Geogaceta -- Nº 45, (2008)

Permanent URI for this collectionhttps://hdl.handle.net/10272/8139

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Distribución de Mg en conchas de Crassostrea gigas : control microestructural y correlaciones cristaloquímicas
(Universidad de Huelva, 2008) Ibisate, Ruth; Pizarro, José Luis
The realization of geochemical studies on the right valve of Crassostrea gigas's shells has allowed demonstrating a microestructural control on the concentration of Mg. The transects studied in this work show that the ratio Mg/Ca is higher in the Prismatic (SP) and Chalk microstructures than in the Regular Foliated (RF) one. Fhe faster precipitation of SP and Chalk could be the reason for the behaviour of the Mg. Fhe unit cell parameters of the principal microstructures in a C. gigas valve have been determined, looking for good correlation between the content of Mg (ppm) and the volume of the unit cell. Fhe presence of Mg2+ (ionic radius=0.65 A) instead ofCa2+ (ionic radius=0.99 A), generate an important lattice distortion along the c-axis, allowing the presence ofanother cations, such as Na+(ionic radius=0.96 A).
Zonación estructural en una zona de cizalla en serpentinitas (Falla de Peña Parda, peridotitas de Ronda)
(2008) Esteban, José Julián; Cuevas, Julia; Tubía, José María
We study deformation structures in a serpentinite-bearing normal shear zone in the Ronda peridotites, southern Spain. The fault zone displays a structural zoning composed by four domains showing similar strain gradients. Deformation is partitioned into distributed deformation expressed by foliated serpentinites and S-C structures and localized deformation expressed by R and P shear planes at lower and upper portions, respectively, of each domain. Such a structural zoning suggests that stable shear creep alternates with intermittent seismogenic events during the fault activity
Travertinos ligados a fallas: ejemplos del desierto de Tabernas (Almería, Cordillera Bética)
(2008) Sanz de Galdeano, Carlos; Galindo Zaldívar, Jesús; Morales, Salvador; López Chicano, Manuel; Azañón, José Miguel; Martín Rosales, Wenceslao
In the Tabernas desert there are several sectors with Quaternary travertines not formed in the proximities of carbonatic rocks, but originated by the rise of deep mineralized water along faults. These travertines have Fe mineralization in its older levels. The mineralization present similitude with that formed in the region during the late Miocene, then connected with the volcanism
The Mendiurkullu Member of the Lareo Formation: a deltaestuarine progradational system from the Etxegarate trough (Early Aptian western Aralar Mountains)
(2008) Millán, María Isabel; Fernández Mendiola, Pedro Ángel; García Mondéjar, Joaquín
Se describe e interpreta el miembro areniscoso y lutítico de Mendiurkullu dentro de la Formación Lareo, en el oeste del macizo montañoso Vasco-Cantábrico de Aralar (Navarra). Contiene arcillas, limolitas y areniscas finas con 13 metros de potencia total. Su edad es Aptiense inferior, parte superior. De muro a techo se reconocen: 1) arcillas con nódulos ferruginosos infrayacentes, 2) limolitas con capas de arenisca fina de base plana y ripples a techo, 3) areniscas de grano fino con estratificación horizontal y cruzada de surco, y 4) areniscas masivas de grano fino-medio rellenando canales. La secuencia vertical estrato y grano creciente se relaciona con la progradación de un sistema deltaico-estuarino, que rellenó el surco de Etxegarate con aportes terrígenos de procedencia meridional
Tectónica de inversión en la Playa de Sopelana (Arco Vasco, Pirineos occidentales)
(2008) Rodríguez, Lidia; Esteban, José Julián; Vegas, Néstor; Cuevas, Julia
This work analyzes the structural features of the Sopelana Fault, developed in extensional conditions during Cretaceous and Tertiary times, and inverted during the Alpine orogeny. The study area is located on the NE limb of the Biscay Synclinorium, a major structure in the Basque Arc. The Sopelana Fault bounds the northern outcrops of the Cenozoic materials in the Biscay Synclinorium. The structural analysis indicates that the inversion process related to the Alpine shortening generates folds verging towards the North and reverse faults, sometimes with a minor strike-slip component of movement. Kinematic criteria along the Sopelana Fault indicate a top to the NE shear sense, consistent with the regional compression direction, approximately NE-SW in the western area of the Basque Arc. The normal component of the Sopelana Fault was not fully recovered after the tectonic inversion that preserves younger materials of Upper Cretaceous and Tertiary times in the hanging-wall block, marked by evaporitic rocks
Resto mandibular de ornitópodo iguanodontoideo (Dinosauria) del Cretácico Inferior de Salas de los Infantes (Burgos) en las colecciones del Institut für Geowissenschaften de Tubinga (Alemania)
(2008) Ruiz Omeñaca, José Ignacio; Pereda Suberbiola, Xabier; Torcida Fernández Baldor, Fidel; Maisch, Michael; Izquierdo, Luis Ángel; Huerta, Pedro; Contreras, Rubén; Montero Huerta, Diego; Pérez Martínez, Gustavo; Urién Montero, Víctor; Welle, Jochen
A dentary fragment that preserves several teeth in situ of an ornithopod dinosaur from the Lower Cretaceous of Salas de los Infantes (Burgos, Spain) is described. The general aspect and the conservation of the rock associated with the fossil suggest that it would come from the Pinilla de los Moros Formation (upper Hauterivian-lower Barremian). The material takes part, together with other fossils of dinosaurs and crocodilians, of a collection gathered at the end of the 1960’s and deposited nowadays in the Institut für Geowissenschaften of the University of Tübingen (Germany). The dentary teeth exhibit a distal primary ridge and a mesial secondary ridge, as typically in basal iguanodontoids. Nevertheless, some teeth show a single subcentral carina and lack subsidiary ridges, as in hadrosaurids. Unlike hadrosaurids, however, the Salas specimen has probably one functional tooth and one replacement crown per dentary tooth position, retaining the plesiomorphic state present in basal iguanodontoids. Due to the fragmentary nature of the material, it is provisionally assigned to Iguanodontoidea indet
Reconstrucción de la posición del frente ártico a partir de las asociaciones de foraminíferos planctónicos durante los estadios isotópicos marinos 14, 15 y 16
(2008) Alonso García, Montserrat; Sierro, Francisco Javier; Flores, José Abel
Planktic foraminifer assemblages and lithic components from IODP core U1314 (northern North Atlantic) were studied with high resolution from marine isotope stage (MIS) 14 to 16 (~ 530-700 ka). This study aims to contribute to a better understanding of the mid-Pleistocene climate shifts. The record shows the evolution of the Arctic front and allows us to infer the relative position of the sea-ice edge. During MIS 16 Arctic front was south of the core location, while during MIS 14 the front was placed northward but near the core location, therefore stage 16 was colder than 14. Besides, during the interglacial stage 15, two brief cold substages were recorded showing that the Arctic front crossed again the core location area
Quantitative tools for environmental reconstructions of the recent estuarine infill using benthic foraminifera
(2008) Cearreta, Alejandro; Leorri, Eduardo; Iriondo, Iratxe; González, María José; Aristondo, Oihana
Con la idea de evaluar la respuesta cuantitativa de los foraminíferos con respecto a la distancia relativa a la boca del estuario (RDEM) en los sistemas estuarinos del sur del Golfo de Vizcaya, se ha desarrollado una función de transferencia basada en un matriz de datos compuesta por 88 muestras y 41 especies obtenidas en seis estuarios del norte de España. La RDEM ha sido considerada como un indicador del gradiente de salinidad. La relación entre los resultados obtenidos e inferidos indica el óptimo funcionamiento de la función de transferencia (r2 jack = 0.76) y permiten llevar a cabo reconstrucciones precisas de la evolución reciente de la RDEM a partir del análisis del registro sedimentario
Prospecciones paleoicnológicas en el sinclinal de Iouaridène (Alto Atlas, Marruecos). Cuantificación de yacimientos y de icnitas
(2008) Boutakiout, Mohamed; Hadri, Majid; Nouri, Jaouad; Díaz Martínez, Ignacio; Pérez Lorente, Félix
The Iouaridène syncline is a is famous palaeontological site among the ichnologists for several reasons: i) the time of the site is known - the first footprint paper were published in 1937; ii) the discovery of the sauropod trackway Breviparopus, Dutuit and Ouazzou, 1980 used as narrow gauge morphotipe by Farlow (1992); iii) the succesive discussions about the age of the “red beds” where the ichnites were found, and in consequence, the variations in the footprint age attributions; and iv) the discussion about the swimmer dinosaurs in manus-only sauropod trackways. The exploration on the area and the bibliographical review have allowed to verify many of the former suppositions and to adjust the age of the mentioned sauropod trackway, fact of great importancy in the dinosaur palaeoichnology
Perfiles de Mg, Sr y Na en conchas de Crassostrea gigas recogidas en puertos deportivos del oeste de la costa de Bizkaia: Control estacional y ontogenético
(2008) Ibisate, Ruth; Elorza, Javier
The geochemistry of the umbo of the right valve of Crassostrea gigas from three Biscay coast sites (Getxo, Plentzia and Zierbena) has been analyzed to determinate a seasonal and ontogenetic control on the distribution of the molar ratios Mg/Ca, Sr/Ca and Na/Ca (mmol/mol). The ratio Mg/Ca shows a good correlation with the marine water temperature, defining a sinusoidal profile correlated with dark zones (produced in warm periods) and bright zones (produced in cool periods). The molar ratio Sr/Ca can be correlated with the water temperature but other factors, like ontogenetic or replacements in the unit cell, have to be considerate. The ratio Na/Ca shows a descendent behaviour from the younger stage to the older one, confirming an ontogenetic control
Nuevos restos de ornitópodo (Ornithischia: Ankylopollexia) del Jurásico Superior de Tazones, Asturias (Formación Tereñes)
(2008) Ruiz Omeñaca, José Ignacio; Piñuela, Laura; García Ramos, José Carlos
Two dorsal vertebral centra of an ornithopod dinosaur from the Late Jurassic of the Principality of Asturias (north Spain) are described. They come from an outcrop of the Tereñes Formation (Kimmeridgian) at Tazones harbour (Villaviciosa). They are identified as a juvenile indeterminate ankylopollexian. The vertebrae are the first dinosaur bony remains found to date in the Tereñes Formation, where dinosaur footprints are, on the other hand, very abundant. We estimate that the owner of the vertebrae was 4.6-5 meters in total length. When adult, the Tazones ankylopollexian were capable of make the big ornithopod footprints recovered in the Kimmeridgian-Tithonian of both Asturias and Portugal, made by individuals up to 2.8 m in hip height (~7.8 m of total length)
Morfoestratigrafía y cronología de registros fluviales del Pleistoceno superior en Bardenas Reales de Navarra: implicaciones paleoambientales
(2008) Sancho, Carlos; Muñoz Jiménez, Arsenio; Rhodes, Edward; McDonald, Eric; Peña, José Luis; Benito, Gerardo; Longares, Luis Alberto
Quaternary gravel deposits covering the bottom of the Bardena Blanca depression (Central Ebro Basin, Navarra) have been studied. Three Late Pleistocene units (Qt1, Qt2 and Qt3) of gravel accumulation have been differentiated using geomorphologic mapping, sedimentological analysis and optically stimulated luminescence techniques. Chronological data show ages of 92, 52 and 15-21 ka respectively, which are closely related to cold climate signals at regional scale. Aggradation in braided channel systems was mainly controlled by increases in runoff and sediment supply
Lucien Cayeux (1864-1944): un ilustre precursor en la enseñanza de la Petrología Sedimentaria
(2008) García Garmilla, Francisco; Aranburu Artano, Arantza
Lucien Cayeux (1864-1944) was a crucial scientific figure in France during a particularly hard time in Europe owing to the two World Wars and the social and economic crisis. His ideas about the relevance of sediments and sedimentary rocks with regard to both scientific and economic aspects led to him to recover that the study of ancient sediments would be as much important as that of igneous and metamorphic rocks, which have been the geology stars by that time. His technical contributions were shaped into three great marvelously-illustrated monographies devoted to both siliceous, carbonate and ferruginous rocks. In addition, his main pedagogical output was the valuable atlas for petrographic studies of sedimentary rocks, which has been the essential reference for all the further didactic texts and atlas on Sedimentary Petrology
La fauna de vertebrados del yacimiento Holoceno (Aziliense) de Aizkoltxo (Mendaro, Gipuzkoa)
(2008) Murelaga, Xabier; Mujika Alustiza, José Antonio; Bailon, Salvador; Castaños, Pedro; Sáez de Lafuente, Xabier
During the excavation of the Azilian levels from the site of Aizkoltzo in 2003 several vertebrate remains were found. Mammal species are represented in the site by, five rodents, two insectivores, five artiodactyls and three carnivores, the reptilians by one saurian and three ophidian and the amphibians by one anuran. The vertebrate assemblage indicates a humid temperate climate quite similar to that occurring in the area at present day. The macromammals assemblage of Felis silvestris, Meles meles, Sus scrofa and Capreolus capreolus is usual in the Postglacial of the Cantabrian Basin
Influencia de la batimetría y tipo de sedimento en la distribución de la microfauna (foraminíferos bentónicos y ostrácodos) en la plataforma marina vasca
(2008) Pascual, Ana; Martín Rubio, Maite; Martínez García, Blanca; Rodríguez Lázaro, Julio
In this work we describe the microfaunal bathymetrical distribution (foraminifers and ostracods) in the benthos of the Basque continental shelf, by studying the spatial distribution of assemblages. This distribution is controlled by environmental parameters related to depth and type-sediment. A total of 114 species of benthic foraminifers and 88 species of ostracods have been taxonomically identified. Most abundant benthic foraminifer species are Lobatula lobatula, Cibicides refulgens, Gaudryina rudis, Textularia sagittula, Cassidulina laevigata and Globocassidulina subglobosa. Most abundant ostracod species are Carinocythereis carinata, Costa edwardsii, Cytheropteron nodosum, Pterygocythereis ceratoptera and Pterygocythereis jonesii. Foraminifer and ostracod assemblages are distributed accordingly with bathymetry defining three fringes: littoral-inner shelf (<70 m), middle shelf (70-130 m) and outer shelf (>130 m). Inside these bathymetric fringes the sediment-type is the main factor of control for the relative abundance of the species, in particular the percentage of fine-grained (silt-clay) particles in the sediment. The occurrence of estuarine species in areas of the Basque shelf evidences the pattern of currents responsible of the sedimentary dynamics in this shelf
Geocronología de la sucesión arqueoestratigráfica de Los Estragales en la Terraza Compleja de Butarque (Valle del río Manzanares, Madrid)
(2008) Pérez González, Alfredo; Rubio Jara, Susana; Panera, Joaquín; Uribelarrea, David
In the low valley of Manzanares river, south of Madrid, is located the Butarque Complex Terrace formed by piling up of alluvial deposits of the Upper Pleistocene. In Perales del Río they have been excavated and picked up industries of the Middle Palaeolithic mainly in flint, in the sites of Los Estragales 1, 2 and 3, dated by TL and OSL between the Eemien (5e) and MIS 4. The terraces overlapped with the Butarque Complex Terrace, at +11-12 m, +8m and La Gavia II, they have been deposited during the Heinrich events H4, H2 and H1, of agreement with the luminiscence datings
Factores que controlan la relación Sr/Ca en foraminíferos planctónicos y su repercusión en las reconstrucciones de paleotemperaturas basadas en corales
(2008) González Mora, Beatriz; Pérez Martín, Rubén
Samples from core ODP site 977, retrieved in the Alboran Sea (Western Mediterranean Sea), have been studied in order to better constrain the factors controlling the Sr/Ca ratio in planktonic foraminifers. For this purpose, this ratio has been measured in two different species, Neogloboquadrina pachyderma (right coiling) and Globigerina bulloides, in samples from the marine isotope stage 7 (250-190 kyr). The fast and pronounced fluctuations in shell Sr/Ca observed between substages cannot only respond to water salinity, pH nor temperature changes. However, the results obtained suggest that shell Sr/Ca variations in planktonic foraminifers from the Alboran Sea are also related to Sr/Ca glacial/interglacial changes in the ocean. This would mean that the paleotemperature reconstructions based on corals, might be revised since coral Sr paleothermometry would have underestimated sea surface temperature during glacial episodes
Fábricas sin-metamórficas, mecanismos y régimen de la deformación en las granulitas de alta presión de Cabo Ortegal (NO de España)
(2008) Puelles, Pablo; Ábalos, Benito
High-pressure granulitic tectonites from shear zones at the contacts between the Bacariza Formation and its bounding units developed after eo-Hercynian subduction, during the initial exhumation of the Cabo Ortegal complex. Structural, petrographic, and crystallographic analysis of these tectonites with the EBSD technique enables us to unravel different, syn-metamorphic, deformation mechanisms in the minerals of the high-pressure granulitic assemblage. Dislocation creep and recovery were the main deformation mechanisms in garnet during peak metamorphism, followed by porphyroclast rigid rotation. The matrix minerals accommodated subsequent ductile deformation, still under high-pressure. Mass transfer, anisotropic growth and dislocation creep dominated deformation of augite. Subgrain rotation-recrystallisation by climbaccommodated dislocation creep operated in plagioclase and dislocation creep by <a>prism-slip in quartz. Subsequent, static amphibolite-facies retrogradation was followed by decompression-related microfracturing during exhumation through medium- to upper crustal realms. Ductile rock deformation was non-coaxial and accommodated a top-to-the-NE displacement of hangingwall blocks
Evolución térmica de distintas masas de agua a lo largo del estadio isotópico marino 7 basada en el Mg/Ca de la concha de los foraminíferos planctónicos
(2008) González Mora, Beatriz; Sierro, Francisco Javier
Mg/Ca measurements have been performed on tests from the planktonic foraminifers Globigerinoides ruber (white) and Globigerina bulloides in samples from ODP site 977A in the Alboran Sea (Western Mediterranean) in order to estimate their calcification temperatures between 250 and 190 ka and therefore, analyse the evolution of different water masses in the Alboran Sea during that time. The results obtained are similar to the sea surface temperatures estimated by other methods in previous studies carried out in the same core. All substages in marine isotope stage 7 are well defined in the paleotemperature estimates, excepting substage 7.2 which is not recognized in Globigerina bulloides. Warm substages were characterized by strong seasonality and thermal stratification of the water column. By contrast, less pronounced seasonality and basin stratification seem to have prevailed during cold substages
Estructura del complejo alcalino de Rangel (Salta, Argentina)
(2008) Vegas, Néstor; Hongn, Fernando Daniel; Tubía, José María; Menegatti, Nilda
This work deals with the structure and emplacement of the alkaline complex of the Sierra de Rangel, a Cretaceous stock intruding in Ordovician metamorphic rocks of the Puna region at Salta, northwest Argentina. Field structures and magnetic fabrics reveal a complex structure composed by multiple sheets and feeding chanels. Both, the ascent and the lateral spreading of magma exploited old fractures in the country rocks

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