Geogaceta -- Nº 15, (1993)

Permanent URI for this collectionhttps://hdl.handle.net/10272/13958

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Análisis de la fracturación en la cuenca cenozoica de As Pontes (La Coruña)
(Sociedad Geológica de España, 1994) Ferrús, B.; Santanach, P.
Minor fault analysis using Angelier and Mechler (1977) and Etchecopar et al. (1981) methods have been carried out in the Cenozoic As Pontes Basin (NW Spain).The paleostress tensors obtained are in agreement with the deformation fie ld defined by large scale faults. The orientations of a 1 and a 3 are parallel to those of the regional shortening (N-S to NNW-SSE) and extension (E-W to ESE-WNW) directions
Zonas de cizalla dúctil en el Complejo Basal de Fuerteventura
(Sociedad Geológica de España, 1994) Casillas Fernández, R.; Ahijado, A.; Hernández Pacheco, A.
The oldest plutonic rocks of the Basal Complex of the Fuerteventura Island In the area of Amanay are an alkaline ultramafic-carbonatite complex. In certain areas these rocks are affected by two ductile shear systems with respectively general NW-SE and NE-SW orientations. The deformation related to these shear zones originate, in certain instances, a marked mylonitic foliation and the formation of folds that change notabily the structures and textures of the affected rocks. The geometric relation that exist between these structures and the location of the gravimetric and magnetic anomalies of the Island, its oceanic counterpart as well as the morphology of the sedimentary basins located to the N and NW, may point to the existence of Important oceanic fractures in this sector of the North Atlantic.
Yesos de Calatayud: aplicación del estudio de facies y geoquímica de sulfatos al conocimiento de un sistema evaporítico
(Sociedad Geológica de España, 1994) Ortí, Federico; Rosell, L.; Fallick, A. E.; Utrilla, R.
The study of depositional and diagenetic calcium-sulphate evaporites in the Calatayud Gypsum (Zaragoza prov., Spain), reveals the existence of a NW to SE elongated and relatively asymmetrical arrangement in this Miocene lacustrine system. In this particular arrangement a marginal belt exists of bioturbated gypsum, surrounding a central body formed by nodular laminated-facies. This marginal belt is narro win the N W zone and wider in the SE zone. The isotopic compositions (8'30 , 8 34S) of all the studied samples suggest that a concentration gradient occurred in the basin towards the NW area of the central body, where the more saline waters and the depocentre were probably located.
Variaciones laterales del "Nivel de Fuentes", Precámbrico-Cámbrico de la Zona Centro-Ibérica
(Sociedad Geológica de España, 1994) Santamaría Casanovas, J.; Remacha Grau, Eduard
The "Nivel de Fuentes", in the Valdelacasa Allogroup (Precambrian-Cambrian), can be divided in five subunits. Each one of them is build-up by a basal megabreccia overlaid by a fine-grained turbidite wedge that tends to pinch-out toward the central region of the Valdelacasa anticline. The isochron character ofthe "Nivel de Fuentes" is rejected because really it is multievent
Un episódio volcánico pre-Cañadas en la Isla de Tenerife
(Sociedad Geológica de España, 1994) Huertas, María José; Ancochea, Eumenio; Cantagrel, J. M.; Coello Bravo, Juan Jesús; Fúster, J. M.; Ibarrola, E.
Based on new radiometric data, a Pre-Cañadas volcanic building of 3.5-3.0 Ma has been defined. This new building is mainly compared of basaltic rock cropping out in several gorges to the S of Cañadas Building, inside of the <<Pared de las Cañadas>>, <<Boca de Tauce>>, and <<La Grieta>> and <<La Angostura>> valleys
Tectónica distensiva y halocinesis en el margen SO de la cuenca Vasco- Cantábrica
(Sociedad Geológica de España, 1994) Serrano, A.; Hernaiz Huerta, Pedro P.; Malagón, J.; Rodríguez Cañas, C.
Extensional tectonics and associated halokinetics processes controlled the sedimentation in the southwestern margin of the Basco-Cantabrian basin during Upper Jurassic and Lower Cretaceous times. The development of Mesozoic growth faults, compressive features at present, controlled the geometry and limits of the sedimentary bodies deposited at those times
Sobre la posición estratigráfica de las "Margas de Gor", Sierra de Baza, Cordillera Bética
(Sociedad Geológica de España, 1994) Martín Pérez, J. A.; Viseras, César
The marly sediments traditionally known as "Cor Miocene" are located at the bottom of a very thick Middle Miocene detritic ensemble composed by clasts of alpujarride, malaguide and subbetic provenance. Locally they are overthrusted by Triassic Alpujarride dolostones. They are though to have been deposited In the foredeep basin related to the North-Betic Strait, located to the north of the Betic Internal Zone
Significado de los enclaves ricos en biotita en el plutón de Mora-Gálvez (Toledo)
(Sociedad Geológica de España, 1994) Andonaegui, P.
Biotite-rich enclaves are conspicuos in the peraluminous granites. They had been interpreted as either melting restites or trapped xenoliths at different crustal levels. This work studies the biotite chemical composition in two mica-rich enclaves from Mora-Galvez pluton (Toledo). Based on these data, these mica-rich enclaves are interpreted as metamorphic xenoliths trapped at mid-crustal levels and variably reequilibrated with the host granite magma. Thus, a restitc origin is ruled out
Sedimentología, magnetoestratigrafía e isotopía de los depósitos fluviokársticos de la Cueva del Reguerillo (Patones, Madrid): interpretación paleoambiental
(Sociedad Geológica de España, 1994) Torres, Trinidad de; Cobo, R.; Hoyos, M.; Mansilla, H.; Soler, Vicente
This paper deals with the palaeoenvironmental interpretation of the Reguerillo Cave fluviokarstic section through sedimentological, magnetostratigraphycal and isotope analysis studies. Three moisture decreasing sequences (water available in the karst) near the Gauss-Matuyama magnetozones boundary have been determined
Sedimentación lacustre en la cuenca cenozoica de As Pontes (A Coruña)
(Sociedad Geológica de España, 1994) Sáez, A.; Cabrera, L.
The lacustrine and swampy sequences recorded in the As Pontes basin are rather diverse in terms of facies and sequential arrangement, depending on the considered basin zone. Since these sequences developed synchronously and very dose, the paleoclimate conditions had to be similar and the observed differences must be attributed to the tectonic influence
Remagnetizaciones asociadas a diagénesis y su relación con el emplazamiento de láminas cabalgantes en el Pirineo Meridional
(Sociedad Geológica de España, 1994) Dinarès Turell, Jaume
Paleomagnetic analysis in conjunction with petrographic Observations on Mesozoic carbonates from the southern Pyrenees reveals that the magnetization of thoserocks is a secondary CRM residing in both goethite and hematites of diagenetic origin. Time constraints indicate that hematite is older in age and is associated to a dedolomitization process which probably spanned longer in the Sierras Marginales than in the Montsec units. The characteristics o f the unraveled components a llo w to speculate a b o u t some paleoenviromental and tectonic aspects
Precisiones estratigráficas sobre el límite inferior de la Formación Artés (Paleógeno, cuenca del Ebro)
(Sociedad Geológica de España, 1994) López Blanco, Miguel; Piña, J.; Marzo, M.
According to its original definition, the Artes Formation is formed by the ensemble of continental, red mudstones and sandstones interbedded with conglomerates resting on top of the marine deposits of the Bartonian to Priabonian Santa Maria Croup. However, detailed mapping clearly shows that those marine rocks are laterally equivalent to distal alluvial fan facies of the "Artes type". On the basis of our present sedimentological knowledge these facies can not be differentiated from those forming the Artes Formation sensu stricto .Therefore, we propose a new definition for the entire formation that includes its subdivision into two members
Petrología y geoquímica del plutón aplopegmatítico de Peña Madrid (Sierra de Guadarrama, S.C.E.)
(Sociedad Geológica de España, 1994) Huertas, María José; Villaseca, Carlos
The Peña Madrid aplo-pegmatitic pluton is a very fractionated l-type granite with typically MgO, Ti02, Ba, Sr, Nb and XREE low contents. They intrude as a sheet-like body in the Las Navas del Marqués batholith developing an «in situ» differentiation from the roof margins towards the inner parts. The roof granites show the most primitive magmatic characteristics: the Ti and Mg richest biotites and higher MgO, Ti02, Ba, (Sr, Zr) whole-rock contents
Origen de las brechas de la base del Jurásico de Leitza (Cordillera Vasco-Cantábrica oriental, Navarra)
(Sociedad Geológica de España, 1994) Gallego, R.; Aurell, Marc; Bádenas, Beatriz; Fontana, B.; Meléndez Hevia, Guillermo
ExtensionsI tectonic activity at the Triassic-Jurassic boundary in the eastern Basc-Cantabric Range (N Spain) in v o lv e d the generation o f a set o f semigraben basins. The largest basin appears related to the Leitza fault, which determined both the accumulation of a thick succession of a caothic and poorly sorted breccia and the upwelling of basalts. These breccias grade up into massive dolomites deposited in shallow to supratidal marine restricted environments. Sinemurian relative sea level rise involved the flooding of these basins and the setting of an extensive carbonate ramp
Observaciones sobre la posición estratigráfica de las formaciones de rudistas de Sant Corneli (cuenca cretácica surpirenaica central)
(Sociedad Geológica de España, 1994) Gili, E.; López, G.; Obrador, A.; Skelton, P. W.; Vicens, E.
Rudist formations crop out around the Sant Corneli anticline (South-Central Pyrenees), both on its southern flank (les Collades de Basturs) and on its northern flank (Vilanoveta). Earlier biostratigraphical studies assigned different ages to these two exposures, the first being considered Middle-Upper Santonian and the second, Coniacian-Lower Santonian, and these assignments have been uncritically accepted in a number of recent sequence stratigraphical studies of the Cretaceous basin. However, no direct evidence for any difference in age of the two formations is provided by the (benthic) fossils contained in them, which comprise similar, broadly ranging taxa. Rather, ages had been asssigned by interpreted correlations with other units, which we dispute. Our studies of the Vilanoveta rudist formation suggest that it is not equivalent to the Coniacian-Lower Santonian Montagut Member, but is instead correlable with the Lower-Middle Santonian sediments of the Prats de Carreu Member. This conclusion in turn implies a similar (if not identical) age of deposition to that of the lithologically comparable rudist formation of les Collades de Basturs, to the South. Our preliminary studies of stratigraphically sensitive taxa from the two formations (e.g. inoceramids) support the latter interpretation, so casting doubt on the sequence stratigraphical models that have been based on the old biostratigraphical data
Nuevos datos sobre el Cretácico inferior al Norte de la provincia de Alicante. La serie del Castell de la Solana. Zona Prebética
(Sociedad Geológica de España, 1994) Estévez, Antonio; López Arcos, M.; Castro Jiménez, José Manuel
The Sierra del Castell de la Solana (NE Alicante province) exhibits a thick section (about 750 m ) of Lower Cretaceous age. I tis adscribed to the Prebetic, in the External Zones of the Betic Cordillera. The stratigraphic unit is made up mainly of carbonate platform limestones, minor sandstones, and hemipelagic marls and marly limestones. The sedimentary evolution deduced started with a mixed platform during the Berriasian-lower Valanginian; an intra-Valanginian discontinuity gave place to the development of an hemipelagic environment, that shallowed d uring the upper Barremian-lower Aptian. Since the upper Aptian to the upper Albian three episodes of progradation of carbonate platforms took place. The upermost Albian-lower Cenomanian(?) is represented by external platform deposits
Notas sobre la inversión tectónica y aloctonía de la cuenca Vasco-Cantábrica
(Sociedad Geológica de España, 1994) Malagón, J.; Hernaiz Huerta, Pedro P.; Rodríguez Cañas, C.; Serrano, A.
The SW margin of the Basco-Cantabrian basin has suffered during the Alpine Orogeny the tectonic inversion of previous extensional structures and the overlapping of the Mesozoic series of the Plataforma Burgalesa over the Tertiary sediments of the Duero basin
Notas sobre la estructura cabalgante de Rojas-Santa Casilda
(Sociedad Geológica de España, 1994) Rodríguez Cañas, C.; Hernaiz Huerta, Pedro P.; Malagón, J.; Serrano, A.
The easternmost part of the Plataforma Burgalesa Frontal Thrust (Basco-Cantabhan Basin) is the Rojas Santa Casilda Structure. This unit has suffered a displacement first towards the South and later towards the Southeast over the Tertiary sediments of the Duero Basin. This displacement can be explained through a compression with a N-S direction, changing to the SE when finding the 'San Pedro wells High'. This high acted as a barrier that obstructed the continuation of the movement to the South
Movimientos verticales recientes en Cataluña a partir de nivelaciones de precisión
(Sociedad Geológica de España, 1994) Giménez, J.; Suriñach, Emma; Goula, Xavier; Fleta, J.
To determine recent vertical movements (R.V.M.) from precise leveling data we have compared the original height differences recorded in the field by the Instituto Geografico Nacional in two different campaigns. The accuracy, number of releveled bench marks and leveling paths of the two campaigns are adecuated to measure R.V.M.. The two studied profiles show significatives R.V.M.. Two steps of about 150 mm ± 30 mm, in 37 and 38 years (4 mm/year of relative velocity), which have, partially, tectonic origin has been obtained
Los museos de mineralogía y de petrología aplicadas, en la renovación pedagógica de la enseñanza de la Geología
(Sociedad Geológica de España, 1994) Mata Perelló, Josep Maria
Through this information, it will be tried to analyse the role that the museums of geology can (and should) play, with tematic sections of mineralogy and petrology, in the way to the pedagogical renovation of the teaching of geology, and specially about the two matter before mentioned from primary education to the specializated university education; for example: at the minery studious

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