Geogaceta -- Nº 24, (1997)

Permanent URI for this collectionhttps://hdl.handle.net/10272/10205

Browse

Now showing 1 - 20 of 78

Evidencias morfogenéticas cuaternarias en el karst de la Sierra del Endrinal (Grazalema, Cádiz)
(Sociedad Geológica de España, 1997) Rodríguez Vidal, Joaquín; Álvarez, G.; Cáceres Puro, Luis Miguel; Martínez Aguirre, Arancha; Alcázar, J. M.
The geomorphological observations made until now reveal a long morphogenic history for the karst of the Eridrinal: mountains; going back to pre-Quaternary times. The erosion surfaces mapped (Sl, S2 and 53) have å biostatic genesis and are linked to humid media with forest cover, favouring carbonation below a karst- cover. The rëlatiônship between speleothems and geomorphology seems to indicate that surfaces 1 and 2 are basal surfaceS of weathering, with biostatic genesis, which would remain active from at least 300 ky BP (Middle Pleistocene), with a petibd of intense carbonation during the isotopic (cold) state 6 between 190 and 140 ky BR Surface 3, of retent genësiS (Late. Pleistócene to Holocene), is the result of a general biostatic situation, with Climatic and anthopögenic rhexistatic disturbances that have movilized, under the action of water flow ånd gravity, the detPitús and regoliths generated in previous. epochs. Regional palaeoenvironmental indicators show a climatic change towards greater aridity during the transition from Middle to Late Pleistôcene
Uso del 137Cs para la datación de sedimentos intermareales. Un ejemplo de la ría de Aveiro (Portugal)
(Sociedad Geológica de España, 1997) Daza, Mª. J.; Quintana, Benito; Barba, Pedro; Bernardes, C. A.; Corrochano, A.
In this work, we show the preliminary results on the 137Cs dating of the tidal flood sediments in the barrier-island system of Aveiro (Portugal). The ”7Cs activity enable us to establish four isochrones which limit the last four decades, through the correlation of historical data of137Cs atmospheric concentration. The sediment acumulation rates on the intertidal flat is calculated to be 0.6 cm yr1
Un sistema de fallas normales sinsedimentarias en las unidades de facies Urgon de Aliaga (Teruel, Cordillera Ibérica)
(Sociedad Geológica de España, 1997) Simón Gómez, José Luis; Liesa, Carlos L.; Soria, Ana Rosa
System of conjugate, E-W to NE-SW striking normal faults is reconstructed from mapping and structural analysis of deformation in the Urgon deposits of the Aliaga region. Those were mainly active during the Aptian age, giving rise to significative changes both in thickness and lithology of the stratigraphical unities. An unconformity found in the Escucha Formation clearly separates syn- and post-rift deposits in the western zone of the studied area. The faults were tilted and folded during the Palaeogene within the Campos-Aliaga anticline
Un nivel de concentracjon de briozoos en el Cuisiense inferior ; de Esdolomada (Formacion Murillo, Valle del Isabena)
(Sociedad Geológica de España, 1997) Reguant, Salvador
The presence of a condensation bed, consisting of a dense lumachellic marly limestone with a nearly monospecific bryozoan (Teichopora clayata Gregory) is indicative of a change in tendency from transgressive to regressive within the transgressive interval constituting the Murillo Formation in the Southcentral Pyrenees
Un húmero de iguanodóntido (Ornithischia: Ornithopoda) del Cretácico inferior (Aptiense) de Morella (Castellón, España)
(Sociedad Geológica de España, 1997) Ruiz Omeñaca, José Ignacio; Santos Cubedo, Andrés
An incomplete right humerus of an iguariodohtid ornithopod is described. It has been recovered in Morelia (CastelIòni Spain), in deltaic sediments from the Morelia Fm. (Lower Aptian) in the Maestrazgo Basin (Iberian Range)...Its form resembles the humerus of Iguanodon spec/es, and ihe size.tits in with the size variability of I. bernissartensis. We think that size is not a diagnostic character for the ornithopod taxi, and the humerus is assigned to Iguànòdòn sp.
Tectónica de inversion en el sector central del Arco Vasco (Cuenca Vasco-Cantábrica)
(Sociedad Geológica de España, 1997) Cuevas, Julia; Aranguren, A.; Badillo, J. M.; Tubía, José María
We report the existence of a thrust system in the central part of the Basque Arc (Basque-Cantabrian basin, Guipúzcoa). From bottom to top, the thrust system is formed by theAia, Pagoeta and Azpeitia allochthonous sheets. The kinematic and structural analysis provides a top to the NE movement, and reveals the widespread reactivation of normal faults during the Pyrenean inversion tectonics
Strain analysis using deformed quartz veins
(Sociedad Geológica de España, 1997) Druguet, Elena; Griera, Albert
A detailed strain analysis of structures developed in anisotropic rocks from the Cap de Creus area is made using deformed quartz veins. Data on stretch of differently oriented veins allow to calculate the best-fit ellipsoids for different localities applying the minimum squared method. The results show that regional deformation in this area involved NW-SE shortening, with area loss in the horizontal section, and vertical extension. Structural and rheological controls are suggested to explain the partitioning of deformation inferred from this analysis
Sobre la identidad de Pedro de la Barrera, un personaje presente en la obra del franciscano José Torrubia
(Sociedad Geológica de España, 1997) Truyols, J.
In his book "Aparato para la Historia Natural española", José Torrubia figures the first findings of Spanish fossils. Pedro de la Barrera, whose identity was unknown, intervined in this discovery. The possibility is discussed that he is in fact the botanist and French doctor Pierre Barrère, author of "Observations sur l'origine et la formation des pierres figurées" (1746)
Sobre las especies de Iguanodon (Dinosauría, Ornithischia) encontradas en el Cretácico inferior de España
(Sociedad Geológica de España, 1997) Ruiz Omeñaca, José Ignacio; Canudo, José Ignacio; Cuenca Bescós, G.
Up to the moment, two species of Iguanodon had been cited in the Lower Cretaceous of Spain: I. cf. atherfieldensis and I. bernissartensis. In general, the size has been the diagnostic character to separate I. atherfieldensis from I. bernissartensis, and many of the spanish Iguanodon remains would be regarded as Iguanodontidae indet or Iguanodon sp. A third species (1. cf. fittoni) is situated in the Jurassic-Cretaceous transition
Reconocimiento de acumulaciones travertínicas fósiles en la Fm. Aguilar (Kimmeridgiense-Berriasiense de Palencia y Burgos): implicaciones paleoecológicas y paleohidrológicas
(Sociedad Geológica de España, 1997) Hernández, José María; Diéguez, C.; Pujalte, Victoriano; Robles, Sergio; Wright, V. P.
Fossil travertine deposits have been recognized in the Aguilar Fm., which are intercalated vyithin the typical lacüstrine/palustrine limestones of this unit. Microscopically, they are characterised by numerous plant, remains and microscopically by abundant features atributáble to microbial, activity. The travertine accumulation occurred next to an important fault line that was contemporaneously active. 'Because of that; they are thought to record former hot-springs within a discharge-type water inflow system
Primeros datos sobre los quelonios del Cretácico superior eje Lleida
(Sociedad Geológica de España, 1997) Murelaga, Xabier; Pereda Suberbiola, Xabier; Astibia, H.; Lapparent de Broin, F. de
Chelonian plate remains from the uppermost Cretaceous (Maastrichtian) of the Lleida Province in Catalonia are described for the first time. Both cryptodire and pleurodire turtles are represented in the assemblage. An hypoplastron from Fontllonga (Ager syndine) and a peripheral plate fragment from Biscarri, near Isona (Tremp Basin) are referred to a bothremydid cf. Polysternon sp.; isolated pleural and peripheral plates from an indeterminate locality of the Tremp area are assigned to the Solemydidae as cf. Solemys sp. Both Polysternon and Solemys are fresh-water turtles and common components of the continental vertebrate fauna of the Ibero-Occitan realm at the end of the Cretaceous
Precisiones sobre la sistemática de Iberomys Chaline, 1972 (Arvicolidae, Rodentia, Mammalia) del Pleistoceno inferior de la Sierra de Atapuerca (Burgos, España)
(Sociedad Geológica de España, 1997) Laplana, César; Cuenca Bescós, G.
The Iberomys lineage is represented by the species I. huescarensis (Ruiz Bustos, 1988), at the lower levels (TD3 to lower TD8) of Trinchera Dolina (Sierra de Atapuerca, Burgos), and not by I. brecciensis Ciebel, 1847 as stated previously. Both species mainly differ in the communication of triangles T4 and T5 of the first lower molar dental pattern, broad in I. huescarensis and narrow in I. brecciensis. I. huescarensis is the ancestral species of the I. brecciensis-cabrerae lineage, and characterizes the late Lower Pleistocene and the transition Lower-Middle Pleistocene in the Iberian Peninsula
Parasecuencias transgresivo-regresivas: ejemplos de afloramiento en el Eoceno de la sierra de Entzia (provincia de Araba)
(Sociedad Geológica de España, 1997) Payros, Aitor; Pujalte, Victoriano
Two main fades associations coexist in the Middle Eocene limestones of the Entzia ridge (Araba provincej, one representative of a tidal flat environment, the other of a mariné ramp setting. Analysis of their sequential arrangement has made it evident the existence of two orders of parasequence organization. Each of the parasequences of the lower (4th?) order was built during a progressive transgression and ended with a rapid regression. Parasequences of the higher (5th ?) order began with minor transgressions and continued with minor regressions. Parasequences have often been thought to represent simple upward-shoaling successions bounded by flooding surfaces. Our findings indicate a greater complexity and diversity in parasequence development. The significance of such variability, however, still needs further studies
Origen de la surgencia del Balneario de San Andrés (Provincia de Jaén)
(Sociedad Geológica de España, 1997) Hidalgo Estévez, Mari Carmen; Rey Arrans, Javier; Redondo, L.
The hydrogeological context of the San Andrés spa (province of Jaén) is analysed in this work. Piezometric data, hydrochemical analysis and groundwater quality trends are discussed for groundwater samples obtained from the main aquifer units in the region (jurassic carbonatic aquifer and miocene detrital aquifer) in order to stablish the origin of the San Andrés spring. Considering altitude, discharge rate, temperature and hydrochemical features of the spring, it seems to be related to the miocene hydrogeological unit
Neotectómca transpresiva en la plataforma continental Suribérica Atlántica
(Sociedad Geológica de España, 1997) Maestro González, Adolfo; Somoza, L.; Díaz del Río, Víctor; Vázquez Garrido, Juan Tomás; Martín Alfageme, S.; Alveirinho, J. M.; Barnolas, Antonio; Vegas, Ramón
Detailed structural, interpretátioh of a network of high-resolution seismic lines runnig across, , and along the continental shelf of Faro (south-lberian Atlantic margin) provides evidences of recent deformation structures associated with the Africa-Eurasia plate boundary. In these seismic profiles, palm-tree type flower structures interpreted as strike-slip faults affect the non-consolidated Holocene muddy shelf deposits and the underlying semi-cemented sandy shelf-wedges of the Pleistocene units. These structures are lined up following a ENE-WSW. direction, associated with the existence of a deeper dextral transcurrent basement fault with recent active seismicity between the southern Coringe Bank, Horseshoe Plain, Faro continental shelf and northern of Guadalquivir basin
Medidas de deformación finita en la Cuenca de Cameros a partir de maclas de calcita en grietas de tensión
(Sociedad Geológica de España, 1997) García Cuevas, C.; González Casado, J. M.
In the central part of the Cameros basin (NW Iberian Chain) has been analysed the orientation of calcite c-axes and e-twin from the sparitic grains that filled extension veins in this region. The c-axls orientations allow to establish that during the mesozoic extensional episode, when was developed this basin, besides of an extension NE-SW also existed another with a NNW-SSE trend, this last extension direction probably has a regional character. The calcite e-twins show the existence of two different orientations for strain ellipsoids. A first group has orientations that would be compatible with structures associated with the development of the basin inversion and with the NE-SW schistosity. While the other is almost perpendicular to the former and it is compatible with a NW-SE compression not described until the moment. This last deformation episode probably has a regional meaning (Cuadarrama compression? from Capote et al., 1990), and it likely also has a relative importance in the development of structures that show this region
Los paleofluidos en el grupo Oncala, Cuenca de Cameros (la Rioja, España): Datos de mclusiones fluidas, isotopos de oxigeno y SEM
(Sociedad Geológica de España, 1997) Mantilla Figueroa, L. C.; Casquet Martín, César; Mas, José Ramón
Combined microthermometric and Raman study of fluid inclusions from quartz-calcite veins from the Oncala Group (Cameros Basin), shows that earlier fluids must be described by reference to the complex H20+NaCI+C02+H2S+(N2+CH J+Se system. Moreover at the time of trapping fluids were heterogeneous (effervescence) consisting at this stage of an aqueous low salinity fluid and a C02+H2S-rich gas phase. Younger fluids were low-salinity aqueous solutions. Oxygen-isotope thermometry on quartz-calcite pairs suggests that temperature of vein-forming fluids was close to 2 7 0°C, implying that regional temperatures in the Oncala Croup probably were lower than in the overlaying Urbion Croup. Also composition of flu ids was significatively different in both realms. A case of thermal inversion and hydrological incomunication betweeen the two groups is thus envisaged, uppermost black shales acting thus as a first order geological barrier between the two groups. The composition of vein-forming fluids, and the presence of pyrobitumen, in the Oncala Croup rocks suggests that conditions of deep burial diagenesis in the gas windows were attained. Thermochemical sulfate reduction involving hydrocarbons (oil), probably resulted in the complete destruction of the latter releasing pyrobitumen as a solid residue
Los braquiópodos jurásicos en el "Aparato para la historia natural española" de José Torrubia (1754)
(Sociedad Geológica de España, 1997) García Joral, Fernando; Goy, Antonio
Jurassic brachiopods collected by Torrubia in the Molina de Aragón Area and described by this author in 1754 are studied. Most of the specimens figured on his publication have been assignated to the species currently recognized in the region
Lineamientos y fracturacion en el extremo oriental de la Rama Aragonesa de la Cadena Iberica (cuenca de Montalban)
(Sociedad Geológica de España, 1997) Tena, S.; Casas Sainz, Antonio; Soriano, María Asunción
The analysis of Landsat lineaments at the eastern end of the Aragonian Branch (comprising the palaeozoic core of the Montalban anticline, the Tertiary Montalban basin and several outcrops of Mesozoic rocks) shows a constant NE-SW direction maximum throughout the area, with a secondary NW-SE maximum. The lineament pattern remains unchanged when analysing separately lineaments in rocks of different ages (Paleozoic, Mesozoic, Paleogene, Neogene). The maximum density estimated from cumulative length of lines is 2 km per km2. The comparison with geological maps and field observations allow to interpret lineaments as fractures and faults, many of them with little or no offset. The main NE-SW trend seems to correspond to Late Variscan faults reactivated during the mesozoic as extensional faults at the Mesozoic basins North and South of the studied area. The NW-SE maximum coincides with the main structural trend of the Aragonian Branch. Lineaments trending N-S to NNW-SSE are scarce and limited to the surroundings of the Alpeh6s fault
José Torrubia y su aportación al método científico en paleontología
(Sociedad Geológica de España, 1997) Sequeiros, Leandro
Some considerations about the methodological principles mantained by losé Torrubia in the Aparato para la Historia Natural Española (published in 1754) about the hypothesis concerning the origin qf fossils are presented. Torrubia accepted also the Francis Bacon, Piquer and William de Baillou ideas, being considered as innovator in the scientific method in Spain

Browse

Recent Submissions