Geogaceta -- Nº 20-1, (1996)

Permanent URI for this collectionhttps://hdl.handle.net/10272/11000

Browse

Now showing 1 - 20 of 66

Reflexiones sobre la Palinología del Cuaternario y su aplicación en la reconstrucción paleoambiental y paleoclimática. ll: Interpretación de los cambios de vegetación
(Sociedad Geológica de España, 1996) Ruiz Zapata, Blanca; Dorado Valiño, M.; Gil García, María José; Martín Arroyo, Tomás; Valdeolmillos Rodríguez, A.; Andrade Olalla, A.
To determine the causes ofthe vegetation changes is the most important factor in paleoenvironmental and paleoclimatic reconstructions from pollinic analyses. The perturbances which lead to these changes can be natural or anthropogenic ones. From 3.500 years B.Ê it becomes more dificult to interpret the vegetation changes due to the vegetation «response» to the natural perturbances can be hid by the anthropogenic activity
Descenso eustático messiniense en una cuenca atlántica. El cañón submarino del Río Guadalquivir. (SO de España)
(Sociedad Geológica de España, 1996) Martínez del Olmo, W.; Riaza Molina, C.; Torrescusa Villaverde, S.
Numerous seismic lines allow {he identification of a deep and long erosive canyon incised during the Messinian on shelfal and basinal deposits of Upper Tortonian and Messinian s.s. age. Reconstructions of the pre-erosional sedimentary architecture and other regional data support the interpretation of the erosion being of submarine origin and probably related with a Guadalquivir paleo-river
Un nuevo Rombífero, Homocystites geyeri n. sp., en el Ordovícico de El Viso del Marqués (C. Real)
(Sociedad Geológica de España, 1996) Gil Cid, M. D.; Domínguez Alonso, P.; Escribano Rodenas, M.; Silván Pobes, E.
Homocystites geyeri n. sp., a new Cheirocrinidae Rhombifera is described from lower Caradocian section from the eastern Sierra Morena zone. The paleoasodation in which Homocystites geyeri n. sp. is found, include some new echinodermes-like organism such as Macrocystella, Dendrocystites, Bohemiaecystis, and crinoids
Transición Cretácico/Terciario en depósitos continentales de la cuenca de Tremp-Graus: datos preliminares de isótopos estables de C y O
(Sociedad Geológica de España, 1996) López Martínez, N.; Ardévol, Ll.; Arribas Mocoroa, María Eugenia; Civis-Llovera, Jorge; González Delgado, José Ángel
Continental deposits around the Cretaceous/Tertiary boundary have been studied for stratigraphy, sedimento/ogy, paleontology and stable isotopes ("C and ,aO) in the Benabarre and Fontllonga sections (Tremp and Ager syndines, Southern Pyrenees). Similarities in lithology, sedimentary evolution, fossil content and isotopic values allow us to interpret these deposits as part of a single basin. A shift in the isotopic content (rise in ,bO and fall in ,JC) around the K/T boundary is detected. The increase in inO may be linked to higher temperatures and/or to evaporation. The ,3C fall matches the «z event» described in marine environments and interpreted as due to a decrease in marine organic productivity. In non-marine environments however it could indicate an increase in plant production
Terricola atapuerquensis(arvicolidae. rodentìa) nueva especie en el Pleistoceno medio de Atapuerca (Burgos, España)
(Sociedad Geológica de España, 1996) Gil Bazán, E.
A new species of ARVICOLIDAE, Terricola atapuerquensis. is described in [fie upper levels of Middle Pleistocene from the Trincherà del Ferrocarril of Atapuerca (Burgos.Spain)
System Tracts, Secuencias de Depósito y Megasecuencias: geometrías y modalidades de superposición
(Sociedad Geológica de España, 1996) Martínez del Olmo, W.
The geometry and the areas of erosion/deposition of the System Tracts of which Depositional Sequences are made up of, and the ways in which the fatter are superimposed, are controlled by several factors. These factors can be considered to be grouped in a decreasing order of revelance, as follows: 1) Configuration Factor. 2) Depositional Area Factor and 3) FYogradation Factor. The first factor determines three big scale configurations, while the other two make possible the identificación of Depositional Sequences according to eight basic geometries
Sedimentación cuaternaria en la plataforma y el talud continentales del Golfo de León (Mediterráneo nor-occidental). 2- parte: Orden de ciclicidad de las secuencias sísmicas en alta resolución y cronoestratigrafía isotópica
(Sociedad Geológica de España, 1996) Torres, J.; Savoye, B.; Droz, L.; Canals, M.
This study tries to establish the chronostratigraphy of the Late Quaternary high-resolution seismic units off the present Rhône Delta. Previous works have associated the deposition of these seismic units with 5th order glacio-eustatic cycles. We have compared (7) the thickness of ¿he studied series with a multichannel seismic profile, tied with o¡¡-exploration wells drilled near the study area and (2), the stacking pattern of the Rhône shelf seismic units with other Plio-Quaternary deltaic margins in the Mediterranean. Available 14C dates concerning the youngest seismic units have been also used and plotted on the Late Quaternary high-resolution eustatic curve. Each seismic unit (B-F) has been associated with a 4th order instead 5th order glacio-eustatic cycle. This hypothesis is used to built up the absolute chronostratigraphy of the series, using the SPECMAP record
Sedimentación cuaternaria en la plataforma y el talud continentales del Golfo de León (Mediterráneo nor-occidental). 1- parte: Estratigrafía sísmica de baja y alta resolución
(Sociedad Geológica de España, 1996) Torres, J.; Droz, L.; Savoye, B.; Canals, M.
This paper is focused on the seismic stratigraphy of the Culf of Lions continental shelf and slope, off the present Rhone Delta. A low resolution multichannel seismic profile allows to divide the Plio-Quaternary section in 10 seismic units (S9-Sf0) bounded by unconformities. The Plio-Quaternary boundary has been tentatively correlated on this profile from oil-exploration wells drilled near the study area. High-resolution seismic profiles allows a more detailed analysis of the uppermost part of the sedimentary section. The continental shelf section is divided into 6 major units (A-F) bounded by unconformities. ■ These units are Quaternary in age and correlate with units 5? and S,0 on multichannel seismic records. Units B-F shows a wedge shaped geometry and reach a maximum thickness at the shelf edge. These wedge-shaped seismic units are traced onto the slope in an intercanyon area. Detailed analysis of the seismic facies on the slope shows that the sedimentary series defines cycles. Each basic cycle is composed of a couplet of two different sub-units: a lower mostly transparent sub-unit which correlates with a wedge shaped seismic unit on the shelf, and an upper mosdy layered seismic unit on the slope which correlates with an erosiona/ unconformity on the shelf. These sedimentary cycles are supposed to be related with sea-level fluctuations
Sedimentación litoral en el límite Devónico/Carbonífero del Suroeste Portugués (Zona Surportuguesa)
(Sociedad Geológica de España, 1996) Moreno Garrido, María Carmen; Pereira, Z.; Oliveira, J. T.; Sierra del Pino, Sonia
Devonian-Carboniferous boundary at the Southwestern Portuguese Domain (South Portuguese Zone) is characterized by a shallowing detrital sequence which caps the Tercenas Formation. Sedimentation ocurred in a littoral setting with, at least, two different depositionsI environments: a wave dominated nearshore, lineal in morphology, and a wave/tidal dominated coast with a more complex morphology (i. e. a bay or a estuary)
Secuencias deposicionales del Cretácico superior no terminal (Turoniense superior - Campaniense inferior) en la zona central de la Península Ibérica (Cordillera Ibérica y Sistema Central)
(Sociedad Geológica de España, 1996) García, A.; García Hidalgo, J. F.; Segura, M.; Gil, J.; Carenas, B.; Ruiz, G.
The Upper Cretaceous (Upper Turonian - Lower Campanian) in the central Iberian Peninsula is divided into 4 depositional sequences with an eustatic origin, which are correlated to the UZA 3-1 to UZA 3.4 of Haq et al. (1988) cycles chart, These sequences allow the establishment oí new temporal relationsships between well-known lithostratigraphic units. Tectonic also plays an important role both in the northwestwards shift of the Iberian basin during Upper Turonian -Lower Coniacian; and in the intra-Santonian events: an angular unconformity in the south border of the Central Mountains and a southeastwards shift in the basin allowing a brief Tethys - Atlantic connection
Relaciones genéticas entre las unidades litoestratigráficas del Cretácico medio y superior de la Cordillera Ibérica Occidental
(Sociedad Geológica de España, 1996) Segura, M.; García, A.; García Hidalgo, J. F.; Carenas, B.; Ruiz, G.; Gil, J.
During last 20 years the Midc/le and Upper Cretaeous in the Iberian Ranges have been widley studied. Stratigraphic correlations between regional series, however, have been problematic since there exist common faces changes, and fossils with chronostratigraphic value are restricted to the SE (Albian -Cenomanian) or NW (Turonian - Coniacian) part of the basin. On the other hand, Sequence stratigraphic studies allow reconigtion of sequences and parasequences, which can be used in order to obtain more accurate correlations with the extension along the sedimentary basin of the fossiliferous data included in any sequence or parasequence. A stratigraphic cross section along the Iberian basin, from Siete Aguas-Malacara (Valencia), in the 55, to 5t° Domingo de Silos-Carazo (Burgos), in the NW, is presented showing the proposed correlation for the 72 recognized sequences (Albian-Coniacian), and for the main litostratigraphic units (75 formations, including several Members, and 2 Beds)
Relaciones tectónica-sedimentación en el Aptiense de Sierra Larga, Jumilla (Murcia)
(Sociedad Geológica de España, 1996) Arias, Consuelo; Masse, J. P.; Vilas, Lorenzo
Aptian shallow water carbonates of the Sierra Larga antiform (Prebetic of Murcia) show rapid vertical and lateral facies and thickness variations with well defined sequences. Each sequence consists of a lower terrigenous unit followed by an upper carbonate unit. Relatively to normal and listric fault bounding rotated blocksi, the terrigenous and carbonates show a specific spatial distribution which document a structural control. Tectonic is not only involved in facies distribution but also in sequenciality Local tectonic activity was reduced through time therefore regional factors tend to be gradually dominant in the sedimentary record
Reflexiones sobre la Palinología del Cuaternario y su aplicación en la reconstrucción paleoambiental y paleoclimática. I: Representación polínica de la vegetación
(Sociedad Geológica de España, 1996) Ruiz Zapata, Blanca; Andrade Olalla, A.; Dorado Valiño, M.; Gil García, María José; Martín Arroyo, Tomás; Valdeolmillos Rodríguez, A.
The Palinological Methodology presents some objections that must be beared in mind when the pollinic analyses are used for paleoenvironmental and paleoclimatic reconstructions. In this work the objections affecting the accuracy of the pollinic representation of vegetation are reviewed. These objections are production and dispersion of pollen grains, differential conservation, determination level and representation of the different types of vegetation
Rasgos estratigráficos de la sucesión del Ordovícico Superior en Portilla de Luna (Zona Cantábrica, noroeste de España)
(Sociedad Geológica de España, 1996) Gutiérrez Marco, Juan Carlos; Aramburu, C.; Arbizu, M.; Méndez Bedia, I.; Rábano, Isabel; Villas, E.
Upper Ordovician rocks have been characterized for the first time in the Cantabrian Zone of the Hesperian Massif. The sequence consists of a lower siliciclastic unit of Caradoc-(‘basal Ashgill age developed as an alternation of shales, siltstones and sandstones, overlain by an upper unit of fossiliferous limestones with marly intercalations, of pre-Hirnantian (mainly Cautleyan-Rawtheyan) age. Ashgill fossils are fairly abundant in the limestone unit, and there have been identified brachiopods of the «Nicolella fauna», echinoderms of the «Heliocrinites fauna» and trilobites of the Qvalocephalus biofacies
Primera identificación de materiales del Ordovícico Medio en la sección de Los Barrios de Luna (Zona Cantábrica, noroeste de España)
(Sociedad Geológica de España, 1996) Aramburu, C.; Gutiérrez Marco, Juan Carlos; Méndez Bedia, I.; Arbizu, M.; Rábano, Isabel; Truyols, J.
Fossiliferous shales of the Luarca Formation are identified for the first time in the southern part of the Pliegues y Mantos domain of the western Cantabrian Zone. The outcrop consists of 10,6 m of dark shales and micaceous silts tones, tectonically intercalated between the La Matosa (Middle and Upper Cambrian) and Tanes (Arenig) members of the Barrios Formation, close to the classical section of this unit. The occurrence of a diverse assemblage of trilobites, graptolites, ostracods, brachiopods, echinoderms, molluscs and some acritarchs and chitinozoans confirms a Middle Ordovician age for the shales, whereas the age of the top of the Barrios Formation does not exceed the Arenig
Presencia de cefalópodos del tránsito Anisiense-Ladiniense en las facies Muschelkalk de la Zona Subbética (Cordillera Bética)
(Sociedad Geológica de España, 1996) Goy, Antonio; Pérez López, Alberto
The recorded associations of ammonites found in the Muschelkalk fades of Valdepeñas de Jaén (Ptychitidae, Proarcestes, Reitziites, Hungarites) and of Calasparra, Murcia (Eoprotrachyceras, Negebites, Israelites, GevanitesJ allow for the first biochronostratigraphic characterization of the Anisian-Ladinian boundary in the Subbetic Zone of the Betic Range
Particularidades de los macroforaminiferos del Cenomaniense de la Cordillera Ibérica: implicaciones paleobiogeográficas
(Sociedad Geológica de España, 1996) Calonge, Amelia; Caus, E.
The distribution of Larger Foraminifera in the Iberian Range during the Cenomanian is being studied. The occurrence of Ovalveolina maccagnoae, Sellialveolina viallii and Pseudedomia drorimensis on the shelves of the lower depositional cycle (Upper Albian-Middle Cenomanian) implies a Tethysian origin of the sediments. In contrast, during the upper depositional cycle (Upper Cenomanian) the Larger Foraminifera assemblages are related to the Pyrenean Culf with the exception of Cisalveolina. Us occurrence in the north-eastern part of the Iberian Range, however, indicates a communication with the Tethys realm. The Cenomanian age attributed to the uppermost shallow platform facies implies that carbonate sedimentation stopped before the deposition of Middle Turonian hemipelagic sediments
Para un catalogo critico de las unidades litoestratigraficas (y afines) del Paleogeno surpirenaico y de la Cuenca del Ebro
(Sociedad Geológica de España, 1996) Reguant, Salvador
A compilation of the Paleogene lithostratigraphic (and closely related) units created from Southpyrenean and Ebro Basin, in comparison with those contained in the volume devoted to Spain of the «Lexique Stratigraphic International» shows the increase, from 60s until now; of stratigraphic research. The result Is an enormous growth in the number of defined lithostratigraphic units. It is, then, necessary to make a critical catalogue of this kind of stratigraphic units to clarify which units are well defined and what is their exact meaning. It also appears to be necessary to avoid the confusion produced by defining, with the same pattern, both genetic and descriptive stratified rock-units
Paleontología y estratigrafía del Plioceno inferior de la cuenca de Asilah (NW de Marruecos)
(Sociedad Geológica de España, 1996) González Delgado, José Ángel; Civis-Llovera, Jorge; Alonso Gavilán, G.; Andrés, I.; Ben Moussa, A.
The sedimentology, taphonomy and paleontology (Molluscs and Foraminiferids) of the Pliocene in the Asilah Basin are studied. On the basis of the plankton, a Lower Pliocene age is pointed out for the Basin (co-occurrence of Cloborotalia margaritae and Globorotalia puncticulata). 45 tax a of Benthic Foraminiferids and 91 of Mollusca (mainly Bivalves) are recorded. The assemblages are interpreted as living in infralittoral stormy and warm depositionsI environments
Orientaciones de esfuerzos en la corteza superior: determinación a partir de sondeos de exploración de hidrocarburos en la Península Ibérica y en cuencas adyacentes
(Sociedad Geológica de España, 1996) Jurado, M. J.
Hydrocarbon exploration activity by oil companies in Spain has resulted in the acquisition of valuable data to analyze the stress orientation in the first 5 to 6 km of the Earth's upper crust. Borehole breakout analysis perfomed on borehole geometry logs give an indication on the orientation of the maximun horizontal compressive stress. 50 of the available exploration wells were selected to perfom the stress analysis that should provide with new present-day stress indicators in different domains of onshore and offshore areas in the Iberian region. The first results have been obtained for NE Iberia and neighboring offshore Mediterranean, Research in progress will provide with new stress indicators among Others for southern Iberia (Guadalquivi basin, Alboran basin, Betics and intrachain basins) and northern Iberia (Bay of Blscay-Cantabrian offshore)

Browse

Recent Submissions