Geogaceta -- Nº 18, (1995)

Permanent URI for this collectionhttps://hdl.handle.net/10272/11002

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Variación de la fábrica del cuarzo en el manto de Los Reales (Cordilleras Béticas)
(Sociedad Geológica de España, 1995) García San Millán, R. S.; Tubía, José María
Quartz fabrics from tectonites belonging to the metamorphic sequence of the Los Reales nappe, in the Betic cordillera (SE Spain), provide a fabric zoning which mainly reflects different temperature conditions during plastic deformation. In XZ section the most representative diagrams of quartz c-axes range from pronounced maxima near the stretching lineation in granulitic samples, through maxima over the Y-axes in migmatites, to maxima at high angles to the foliation in the schists. This fabric variation. suggests that [c]-slip was dominant in granulitic rocks whereas <a>-slip on prismatic and basal planes, respectively, were activated in migmatites and schists
Unidades alpujárrides y maláguides al NE de Granada (Cordillera Bética)
(Sociedad Geológica de España, 1995) Sanz de Galdeano, Carlos; Delgado, Francisco; López Garrido, Ángel Carlos
In the southern part of the area situated to the NE of Granada three Alpujarride units, verging northward, are distinguished, meanwhile in the norther part the units present southward vergences and exhibit a palaeogeographic transition from the Malaguide to the Alpujarride complexes. The La Mora unit belongs to the Alpujarride Complex
Una nueva interpretación sobre las relaciones entre el emplazamiento de granitoides y el metamorfismo regional hercinianos en el Pirineo oriental
(Sociedad Geológica de España, 1995) Enrique Gisbert, Pere
The Hercynian outcrops of the Cap de Creus (Eastern Pyrenees) allow to relate the intrusion of calcalkaline m agm as to low-pressure and high-temperature regional metamorphism. The coexistence o f basic and intermediate magmas with anatectic migmatites, and a well-developed field of pegmatitic bodies inside the sillimanite zone, suggest that hot mantle or deep crustal-derived magmas ascending to the upper levels of the crust were the heat source for such high-thermal gradient regional metamorphism. Shallow-level emplaced batholiths and andesitic volcanism in the Hercynian Pyrenees might have been fed by this magmas, mixed in several degrees with the anatectic melts
Travertinos de río Blanco (Soria): edad y evolución
(Sociedad Geológica de España, 1995) Torres, Trinidad de; Canoira, L.; Cobo, R.; Coello Bravo, F. J.; García Alonso, P.; García Cortés, Ángel; Hoyos, M.; Llamas, J. A.; Mansilla, H.; Soler, Vicente; Valle Hernández, María
Electro Spin Resonance and Amino Acid Racemizaton dating of Rio Blanco travertine deposits allowed to place travertine platforms bulidup into 9, 7 and 5 Oxigen Isotope Stages. Through topographical situation relative stratigraphy does ?nt work properly because "Las Chorroneras" barrier-water fall influence in backfilling process and local water table
Tipología de los granitoides y rocas asociadas del complejo migmatítico de la Punta deis Farallons (Cap de Creus, Pirineo Oriental)
(Sociedad Geológica de España, 1995) Druguet, Elena; Enrique Gisbert, Pere; Galán, Gumer
The Punta dels Farallons migmatitic complex (Cap de Creus, eastern-Pyrenees) consists of an association of partially migmatized sillimanite schists, small heterogeneous bodies of granitoids and quartz-gabbros, and a voluminous pegmatite dike swarm. The igneous rocks have been divided in to two associations: (i) a cafemlc association which includes quartz-gabbros, quartz-diorltes, tonalites, granodiorites and granites, (ii) a peraluminous association, anatectic in origin, comprises leucogranites and pegmatites. It is considered that some of the migmatites were formed by insitu partial melting of the most pelitic metasediments, while others seem to be related to the injection of granitoid veins. Local anatexis and the ascent of intermediate-basic magmas are both considered to be involved in the development of the migmatitic complex
Significado de la discordancia de Mediano en relación con las estructuras adyacentes (Eoceno, Pirineo Central)
(Sociedad Geológica de España, 1995) Teixell, Antonio; Barnolas, Antonio
Detailed mapping in the Mediano anticline and surrounding areas reveals that it grew in interference on a tilted limb of a preexisting triassic-cored dome. The well-known unconformity at Mediano is not related to anticline growth but is a previous regional feature that occurs over a larger zone, being associated to the triassic dome. The use of the unconformity and related onlapping series to model the growth of the Mediano anticline should be taken with caution
Resultados preliminares sobre aguas subterráneas salinas en los granitos del sector meridional de la sierra de Guadarrama (Navalagamella, Madrid)
(Sociedad Geológica de España, 1995) Hidalgo Moreno, A. J.; Martín Loeches, Miguel
At southern sector of central range, neighbouring to Tajus basin, there were located high conductivy groundwater samples with hydrochemical facies Cl-Na-Ca. This composition delay remarkably to regional chemical facies. This paper shows the preliminary purposes concerning to the characteristics hydrochemical so as to infer the probable hypothesis so that give rise to this high salinity
Propuesta de caracterización tipológica de yacimientos españoles de metales preciosos
(Sociedad Geológica de España, 1995) Castroviejo, Ricardo
Last decade's intensive exploration for precious metals in Spain led to a new understanding of various types of deposits and prospects and to the modification of previous schemes, allowing the systematic (typological) classification o f the Spanish precious metals deposits shown in Table 7: 9 large groups and 79 types are defined in the framework of the Iberian Geology. Hypogene deposits in the Hercynian Hesperian Massif, and epithermal gold deposits in the Neogene calc-alcaline Volcanic Province of SE Spain have been very much explored and are therefore emphasized, although their mining production is by far not to compare with the precious metals output from the SW Iberian Pyrite Belt. The exploration significance of the main types and some problems for future research are discussed
Problemática del uso de los tomamuestras de succión en el estudio de la ZNS en el polje de Zafarraya (Granada y Málaga)
(Sociedad Geológica de España, 1995) Gámez Vintaned, José Antonio; Pulido Bosch, Antonio; Morell, I.; Cherif, L.; López Chicano, Manuel
In the polje of Zafarraya, two experimental sites have been Installed and equipped with seven porous ceramic cups each, with depths of between 0.25 and 3 m. The main problems related to preparation involve washing the cups and the depth of the piezometric level, which is close to the surface during winter. The preliminary results obtained are examined
Presencia de la amalgama Au-Ag-Hg en el Cinturón Piritico Ibérico, mina de la Zarza, (Huelva)
(Sociedad Geológica de España, 1995) Ruiz, C.; Samper, Josefina
In the La Zarza Mine gold is found as native gold and as Au-Ag-Hg amalgam first discovered in the Iberlam Pyritic Belt. The average amalgam composition obtained by Microprobe Data analyses is A u 03(/ \ g 052Hg0 W. This composition Is similar to that obtained In two massive volcanogenetlc deposits in Canada and Sweden, except for the La Zarza's higher Hg content. Cold deposition took place in two distinct periods: in the first, as native gold included in pyrite; in the second, as an Au-Ag-Hg amalgam, during the pyrite recrystallization process. During this process gold was released, together with silver and mercury, towards the pyrite microfractures by solid state diffusion
Preliminary stratigraphic results in late Cenozoic carbonate deposits from borehole cuttings in New Providence Island (Great Bahama Bank)
(Sociedad Geológica de España, 1995) Caracuel, Jesús Esteban; McNeill, D. F.; Pérez López, Alberto
On the basis of borehole cuttings from 2 cores located near the NE edge of the Great Bahama Bank (New Providence Island), we studied fades evolution of the Lucayan Fm. and the pre-Lucayan carbonates. Three depositional sequences were identified, perhaps correlative to prograding secuences a, b, and c (megasequence A; Pliocene-Holocene, in Eberli and Ginsburg, 7 989) and perhaps also to 3rd Order depositional cycles 3.10, 3 .9, and 3 .8 in the 2n d O rd e r cycle TB3 (Haq et a!., 1988). The upper limit of dolomitization in this sector o f the Bahamas platform was found in cores around 50 m depth.
Preliminary report of seepage mound occurrences in Spain. Comparison with carbonate mounds from the Amargosa Desert, western USA
(Sociedad Geológica de España, 1995) Calvo, J. Pedro; Pozo Rodríguez, Manuel; Jones, B. F.
Los seepage mounds son depósitos de geometría dómica debidos a flujo y descarga de aguas subterráneas, estando su posición relacionada con zonas lineales de fractura. Describimos en este trabajo dos ejemplos de este tipo de estructura, reconocida por primera vez en nuestro país en formaciones continentales de edad Mioceno (cuencas de Madrid y Las Minas de Hellín). Sus rasgos son comparados con los observados en seepage mounds del Desierto de Amargosa, Plioceno, oeste de Estados Unidos. El modelo de formación propuesto para estas estructuras tiene en cuenta el efecto de deformación sobre sedimentos lacustres suprayacentes debido a la presión de crecimiento hacia arriba de los montículos
Precisiones sobre la bioestratigrafía de las Clavatoraceas del Valanginiense de la Sierra del Pozo (Provincia de Jaén, SE de España)
(Sociedad Geológica de España, 1995) García Cortés, Ángel; Ortiz, José Eugenio; Mansilla, H.; Torres, Trinidad de
Some Clavatoraceae species have been determinated at the top of the Upper Berriasian-Lower Valanginian depositional sequence. Age determination is highly consistent with dating obtained through Foraminifera studies and formers carried out in the Maestrazgo Basin (Eastern Iberian Ranges). However, anagenetic transformation of Clavator harrisii (PECK) seems to take place during the Lower Valanginian and not later
Posibilidades cerámicas de las pizarras Paleozoicas de Almuradiel (Ciudad Real)
(Sociedad Geológica de España, 1995) Parras, J.; Sánchez, C. J.; Luque, F. J.; Rodas, M.; Acosta, A.
Raw materials used in the manufacturing of white stoneware mainly consist of illitic and kaolinitic clays, containing <7.5% of iron oxides. Quarlzitic sands and feldspars are commonly added to improve their physico-chemical properties. This paper deals with the ceramic applications of altered shales (illitic and pyrophyllitic clays) and with the influence of different additives on their ceramic characteristics.
Paleoesfuerzos alpinos en el borde suroccidental de la cuenca de Madrid (Montes de Toledo)
(Sociedad Geológica de España, 1995) Martín, S.; Vicente, Gerardo de
The paleostress analysis are used here to outline the Alpine deformation of the contact between the Toledo Mountains and the Madrid Basin. This limit results from a system of E-W-trending reverse faults, NW-SE-trending dextral normal strike-slip faults and NNE-SSW-trending sinistral normal strike-slip faults
Oscilaciones eustáticas de alta frecuencia en el Neógeno superior de Sorbas (Almería, sureste de España)
(Sociedad Geológica de España, 1995) Dabrio, Cristino José; Polo, María Dolores
A brief description of detail stratigraphy of the Late-Neogene Terminal Carbonate Complex and the Sorbas Member, and the precise role of the stromatolite layers that occur interbedded. The vicinity to the sources of coarse-gained sediment input, mobility of the sea-bottom, and the topographic elevation reached by the sea during high stands of4th/5th order oscillations control the development of stromatolites. Recognition of high-frequency (fourth and fifth-order cycles) inside a third-order (TB 3.4)'eustatic cycle
Origen de las piritas de la cuenca de Cameros, (La Rioja)
(Sociedad Geológica de España, 1995) Alonso Azcárate, Jacinto; Rodas, M.; Mas, Ramón; Velasco, Francisco
The pyrite mineralizations of the Cameros basin has been traditionally interpreted as diagenetic. On the basis of trace element content, S isotopes study, pyrite inclusions and geologic observations, the pyrite crystals seem to be associated to a mobilization process of previous sedimentary pyrites during the hydrothermal metamorphism that affected the basin
Modelo de interacción de las corrientes de marea en la desembocadura del estuario mesomareal del Río Guadiana, (S.O. España-Portugal)
(Sociedad Geológica de España, 1995) Morales González, Juan Antonio
The mesotidal Guadiana River Estuary, and all the estuaries located along the Huelva Coast present ebb tidal deltas infront of their mouth, that are unexplainly curved to west; in the same way, authors have observed turbidity plumes west directed. At this moment anybody do not have explain for the origin of the littoral current that product this curve sense. This paper gives data that certify a tidal origin for these currents, explaying the observed phenomena by a interactive model of the tidal currents in the open coast with the tidal currents comming out from the estuary mouth
Mecanismos generadores de escorrentia en la vertiente de sierra de Gador (Almería)
(Sociedad Geológica de España, 1995) Martín Rosales, Wenceslao; Pulido Bosch, Antonio; Vallejos, Ángela
The factors contributing to the generation of runoff episodes on the southern edge of the Sierra de Gâdor are analised. The study includes the analysis o f physical characteristics as well as the temporal distribution of rainfall in the Carcauz basin, which is representative of the watershed considered. Despite the high permeability overall, there are areas which are prone to flooding, representing a risk to productive agricultural areas at the foot of the basin
Los yacimientos Plio-Pleistocenos del Grupo Peninj (Oeste del lago Natrón, Tanzania)
(Sociedad Geológica de España, 1995) Luque, L.
During July 1994 field work was performed at the Peninj Group Sedimentary Formations (Plio- Pleistocene) of West lake Natron (Northern Tanzania). As a result several palaeontological and archaeological bearing sites were found and located in the local stratigraphical sequence

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