Geogaceta -- Nº 12, (1992)

Permanent URI for this collectionhttps://hdl.handle.net/10272/13962

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Zonación ambiental de «mounds» algales del Carbonífero de la Zona Cantábrica (NO de España)
(Sociedad Geológica de España, 1992) Fernández González, Luis P.; Barba, Pedro
Limestones are conspicuous within the shallow water rocks of the Carboniferous (Namurian-Westphalian) foreland basin sequences of the Cantabrian Zone. These limestone bands, containing oustanding algal bioherms, show a well defined facies spectrum with three main boundstone facies (Donezelia boundstone, Tu- biphytes-briozoa boundstone and phylloid algae boundstone). Both the entire facies association and' more specifically, the algal boun dstone facies showa pattern of distribution which seems to reflect the interplay amongst several environmental factors. Water depth and delta-derived efluents and its fine terrigenous (clay) suspension load are thought to have been the main controlling features through their influence in other parameters such as bottom energy, salinity and depth/llgth distribution and bottom illuminatio
Variación del patrón de diaclasas a lo largo de la serie neógena de la Sierra de Sigena (Huesca): Posible relación con el campo de esfuerzos y su perturbación
(Sociedad Geológica de España, 1992) Arlegui, L. E.
Neotectonic joints in the Ebro basin strike uniformly NNW-SSE, perpendicular or nearperpendicular to the direction of <33 in the moment it developed. Within the Sierra de Sigena there are joints with anomalous strikes. They show a vertical evolution becoming more similar to the regional fracture pattern as higher in the slope they appair. In the middle portion of the slope this set coexists with the regional-striking joints We interpret this joint distribution as a consequence of stress deflection caused by major faults in the basament, which shows possible attenuation upwards
Un modelo alternativo al Anticlinal del Manubles (Cadena Ibérica Occidental)
(Sociedad Geológica de España, 1992) Alvaro, J.; Liñán Guijarro, Eladio; Pocoví Juan, Andrés
A new structural map for the Cambrian outcrops located between Ateca and Morns (Occidental Iberian Chain) is presented. Based on this map and our tectonic data we suggest an alternative model for the vManubles Anticlinal», wich is characterized by two tectonic units resulting by thrusting toward the 5W a previous folded and thrusted hercynian structure
Transporte de sedimentos en suspension en la parte baja del río Ebro (Mediterráneo Occidental). Impacto ambiental de las presas
(Sociedad Geológica de España, 1992) Palanques, Albert; Guillén, J.
Seven surveys were carried out to study the suspended sediment transport in the lower course of the Ebro River. Damming of the river and its tributaries has caused a high retention of the sediment load and has regulated the fluvial discharge. At present sediment discharge is less than 1 % of the sediment that the Ebro River discharged into the sea before the construction of the dams
Synonimy of Castillomys rivas Martin Suarez and Mein, 1991, Castiliomys Plinensis Ruiz Bustos, 1991 and C. Crusafonti Meini Ruiz Bustos, 1991
(Sociedad Geológica de España, 1992) Mein, P.; Martín Suárez, E.
Castillomys rivas Martin Suárez and Mein, 1991, Castillomys plinensis Ruiz Bustos, 1991 and C . crusafonti meini Ruiz Bustos, 1991 are considered to be synonyms. Accord ing to the International Code of Zoological Nomenclature Castillomys rivas has priority over the other two
Sobre la presencia de Bastnaesita y su papel en la evolución geoquímica del Complejo Alcalino del Galiñeiro (Galicia, España)
(Sociedad Geológica de España, 1992) Corretgé Castañón, Luis Guillermo; González Montero, M. P.; Suárez Hernando, Oier
In this papaer were port the existence of bastnaesite (REE-fhjocarbonate) in the Galiñeiro alkaline complex (Pontevedra, Galicia); we show an aproximaron to ist chemical composition by electron -microprobe, and we discuss the participation of fluoride complexes in the processes of transport and enrichment of rare earth elements (mainly LREE) in these rocks
Significado de bioturbaciones en un medio evaporítico continental (Mioceno de la Cuenca de Madrid)
(Sociedad Geológica de España, 1992) Rodríguez Aranda, J. Pablo
Several types of bioturbation traces have been recognized within sedimentary deposits belonging to the Miocene Lower and Intermediate Units of the Eastern part of the Madrid Basin. The bioturbation traces are developed in muddy, carbonate and gypsiferous deposits that are interpreted as mudflat, ephemeral ponds and brackishto-saline lake facies. The bioturbation traces, whether caused by roots or meiofauna, inform about the depositional paleoenvironment. On the other hand, they influence both depositional and diagenetic fabrics
Reconocimiento hidroquímico de zonas endorreicas del Karst evaporítico de Antequera (Málaga)
(Sociedad Geológica de España, 1992) Benavente Herrera, José; Almécija Ruiz, Carmen; Carrasco Cantos, Francisco; Rodríguez Jiménez, P.; Cruz Sanjulián, J. J.
Some small temporary and permanent lakes near Antequera (Malaga) have been monitored in order to identify their main hydrochemical features. They display a wide variety both in chemical facies and salinity. The origin of these wetlands is related to triassic evaporite karst: closed depressions induced by dissolution and collapse. The results show in general a close similarity between these waters and those of the most significative springs that drain this karst, with a overimposed effect of saline concentration due to evaporation
Principales estructuras biogénicas en el Plioceno marino de la Cuenca del Baix Llobreeat (Catalunya)
(Sociedad Geológica de España, 1992) Gibert, J. M. de; Martinell, Jordi
The Pliocene basin of the Baix Llobregal (Catalonia) has proportionated an important record of trace fossils. These are a result of both bioerosion activity in hard substrates and bioturbation in the soft sediments. The ich-notaxa found indicate a shallow sedimentary environment.
Primeras aportaciones a la Paleoicnología del grupo Murero (Cámbrico inferior-medio) en Murero. (Provincia de Zaragoza. Cadena Ibérica Occidental)
(Sociedad Geológica de España, 1992) Gámez Vintaned, José Antonio; Mayoral Alfaro, Eduardo
The distribution of occurring ichnotaxa along the «rambla de Valdemiedes -1 » section (RVi), Murero Croup, locality of Murero (Occidental Iberian Chain; province of Zaragoza, Spain) and ils relations with the biofacies are analized. The term ichnoassociation is defined, and four palichnological units are established; they are represented by a total of three ichnoassodations, each contents of wichis described. These are the aff. Planolites (in Valdemiedes and Mansilla formations), Planolites montanus (in part of the Valdemiedes formation) and a ff. Planolites and Diplichnites ichnoassociations (In Murero formation). The aff. Planolites and Diplichnites ichnoassociation développes in more diversified ecosystems than the aff. Planolites ichnoassociation do, of wich the former is derived. This evolution, binded to a generalized transgressive trend, is interrupted by the establishment in the uppermost Lower Cambrian of the Planolites montanus ichnoassociation. This one is interpreted as a product of the environmental and ecological crisis caused by the Valdemiedes geoevent.
Nuevo yacimiento de vertebrados del Mioceno Superior al Sur de Madrid (Cerro Batallones, Torrejón de Velasco)
(Sociedad Geológica de España, 1992) Morales, J.; Capitán, J.; Calvo, J. Pedro; Sesé, C.
We are presenting the finding of a new site of vertebrate fossils in C° Batallones (Torrejdn de Velasco), which is situated in the southern area of the Madrid basin. The site lies in facies which correspond to the top of the Miocene Intermediate Unit than now can be dated as Upper Vallesian, estimated age of the accompanying faunal assemblage. The accumulation of fossil bones is notable for the grand diversity and overwhelm ing predominance of carnivors (more than 98% of the remains), which suggests the existence of a natural trap responsible for the unusual ossiferous accumulation
Nuevos datos sobre el neogeno continental en el sector noreste de la cuenca de Granada, Cordillera Bética
(Sociedad Geológica de España, 1992) Ruiz Bustos, A.; Martín Martín, Manuel; Martín Algarra, Agustín
Three new microvertebrate sites in the Granada basin, are studied. These sites allow to precise the biostratigraphy and paleoecoiogy o f the continental deposits (lacustrine marls a nd claystones) in the area
Nota preliminar sobre la presencia de sudoita en las metapelitas de la unidad de Trevenque, Alpujárrides centrales
(Sociedad Geológica de España, 1992) Azañón, José Miguel
Sudoite (MgAl)(Ai2)(SijA 1)0l0(OH)a has been found in the metapelltic formation of the Trevenque Unit. This mineral appears as a secondary phase produced by transformation of HP-LT characteristic minerals. Sudoite grows during the subsequent decompression stage. The P-T path after the metamorphic peak in the Trevenque Unit is constrained by the proposed limiting reactions of the sudoite stability field
New data on the Spherules from the Cretaceous-Tertiary Boundary Layer at Caravaca (SE Spain)
(Sociedad Geológica de España, 1992) Martínez Ruiz, Francisca; Acquafredda, P.; Ortega Huertas, M.; Palomo, I.
Las esférulas de la lámina de sedimento que marca el tránsito K/T en Caravaca están compuestas de Kfs prácticamente puro (S il 0 } O eA l 1i02K0 93 N a 0Xt1) con texturas fibroradiales y dendriticas. Inicialmente fueron interpretadas como derivadas directamente de un supuesto cuerpo extraterrestre (Smit y Klaver, 1981). Por el contrario, Montanari (1983) considera que el Kfs ha reemplazado diagenèticamente a un mineral precursor. En este trabajo se presentan los primeros datos de análisis realizados en algunos núcleos de las esférulas de Kfs, que constituyen el precursor de las mismas y que responden a una composición de tipo m áfico: ( S ¡ 0 2 = 5 6 % ; A I2O j - 1 0 % ; M g O - 8 .5 % ; Fe O = 13% ; C aO = 3% ; Na20 = 2 % ; K20 = 0.9% ). Su estado actual de preservación nos permite sugerir que el mineral precursor es un anfibol derivado de la alteración de un piroxeno
Neotectónica y morfología en la región de Muñico (Avila)
(Sociedad Geológica de España, 1992) García Blanco, C.; García Palacios, A.; Hernando Laosa, L. A.; Gallego Abellán, J; Temiño Gordo, I.
The studied area shows morphological characteristics reflecting the local tectonics and the Alpine fracturation patterns, which might be related to the reactivation of previous tardihercinian trends. The deformation affect both the basement and the teitiary cover resulting in "Cuesta "-type landscapes, whose analysis allows us to establish the age of the movements corresponding to the last Alpine tectonic pulses
Morfología y Zonación de los Granates en el plutón granítico de Ponferrada (España)
(Sociedad Geológica de España, 1992) Santo, G del; Corretgé Castañón, Luis Guillermo; Suárez Hernando, Oier
Carnet occurs as an accesory phase mainly in the aplitlc facies of the Ponferrada Pluton (BoatLos Ancares Belt) (LeDuc, 1970; Su&rez, 1970). Three different types of garnet have been recognized on the basis of their morphology and textural relationships. Electron micropobe analyses reveal several zonation patterns mainly defined by the variation of Mn and Fe contents. The study of chemical zonation in garnet also proved to be useful in timing the growth of garnet with respect to quartz
Metodología de investigación geotècnica de la inestabilidad de Ladera de Boó (Asturias)
(Sociedad Geológica de España, 1992) Miguel Laguna Megal, L.; Mulas de la Peña, J.
Here is commented the research countryside applied in the geothecnical study of a slope unstability in Boo, a little village In Asturias. The quick progresión of such unstabilityand the high doubts in the geological model at the beggim ing, forced to carry out a dynamic research
Materia orgánica en la Fm. Arenas de Utrillas de Picofrentes (provincia de Soria): diagénesis mineral y orgánica
(Sociedad Geológica de España, 1992) Marfil Pérez, Rafaela; Callaba, A.; Gómez Gras, David
By Rock-Eval pyrolysis method, fluorescence, microscopy and S.E.M. with E.D.A.X. analysis, the organic matter rich horizonts at the top of Utrillas Fm. in Picofrentes log were studied. Ail samples are potencially good source rocks for hydrocarbons and they show type I (lacustrine o.m.), being located in the inmature zone close to the oil window boundary. The reaction between the organic acids liberated in the o.m. decarboxylation process, in the intercalated lutites, leads to the diagenetic alteration of K-feldspar to kaolinite and gibbsite and the enhancement of the porosity in the arkosic sandstones
Magnetoestratigrafía del Triásico medio de la Cadena Costero Catalana. Resultados iniciales
(Sociedad Geológica de España, 1992) Parés, J. M.; Garcés Crespo, Miguel; Pascual, J. O.
A magnetostratigraphic reconnaissance of the Middle Muschelkalk red beds from the Catalan Coastal Range is presented. The selected section is composed by red mudstones and sandstones 25 mt thick. Although the sedimentay section is not continuously exposed, it is apparently complete and records a lithologic sequence that provides a basis for detailed stratigraphic correlation and temporal calibration as well. It is emphasized the role of the paleomagnetism as a time-line tracer in the correlation between the three defined units (Buntsandstein, Muschelkalk and Keuper) and the stages that constitute the chronostratigraphic subdivision o f the Triassic period
Litologías manganesíferas del área central de Ossa-Morena (SW de Badajoz)
(Sociedad Geológica de España, 1992) Jiménez Millán, Juan; Ruiz de Almodóvar Sel, Gabriel; Velilla, N.
Mangenese lithologies from Oliva de la Frontera area occur in the Cumbres-Hinojales unit (Ossa-Morena South-Central Belt) within a Lower Ordovician age volcanosedimentary sequence. Petrographic study allows to differentiate six Mn-Fe lithologies: Mn-crystal tuffs, Mn-shales, cotfcules, Mn-pyroxenoid rich rocks, braunite layers and hematite layers. Al/(Al+Fe-f-Mn) and Na/(Na+K) discriminating ratios support the above classification. Geologic, mineral, textural and geochemical data provide dues about the mixture process among volcanic, terrigene and chemical materials that originated the protolliths o f the metamorphic manganese lithologies

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