Geogaceta -- Nº 23, (1997)

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Yacimientos de Carofitas en la Depresión Intermedia (Cuenca-Guadalajara, España Central)
(Sociedad Geológica de España, 1997) Ortiz, José Eugenio; García Cortés, Ángel; Cólliga, L. A.; Mansilla, H.; Torres, Trinidad de
This paper deals with the study of some Charophyta associated to some tertiary mammal sites in the Depresión Intermedia Basin. It has been made a first attemp to correlate micromammal biozones with Charophyta biostratigraphical distribution. All the ages obtained from Charophyta assemblages cover longer periods than studies based on micromammals. However, data obtained from Albalate-1 site might show an accurate age that could be situated in biozone E of Daams and Freudenthal (1981) (Middle Aragonian). Three sites whose ages were not clearly determined have been eventually dated, two of them of Upper Cretaceous age
Un nuevo sondeo de investigación paleoambiental del Pleistoceno y Holoceno en la turbera del Padul (Granada, Andalucía)
(Sociedad Geológica de España, 1997) Nestares, T.; Torres, Trinidad de
This paper deals on a short description of a new borehole (100 m depth) drilled on Padul Pleistocene and Holocene peat bog for palaeoenvironmental research. An excellent correlation has been found between the Menendez Amor and Florschutz former borehole litolog and the present one. Two detailled short field section are described too
Unidades evaporíticas de la Cuenca de Calatayud (Mioceno inferior-medio, Zaragoza)
(Sociedad Geológica de España, 1997) Ortí, Federico; Rosell, L.
The large evaporitic formation known as the Calatayud Gypsum (Lower-middle Miocene) may be subdivided into two (informal) units, lower (l.e.u.) and upper (u.e.u.), each one displaying differentiated sedimentologlc and diagenetic features. In these lacustrine units a facies change is observed from the margin (low salinity, massive lithofacies, primary gypsum preserved) to the centre (higher salinity, laminated lithofacies, secondary gypsum) of the basin. The thick l.e.u. contains calcium-sulphates and sodium-bearing sulphates (mainly glauberite), whereas the u.e.u. contains calcium-sulphates and associated carbonates. The depocenter of the u.e.u. shifted toward the SE with respect to the l.e.u. In both units, meganodular anhydrite, which generated in a sabkha environment and associated with red lutites, intercalates in the transitional zone between the central (laminated lithofacies) and the marginal (burrowed gypsum with abundant chert) zones. In the subsident Morata zone, there is a distinct cyclicity (gray lutites-laminated sulphates) in the two units; this succession exceeds a total thickness of 200 m.
The record of the tsunami produced by the 1755 Lisbon earthquake in Valdelagrana spit (Gulf of Cádiz, southern Spain)
(Sociedad Geológica de España, 1997) Dabrio, Cristino José; Goy, José L.; Zazo, C.
Several washover fans breaking through the spit of Valdelagrana existing in middle 7 8th Century in the Guadalete estuary (Bay of Cadiz) are interpreted as the trace of the exceptional tsunami generated by the AD 1755 Lisbon earthquake, based on geological, morphological and historical arguments
Sobre el origen de la relación científica que existió entre Casiano de Prado y Edouard de Verneuil
(Sociedad Geológica de España, 1997) Truyols, J.
The geologist Casiano de Prado and Edouard de Verneuil always had a good scientific as well as personal relationship, started in 1847 and maintained up to Casiano de Prado's death in 7 866.Nevertheless in recent years a different version on the origin of this relationship has been set up, postponing to 7 862 the time for their just- personal contact. This communication intends to show the unlikeliness of the new interpretation
Síntesis de la evolución geomorfológica de Galicia Occidental
(Sociedad Geológica de España, 1997) Pagés Valcarlos, J. L.; Vidal Romani, J. R.
This paper presents an actualization of the ideas about the geodinámicaI and geomorphological setting of Western Galicia, as well as the cenozoic evolution, and a model were the evolutionary sequence is proposed. The present relief seems to be a response to the fluvial action (incision and processes of captures), as a consequence of the base level changes along the Cenozoic. The Rías were formed in that way, together with widespread entrenchment of the drainage net of western Calida
Réplica a la publicación de cierto juicio estratigráfico relacionado con las bauxitas de la sierra de Boada (Alós de Balaguer, Pirineo leridano)
(Sociedad Geológica de España, 1997) Ullastre, J.
The age of the top of the sierra de Boada bauxites outcrop is not Cenomanian as proposed by Molina et al., 1994 but Upper Senonian
Relaciones entre las polaridades paleomagnéticas y las edades radiométricas del volcanismo de Campo de Calatrava (Ciudad Real)
(Sociedad Geológica de España, 1997) Gallardo Millán, José Luis; Gomis Coll, E.; Dinarès Turell, Jaume; Pérez González, Alfredo
The radiometric dates from the «Campo de Calatrava» volcanism presents wide error intervals due to the low Ar40 contain. When the paleomagnetic polarities are compared with radiometric analysis, the age may be determinated exactly. It's also possible to deduce some volcanics aspects as, the remaining volcanic activity, to identify different volcanoes, and to detect a reverse polarity state
Realaspis? pradoanus (Verneuil y Barrande) (Trilobita, Cámbrico Inferior): revisión de su material tipo e implicaciones taxonómicas
(Sociedad Geológica de España, 1997) Rábano, Isabel; Gutiérrez Marco, Juan Carlos
The type specimen ofthe Lower Cambrian (Bilbilian) trilobite «Ellipsocephalus pradoanus» Verneuil & Barrande, 1855 is redescribed and illustrated. It is stored in the Verneuil collection ofthe Claude-Bernard University at Lyon (France). By means of the cranidial characteristics it has been doubtfully related with the genus Realaspis, and the poor preservation of the lectotype of R. ? pradoanus supports the restriction of the species to this unique specimen
Pliegues tumbados en los Alpujárrides de Sierra de Las Estancias (Cordilleras Béticas orientales)
(Sociedad Geológica de España, 1997) Galindo Zaldívar, Jesús; Jabaloy, A.; Campos, J.; Fernández Fernández, Estefanía
The structure of Los Blanquizares-Oria Alpujárríde unit in northern Sierra de Las Estancias is mainly determined by kilometric recumbeot North vergent folds. Foliation axial planar to these folds is a crenulation foliation in schists. Large folds are deformed by mylonite bands and by the Alpujárríde-Maláguide fault structures. The interference with late open folds develops large 'tête plongeante' structures in the area. In addition, other late deformation structures (normal and strike-slip faults and dykes) have been recognized in the area
Petrología, geoquímica y emplazamiento de diques de composición granodiorítica al sur del complejo plutónico de la Maladeta. (Zona Axial Pirenaica)
(Sociedad Geológica de España, 1997) García Bellés, J.; Lago San José, Marceliano; Arranz, Enrique; Valenzuela Ríos, J. I.
A set of granodioritic dykes, related to the main intrusive episode of the Maladeta Plutonic Complex, is studied. These dykes, that follow the main cleavage strike, cut across deformed Paleozoic country rocks. Their composition (mineralógicaI and geochemical) is calk-alkaline and their emplacement was controlled by the previous hercynlc structure and by a transtensive regime during their interval of emplacement
Origen y desmantelamiento del Antiforme Plio-Cuaternario de Marratxí (Mallorca, España)
(Sociedad Geológica de España, 1997) Silva, P. G.; González Hernández, F. M.; Goy, José L.; Zazo, C.
The so-called MarratxiAnticline, which separates the Quaternary basins oflnca and Palma Bay (Mallorca Island), does not correspond to a true compressive feature. It only represents an NNW-SSE trending antiform resulting from the adaptation, and subsequent dissection, of Quaternary gently-dipping eolian sedimentation of calcarenitic nature coming from the Palma Bay (South limb), to a previous horst-type structural high constituted by structured mesozoic, paleogene and early miocene materials topped by sub-horizontal upper Pliocene littoral calcarenites. These last also constitutes the moderate to strongly-dipping calcarenitic cuestas of the northern limb of the antiform. Its structuration can be explained in terms of Plio-Quaternary surficial monoclinal folding, probably linked to rollover-type processes along previous lateral ramps generated during the early Miocene nappe emplacement phase along the northern border of the mentioned structural-high. Topographic disruption promoted by this structure gave place to Quaternary defeating of the drainage coming from the Sierra de Tramuntana to the Palma Bay. Subsequent late Pleistocene headward erosion along the ses Mates creek, probably linked to the Last Glacial sea-level drop, lead the generation of the presently transverse drainage
Nuevos datos petrológicos, geocronologia (Rb-Sr) y geoquímica isotópica (Sr, Nd) del plutón de Ventosilla (Sierra de Guadarrama, Sistema Central Español)
(Sociedad Geológica de España, 1997) Villaseca, Carlos; Barbero, Luis; Reyes, J.; Santos Zalduegui, José Francisco
Whole rock Rb-Sr ¡sotopic analyses on granites from Ventosilla pluton yield an age of 346 ± 63 Ma, and intercept at 0.708688 ± 0.00094. This age increases the time-span of the Hercynian plutonism in the area up to 70 Ma. The presence of a complex residual mineralogy and their Sr and Nd isotopic signatures, overlapping the previous isotopic data on peraluminous granites from the Spanish Central.System, suggest melting of mainly crustal sources for the origin of this pluton
Nuevos datos para la estimación de los valores de levantamiento desde el Tortoniense Superior a la actualidad en la parte centro-occidental de la Sierra de Carrascoy (provincia de Murcia)
(Sociedad Geológica de España, 1997) Sanz de Galdeano, Carlos; López Garrido, Ángel Carlos; García Tortosa, F.J.
The existence of sediments of the Late Tortonian near the top, and in the slopes, of Sierra de Carrascoy, deposited above a former erosionaI surface excavated in the basement, permits precise estimation of the vertical displacements occurred in this are a in the last 5 m.a. The value of 0,2 mm/y has been exceeded in several moments of this interval of time
Nd isotopic heterogeneity in Iate-Hercynian granitic plutons from Central Spain
(Sociedad Geológica de España, 1997) Villaseca, Carlos; Barbero, Luis; Reyes, J.; Santos Zalduegui, José Francisco
Some Hercynian granitic plutons from Central Spain show variation in initial Nd isotopic ratios defining different trends with increasing silica content. There is a decoupling between the Sr and Nd isotopic systems as these plutons present homogeneous initial Sr ratios. Magmatic processes could explain this Nd isotopic disequilibrium; it is suggested that Nd-bearing restitic or early precipitating accesory phases could control the Nd isotopic heterogeneity of the granites
Modelos de extinción de foraminíferos planctónicos en el limite Cretácico/Terciario (K/T) de El Mulato (México) y Agost (España)
(Sociedad Geológica de España, 1997) Arz, José Antonio; Arenillas, J. I.; López Oliva, J. G.; Molina, Eustoquio
The Cretaceous/Tertiary Boundary (K/T) is still a controversial case in the history of the Earth. This boundary has been one of the most investigated subject during the last 17 years, trying to find clues to better understand the event (s), that culminated with the disappearance of several groups of organisms including dinosaurs and planktic foraminifera. Data from El Mulato in NE Mexico and Agdst (Spain) in the western Tethys may'support respectively both theories; a gradual disappearance and amassive catastrophic instantaneous extinction of organisms 65 M a. ago. Comparison of data shows that at El Mulatd the sudden disappearance of Cretaceous planktic foraminifera and the simultaneous first appearance of tertiary species indicates a hiatus at exactly the K/T boundary transition, superposed by a gradual extinction pattern associated to several events. At Agost a catastrophic instantaneous mass extinction is indicated at the K/T boundary This extinction pattern may be related to the impact of a celestial body that caused an extinction, one of the most important during the development of life
Lower Miocene stable isotopes (8180, 813C), biostratigraphy and environments in the Foz da Fonte and Penedo sections (Setúbal Península, Portugal)
(Sociedad Geológica de España, 1997) Antunes, Miguel; Civis-Llovera, Jorge; González Delgado, José Ángel; Legoinha, P.; Nascimento, A.; Pais, J.
Se estudia el contenido micropaleontológico de dos secciones del Mioceno marino (Burdigaliense) de la cuenca inferior del Tajo (proximidades de Lisboa): Foz da Fonte y Penedo). Se presenta una biostratígrafía, y se interpretan paleoambientes a partir de las asociaciones de foraminiferos y ostracodos. Las curvas isotópicas 5I3C y 8,80 presentan en ambas secciones fuertes oscilaciones, sobre todo en el contenido de 8'3C de Pectínidos (diferencias de 5§). Los datos de S'sO realizados sobre Pectínidos sugieren un enfriamento a lo largo del Burdigaliense; no obstante la temperatura de las aguas debió de ser mas alta que la actual. Se observan valores más altos de S'3C en la sección de Penedo con respecto a la de Foz da Fonte, lo que está en acuerdo con la mayor distalidad de la primera
Ley de distribución de planos de debilidad en la Sierra de Atapuerca (Burgos): aplicación al drenaje del karst
(Sociedad Geológica de España, 1997) Eraso, A.; Domínguez, M. C.; Ortega, A. I.; Martín, M. A.; Gavilán, C. J.; Paredes, C.; Gallego, N.; Giralt, Santiago
In this work, we apply a method, which has been widely verified, of the study and use of the microtectonic data gathered in the field (parameters used are strike, dip and sense of dip of tectoglyphs: stylolite plans, mineral veins and fault plans), for analysis and quantification of the directional anisotropy in the lime outcrop of Atapuerca. We obtain four main drainage directions: N 7 7 7°-120°, N 93°, N 756° and N 6° with 14,8%, TO,9% , 7 0,8% and 8,6% probabilitys respectively. Each with its own normal distributions overlaping to themselves. The contrast of the drainage prediction and conduit directions polimodals shows that the maximum error between prediction modes and the found in the direction of the caves is 3,9%
Las unidades litoestratigráficas del tránsito Triásico-Jurásico en la región de Lécera (Zaragoza)
(Sociedad Geológica de España, 1997) Gómez Alday, Juan José; Goy, Antonio
One of the main challenges in the stratigraphy of the Mesozoic sediments of the Iberian Ranges is the recognition ofthe Triassic-Jurassic boundary. Subsurface data provided by the hydrocarbon wells drilled in the not outcropping portions of the basin show the presence of a thick evaporitic section interbedded between the Imon and the Cuevas Labradas Fms. These evaporites are normally dissolved in the surface, where they are represented by the Carniolas of Cortes de Tajuna Fm. However, unusual cropping out of these evaporitic succession at the Lecera region has provided the opportunity to study a surface section of these evaporitic materials. The Lecera Formation, defined in this work, is composed of gypsum, anhydrite and carbonates, and can be correlated with surface and subsurface data. Palynological data confirms a Carnian age for the Keuper facies and an Hettangian age for the Carniolas located on top ofthe Lecera Fm. Regional data indicate a Rhaetian age for the carbonates of the Imon Fm. All these data confirm that the Triassic-Jurassic boundary should be located inside the here defined Lecera Fm.
La sección del Carbonífero en el Priorat Central (Prov. de Tarragona)
(Sociedad Geológica de España, 1997) Maestro Maideu, E.; Estrada, R.; Remacha Grau, Eduard
The Carboniferous outcrops in the Central Priorat (Fig. V, Catalan Coastal Range, record a turbidite succession ranging from Tournaisian to a possible Westphalian, in which three allogroups can be recognized. From base to top these groups are named Torroja, Bassetes and Poboleda. The Torroja group records the inversion stages of a compressive basin by a basal succession of south margin derived megabreccias, underlying a fine-grained turbidite slope-delta wedge evolving from NW. The Bassetes and Poboleda groups have a terrigenous character and have been divided in composite depositional sequences (Fig.2), recording different large channel-levee systems, evolving upward to slope-delta wedges. Gravel and sand-rich turbidites are NW derived and are located in relatively proximal positions of large turbidite systems. Composite depositional sequences record uplift-denudation cycles. SEDEX deposits are placed into the Bassetes group

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