Geogaceta -- Nº 21 (1996)

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Texturas superficiales en los granos de cuarzo de las arenas del Plioceno superior de la zona Jerez-Lebrija (SW de España)
(Sociedad Geológica de España, 1996) Moral Cardona, J. P.; Sánchez Bellón, A.; Domínguez Bella, S.; Gutiérrez Mas, José Manuel; López Aguayo, F.; Antonio Caballero, M.
In the Jerez-Lebríja area (SW Spain) there are deppsits of Pliocene sands which are exploited in various quarries. The analysis of the surface features presented by the quartz grains from these sands refveals different stages in their evolution of the grains. The first of these stages is recorded in the form of conchoidal fractures and arcuate steps; the second is represented by an assemblage of features comprising isolated Vs, grooves and chattermark trails. In a posterior stage chemical features were developed in relation to tropic climatic Conditions
Réplica al artículo: «Características geoquímicas preliminares de azabaches artesanales del Kimmeridgiense de Asturias» (C.G. Blanco, M. Valenzuela, C. Suárez de Centi, M. Fernández Pello; Geogaceta 20(3): 677-680)
(Sociedad Geológica de España, 1996) Suárez Ruiz, I.; Iglesias, M. J.
The article of C. G. Blanco, M. Valenzuela, C. Suárez de Centi y M. Fernández Pello published in Geogaceta (1996), 20(3): 677-680 contains serious deficiencies and a lack of scientific rigour that undermines the vality of its conclusions. The autors mentioned show a surprising ignorance of the origen, characteristics and fundamental properties of the material used in their work (Spanish jet) failing to cite most of the previous works that have already dealt with this material. As a result, C. G. Blanco eta I give as "original results" previously reported by other authors. Moreover, given the complex and heterogeneous nature and the special composition of Spain jet, the failure to include the basis of the elemental analysis and the confusion in the units in which the data are expressed have led to a very low degree of accurancy in the authors'deductions. Furthermore, the classification of this jet as a relatively immature material is based on false suppositions. Finally, some of the conclusions drawn by C. G. Blanco et at\ clearly contradict widely accepted results without any scientific justification
Racemización de los aminoácidos de braquiópodos y pelecípodos de la sección de Cuesta Colorada (Almería, SE de España)
(Sociedad Geológica de España, 1996) Torres, Trinidad de; García Alonso, P.; Canoira, L.; Llamas, F. J.; Coello Bravo, F. J.; García González, L.; Nestares, T.; Peláez, A.; Rodríguez Alto, N.
This paper deals on the new Cuesta Colorada section study. A recent road cut allowed to study a more compietiogofthe former interpreted Pliocene - Pleistocene boundary. A great number of pelecipoda and brachiopoda shells from different strata were picked up for amino acid racemization analysis also, and the obtained results were compared with the palaeomagnetic interpretation
Procesos kársticos en la Formación Calcarenita de Niebla (Huelva)
(Sociedad Geológica de España, 1996) Cáceres Puro, Luis Miguel; Rodríguez Vidal, Joaquín; Rodríguez Ramírez, Antonio; Cantano Martín, Mercedes
The development of a covered karst in the Miocene calcarenite formation in the N area of Niebla (Huelva) has been studied. The cover consists of sediments of Quaternary terraces of the River Tin to (T9, T8, T7 and T6), and to a lesser degree, fragments of Mio-Piiocene days («blue marls»). Solution of the calcarenite has originated vertical pipes of varying size evolving in the top to form funnel-shaped channels of preferential solution. These karstified areas generate dosed depressions that appear on the surface as alluvial dolines, basically bowl-shaped with smooth edges. Later erosion by streams has resulted in fluvial capture of the depressions and the breaking up of the alluvial cover, obstructing identification of the these landforms
Presencia del Alogrupo de Figols en las turbiditas de la base del Grupo de Hecho (Barranco del Sorrosal, Prov. de Huesca)
(Sociedad Geológica de España, 1996) Remacha Grau, Eduard; Raïmat, C.; Oms, O.; Cardona, D.; Mutti, E.
The turbidite equivalent of the Figols Allogroup can be recognized at the base ofthe Hecho Croup. Three deposition a! sequences -Figols 1,2 and 3- are recorded and are organized in third order stages of growth. All the sequences have similar features in the first stage. Lower boundaries are tectonically induced. A sudden zonal basinward shifting occurs and depositional systems (lobes) are developed. Second and third stages are well developed in Figols 2 and 3. The second stages record a strong and progressive landward shifting in both systems and the third stages are the basinat expression of the foreland carbonate ramps
"Piedras Geodes" y nodulos silúricos en el Aparato para la Historia Natural española (1754) de José Torrubia
(Sociedad Geológica de España, 1996) Gutiérrez Marco, Juan Carlos; Rábano, Isabel; Bombín Espino, M.; García Palacios, A.; Herranz Araújo, P.
Torrubia (1754) was the first to describe the presence of nodules in the Silurian black shales cropping out in the old tile works near El Pobo de Dueñas in the province of Guadalajara. He called them «geode-stones» reminiscent to «little cakes and diceboxes», considering them as petrefacts of nonorgan ic origin. The presence of nodules in Silurian graptolite facies in several i be rían localities is also briefly examined, and the diverse popular interpretations of these structures in the country are also annotated (i.e. «moorish heads», mammut-coprdlites, turtles or even «copro/ithus neanderthalensis»
Los yacimientos pleistocenos de Torralba y Ambrona y sus relaciones con la evolución geomorfológica del Polje de Conquezuela (Soria)
(Sociedad Geológica de España, 1996) Pérez González, Alfredo; Santonja, M.; Gallardo, J.; AIeixandre, T.; Sesé, C.; Soto, E.; Mora, R.; Villa, P.
The Ambrona and Torralba archeological sites are related to the pleistocene evolution of the Conquezuela-Ambrona-Torralba polje. A study made of the centre-south sectors of this polje, nowadays highly degraded In part though being dissected by the river Masegar, shows that Torralba and Ambrona occupy different geomorphological positions. This would mean that both the age and strati graphic formations of the sites are different
Lignitos uraníferos de Calaf: Estudio cinético de lixiviación en medio bicarbonatado
(Sociedad Geológica de España, 1996) Grau i Girona, R.
Humic acids contained in lignites ha ve hihg capacity to link with uranil ion and other heavy metals. The aim of this paper is to study the uranil-1 ignite link and the determination of the funtional groups which participate in it For that, the complejation of uranium with sodium bicarbonate have been studied and the kinetic equation of the system obtained. Later, through iR spectroscopy the funtional groups participating in the link with the uranil ion have also been obtained
Importancia de la bioerosión en ostrácodos actuales del litoral de Huelva (SW España)
(Sociedad Geológica de España, 1996) Ruiz Muñoz, Francisco
The analyses of 69 samples from the Huelva littoral (SW Spain) leads to establish the importance of the b/oerosion phenomenes in the ostracod population. Three evidences of organic interaction has been found, according to different predators and the effects of gastric juice
Geomorfología de las terrazas fluviales del tramo bajo del río Guadalquivir. Implicaciones evolutivas
(Sociedad Geológica de España, 1996) Rodríguez Ramírez, Antonio; Cáceres Puro, Luis Miguel; Rodríguez Vidal, Joaquín; Clemente Salas, Luis; Cantano Martín, Mercedes
Fluvial landforms occupies a considerable area of the study zone. Up to now, these deposits have been interpreted as an extensive piedmont glacis. However, detailed geomorphological mapping has distinguished up to six levels of terraces, with NE-SW orientation. These levels have been correlated with those previously studied in other zones of the Guadalquivir valley, using altitudinal, sedimentological and edaphic criteria. An approximate chronology has been established, ranging from the end of the Lower Pleistocene to the beginning of the Upper Pleistocene. It reveals a gradual pushing of the terraces SE-wardson the Neogenic materials ofthe basin. The most recent levels are sited below the Guadalquivir marshland, with an area of maximum subsidence on a NE-SW axis, coincident with that of the Betic olisthostromic edge in this zone
Fluidos asociados a la formación de epidota + (clorita + cuarzo) en las pegmatitas del plutón de La Cabrera (Sistema Central Español)
(Sociedad Geológica de España, 1996) Lozano Fernández, R. P.; Bachiller, N.; Casquet Martín, César
Fluids related to the epidote+chlorite+quartz and calcite (Flaumont/te) alterations present in the cores of pegmatites from La Cabrera pluton have been determined. Two types of fluids are involved: a) Alow salinity (0.4-4.5 wt% NaCI equiv.) NaCI-H20 fluid is the responsable for the first type ofalteration. Temperature was probably dose to 300°C. b) A moderate to high salinity (15.3-24.5 wt% Nad equiv.) heterogeneous (liquid + gas) CaCi2-NaCt-H20 fluid was involved in the second alteration under conditions of PffM probably very dose to hydrostatic. These alterations probably took place as discrete hydrothermal events of different ages
Evolución de los fluidos hidrotermales en la génesis de los sulfuros masivos de Aznalcóllar (Faja Pirítica Ibérica): evidencias a partir de inclusiones fluidas
(Sociedad Geológica de España, 1996) Toscano Macías, Manuel; Sáez Ramos, Reinaldo; Ruiz de Almodóvar Sel, Gabriel
Fluid inclusion data from Aznalcdllar and Los Frailes stockworks indicate that hydrothermal fluids changed continuously in temperature and salinity, both in time and space. Th values change from 140 to 380 °C and salinity from 0.4 to 12.4 NaCI eq. The highest values for both parameters ha ve being found for central stockworks and later fluids. Statistic population analysis of fluid inclusion data points to three stages of hydrothermal activity, at low (<200 °C), intermediate (200-300 °C) and high temperatures (300-400 °C). Salinity values show similar variation trend with higher values for the last hydrothermal stage
Estructuras sedimentarias de deformación (sismitas) inducidas por licuefacción con un simulador de terremotos
(Sociedad Geológica de España, 1996) Caselles, J. O.; Moretti, M.; Alfaro García, Pedro; Canas, J. A.; Clapés, J.
This study is a first attempt to reproduce se¡smites in laboratory using a shaking table and natural sediments. The deformation linked to liquefaction-fluidization processes has been analysed, contlnously controlling the Interstitial pressure and acceleration. Morphologically, two main types of structures have been observed: fluid escape and load. The morphological variety is primarily controlled by the type of sedimentary column
Emplazamiento en una zona de cizalla dúctil - frágil transtensiva para el Plutón de Pájara, Fuerteventura, Islas Canarias
(Sociedad Geológica de España, 1996) Muñoz, Mercedes; Sagredo, J.; Rincón Calero, P. J.; Vegas, Ramón
The mésostructures within the host-rocks as well as the internal deformation ofthé Pájara Pluton in Fuerteventura, allow the definition of a N 5-15 E directed ductile-brittle transtensive shear-zone, that conditioned the emplacement of the intrusive core represented by this ptutonic body. We ha ve indirectly estimated an age of 22-21 Aia for this shear-zone, which is considered as coeval to the thermal metamorphism
Elementos trazadores de procesos urbanos: el caso de la plata
(Sociedad Geológica de España, 1996) Jiménez de Grado, M.; Miguel, E. de; Llamas, F. J.; Jiménez Álvarez, M.; Mazadiego, L. F.
As part of a wider effort to characterise the origin and pattern of distribution of trace elements in urban environments, a sampling campaign of soils, sewage sludge from municipal waste water treatment plants, and composted sludge, was carried out between 1994 and 1996. All the samples were oven dried, acid digested and analysed by ¡CP-AES. The information thus gathered strongly suggests that the two main sources of trace elements in urban soils are the deposition of atmospheric particles generated from traffic (and, to a lesser extent, from other urban sources), and the application of composted sewage sludge. Agproved to be an excellent tracer of the latter process, since sewage sludge is the only significant urban source of this element. Furthermore, the difference in Ag concentration between soils with and without compost application is from 5 \ig/g for the former to below 1 /lg/g for the latter
Dos nuevos yacimientos con graptolitos silúricos en la región de Alange (Badajoz)
(Sociedad Geológica de España, 1996) Gutiérrez Marco, Juan Carlos; Porro Mayo, T.; Herranz Araújo, P.; García Palacios, A.
Two new fossil localities yielding graptolites of the, (undgreni and leintwardinensis biozones (early Homerian and basal Lùdfordiàn, respectively) are studied from the Al an gè region, which lies on the southernmost part of the Central Iberian Zone, Previous mentions to graptolites from a nearby outcrop were also reviewed and the original specimens reassigned to some earlier horizons in the Wenjock AH these data confirm the presence of Silurian rocks over a region very imprecisely known in terms of Paleozoic sedimentary geology and paleogeograppy
Dominios y facies deposicionales estuarinos de la desembocadura del Río Tinto (Huelva, España)
(Sociedad Geológica de España, 1996) Morales González, Juan Antonio; Pendón Martín, José Gabriel; Jiménez, I.; López López, Manuel; Borrego Flores, José
Two estuarìne domains were distinguished in the inner mesbtidai estuary of the tinto River (S. W. Spain): central and fluvial domains; the former being subdivided into lower and upper domains. Coring and vi braco ring ofthe Ho focene sediment allowed the distinction of six depositional facies within these domains: (1) estuarìne channel, (2) tidal channel, (3) channel margin, (4) marsh, (5) fluvial flood plain and (6) fluvial bar. These facies are sequentially arranged from subtidal Into supratidal zones which meaning is the result of the infilling process of the estuary as a consequence of: (1) the stabilized sea level about 6000years BP, and (2) the great rates óf sediment accumulation
Distribución de minerales pesados en los sedimentos de la plataforma continental de Cádiz
(Sociedad Geológica de España, 1996) Gutiérrez Mas, José Manuel; Moral Cardona, J. P.; Parrado Román, J. M.; Jódar Tenor, J. M.
The heavy minera!, distribution on recent sediments of continental shelf of Cadiz; shows great relation with the granulómetric distribution, -source areas, hydrodynamic behavior grains and the depositlonal regimen. Ultrastable heavy minerals are predominate in south sector, in coincidence with quarzitic sand deposits sedimentation low rate and high maturity of the sediments. Nortward, in neighboring prodeltaic muddy sediments to the Guadalquivir aver mouth, meta stables heavy minerals predominate, in coincidence with high sedimentation rate and a greater mineralógica! variability in the sediments, dye to the. fluvial contribution. The main mineralógica! assemblage is: epi dote, garnet, rutile and zircon, very similar to the. sho wed by other author.es in neighboring littoral and continental, areas. The main source areas are in the Iberian Masif(Sierra Morena), Cordillera Be tica and Depresión óf Guadalquivir. The main transport agents are the Guadalquivir and Guadalete rivets and others which ha ve their mouth nortward of the study area. Others sources of sediments to the. continental margen can be related with the Atlantic Water Flow and, Mediterranean Out Flow from external zones to this geographical area
Distribución de facies recientes en los fondos de la Bahía de Cádiz
(Sociedad Geológica de España, 1996) Gutiérrez Mas, José Manuel; Achab, M.; Parrado Román, J. M.; Moral Cardona, J. P.; Sánchez Bellón, A.; González Caballero, J. L.; López Aguayo, F.
Thè distribution of fàcies in thè bottoms ofthe Bay of Cadiz is studied in a preliminary phase of a wider study about the sedimentary èxchange between the continent and continental margin. Two sectors are distinguished, the inner one is clayely-muddy and the external one is sandy showing the grain size distribution the main transport path ofthe ebb tidal current and of those generated by the stórm wa ve. The quartz is majority in sandy areas and phyllosilicates in muddy sectors. The day fraction is Hite> kaolin ite > smectite = iiite-smectité (l-S) = chlorite. The sedimentation rate is contro led by the supp/yes of Guadatele riverir) the northern margin. To the south, the lack of rivers is supplemented for the action of tidal currents that drain the inner areas of the bay, and by the contributions of the emerged tidal flat through tidal inlets and sudicia/ drainage waters. The sediments deposited in the bottom of the lagoon, after their remotion by the east'and south wave, are transported toward the external bay zone by the ebb current, leaving a muddy trace which follows the morphology ofthe coast and bottom until to reach the continental shelf
Controles composicionales, diagenéticos y de microfábrica sobre las características de la roca madre jurásica del petróleo del Campo de Salam (Western Desert, Egipto)
(Sociedad Geológica de España, 1996) Marfil Pérez, Rafaela; Dorronsoro Urrutia, C.; Rossi, C.; Permanyer, Albert
Petrographic, mineralógica! (XRD), bulk geochemical (TEM, SEM and BSE) andpetrophysical analysis of selected shales, siltstones, coaly shales and coals from Jurassic Khatatba Fm. and Cretaceous Alam El Bueib (AEB) Fm. in the Salam oil field (Western Desert, Egipt) reveal a similar whole mineralógica/ composition but with variable day composition. This is composed of kaolinite and subordinated l-S mixed layers in the Khatatba Fm. being composed of kaolinite, illite, i-S mixed layers and chlorite in the AEB Fm.. This difference could have influenced on the type of HCgenerated as several authors have shown. Also the day microfabric shows some difference between the more open structure of the flocculated continental kaolinite in the Khatatba Fm. and the oriented and more compacted marine days (in both formations). The abundant silt quartz grains in the shales of the two formations have favoured the conected microporosity on the primary migration of HC to the interbedded sandstones. The high content in globular organic remains replaced by framboidal pyrite and bitumen and the amorphous organic ground mass of the Khatatba shales indicates that the best oil-source rock could bé the organic shales instead of the carbonaceous shales in the Khatatba Fm

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