2TiO/j) or in the magnetite phase (Fe3OJ. It has been found that the greater the enrichment in the magnetite phase of the titanomagnetites, the higher the magnetic susceptibility value for chemically similar rocks. Both magnetic and chemical data may be used to characterise the rocks (potential sources of sediments) which has important implications for sedimentary provenance studies
Quimismo de las lutitas del Cretácico Inferior en el sector central de la Cuenca Vasco-Cantábrica
(Sociedad Geológica de España, 1996) Yusta, Iñaki; Velasco, Francisco; Herrero, J. M.
A lithogeochemical study of Lower Cretaceous shales (195 samples) from the Basque-Cantabrian region has been carried out to evaluate average values in major and trace elements. Mineralogy and chem ic al co n te n t o f m a jo r oxides reveal a tro p ic a l w ea th erin g in the source area. Lo w e r co ntents in Fe, Cu, Ni and Zn, both in shale and black shale, in comparison with rock averages reported in the literature, might be related with metal leaching processes suffered by these terrigenous sediments, compatible with ore accumulation in the urgonian limestone platforms
Propiedades cerámicas de las pizarras de la Cuenca Carbonífera de Puertollano (Ciudad Real) : Estudio preliminar
(Sociedad Geológica de España, 1996) Parras, J.; Sánchez, C. J.; Sánchez, V.; Higueras, Pablo L.
This paper deals with the preliminary study of the possible ceramic applications of wastes generated in the coal mines of Puertollano (Ciudad Real - Spain). The mineralogical and chemical composition, as wells as the technological tests, of shales Interbedded with the coal, point that these shales are suitable raw materials for the ir use in the ceramic tile Industry of white or light colored types
Procesos geotérmicos causados por la circulación del agua subterránea en el contacto entre ¡a Sierra de Cameros y la Depresión Terciaria del Ebro
(Sociedad Geológica de España, 1996) Coloma, Pablo; Sánchez Navarro, José Ángel; Martínez Gil, F. J.
The practically important part of geothermal systems belong to the convective type where the termal energy is transported by movement of groundwater. Both geothermics and hydrology (aquifer geometry and groundwater flow patterns) should be in very close cooperation at the Interpretation of geothermal anomalies. In this work it is show an example: the geothermal processes along the Cameros Chain/Ebro Tertiary Basin contact
Procesos de dolomitizacíón acaecidos en las sedimentitas carbonáticas del Ordovícico Inferior de la Precordillera, San Juan, República Argentina
(Sociedad Geológica de España, 1996) Matheo, S. D.; Spalletti, L.; Muruaga, C. M.
Dolomitization processes are recognized in the Lower Ordovician San Juan Formation, Central Argentine Precordillera. The sedimentary sequence is composed by limestones with different textures, predominantly wackestone and biodastic packstone in massive and well laminated deposits, with typical tabular stratofabric. The main early diagenetic features are represented by incomplete fibrous calcite cement and eogenetic dolomite. Late calcite cement, polimodal dolomite and stylolites are the main burial diagenetic products. The late stages of diagenesis are signed by a third type of dolomite
Primeros datos acerca de la evolución química de los Filosilicatos en el complejo Malaguide durante la fase Metamòrfica Alpina
(Sociedad Geológica de España, 1996) Ruiz Cruz, María Dolores
Compositional trends in the Maláguide Paleozoic, a very low-grade metamorphic complex of the Betlc Cordilleras, have been investigated in the Málaga area using bulk-rock mineralogy, clay mineralogy and chemical composition of phyllosilicates. Chemical trends, characterized by the general decrease on Si and Al contents, and the simultaneous increase on Fe+Mg content and Fe/(Fe+Mg) ratio. This can be interpreted in terms of boths, increasing temperatures, and differences in initial bulk chemistry. It is concluded that: (a) Most of the phyllosilicate reactions during the alpine event took place in a close system, with scarce exchanges between coarse- and fine-grained beds, (b) The general trends lead to a transition from di,trioctahedral species toward trioctahedral ones, as a function of increasing depths
Precisiones terminológicas entre mecanismos de fragmentación y emplazamiento de rocas volcanoclásticas
(Sociedad Geológica de España, 1996) Martínez González, R. M.; Lago San José, Marceliano; Vaquer Navarro, R.; Arranz, Enrique; Valenzuela Ríos, J. I.
Recent volc anic erup tion s have p ro v id e d firs t-h a n d data fo r the study o f «pyroclastic» deposit mechanisms. This study adds to the term «pyroclastic» a depositional meaning. As a result of this expanded meaning, the term «pyroclastic» is not only used for a fragmentation mechanism, but also for a way of em pla cem ent. Taking in to ac c o u n t th e im p o rta n c e , o f volcaniclastic deposits fo r basin analysis, we propose, when using the term «pyroclastic», to clearly state the differences between fragmentation and emplacement mechanisms
Piroxenos relictos: una clave para la interpretación del vulcanismo en la Faja Pirítica Ibérica
(Sociedad Geológica de España, 1996) Fernández Martín, M. L.; Sáez Ramos, Reinaldo; Pascual Martínez, Emilio
Relict cllnopyroxenes from strongly altered basalts sampled in the Sotiel-Torerera area (central sector of the Iberian Pyrite Belt, southwestern Iberian Massif, Spain), have been analysed by EMP. It has been found that clinopyroxene cores are Ti-rich, representing the pyroxene compositions equilibrated with basaltic magma. An alkaline magma character is consequently deduced. Finally, it is suggested that data from relict minerals may indicate the original magma character better than whole-rock geoshemistry, in this and other cases in which rock alteration Is both intense and polyphased
Petrografía, por técnicas digitales, de las adiciones de Filler Calizo. Metodología
(Sociedad Geológica de España, 1996) Ángel Martínez, M. C.; Martínez Murciano, J.; Rodríguez Mateos, F.; Carmona Guillén, F.; Prendes Rubiera, N.
This article describe the different stages in the processing of images obtained for characterizing several parameters of a calcareous filler (grain size, microfractography, etc). From the parameter Cx and C , we obtain a distance map to calculate the microfissuration of aggregate
Patologías del hormigón. Interacción entre el ataque por Sulfatos y la reacción Álcali-Árido
(Sociedad Geológica de España, 1996) Ángel Martínez, M. C.; Fontao Orosa, I.; Leiro López, A.; López Ramos, S.; Mateo Sanz, B.; Prendes Rubiera, N.
The presence of both alkali-aggregate reaction and sulphate attack products In concrete samples has lead to the necessity of determining the formation sequence of such products. M.E.B.-E.D.X. studies have confirmed that silica gel is formed first and afterwards sulphates are activated, which promote the gel formation as a result of ions release to the solution

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