Geogaceta -- Nº 25, (1998)

Permanent URI for this collectionhttps://hdl.handle.net/10272/10147

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Petrología de diques doleríticos y basaltos, Pérmico superior, en el Macizo de Cinco Villas (Pirineo Navarro)
(Sociedad Geológica de España, 1998) Lasheras Adot, E.; Lago San José, Marceliano; García Bellés, J.; Arranz, Enrique
The Upper Permian magmatism in the Cinco Villas Massif (Navarra, Western Pyrenees), is represented in two kinds ofcogenetic products: a) three reduced basins, with strongly altered basaltic sills and b) dolerite dykes, with two types (augite-rich and plagioclase rich), outcropping in Yanci-Aranaz area. The study of the chemical composition ofthe piroxenes indicates a sub-alkaline to alkaline affinity for thjs magmatism
Vertidos de escorias en el Rio Oka (Reserva Natural de la Biosfera de Urdaíbaí, Vizcaya): Aspectos mineralógicos y geoquímicos
(Sociedad Geológica de España, 1998) Irabien, María Jesús
As a part of a wider effort to provide a view of the environmental conditions of some basque rivers, mineralogy and heavy metal geochemistry of foundry slags dumped in the Oka river (Vizcaya) and sediments were studied. Slags are composed of iron-enriched minerals (fayalite, wüstite, hematite and goethite), while quartz, calcite and phyllosilicates are the main component of sediments. Geochemical results confirm the low capacity of thesé slags as a significant source of heavy metals to the environment
Variación en los parámetros del sistema calcocarbónico del agua subterránea por infiltración del lixiviado del vertedero de La Mina (Málaga)
(Sociedad Geológica de España, 1998) Vadillo Pérez, Iñaki; Carrasco Cantos, Francisco; Andreo Navarro, Bartolomé; García de Torres, A.; Bosch Ojeda, C.
The leachate produced ¡n La Mina landfill has affected the groundwater quality in its surroundings. The chemical composition of the waters from two wells points and the main spring of the aquifer have been controlled. Great amounts of calcium, magnesium and inorganic carbon have been detected In the water samples of the affected points. A hydrochemistry computer code has been used to calculate the PC02 and the saturation indexes of calcite, aragonite and dolomite. The PC02 values are higher than the calculated in the aquifer in natural conditions, because it comes from the C02 produced in the landfill. PC02 is the main parameter that controls the dolomltlc marbles dissolution and the amount in calcium, magnesium and Inorganic carbon In the water samples. All these concentrations produce an increase In the saturation Indexe
Una discontinuidad estratigráfica de 6 m.a. en las calizas albienses de Aitziber (Navarra)
(Sociedad Geológica de España, 1998) Quintanar Soto, A. B.; Fernández Mendiola, Pedro Ángel; Caron, M.
The Aitziber calcarenites is a sedimentary unit of Upper Albian (appenninica with buxtorfi zone) age. The top of this unit records an unconformity of at least 6 m.a.. The hiatus extends from the uppermost Albian to lower Turonian
Tortugas y sirenios fósiles en el Eoceno marino de Navarra y Cuenca de Jaca
(Sociedad Geológica de España, 1998) Astibia, H.; Murelaga, Xabier; Payros, Aitor; Pereda Suberbiola, Xabier; Tosquella Angrill, Josep
We report several remains of turtles and sirenians from the marine Eocene (Bartonian) of the Pamplona Area (Navarre) and Santa Cilia de Jaca (Huesca), South Pyrenean Basin. Turtles are represented by fragmentary neural plates and sirenians consist of two caudal vertebrae. All this material is not diagnostic and is here referred to as Chelonii indet. and Sirenia indet. respectively. This is the first report of marine tetrapod fossils in the Eocene of Navarre. Current palaeogeographic data suggest that the connexion between the Atlantic and Mediterranean faunal provinces was probably not made across the Pyrenean Gulf, but following the southern area of the Iberian Plate
The largest mercury anomaly on Earth (Almadén, Spain): a mantle-derived feature?
(Sociedad Geológica de España, 1998) Higueras, Pablo L.; Oyarzun, Roberto; Morata Céspedes, Diego; Munhá, José
The Almadén Hg deposits are associated with deeply altered magmatic rocks, which main features are briefly described here. Geochemical, including isotopic, data on these rocks suggest that they are derived from deep mantelic sources. The volcanic units underwent low-pressure alteration processes, probably related to the geothermal evolution of the district along with the magmatic activity (Silurian-Devonian). As a conclusion, this magmatism could have been the responsible for the mobilisation of mercury concentrated in the district deposits
Sondeos de investigación en un acuífero kárstico costero (Castell de Ferro, Granada)
(Sociedad Geológica de España, 1998) Pulido Bosch, Antonio; Pulido Leboeuf, P.; Vallejos, Ángela; Calvache Quesada, María Luisa; Gisbert, Josep; Andreu Rodes, José Miguel; Sánchez Martos, Francisco; Molina, Luis
Data from 4 investigation boreholes, drilled in the marbles of the Castell de Ferro aquifer and separated some 5 m each one from the next one, are discussed. Several karstic discontinuities are detected at different depths depending on which borehole they are in. Flowmeter measurements show the presence of vertical flows at different positions. An electrical conductivity anomaly is detected and interpreted as a result of the drilling method
Sistemas de protección de costas (I): Regeneración de playas. El ejemplo del Maresme (1987-1998)
(Sociedad Geológica de España, 1998) Serra, Jordi; Bautista, R.; Maia, L. P.; Montori, C.
After repeated construction of permanent structures to prevent erosion in the Maresme coast (NE Barcelona), artificial nourishment of beaches started in late 80's. Ten years of beach monitoring have allowed to evaluate the short and medium-term evolution of these beaches and the relations between nourishment, marine climate and storms versus coastline stability and sedimentary budget
SISTEMA DE PROTECCIÓN DE COSTAS (II): DRENAJE DE PLAYAS (BMS). EXPERIENCIA DEL SISTEMA EN EL DELTA DEL EBRO
(Sociedad Geológica de España, 1998) Serra, Jordi; Bautista, R.; Maia, L. P.; Montori, C.
The Ebro Delta Coast is under a continuous coastal retreat estimated in about 50 m/year in the delta front, due to the reduced sediment transport by the river. Two experimental actions were tested to protect this coast. The first was a beach nourishment of a pilot zone near the river mouth in 1994; its inefficiency was pointed out by the monitoring of the fill evolution. The second one was the installation of a new system for beach stabilisation in this area in 1 996: the "Beach Management System (BMS)". The evaluation of the first year of continuous survey of the system show up to now good results, maintaining the position of the shoreline and a growth of the profiles volume
Relaciones estadísticas entre las propiedades hidrodinámicas y geoeléctricas del acuífero de Charf El Akab ( Marruecos )
(Sociedad Geológica de España, 1998) Achagra, L.; Sarroukh, M.; Benjbara, A.; Stitou el Messari, Jamal; Cerón García, Juan Carlos
It is considered the examen of statistical relationship between the transmissivity and transverse resistance of the water bearing materials of the CharafEl Akab, where larges samples of both parameters are available, is presented. The best correlation between these two parameters is found by the geometrical regression after logarithmical transformation (X) of transversal resistance (TRJ values, when we undertake the correct value of T and TR for give it to the same piezometric head. The results of the statistical relationship appears to be sufficient precision
Relación entre la macroestructura del sector oriental de la Cuenca de Almazán y la ubicación de los manantiales termales de Deza, Embid, San (taquillo, Alhama y Jaraba (provincias de Soria y Zaragoza)
(Sociedad Geológica de España, 1998) Coloma, Pablo; Sánchez Navarro, José Ángel; Baquer, E.
The Deza, Embid, San Roquillo, Alhama and Jaraba thermal springs are located in the contact between the Almazan Basin and the Iberian Chain (Aragonesa Branch). The study of deep-geophysics, surface geology and groundwater weels has permitted to interpret the macro-structure and to explain the groundwater-flow, hydrogeochemistry and location of the thermal springs
Procesos de transformación y neoformación de esmectitas en los materiales volcanoclásticos de la isla de La Palma (Canarias)
(Sociedad Geológica de España, 1998) Vegas Salamanca, J.; García Romero, E.; Marfil Pérez, Rafaela
Clay minerals from the volcaniclastic deposits of the three different sedimentary settings (paleosols, continental lacustrine and transitional, fan delta) have been studied by X-ray, MEB y TEM. The clay fraction of this sediments consist largely of smectite (saponite) with minor irregular chlorite-smectite mixed layers and illite; they occur as replacement of ferromagnesian minerals, plagioclase microlites and glass matrix of the volcarenite and they are inferred to be direct diagenetic alteration products of volcanic components
Procesos hidrogeoquímicos en los materiales carbonatados del borde meridional de la Sierra de Gádor (Almería)
(Sociedad Geológica de España, 1998) Vallejos, Ángela; Pulido Bosch, Antonio; Sánchez Martos, Francisco; Martín Rosales, Wenceslao
From data obtained in several wells of Sierra de Cador, the main hydrochemical characteristic of groundwater are stablished. Using different diagrams it's possible to define some hydrochemical processes taking place into the aquifer. Processes of ionic exchange -direct or indirect- provoke changes in the original composition of the groundwater
Primeros resultados magnetoestratigráficos del Triásico Medio-Superior (Ladiniense-Karniense) en la Cordillera Ibérica occidental (Cuevas de Ayllón)
(Sociedad Geológica de España, 1998) Ruiz, V. C.; Sopeña, Alfonso; Rey, Daniel; Villalaín, Juan José; Gialanella, P. R.; Osete, M. L.
A magnetostratigraphic investigation on a Middle-Late Triassic section outcropping at Cuevas de Ayllon (westernmost margin of the Iberian Ranges, Spain) has been performed. The section mostly consists of a thick sequence of interbedded mudstones and sandstones. The age of the sampled formation has been established as Ladinian-Karnian on the basis of palynological assemblages. 123 samples were subjected to a progressive thermal demagnetization up to 680 °C.A multicomponent magnetization behaviour has been observed. The characteristic component could be isolated from 575-620 °C up to 680 ° C, in 74 samples showed both polarities and allowed to define a consistent magnetic zonation. The data presented will contribute to the construction of a standard polarity scale for the Triassic time span
Paleoesfuerzos en las cuencas de antepaís en la parte noroccidental del arco de gibraltar (mioceno superior-actualidad)
(Sociedad Geológica de España, 1998) Camacho Cerro, Manuel Alejandro; García Navarro, Encarnación; Fernández Rodríguez, Carlos; Alonso Chaves, Francisco Manuel
Graphical and numerical methods of fault slip data inversion have been applied to obtain palaeostress reconstructions in Neogene and Quaternary basins, located in the northwestern part of Gibraltar Arc. The most important brittle structures affecting these sediments are high-angle faults with oblique-slip. Two sets of faults with NW-SE and NE-5W trends have been distinguished. The trend of the major axis of the palaeostress ellipse in the horizontal plane has rotated from E-W in the Upper Miocene to NW-SE in the Pliocene-Quaternary
Nuevos datos sobre macroflora del Plioceno en el Suroeste de la Península Ibérica (Lepe, Huelva, España)
(Sociedad Geológica de España, 1998) Muñiz Guinea, Fernando; Mayoral Alfaro, Eduardo; Barrón, E.; Cachão, Mário
A new macroflora outcrop, post-Upper Zanclian (Lower Pliocene at least) in age is discovered at first time in the Southwestern sector of the neogene Guadalquivir Basin (near to Lepe, Huelva, Spain). The taxa are mainly represented by Daphnogene, Laurophyllum, Acer, Platanus, Salix, and doubtful Ginkgo and Zelkova remnants. This macroflora indicates a subtropical paleoclimatic conditions, under high temperatures related with marsh zones or flows, and probably, with episodic dry seasons events. These results are congruents with the former microflora (pollen) data established in the region and they are also rather similar with the pliocene climatic conditions of the catalonian (NE of the Spain) and portuguese basins
Nueva interpretación de la geología de la mina romana de Las Médulas. El Bierzo, León
(Sociedad Geológica de España, 1998) Hacar, M.; Pagés Valcarlos, J. L.; Alonso, Ángela
In the Las Médulas site, red tertiary facies were exploited for gold during roman times. That facies, mainly composed by conglomerates and sandy silts have been interpreted as the final phase of infilling of an endorreic, tectonically controlled basin. However, a careful study of the geometry and organisation of the different units points out a new interpretation: that the serie was the consequence of the evolution of a fluvial system which progressively entrenched, resulting in a sequence of at least seven levels of terraces, where erosive phases alternating with aggradational periods can be distinguished
Modelización hidrogeoquímica del agua de infiltración en la Cueva de Nerja (Málaga)
(Sociedad Geológica de España, 1998) Cardenal Escarcena, J.; Benavente Herrera, José; Andreo Navarro, Bartolomé; Carrasco Cantos, Francisco
A hydrochemical study of the drip water in the Nerja Cave has been carried out using geochemical modeling. Results indicate that major ions in the infiltration water are meteoric in origin (évapotranspiration of rain water plus equilibrium with a soil Pc02 of TO 25 atm) but sequential dissolution of calcite and dolomite also occurs in an open system to C02. Moreover, because the low discharge rate of the drip water points, this water maintains long contact with the cave atmosphere before enough volume can be sampled for a complete analysis. Thus measured pH are strongly affected, so modeled pH are lower (even 0.3-0.6 pH-units) than those measured ones
Mineralización de elementos del grupo del platino (EGP) en las cromititas de los macizos ultramáficos del Complejo de Cabo Ortegal
(Sociedad Geológica de España, 1998) Moreno, T.; Lunar Hernández, Rosario; Prichard, H.; Monterrubio, Serafín; Ortega, Lorena
Many different platinum-group minerals (PCM) have been observed in the chromitites of the Cabo Ortegal complex, one of five Paleozoic ultramafic bodies that crop out in the NW of the Iberian Peninsula. Chomitites are inhomogeneously distributed within the >1100 m-thick serpentinized ultramafic sequence, and can contain up to 13 ppm of total platinum-group elements. Six PCM assemblages are described in these samples including Pt-Pd-sulphides, Pt-Rh alloys, As-, Bi-, Sb- and Te-bearing PGM, PCM enclosed in chromite grains, Hg-, Pb- and Au-bearing PCM and Pt-Pd-bearing oxides. Whereas the PCM enclosed in chromite rims, mostly laurites, are interpreted as being of primary origin, most of the PCM occurring on chromite rims, or distributed within the serpentinized silicates, have complex alteration textures indicating a secondary origin
Minerales del grupo del platino y fases asociadas en el depósito de Ni-Cu-(EGP) de Aguablanca, SW España
(Sociedad Geológica de España, 1998) Ortega, Lorena; Moreno, T.; Lunar Hernández, Rosario; Prichard, H.; Sierra, J.; Bomati, O.; Fisher, P.; García Palomero, F.
Aguablanca is a Ni-Cu-(PCE) sulphide mineralization associated to mafic facies of the Santa Olalla hercynian intrusion. The sulphides occur as disseminated ore, massive ore and brecciated ore related to gabbros, norites and minor piroxenites and peridotites. Sulphide mineralogy includes pyrrhotite, pentlandite, chalcopyrite and pyrite. The study of polished samples by scanning electron microscopy has enabled to identify discrete platinum group minerals for the first time in the Aguablanca mineralization. The major platinum group minerals (PCM) are palladium- and palladium-platinum-bearing tellurides such as michenerite (PdBiTe), merenskyite (PdTej, palladian melonite ((Pd, N'OTeJ and members of the solid solution series merenskyite-moncheite (PdTe2-PtTeJ. Sperrylite (PtAsJ is the other main Pt-bearing mineral. Phases containing other platinum group elements are rare and include a Os-lr-bearing sulphoarsenide (irarsite?). Associated minerals include native gold, tellurobismuthite (BiJeJ, bismuthite (Bi2Sj, hessite (Agje), volynskyite (AgBiTeJ and galena. This PCM assemblage is typical of intramagmatic sulphide deposits related to gabbroid rocks

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