Transformação ambiental de um estuário industrializado no século XIX: o registo sedimentar de Avilés (Asturias, N Espanha)

ABSTRACT: The Avilés estuary is one of the most important industrial ports in northern Spain, whose natural characteristics have been largely altered since the 1830s. Here, the environmental transformation of this estuary during the 19th century is explored using a multi-proxy approach including benthic foraminiferal content, sedimentology (grain-size), trace metals and short-lived radionuclides (210Pb and 137Cs) analysed from a 50-cm-long sediment core and a surface sample collected from the middle part of the estuary in the Pedro Menéndez Channel. The obtained results provide evidence that indicate an evolution from a naturally-driven environment with high a marine influence towards a more restricted setting under brackish conditions. The observed environmental change is interpreted as being mostly derived from physical modifications linked to the marsh reclamation and channelling starting in 1833 and intensified since 1860. This study provides a preindustrial environmental reference framework for future studies in coastal areas of the NW Atlantic Iberian margin.RESUMO: O estuário de Avilés é um dos portos industriais mais importantes do norte de Espanha, cujas características naturais foram bastante alteradas desde 1830. A transformação ambiental deste estuário durante o século XIX é estudada usando uma abordagem multi-proxy incluindo foraminíferos bentónicos, sedimentologia (dimensão do grão), metais traço e radionuclídeos de vida curta (210Pb e 137Cs) analisados a partir de sedimento de um testemunho de sondagem com 50 cm de comprimento e uma amostra recolhida à superfície na parte média do estuário do Canal de Pedro Menéndez. Os resultados obtidos fornecem evidências que indicam evolução de um ambiente com elevada influência marinha para um ambiente mais restrito em condições salobras. A alteração ambiental observada é interpretada como resultado de modificações físicas ligadas à recuperação e canalização de pântanos a partir de 1833, e intensificada desde 1860. Este estudo fornece um exemplo de referência ambiental pré-industrial para estudos futuros em áreas costeiras da margem NW Ibérica do Atlântico.info:eu-repo/semantics/publishedVersio

Datación paleomagnética de la parte sur del dique de Messejana- Plasencia

A Paleomagnetic investigation of 11 sites across the southern part of Messejana-Plasencia dike has been carried out. The magnetic behaviour o f pilot samples indicates that thermal demagnetisation is more effective than alternating field cleaning (AF) in isolating the Characteristic Remanent Magnetisation (ChRM). Therefore thermal demagnetisation was systematically used with the remaining samples. The ChRM is well grouped. Most sites exhibit normal polarities with the exception of two sites, where samples with reversed polarities have been observed. The paleomagnetic pole derived from the sites is well defined, with values of Plat=72.5, Plong=243.7 and Al);=6.0. This coincides with the pole calculated in a previous investigation (Schott et at. 1981) o f the dike. It is also in agreement with Toarcian poles from the Iberian Range (Osete et al. 2000) and statistically different from the Oxfordian Pole obtained in the same region. Previous radiometric studies suggested that the age o f dike intrusion is 160-200Ma. Paleomagnetic data indicates that the age o f intrusion can be constrained between 180-200Ma

The Traspena meteorite: heliocentric orbit, atmospheric trajectory, strewn field, and petrography of a new L5 ordinary chondrite

The Traspena meteorite fell on 2021 January 18 about 20 km south-east of the city of Lugo (Galiza, Spain), shortly after a huge and bright fireball crossed the sky for 4.84 s. Astrometric measurements obtained from the fireball cameras of the Universidade de Santiago de Compostela (USC) as well as from many casual videos were used to determine the atmospheric trajectory of this meteoroid which penetrated the atmosphere and generated sound waves that were detected at three seismic stations. The original meteoroid had a diameter of about 1.15 m and a mass around 2620 kg. It impacted the Earth’s atmosphere with a steep entry angle of about 76∘.7 from a height of 75.10 km until fading away at 15.75 km with a velocity of 2.38 km s−1. Before the impact, this small asteroid was orbiting the Sun with a semimajor axis of 1.125 au, a moderate eccentricity of 0.386, and a low inclination of 4∘.55. A weak evidence of dynamic link with the PHA (Potential Hazardous Asteroid) Minos was investigated. During the atmospheric entry, two major fragmentation events occurred between heights of 35 and 29 km at aerodynamic pressures between 1 and 5 MPa. The strewn field was computed after calculating the individual dark flights of the main body along with two smaller fragments. Fortunately, 2 month after the superbolide, a 527-g meteorite was found. It was examined using several geochemical and petrographic analyses which allowed us to classify it as a moderately shocked (S3) L5 ordinary chondrite with a bulk density of 3.25 g cm−3This paper was supported by the Xunta de Galicia (Spain) under the ED431B 2020/38 grantS

Multiteide Project: Multiparametric characterization of the activity of Teide-Pico Viejo volcanic system

European Geosciences Union General Assembly (2017. Viena)Teide-Pico Viejo complex stands for one of the major natural volcanic hazards in the Canary Islands, due to the expected types of eruptions in the area and the high number of inhabitants in Tenerife Island. Therefore, it is necessary to have a volcanic alert system able to afford a precise assessment of the current state of the complex. For this purpose, the knowledge of the expected signals at each volcanic activity level is required. Moreover, the external effects that can affect the measurements shall be distinguished, external influences as the atmosphere are qualitatively known but have not been quantified yetCentro Geofísico de Canarias, Instituto Geográfico Nacional, EspañaObservatorio Geofísico Central, Instituto Geográfico Nacional, EspañaInstituto Geológico y Minero de España, EspañaLaboratoire GéoSciences Réunion, Institut de Physique du Globe de Paris, Centre National de la Recherche Scientifique, EspañaPeer reviewe

The Traspena meteorite: heliocentric orbit, atmospheric trajectory, strewn field, and petrography of a new L5 ordinary chondrite

The Traspena meteorite fell on 2021 January 18 about 20 km south-east of the city of Lugo (Galiza, Spain), shortly after a huge and bright fireball crossed the sky for 4.84 s. Astrometric measurements obtained from the fireball cameras of the Universidade de Santiago de Compostela (USC) as well as from many casual videos were used to determine the atmospheric trajectory of this meteoroid which penetrated the atmosphere and generated sound waves that were detected at three seismic stations. The original meteoroid had a diameter of about 1.15 m and a mass around 2620 kg. It impacted the Earth’s atmosphere with a steep entry angle of about 76 . ◦7 from a height of 75.10 km until fading away at 15.75 km with a velocity of 2.38 km s −1 . Before the impact, this small asteroid was orbiting the Sun with a semimajor axis of 1.125 au, a moderate eccentricity of 0.386, and a low inclination of 4 . ◦55. A weak evidence of dynamic link with the PHA (Potential Hazardous Asteroid) Minos was investigated. During the atmospheric entry, two major fragmentation events occurred between heights of 35 and 29 km at aerodynamic pressures between 1 and 5 MPa. The strewn field was computed after calculating the individual dark flights of the main body along with two smaller fragments. For- tunately, 2 month after the superbolide, a 527-g meteorite was found. It was examined using several geochemical and petrographic analyses which allowed us to classify it as a moderately shocked (S3) L5 ordinary chondrite with a bulk density of 3.25 g cm −3 .This paper was supported by the Xunta de Galicia (Spain) under the ED431B 2020/38 grant.Peer reviewe

Estudio de las propiedades magnéticas de los sedimentos del límite cretácico-terciario

El trabajo aborda el análisis, desde el punto de vista del magnetismo de rocas, de los materiales sedimentarios del límite Cretácico-Terciario (límite K-T, 66 Ma). Este límite viene marcado por una de las grandes extinciones masivas que han jalonado la historia de la vida a lo largo del Fanerozoico. Además, coincidió con el impacto de un cuerpo extraterrestre contra la superficie terrestre, con un tamaño estimado de ~10 km, responsable de la formación de la estructura de impacto de Chicxulub (Yucatán, México). Los efectos medioambientales, a corto y largo plazo, del impacto finicretácico han sido propuestos como la causa de la extinción masiva del límite K-T. Los materiales meteoríticos y terrestres movilizados por dicho impacto se encuentran distribuidos globalmente en una fina capa sedimentaria que marca la frontera entre los periodos Cretácico y Terciario y que aparece en un gran número de secciones sedimentarias: la denominada lámina de impacto. El presente estudio se centra en la caracterización detallada de las propiedades magnéticas de los sedimentos del límite K-T, en especial del material de la lámina de impacto, y en la evaluación de la técnica magnética como herramienta para el estudio de horizontes de impacto en el registro estratigráfico. Otros objetivos son la obtención de información acerca de variaciones medioambientales en el Cretácico final- Paleógeno basal, la obtención de información acerca de los mecanismos de generación y emplazamiento de las fases meteoríticas magnéticas, el estudio de los procesos diagenéticos que han afectado a la lámina de impacto del límite K-T después de su deposición, y la obtención de información acerca del potencial de preservación de dichas fases magnéticas (su potencial de supervivencia a lo largo del tiempo geológico, en comparación con otros marcadores de impacto como la abundancia de iridio y otros elementos del grupo del platino, PGE), o dicho de otro modo, del estado de preservación y completitud de las secciones analizadas. Este estudio se ha llevado a cabo en un amplio rango de secciones sedimentarias en todo el globo a diferentes paleodistancias al cráter de Chicxulub: secciones muy lejanas (~11000 km), secciones lejanas (~6500-7000 km) y secciones relativamente cercanas (1000- 1700 km). Con ello se aborda la cuestión de la distribución espacial de las fases minerales meteoríticas con propiedades magnéticas distintivas. Aunque principalmente se han estudiado secciones marinas hemipelágicas/pelágicas, donde las tranquilas condiciones de sedimentación permiten, al menos potencialmente, una preservación buena de la lámina de impacto, también se han analizado algunas secciones muy someras (neríticas) y otras continentales. En total, se han analizado alrededor de 600 muestras procedentes de 21 secciones sedimentarias: cuatro secciones españolas (Agost, Caravaca, Zumaya y Sopelana), una sección danesa (Stevns Klint), una sección tunecina (El Kef), siete secciones mexicanas (El Mimbral, La Lajilla, El Mulato, El Peñón, Rancho Nuevo, Los Ramones y El Tecolote), siete secciones neozelandesas (Woodside Creek, Flaxbourne River, Branch Stream, Mead Strream, Mid-Waipara River, Moody Creek Mine y Compressor Creek) y una perforación del Ocean Drilling Program en el Atlántico Norte (Blake Nose)

Rock magnetic properties across the Paleocene-Eocene Thermal Maximum in Marlborough, New Zealand

Rock magnetic properties have been investigated across the Paleocene-Eocene Thermal Maximum (PETM) in three uplifted sections of Paleogene marine sedimentary rocks in Marlborough, South Island, New Zealand. The sections are exposed along Mead Stream, Dee Stream and Muzzle Stream and represent a depth transect up a continental margin from an upper slope to an outer shelf. Sampling was focused on rock beds previously examined for their biostratigraphy and stable carbon isotope (d13C) composition, and where a prominent clay-rich interval referred to as Dee Marl marks the initial 80-100 kyr of the PETM. Measured magnetic properties include bulk magnetic susceptibility, hysteresis cycles and isothermal remanent magnetization (IRM) acquisition and back-demagnetization curves. A strong inverse correlation between magnetic susceptibility and bulk carbonate d13C is found across the PETM such that Dee Marl has low d13C and high magnetic susceptibility. At Mead Stream this interval also contains increased saturation-IRM, and thus ferromagnetic content. Rock magnetic behaviour across PETM is best explained by an increase in terrigenous discharge. This inference has been made previously for PETM intervals in New Zealand and elsewhere, although with different proxies. Increased terrigenous discharge probably signifies an acceleration of the hydrological and weathering cycles. Some changes in magnetic phases could also reflect a drop in redox conditions, which could represent higher sedimentation rates, greater input of organic carbon, dysoxic bottom waters, or a combination of all three. A drop in redox conditions has been inferred for other marine sections spanning the PETM

Propiedades magnéticas de los sedimentos recientes de la Ría de Bilbao: un relato de contaminación industrial y recuperación postindustrial en el Antropoceno

Resumen de la ponencia presentada en la XV Reunión Nacional de Cuaternario, celebrada en Bilbao, Bizkaia Aretoa del 1 al 5 de julio de 2019Rock magnetic properties of 13 samples of surficial materials and 160 samples of recent sediments obtained from 7 sedimentary cores along the Bilbao estuary have been analyzed in order to investigate the magnetic fingerprint of anthropogenic pollution in this area. The results have been correlated to previously published heavy metal concentrations, main and trace element geochemistry and benthic foraminiferal data, revealing a strong relationship between magnetic properties and industrial pollution, but also a highly complex spatial-temporal interplay of different sources and types of pollutants. Magnetic data are indicative of a progressive but spatially heterogeneous decrease of ferromagnetic pollution in sediments after the deindustrialization of the Bilbao area, with two hotspots of persistent pollution remaining at the mouths of two of the main tributary creeks of the estuary (Galindo and Gobelas).Este trabajo ha sido financiado por el proyecto de investigación Antropicosta-2 (RTI2018-095678-B-C21 (MCIU/AEI/FEDER, UE), MINECOR) y por el Instituto Geográfico Nacional. Agradecemos al Laboratorio de Paleomagnetismo y Magnetismo de Rocas de la Universidad Complutense de Madrid por facilitarnos el uso de sus equipos e instalaciones

Propiedades magnéticas de los sedimentos recientes de la Ría de Bilbao: un relato de contaminación industrial y recuperación postindustrial en el Antropoceno

Resumen de la ponencia presentada en la XV Reunión Nacional de Cuaternario, celebrada en Bilbao, Bizkaia Aretoa del 1 al 5 de julio de 2019Rock magnetic properties of 13 samples of surficial materials and 160 samples of recent sediments obtained from 7 sedimentary cores along the Bilbao estuary have been analyzed in order to investigate the magnetic fingerprint of anthropogenic pollution in this area. The results have been correlated to previously published heavy metal concentrations, main and trace element geochemistry and benthic foraminiferal data, revealing a strong relationship between magnetic properties and industrial pollution, but also a highly complex spatial-temporal interplay of different sources and types of pollutants. Magnetic data are indicative of a progressive but spatially heterogeneous decrease of ferromagnetic pollution in sediments after the deindustrialization of the Bilbao area, with two hotspots of persistent pollution remaining at the mouths of two of the main tributary creeks of the estuary (Galindo and Gobelas).Este trabajo ha sido financiado por el proyecto de investigación Antropicosta-2 (RTI2018-095678-B-C21 (MCIU/AEI/FEDER, UE), MINECOR) y por el Instituto Geográfico Nacional. Agradecemos al Laboratorio de Paleomagnetismo y Magnetismo de Rocas de la Universidad Complutense de Madrid por facilitarnos el uso de sus equipos e instalaciones