Papers by Soledad Garcia Gil
Palinoestratigrafía de la Formación Cuesta del Castillo (Rama Castellana de la Cordillera Ibérica, España)
Geotemas ( Madrid ), 2005
The Muschelkalk sedimentary cycle in the NW Iberian Ranges is composed by Torete Fm overlaid by t... more The Muschelkalk sedimentary cycle in the NW Iberian Ranges is composed by Torete Fm overlaid by two carbonate formations (Tramacastilla Fm and Royuela Fm) passing laterally in to the terrigenous facies of Cuesta del Castillo Fm palynological study of this last formation allow to give a Langobarbian age (Upper Ladinian).
Oceans
Offshore geological hazards can occur in any marine domain or environment and represent a serious... more Offshore geological hazards can occur in any marine domain or environment and represent a serious threat to society, the economy, and the environment. Seismicity, slope sedimentary instabilities, submarine volcanism, fluid flow processes, and bottom currents are considered here because they are the most common hazardous processes; tsunamis are also examined because they are a secondary hazard generated mostly by earthquakes, slope instabilities, or volcanic eruptions. The hazards can co-occur and interact, inducing a cascading sequence of events, especially in certain contexts, such as tectonic indentations, volcanic islands, and canyon heads close to the coast. We analyze the key characteristics and main shortcomings of offshore geological hazards to identify their present and future directions for marine geoscience investigations of their identification and characterization. This review establishes that future research will rely on studies including a high level of multidisciplina...
A detailed geomorphologic analysis, based on multibeam bathymetry and 3,5 kHz and high resolution... more A detailed geomorphologic analysis, based on multibeam bathymetry and 3,5 kHz and high resolution multichannel seismic profiles, has allowed to image the sediment dynamic of the Galicia Bank region. Three types of features have been defined based on their origin: tectonic (fault scarps, seamounts and highs) erosive (slide scars, gullies, channels, moats, furrows) and depositional (slides, contourites, sediment waves, and wedges and lobes formed by mass-flow deposits). The understanding of the interplay among these features has permitted to define three sedimentary systems (slope apron, contourite and mixed) as well as the processes operating across the systems.
Global and Planetary Change, 2022
Incised valleys represent dynamic coastal and shelf systems in continuous change in response to d... more Incised valleys represent dynamic coastal and shelf systems in continuous change in response to different temporal and spatial scales. Their sedimentary record offers valuable data to unveil the effect of different drivers, such as relative sea-level rise, on the evolution of coastal systems and provide invaluable records of palaeoenvironmental changes. In this work, the palaeogeographical evolution of the Ría de Arousa (NW Spain) from the Last Glacial Maximum to the present is reconstructed by identifying the main elements of sedimentary architecture. These elements are characterised using a multidisciplinary approach combining seismic, sedimentary, geochemical and palynological data. The general succession of the sedimentary infilling of the incised valley records an overall transgression in response to postglacial sealevel rise. A large fluvial valley evolves into a tide-dominated estuary and later to a wavedominated estuary as it is progressively flooded. The complex interaction between variable rates of relative sea-level rise and the antecedent morphology exerts a strong control on hydrodynamics within the valley controlling the sediment dynamics and facies distribution, displaying some similarities with conceptual facies models for tide-and wave-dominated estuaries. The analysis of sediment sources also denotes significant changes in response to varying hydrodynamic regimes and climate, shifting from a predominant fluvial source in the earliest phases of the transgression to an increase in local sources (cliffs and local coastal deposits), including a likely reworking of older deposits (sediment recycling) during the Early Holocene. These changing sediment sources may have a clear impact on the palynological signal recorded within the incised valley, hypothetically masking and overprinting the climatic signal during phases of intense reworking of older deposits. Sediment recycling seems extensive within the incised valley and represents a key process that needs to be evaluated to understand the source-to-sink sediment flux to the deeper ocean. Its impact on the sedimentary records may have major implications for palaeoenvironmental studies in coastal settings, stressing the importance of applying multi-proxy approaches.
Journal of iberian geology: an international publication of earth sciences, 1987
Este trabajo ha sido financiado por la CAICYT y CSIC (Proyecto num. 452) y esta incluido en los P... more Este trabajo ha sido financiado por la CAICYT y CSIC (Proyecto num. 452) y esta incluido en los Proyectos nums. 4, 106 y 203 del IGCP (UNESCO).
The junction between the Iberian Ranges and the Central Syslem was a key region during the Middle... more The junction between the Iberian Ranges and the Central Syslem was a key region during the Middle Triassic, due to it represented a key area of the westcrn sector of the Tethys basin margin during that time. Tite sedimentary evolution of this period has been reconstructed taking into account the following points: (1) The space and time relationship between tite lithostratigrapitical formations, as well as tite sedimentary environment represented by them. The different magnitude of sedimentary interruptions; two se (2) dimentary cycles are identified: (a) «Buntsandstein sedimentary cycle», represented towards the end by tite «Cercadillo Sandstones and Siltstones>' Formation with typical fluvial facies and divided in two major sequences (Si and 82); (b) oMuschelkalk sedimentary cycle», comprising a basal siliciclastic formation («Torete variegated Siltstones and Sandstones») with predominant ephemeral fluvial facies passing upwards to carbonate formations («Tramacastilla Dolost...
Palinoestratigrafía de la Formación Cuesta del Castillo (Rama Castellana de la Cordillera Ibérica, España)
The Muschelkalk sedimentary cycle in the NW Iberian Ranges is composed by Torete Fm overlaid by t... more The Muschelkalk sedimentary cycle in the NW Iberian Ranges is composed by Torete Fm overlaid by two carbonate formations (Tramacastilla Fm and Royuela Fm) passing laterally in to the terrigenous facies of Cuesta del Castillo Fm palynological study of this last formation allow to give a Langobarbian age (Upper Ladinian).
The Ria de Vigo is a shallow water submarine incised valley running east to west along the NW coa... more The Ria de Vigo is a shallow water submarine incised valley running east to west along the NW coast of the Iberian Peninsula. Seismic and geochemical analyses from the sedimentary record indicate the presence of methane accumulations mapped as different gas fields, which are related with the presence of microbial communities. The aim of this investigation is to gain an initial perspective into the microbial diversity of the shallow gas fields from the Ria de Vigo. Two gravity corers, one from a gas-free area and another from a gas-accumulation zone, were taken. Genomic DNA was isolated from the recovered sediments and the 16S rRNA gene was amplified by PCR using primers specific for bacteria and archaea. The resulting products were analysed by pyrosequencing in a Genome Sequencer FLX System. The two sequence libraries were compared to the 16S rDNA database from the Ribosomal Database Project. The microbial communities from the two corers were characterised and compared. The differen...
Journal of Iberian Geology, 2002
High-resolution seismic reflection and side-scan sonar records have been analysed and interpreted... more High-resolution seismic reflection and side-scan sonar records have been analysed and interpreted in order to detect shallow gas signatures in the Ria de Muros-Noia (NW Spain). The different gas features have been classified into four types according to their specific seismic signatures: 1) acoustic blankings s.s., with a flat top surface and kilometric extent, 2) acoustic curtains, with a convex top surface and some tens of meters of lateral extent, 3) acoustic columns, with an enhanced reflector at the top and an averaged extent of 20 m, and 4) acoustic turbidity, distinguishable as a diffuse perturbation of the records. At the same time, two different types of gas escape features have been also distinguished: a) acoustic plumes into the water column, rising up to 10 m above the present seafloor, and b) pockmarks on the present seabed, recognised as highly reflective areas in the side-scan sonar records. Mapping of acoustic blankings s.s. reveals the presence of a large gas field ...
Journal of Iberian Geology, 2000
La interpretacion estratigrafica de unidades que contienen glauconita requiere de una adecuada ca... more La interpretacion estratigrafica de unidades que contienen glauconita requiere de una adecuada caracterizacion del grado de evolucion, definido a partir del concepto de madurez (Amorosi, 1995). Su utilizacion es util para determinar la duracion de periodos asociados a bajas tasas de sedimentacion o para caracterizar condiciones paleoceanograficas y paleoambientales en la interfase sedimento-agua del mar. En este tipo de estudios se asume implicitamente que la glauconita actua como un sistema abierto, susceptible de continuos cambios en la estequiometria, como resultado del intercambio de cationes con el agua del mar que, a su vez, inducen reajustes estructurales. La determinacion del grado de evolucion de glauconitas esta asociada habitualmente a la presencia de determinados marcadores, algunos de tipo cualitativo como es el color o bien asociados a la variacion de alguna de sus propiedades fisicas, como es la susceptibilidad magnetica o composicionales y estructurales, como son la ...
espanolLos reservorios de gas somero en los sedimentos marinos del margen iberico o sus escapes s... more espanolLos reservorios de gas somero en los sedimentos marinos del margen iberico o sus escapes se pueden detectar por metodos directos mediante: (1) la medicion de concentraciones elevadas de metano u otros hidrocarburos en la columna de agua o en testigos de sedimentos, (2) la identificacion en el fondo marino de comunidades quimiosinteticas y/o de carbonatos autigenicos y (3) la identificacion (mediante videos submarinos) de crateres (pockmarks) o monticulos de carbonatos y volcanes de fango asociados al escape de fluidos; o por tecnicas indirectas mediante la caracterizacion de anomalias en registros acusticos tales como: (1) la presencia de plumas acusticas en los registros de ecosonda, (2) la identificacion de apantallamientos y/o turbidez acusticos en los registros sismicos de alta resolucion, (3) la interpretacion de reflectividades y (4) de morfologias de crateres o montes submarinos en los registros de sonar de barrido lateral y ecosondas multihaz. En este articulo se pres...
Quaternary Science Reviews, 2019
Journal of Iberian Geology, 2016
Several vertebrae of a sauropterygian specimen have been recovered in Fuencaliente de Medinaceli ... more Several vertebrae of a sauropterygian specimen have been recovered in Fuencaliente de Medinaceli (Soria Province, Castilla y León, Spain). The remains come from late Middle Triassic levels (late Ladinian) of the upper Muschelkalk Facies. This finding represents the first documented evidence of a Triassic tetrapod in Castilla y León. The vertebrae belong to Nothosaurus, a sauropterygian genus found in Europe, Middle East, North of Africa and China. This genus is poorly-known in the Iberian record. The new remains constitute the first evidence of the species Nothosaurus giganteus, or a related taxon, in the Iberian Peninsula, being referred as Nothosaurus cf. giganteus. This study reveals the occurrence of at least two species of the sauropterygian Nothosaurus in the Iberian record.
Estructuras Diapíricas Producidas Por Escapes De Fluidos en La Ría De Pontevedra (Galicia, No España)
Geomorfología de la Región del Banco de Galicia (NW de la Península Ibérica)
Multibeam bathymetry has been used to study in detail the morphology of the Galicia Bank region (... more Multibeam bathymetry has been used to study in detail the morphology of the Galicia Bank region (< 700 m down to 5200 m water depth), in the NW Iberian Margin. Five pshyiographic provinces displaying a complex morphology have been defined. Their geomorphology is characterized by three types of features based on their origin: tectonic, erosive and depositional. Tectonic features are dominant, comprise fault scarps (normal and inverse), seamounts and highs. They condition the general geometry and morphology of the provinces. Erosive and depositional features are mainly related to tectonic features, both their location and genesis. The erosive features comprise slide scars, gullies, channels, and main channels. The valleys eroding the provinces form turbidity systems that drain radially the region of the Galica Bank, transporting the sediment toward the Biscay and Iberian abyssal plains. The depositional features comprise slides and wedges and lobes formed by mass-flow deposits. The...
Multibeam and seismic data acquired during the ERGAP 1 and ERGAP 2 allowed the recognition and st... more Multibeam and seismic data acquired during the ERGAP 1 and ERGAP 2 allowed the recognition and study of three big depressions which are located in the continental slope southeast of the Galicia Bank. These depressions correspond to collapses circular in shape that reach 370 m depth and whose size range between 2000 y 5000 m. Among them the so called BURATO ERGAP have been analysed in detail. Seismic records from this depression indicate its erosive character, the occurrence of a diapir underneath related to a shale layer, numerous faults that extend from the seafloor to the shale layer at both sides of the depression and finally and transparent seismic facies that could be associated to fluid venting. The genesis of this collapses must be explain in the framework of the Cenozoic Pyrenean compressive events, where faulting of the sedimentary cover over a viscous shale layer among other factors can be invoked to explain this outstanding features.
It has been inferred that the rias of Galicia on the passive margin of northwest Spain which tren... more It has been inferred that the rias of Galicia on the passive margin of northwest Spain which trend nearly at right angles to the Paleozoic structural grain appear to be the result of erosion along a weathered fault zone. New data from the Ria de Pontevedra appears to verify such an origin. The sediment fill in Pontevedra indicates that deposition along the eroded fault zone probably began during the emplacement of the late Pleistocene Sl sequence. Deposition of the Holocene S2 sequence, resting unconformably on Sl, reflects not only the Younger Dryas regression, but also the transgressions prior and subsequent to the YoungerDryas regression. Both the Pleistoceneand Holocene sequences are disrupted by mud diapirs at the mouth of the Ria de Pontevedra; the Holocene sequence at the mouth on its southeast side also is disrupted by faults which may be due to slope failure. Mobilization of the mud intruding the strata is probably due to sediment loading.
Marine Geology, 2008
The high-resolution seismic stratigraphy of the Galicia Bank Region and adjacent deposits of the ... more The high-resolution seismic stratigraphy of the Galicia Bank Region and adjacent deposits of the neighbouring Iberian and Biscay Abyssal Plains was included as part of the geological studies conducted in the area where the oil-tanker Prestige wreck is located. This seismic stratigraphy is characterized by five seismic units (5 to 1, from oldest to youngest) lying above an irregular acoustic basement defined by a highly fractured system of horsts and grabens. These faulted systems have controlled the local depositional architecture, deforming, fracturing, relocating and distributing sediments since the Valanginian. Three depositional models of facies can be recognized on the Galicia Bank Region and surrounding abyssal plains: bank, escarpment, and abyssal plain facies. The bank facies reflects the depositional evolution from initial filling to obliterating stages of the horsts and grabens. The escarpment facies has a local distribution and represents deposition associated with active slopes of the faulted escarpments. The abyssal plain facies represents gravity flow deposits coming mostly from the bounded-fault flanks of the Galicia Bank Region. The Valanginian to Quaternary sedimentary evolution of the Galicia Bank Region reflects depositional responses to tectonic condition. The occurrence of mass-movements confirms that the syn-rift period (Valanginian to Aptian age) along the Galicia margin was diachronous, beginning in the Interior Basin and shifting later toward the west of the Galicia Bank Region (Deep Galicia Margin). The Albian to Quaternary post-rift evolution is characterized by a decrease in tectonic activity and sedimentary variations in the style of deposition (valley and related features, mass-movement deposits, contourites, and drape deposits) conditioned by changes in the sedimentary processes, paleoenvironments, and tectonic reactivation of the regional slopes. The effects of tectonic movements persist, as evidenced in areas where faulted escarpments and highs outcrop, and in areas of nearsurface faulting. The syn-rift and post-rift stages have also conditioned the depositional architecture of the Prestige sinking area. The evolution of the surrounding abyssal plains does not reflect the same pattern to tectonic condition.
Marine Geology, 2005
The seismic analysis of the sedimentary infill of the Rı ´a de Vigo reveals that the infill compr... more The seismic analysis of the sedimentary infill of the Rı ´a de Vigo reveals that the infill comprises of a fifth order sequence (18 ky) bounded by a major discontinuity surface. Within the Holocene sequence, several seismic units have been identified; the oldest one originated after the Wu ¨rm glaciation and the origin of its top discontinuity was eroded during the regression (sea level at À120 m) of this last glacial episode (isotopic stages 2 to 4), 18 ky B.P. In some places below this rı ´a infill, another sequence can be identified. This older sequence is associated with the preexisting faults and troughs in the deepest parts of the rı ´a, and it was deposited during the Wu ¨rm glaciation (Miocene-Pleistocene). Eroded sediments were moved from the rı ´as area to deeper zones, where they accumulated in the lowstand system tract. The next sea level rise occured in two steps, producing two transgressive units separated by an hiatus surface. This cycle was interrupted by the next sea level fall (to À 55 m) marked on the seismic records by another recognizable boundary. The next sea level rise took place in several steps (back-stepping) with some stillstands, generating another transgressive system tract in the rı ´a. From that time on, the relative sea level continued rising, depositing the most recent unit which represents the highstand system tract. Separating the highstand system tract and the transgresive unit below there is a consensed section. The analysis of 29 cores provides groundtruthing for our hypothesis. The identified main lithologic units show a transgressive sequence: a granitic rock base, an overlying second unit-locally wedge shaped-and most recently, a marine muddy unit covering the present rı ´a seafloor.
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Papers by Soledad Garcia Gil