Geogaceta -- Nº 46, (2009)

Permanent URI for this collectionhttps://hdl.handle.net/10272/7954

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Caracterización geoquímica y encuadre geodinámico de las anfibolitas y eclogitas del manto de Ojén, Complejo Alpujárride, Cordilleras Béticas
(Sociedad Geológica de España, 2009) Esteban, José Julián; Cuevas, Julia; Tubía, José María
Amphibolite bodies with eclogite relics are found interlayered between the Ojen nappe´s crustal rocks, below the Ronda peridotites of the Betic Cordilleras (southern Spain). We present a geochemical study of such amphibolites and retrogressed eclogites, from which it is possible to deduce a gabbroic origin for their protoliths. We propose that their intrusion in the continental crust took place in a rift setting of Jurassic to Lower Cretaceous age. The recognition of this rifting event in the Alpujarride Complex places an additional constraint for Mesozoic reconstructions of the Western Mediterranean
Reseña preliminar sobre el hallazgo de diáspora asociada a la serpentinización de los macizos de peridotitas de Ronda
(2009) Esteban, José Julián; Cuevas, Julia; Tubía, José María; Vegas, Néstor; Yusta, Iñaki
We report the presence of large aggregates (diameter > 1 cm) of diaspore related to the serpentinization of the Sierra Alpujata massif of the Ronda peridotites (Betic Cordilleras, southern Spain). The diaspore is found in two different but related settings: in narrow metasomatic rims pervading the peridotites from steeply dipping tension joints and in the blackwall zone developed along the normal fault that separates the peridotites from the overlying metamorphic cover. The systematic association of diaspore with chlorite points to very low temperature conditions (T < 100 ºC) for diaspore formation
Registro geológico del máximo térmico del Paleoceno-Eoceno en el Parque Nacional de Ordesa y Monte Perdido (Pirineo Central)
(2009) Robador, Alejandro; Pujalte, Victoriano; Samsó, Josep Maria; Payros, Aitor
The Paleocene-Eocene thermal maximun (PETM) had earlier been documented in basinal and continental settings of the Pyrenean basin clastic units. In this work new data are added from comparatively less well-known platform interior successions outcropping at the Ordesa and Monte Perdido National Park. There, the PETM is recorded by comparatively thin (10-30 m) but laterally extensive accumulations of siliciclastic deposits that are thought to represent an ancient wave- and storm-dominated delta system. Further, the landward pinch-out of the delta suggests that the PETM occurred during an interval of relatively low sea level. Together with other siliciclastic units of the Pyrenean domain, the new data confirms the intensification of the hydrological cycle during the PETM
Redescubrimiento de uno de los primeros restos de dinosaurio del registro español
(2009) Pérez García, Adán; Ortega, Francisco
The information of one of the dinosaur fossils collected by Juan Vilanova y Piera at the end of the XIX century in Mora de Rubielos is updated. MNCN 80000 is an pedal phalanx of an Iguanodontoidea dinosaur found between 1873 and 1893, recently rediscovered at the MNCN of Madrid
Reconstrucción de las condiciones paleoambientales del depósito Pñ (Macizo de Peñalara, Sierra de Guadarrama. Madrid), durante los últimos 2.000 años, a partir del contenido en microfósiles no polínicos (NPPs)
(2009) Ruiz Zapata, Blanca; Gómez González, Clemencia; Gil García, María José; López Sáez, J. Antonio; Santisteban, Juan Ignacio; Mediavilla López, Rosa; Domínguez, Fernando; Vera, María Soledad
The content in non-pollen palynomorphs (NPPs), constitutes an important tool at the time of reconstructing the paleoenviromental changes of a deposit and explaining them in terms of climate and/or anthropic activity. This work show NPPs data from the peat deposit Pñ appear, of periglacial origin, located in the bulk of Peñalara, (Mountain range of Guadarrama, Madrid). 14C data, locate the formation of this deposit in 1.600±40 BP. During this period, the palinological data show a regional landscape formed by forests of Pinus sylvestris, Pinus pinaster and Quercus, as well as presences of Betula, whereas on local scale anthropozoogenic bivouacs are developed to pastures (Poaceae and Plantago lanceolata). The presence of the higrophic pastures (Cyperaceae) is constant throughout all the profile, like the NPPs, of similar ecological affinity and whose variations have been very useful at the time of establishing the humidity fluctuations. Other NPPs has served to demonstrate: the major or minor pastoral pressure, and the variations in the trophic conditions of the peat bog. The changes observed in the vegetation and the uses of the ground, are also stated through the information provided by the values of the pH and the conductivity of the sediment
Reconstrucción paleoclimática del centro de la Península Ibérica durante los últimos 50 ka cal. BP, a partir de los datos físicos y geoquímicos del registro lacustre del mar de Fuentillejo (Campo de Calatrava, Ciudad Real)
(2009) Galán, Luis; Vegas, Juana; García Cortés, Ángel
Physical (magnetic susceptibility and gamma density measurements) and geochemical (TOC, Fe and Ti analysis) analysis were performed to characterize the sedimentary record in Fuentillejo maar-lake (Campo de Calatrava Volcanic Field) in order to reconstruct the paleoenvironmental evolution, which controlled deposition of different sedimentary facies. The upper 20 m of FU-1 sequence point out variations in clastic input, water chemistry and organic fraction in the lake throughout the last 50 kyr cal. BP. Magnetic susceptibility are roughly influenced by diagenetic changes in organic rich sediments
Prospección hidrogeológica en zonas áridas de baja permeabilidad (Tifariti, Sahara Occidental) con el método EM de inducción
(2009) Olaiz Campos, Antonio; Muñoz Martín, Alfonso; Villarroya Gil, Fermín; Lorenzo, Javier de; Castanedo, Cristina; Padín, Antón
The aim of this study is to evaluate electromagnetic induction methods to analyze low permeability rocks in desert areas, as a tool for groundwater surveying. We have focused the field work in large faults zones, previously mapped by satellite images and digital elevation models. This is because in low-permeability rocks (i.e. granites) the groundwater flow is mainly controlled by these discontinuities. The objective is to map the high conductivity zones and their geometry in depth. Obtained results allow us to identify well defined fractures with low apparent resistivities that are the most suitable areas to locate groundwater extractions
Presencia de cenizas y lapilli esferoidales con estructura interna concéntrica (i.e. pelletal lapilli o spinning droplets) en la tefra del volcán Cabezo Segura (Región Volcánica de Calatrava, Ciudad Real)
(2009) Carracedo Sánchez, Manuel; Sarrionandia Eguidazu, Fernando; Gil Ibarguchi, José Ignacio; Arostegui García, Javier
The Cabezo Segura volcano is located in the central part of the Calatrava Volcanic Province. Some deposits of this volcano are formed by singular spherical lapilli and bombs. These lapilli and bombs are the result of welding of ash and fine-grained lapilli droplets (< 4mm) of olivine melilitite composition, spherical morphology and a cored and concentric inner structure. This pattern is similar to that of pelletal lapilli and spinning droplets which appear commonly in kimberlitic, kamafugitic, and carbonatitic pipes. The origin of these peculiar pyroclasts could be related to the fragmentation of a low viscosity magma through magmatic volatile exsolution and the subsequent rotation of magma droplets during ascent within a fluidized system
Partición de la deformación cenozoica intraplaca en el Sistema Central
(2009) Vicente, Gerardo de
A new model for Cenozoic strain partitioning is proposed here for the Central System at the Messejana (Plasencia) fault zone. It explains the simultaneous movement of parallel NE-SW trending thrust and strikeslip faults within a global N-S compression. This process could account for local bends in the shmax trajectories, from NW-SE trending close to the Ponsul-Gata and Gredos thrusts to NE-SW trending along the Messejana left-lateral strike-slip fault. This structural pattern may change current thinking with regard to the paleostress evolution of the Iberia foreland during the Cenozoic
Mineralogía y génesis de gemas de corales silicificados de Sumatra
(2009) Sánchez Muñoz, Luis; Bustillo Revuelta, María Ángeles; García Guinea, Javier; Crespo Feo, Elena; Tormo, Laura
Mineral characteristics of silicified corals from Barisan Mountains (Miocene) of the Western Sumatra (Indonesia) have been studied by optical microscopy, Raman spectroscopy (spectral curves and hyperspectral images) and scanning electron microscopy with energy dispersive microanalyses. Three different parts were recognized in the silicified coral, as follows: (i) the external shell, the radial septae and inner circular walls and the core central part build with opal with some disperse carbon-rich black grains, showing the G and D Raman bands from residual organic matter; (ii) the inner caverns stuffed with mega-quartz crystals of high crystallinity; (iii) chalcedony fibres occurring among both former zones, including moganite mineral as identified by its 502 cm-1 Raman band. During the subsequent processes of burial and diagenesis the delicate organic structure of corals is substituted and consolidated by silica coming from the alteration of ash-flow and interstratified volcanic rocks. In addition, the presence of AgS and Zn-Cu minerals into the coral fissures suggest later hydrothermal processes probably associated with the regional volcanic activity
La sección de San Miguel de Salinas (Cuenca del Bajo Segura). Significado paleoambiental de las asociaciones de foraminíferos en relación con la Crisis de Salinidad del Messiniense
(2009) Corbí, Hugo; Caracuel, Jesús Esteban; Dinarès Turell, Jaume; Lancis, Carlos; Pina, José Antonio; Soria, Jesús M.; Tent Manclús, José Enrique; Yébenes, Alfonso
In the composite section of San Miguel de Salinas the following synthems are represented: MI (preevaporitic Messinan), MII (syn-evaporitic Messinian) and P (post-evaporitic Pliocene). The foraminiferal assemblages of these synthems have been studied in order to reveal the palaeoenvironmental changes related to the Mediterranean Salinity Crisis. The change between MI and MII synthems is characterized by the reduction of the foraminiferal biodiversity. Synthem MII records palaeoenvironmental stress related to the evaporitic deposition during the Salinity Crisis. Synthem P marks an abrupt increase of the foraminiferal biodiversity in coincidence with the Pliocene reflooding of the Mediterranean Sea
La fábrica de las rocas miloníticas de la Zona de Cizalla de Los Llanos (Calzadilla de los Barros, Badajoz)
(2009) Jiménez Díaz, Alberto; Capote, Ramón; Tejero López, Rosa; Lunar Hernández, Rosario; Ortega, Lorena; Monterrubio, Serafín; Maldonado, Casimiro; Rodríguez, David
The Los Llanos Shear Zone bounds the Cabeza Gorda and Zafra units located in the Ossa-Morena Zone (SW Iberian Massif). Within the Cabeza Gorda unit two peridotitic massifs crop out, named Sierra Cabeza Gorda and Cerro Cabrera. The mylonitic rocks consist of metamorphic and peridotitic rocks extensively deformed that exhibit a penetrative foliation. Mylonitic fabrics are characterized by s and d structures and S-C and S-C’ band. Some examples show a crenulation cleavage that points out the existence of at least two deformation stages. Kinematic criteria are widespread, but dextral-reverse movement prevails both in outcrop and thin section. Los Llanos Shear Zone orientation is NW-SE, similar to variscan structures trend in the area, and deforms precambrian and paleozoic rocks. Los Llanos Shear Zone represents a dextral-reverse structure of Variscan age
La evolución Holocena de la Albufera de Valencia
(2009) Santisteban, Carlos de; Marco Barba, Javier; Miracle, María R.
The “Albufera de Valencia” is one of the lagoons of bigger extension in the Iberian Peninsula. It is placed in a sedimentary basin that embraces part of the coastal plain of Valencia province and that expands several kilometers on the continental platform. This lagoon is a shallow paralic lake protected by a beach-barrier. The sedimentary and paleontological record of two cores (Palmar and Pujol), located in the internal part of the beach-barrier, has been studied. This sedimentary record is formed by Holocene sediments, discordantly on Pleistocene materials. The lower Holocene deposits show the existence of a coastal lagoon whose barrier was located eastwards to the present coast line. The modern beach complex extends after the maximum transgressive ca. 6250 years and it is composed by four units of prograding beaches formed during the recent high sea-level stand. The last beach unit might have been formed just after the year 1200 (AD) and has had a quick growth during the last 500 years
Intertidal foraminifera in the Mira estuary, SW Portugal, and their use as sea-level proxies
(2009) Leorri, Eduardo; Fatela, Francisco; Moreno, João; Antunes, Carlos; Cearreta, Alejandro; Freitas, Maria Conceição; Andrade, César
Para evaluar la respuesta cuantitativa de los foraminíferos con en relación con los niveles maréales del estuario de Mira, se han desarrollado una serie de funciones de transferencia basadas en un matriz de datos compuesta por 29 muestras y 95 especies obtenidas en tres transeptos. La relación entre los resultados obtenidos e inferidos indica el óptimo funcionamiento de las funciones de transferencia (r2 jack = 0.87), lo cual implica que reconstrucciones de gran precisión (error: ± 12 cm) de los cambios recientes en el nivel marino son posibles. Por otro lado, es importante estudiar el posible efecto de la relación no lineal entre las mareas y la elevación de las muestras en los errores de reconstrucción
Influencia de la petrografía en las propiedades petrofísicas y de durabilidad del Travertino Clásico. Valoración de su anisotropía
(2009) Benavente, David; Medina Lapeña, Francisco Javier; Martínez Martínez, Javier; Cueto, Nora; García del Cura, María Angeles
The influence of facies on the petrophysical properties and durability of the Classic Travertine is studied. This travertine is a light travertine quarried in Turkey, which is widely used in Spain as building stone and is extremely similar to the Travertino Romano Classico. Its physical properties (pore structure and hygric, thermal, acoustic and mechanical properties) and its resistance to durability tests (freeze-thaw and salt crystallization action) corroborate the good performance of this travertine as a dimensional stone. Its structure and fenestral porosity are the main causes of rock anisotropy. The results show that rock anisotropy has a particularly important influence on the hygric and mechanical behavior of the Classic Travertine, while it has a minor effect on wave velocities and stone durability
Geología de las ultramafitas pre-andinas de Tapo y Acobamba, Tarma, Cordillera Oriental del Perú
(2009) Castroviejo, Ricardo; Feliciano Rodrigues, José; Acosta, Jorge; Pereira, Eurico; Romero, Darwin; Quispe, Jorge; Espí, José Antonio
Ultramafic rocks occur scattered along a 300 km long NNW-SSE trending belt, parallel to the central Peruvian Andes in the Cordillera Oriental, from Tarma (Junín Dept.) to Huancapallac and Tingo María (Huánuco Dept.). The Tarma occurrences (Tapo and Acobamba) are dealt with here, as the first step of a broader research. The Tapo massif comprises strongly tectonised serpentinites with scarce peridotitic relics, amphibolites and podiform chromitites. It was overthrust on early Carboniferous metasedimentary rocks of the Andean basement (Ambo Group), and it shows evidences of a pre-Andean deformational history, not observed in the Ambo Group; the basal thrust plane is folded by the Andean tectonics. The two smaller Acobamba occurrences are also allochtonous and show similar tectonic features. Major and trace element composition of amphibolites point to a tholeiitic basalt (to picrobasalt) protolith, compatible with an ocean-ridge or ocean-island environment. Small podiform chromitite lenses and chromite disseminations also occur; they are strongly deformed, metamorphosed and overprinted by hydrothermal alteration related to deformation, and were the subject of small scale mining. The ores comprise mainly chromite, ferritchromite, spinel, magnetite, ilmenite and scarce sulphides, as well as the secondary minerals stichtite and nimite. Results of this work exclude current interpretations of the Tarma ultramafites as autochtonous igneous intrusives, and point to a new interpretation for their emplacement
Generación de formas de fondo en el canal hidráulico ASSUT-1: Experiencia inicial
(2009) Rosselló Coma, Oriol; Colombo Piñol, Ferrán
Some experiments on transport and accumulation of sediments have been produced as examples of the possibilities of the ASSUT-1 hydraulic channel. Water volume and the channel gradient have been kept constant during the sedimentary experiment.The bed forms generation has been documented through series of pictures. They have been the base for a group of different cartons which illustrates the relationships between the hydraulic conditions and the associated bed forms.The bed forms generated (rhomboid, linguoid, parabolic, lunar and sinuous) were formed in special conditions that the water surface irregularities were in phase
Facies laminadas en la secuencia sedimentaria del lago de Montcortés (Lleida) durante los últimos 6.000 años
(2009) Corella, Juan Pablo; Valero Garcés, Blas; Brauer, Achim; Moreno Caballud, Ana; Pérez Sanz, Ana
The different sedimentological, geochemical and geophysical analysis performed in the Montcortés lake sedimentary record (Pre-Pyrenees, Lleida) helps to interpret the sedimentary evolution of this karstic lake during the last 6.000 years. The deposition of lacustrine varves is continuous during, at least, the last 3.500 Cal. yr BP. This fine lamination is punctuated by massive clastic facies corresponding to turbidite events. A total of 9 litostratigraphic units were recognized corresponding to three different depositional environments that alternate throughout the record; i) a shallow, meromictic lake with very high bioproductivity (unit VI: 6.000- 3.500 Cal. yr BP), ii) a deep, meromictic lake with high bioproductivity (units V, III and I; 3.500-1.250, 500-180 Cal. yr BP and last decades) and iii) deep, meromictic lake with higher clastic inputs (units IV and II; 1.250-500 and 180 Cal. yr BP- last decades). Several slumps deposits have been recognized within the sequence (units A, B and C)
Fábricas sin-metamórficas, mecanismos y régimen de la deformación en las granulitas de alta presión de Cabo Ortegal (NO de España): Réplica
(2009) Puelles, Pablo; Ábalos, Benito
Fábricas sin-metamórficas, mecanismos y régimen de la deformación en las granulitas de alta presión de Cabo Ortegal (NO de España): Comentario
(2009) Fernández Amo, Francisco José

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