Evolución de la vegetación en el sector biogeográfico Castellano Cantábrico durante el Cuaternario Final, a través del registro tobáceo

En esta memoria de Tesis Doctoral se aborda el estudio paleobotánico de seis yacimientos tobáceos situados en las localidades burgalesas de Tubilla del Agua, Sedano, Herrán, Tobera y Frías, y en la alavesa de Ocio. El registro fósil encontrado en estos afloramientos se analiza de forma conjunta con el objetivo de conocer la evolución de la vegetación en el sector biogeográfico Castellano Cantábrico. Este sector se considera el territorio para el cual los hallazgos paleobotánicos son representativos y extrapolables, en tanto que constituye una región homogénea desde el punto de vista florístico, que abarca todos los yacimientos prospectados. El contexto temporal en el que se enmarca este estudio es el final del Cuaternario, desde el Pleistoceno Medio hasta la actualidad. Este intervalo se ha establecido a partir de la edad de los depósitos estudiados, la cual ha sido determinada —para los yacimientos de los que no se disponía de edades fiables— mediante la datación de muestras extraídas de las diferentes unidades litológicas identificadas. Para ello han sido empleadas las técnicas de carbono-14, desequilibrio de las series del uranio y racemización de aminoácidos. Los resultados geocronológicos obtenidos junto con el análisis geomorfológico de los yacimientos han permitido vincular la génesis de las 13 unidades litológicas identificadas con diferentes estadíos climáticos. Estos abarcan un amplio rango de condiciones ambientales, desde las más extremas del Último Máximo Glacial, hasta las más benignas de los Estadíos Isotópicos Marinos interglaciares 1 y 5. Como resultado de la prospección de los depósitos de toba fueron recuperados 1.820 fósiles, la mayoría impresiones foliares, pero también moldes de estróbilos femeninos, ramas y corteza, así como 42 carbones y restos subfósiles de Pinus sp. La identificación taxonómica de estos restos se ha realizado fundamentalmente a partir del análisis de caracteres diagnósticos morfológicos. Como resultado de ello, han sido descritos 28 taxones pertenecientes a las subclases Bryidae, Polypodiidae, Pinidae y Magnoliidae. La flora de los yacimientos estudiados se puede clasificar en tres grupos en función de sus requerimientos ecológicos: (i) uno formado por dos especies de alta tolerancia a la continentalidad —Pinus nigra y Quercus faginea—, las cuales aparecen bien representadas en la mayoría de los depósitos; (ii) otro constituido fundamentalmente por un conjunto de árboles y arbustos que habitualmente tienen el papel de especies acompañantes en los bosques ibéricos submediterráneos y eurosiberianos; y (iii) un tercer grupo compuesto por taxones hidrófitos o edafohigrófilos asociados al ecosistema del fitohermo activo y la vegetación de ribera. En el capítulo de Discusión se propone y analiza la hipótesis de que P. nigra y Q. faginea habrían sido las especies protagonistas de la vegetación zonal del sector Castellano Cantábrico durante el Cuaternario Final. Estas podrían haber persistido como tal incluso durante las épocas más frías, debido a su amplia valencia ecológica y a la capacidad de reproducirse vegetativamente en el caso del quejigo. Por el contrario, los taxones mesofíticos y eurosiberianos pudieron haber sufrido la expansión y retracción de sus poblaciones al ritmo de las oscilaciones climáticas. Sin embargo, la orografía diversa del sector Castellano Cantábrico proporciona emplazamientos en los que se combinan las diversas variables fisiográficas, de tal forma que pudieron haber existido microrrefugios en los que encontraron cobijo algunos taxones mesotérmicos y eurosiberianos durante los periodos glaciales. Por último, la historia evolutiva reciente de la vegetación de este territorio ha estado marcada por la acción antrópica, la cual empezó a ser manifiesta a partir del Neolítico. Esta se tradujo en la degradación y reducción de la cubierta forestal, así como en la extinción del pino laricio del Sector Castellano Cantábrico en los dos últimos milenios. ABSTRACT This PhD Dissertation focuses in the study of six tufa formations located nearby the villages of Tubilla del Agua, Sedano, Herrán, Tobera y Frías, all of them in the province of Burgos, and Ocio, which belongs to the province of Álava. We analyze the palaeobotanical archives of these sites with the purpose of unveiling and understanding the evolution of the vegetation of the Castilian Cantabrian biogeographical sector. This area is considered to be the territory that is represented in the palaeobotanical sample of the studied tufa archives. It is the homogeneous phitogeographical area with the lowest rank that include all the sites. The time frame of this study is the last part of the Quaternary, since the Middle Pleistocene to the present time. This interval is defined by the age of the tufa deposits, which were dated —for the ones that there were not available datings— throughout the analysis of 20 tufa samples taken from the 13 identified lithostratigraphic units. The age of the samples has been determined by using the methods of radiocarbon, U-Th dating and amino acid racemization. Chronological results, along with the chronostratigraphic study of the sites has allowed us to relate the build-up of the 13 identified lithostratigraphic units with different climatic stages. These structures were deposited in a wide range of climatic conditions, from the most extreme ones of the Last Glacial Maximum, to the warmer ones of the Marine Isotopic Stages 1 and 5. A total of 1,820 fossils were recovered from the tufa deposits, most of them were leaf impressions, but also pine cones, branches and bark moulds, along with charcoal and Pinus nigra macro remains. The taxonomical identification of these remains has been done mainly through the analysis of morphological traits. As a result of this process, 28 taxa belonging to the subclass of Bryidae, Polypodiidae, Pinidae and Magnoliidae were identified. The persistency of some taxa can be traced along different climatic stages in this fossil record. This fossil flora can be classified in three different groups: (i) the first one would be composed of two species with high continental climate tolerance —Pinus nigra y Quercus faginea—, which can be found in most of the deposits, (ii) the second group would be mostly formed by trees and shrubs that usually grow in the Iberian forests as an accessory species and (iii) the third one is composed of hydrophytes or hydrophilic taxa associate to the streams, riparian zones or the active tufa ecosystem. In the Discussion chapter we propose and analyse the hypothesis that P.nigra and Q. faginea were the main species of the zonal vegetation of the Castilian Cantabrian biogeographical sector during the last part of the Quaternary. This species could have persisted due to their wide ecological amplitude and also due to the capacity of asexual reproduction in the cases of the oak. On the other hand, mesophitic taxa could have suffered the retraction and expansion of their population following the climate oscillations. However, the diverse orography of the Castilian Cantabrian biogeographical sector provides a variety of combinations of physiographic variables, which could have been suitable refuges for some of the mesophitic taxa. The recent evolutionary history of the vegetation in this territory has been affected by human activities, which started to be relevant since the Neolithic. This led to a reduction of the forests and eventually, to the extinction of P. nigra in the Castilian Cantabrian biogeographical sector in the last two thousands of years.

Agaete revisited: new data on the Gran Canaria tsunamiites.

The tsunami deposits of the valley of Agaete (Pérez-Torrado et al., 2006), north-western Gran Canaria, attributed to the Guimar flank collapse in Tenerife, have been revisited and new data are presented here. Besides the occurrences reported by Pérez-Torrado et al. (2006) a new outcrop was found and named “La Ruina” (at 28º 05’ 47,41” N; 15º 41’ 52,04” W; 71 m asl). The above-mentioned authors suggested the possibility that more than one marine conglomerate deposit could be present in the outcrops of “Llanos de Turmán” and “Berrazales”. At “La Gasolinera” and “La Aldea 1” the conglomerates are formed by a single layer representing one depositional event; at “La Aldea 2”, the conglomerates are composed of two layers directly contacting with each other, but evidence of a time hiatus between them was not found. Although the hypothesis of stacking of two depositional units within the same episode versus deposition of two distinct layers in different time-moments is debatable at the present state of knowledge, the first possibility is favoured. The field evidence at “Llanos de Turman” and “Berrazales” unquestionably shows that terrestrial sediments (colluvia; paleosols) are present and separate two marine conglomerate deposits, indicating that at least two distinct tsunami inundations are needed to explain the stratigraphy. However, at the new “La Ruina” outcrop, besides the two deposits mentioned above, a third and older marine conglomerate was found, clearly separated in time from the ones cited above. The existence of marine conglomerates emplaced in different moments is evidenced by the occurrence of intercalated paleosols, colluvia and other subaerial materials, implying significant time intervals between the emplacement of marine conglomeratic layers. A number of gastropod operculae from the tsunamiites were sent for U-Th dating to try to further constrain the age span of these deposits. The field evidence presented above shows that the emplacement of the deposits is related to, at least, three tsunami events. The lateral correlation between different outcrops is difficult due to variable number of deposits in each outcrop, lateral discontinuity and variability, and to compositional and textural similarity between distinct tsunami sediments. The occurrence of three Pleistocene tsunami deposits in the same area points to a relatively high frequency of tsunamis (generated by landslides, surface rupturing earthquakes, fast entry of voluminous volcanic deposits into the sea or large submarine eruptions). It is possible that this recurrence of tsunami inundations may reflect multiple-phased landslides responsible for the mega-landslide scars prominent in the geomorphology of the neighbouring island of Tenerife. This is a contribution from project “Estabilidad de los edificios volcánicos en Canarias: análisis de los factores geológicos, geomecánicos y paleoclimáticos. Aplicación a los flancos N y S de la isla de Tenerife” financed by MCT, Spain.

Arrecifes de corales de aguas frías como posibles indicadores de emisiones de hidrocarburos en el Golfo de Cádiz

El presente documento trata de exponer la relación existente entre los corales de aguas frías encontrados en el Golfo de Cádiz (Atlántico NE) con los procesos tectónicos y las estructuras relacionadas con la migración y la emisión de fluidos ricos en hidrocarburos (principalmente metano). Para ello, desde el año 2000 hasta la actualidad, se han llevado a cabo diversas campañas oceanográficas en las cuales se han obtenido datos y muestras relacionadas con las emisiones de hidrocarburos al fondo marino. Gracias a los datos y las muestras recogidas durante las campañas se han creado una base de datos, en la que se reúnen todos los datos significativos relacionados con las campañas oceanográficas y con el objeto de este trabajo. Para finalizar, tras la creación de la base de datos, y con las muestras proporcionadas por el IGME recogidas durante la campaña oceanográfica MVSEIS08, se han podido llevar a cabo diversos estudios de laboratorio como la racemización de aminoácidos, análisis de biomarcadores así como la datación de los esqueletos aragoníticos de los corales de aguas frías mediante la técnica de U-Th en un futuro, con el objetivo de esclarecer la relación existente entre estas emisiones de fluidos a través de diversas estructuras y los corales de aguas frías, su edad, y en última instancia determinar los cambios producidos en la composición química de la masa de agua atlántica así como la variación de las corrientes en el Golfo de Cádiz durante el último periodo glaciar. ABSTRACT This project attempts to explain the relationship between cold-water coral found in the Gulf of Cadiz (NE Atlantic) with tectonic processes and structures related to migration and hydrocarbon-rich fluids emissions (mainly methane). Since 2000 until present, have conducted various oceanographic cruises in which data were obtained and samples related to hydrocarbon emissions to the seabed. Thanks to data and samples collected during the cruises, I have created a database in which all gather meaningful data related to oceanographic and the object of this work. Finally, after the creation of the database, and the samples provided by the IGME collected during the oceanographic cruise MVSEIS08 have been able to carry out laboratory studies of racemization of aminoacids, biomarkers analysis and dating of aragonitic skeletons of cold-water corals in a future by U-Th data , in order to clarify the relationship between these fluids emissions through various structures, ages cold-water corals, and ultimately determine changes in the chemical composition of Atlantic water mass and the change of currents in the Gulf of Cadiz during the last glacial period.

Evolución paleoambiental de la Península Ibérica desde hace 1 Ma a partir de los biomarcadores del registro de la Turbera de Padul (Granada)

La Turbera de Padul, en la Provincia de Granada, ofrece unas posibilidades de estudio muy atractivas desde el punto de vista de la reconstrucción paleoambiental. Se trata de una fosa tectónica subsidente de naturaleza detrítica, a cuyo techo aparecen alternantes niveles de turba. El sondeo, de 107 metros, se realizó en un punto donde los estratos de turba aparecen a mayor profundidad, lo que permite obtener un registro geoquímico orgánico con mucho detalle con una antigüedad de hasta 1Ma. Se tomaron muestras cada 20 cm para el análisis de biomarcadores. Estos biomarcadores se obtuvieron mediante extracción Soxhlet, posterior separación de fracciones de diferente polaridad mediante Cromatografía en Columna, con Gel de Sílice y Alúmina, y posteriormente el análisis e identificación por Cromatografía de Gases - Espectrometría de masas, con confirmación de los compuestos químicos identificados por comparación con Bibliotecas de Espectros de Masas. La datación del sondeo se realizó utilizando distintos métodos como datación por 14C, U/Th, y datación por racemización de aminoácidos. Los resultados dataron el muro del sondeo con una antigüedad de 1 millón de años. El estudio de los biomarcadores ha permitido identificar episodios con distintas características en un escenario complejo, como es la Turbera de Padul, donde el aporte de agua por fusión nival complica la interpretación paleoambiental, y es la responsable de la existencia de la lámina de agua en la turbera en periodos secos con temperaturas elevadas. Se han identificado series de n-alcanos, de n-metilcetonas y series de nalcanoles, que han permitido identificar la aportación de materia orgánica de distintas fuentes al sedimento y por tanto la interpretación paleoambiental. La identificación de diterpenoides fenólicos (cis-Totatol, trans-Totarol y Ferruginol) han permitido identificar episodios de clima templado y húmedo con proliferación de cupresáceas, y precipitaciones abundantes. Por otro lado, se han identificado triterpenoides como el Friedelan-3-ona (Friedelin) y el A-norfriedel-8en-10-ona, cuya relación como precursor (Friedelin) y producto (A-norfriedel-8en-10-ona) ha permitido identificar episodios con fluctuaciones del espesor de la lámina de agua y aporte de material vegetal. ABSTRACT The Bog of Padul, in the province of Granada, offers very attractive possibilities for the study of paleoenvironmental reconstruction. It is a subsiding graben of detrital nature, whose upper part appear alternating peat levels. The core of 107 meters, obtained from a borehole drilled in a place where the layers of peat appear deeper, allowing to obtain organic geochemist information along the last 1 million years. Every 20 cm samples for biomarkers analysis were taken. These biomarkers were obtained by Soxhlet extraction, subsequent separation of fractions of different polarity by column chromatography with silica gel and alumina, and then analyzed and identified by gas chromatography - mass spectrometry, with confirmation of the chemicals identified by comparison to mass spectral libraries. The dating of the core was conducted using different methods such as 14C dating, U/Th, and amino acid racemization dating. The results dated the base of the core to be 1 million years old. The study has identified biomarkers episodes with different characteristics in a complex scenario, such as the Bog of Padul, where the contribution of snowmelt water complicates the paleoenvironmental interpretation, and is responsible for the existence of a sheet of water in dry periods with high temperatures. There have been identified series of n-alkanes, n-methyl ketones and series of n-alkanols that have shown the contribution of different organic matter sources to the sediment and therefore allowed to paleo interpretation. The identification of phenolic diterpenoids (cis-Totatol, trans-Totarol and Ferruginol) have identified episodes of mild and humid climate with proliferation of Cupressaceae, and abundant rainfall. In addition, triterpenoids have been identified, as the friedelan-3-one (friedelin) and the A-norfriedel-8en-10-one, whose relationship as precursor (friedelin) and product (A-norfriedel-8en-10-one) has identified episodes with fluctuations on the thickness of the sheet of water and supply of plant material debris.

Empleo de biomarcadores para la reconstrucción paleoclimática. El registro pleistoceno del Mar de Fuentillejo (Ciudad Real)

El registro sedimentario del lago volcánico conocido como maar de Fuentillejo (Centro de España) ofrece la oportunidad de determinar la evolución paleoambiental durante el Pleistoceno medio y superior de la parte Centro-Sur de la Península Ibérica, objetivo principal de esta Tesis Doctoral. Se ha recopilado información sobre otras reconstrucciones paleoambientales en maares de todo el mundo y estudios paleoclimáticos realizados en el registro de la turbera de Padul, relativamente próxima al maar de Fuentillejo. Con ello, se pudo realizar el estado del arte.A lo largo del sondeo continuo (142,25 m) perforado en la parte central del maar de Fuentillejo en el año 2002, se han tomando un total de 613 muestras a intervalos de 20 cm para el análisis de biomarcadores. Los biomarcadores se obtuvieron mediante un equipo de extracción acelerada de disolventes (Dionex ASE 200) y fueron analizados con un cromatógrafo de gases (HP 6890) con detector selectivo de masas (HP 5973). La datación de sedimentos del maar de Fuentillejo ha sido complicada debido a la ausencia de restos orgánicos terrestres. Se seleccionaron seis muestras de sedimento para intentar datar por el método de racemización de aminoácidos: los resultados obtenidos no fueron buenos. Finalmente, el modelo de edad-profundidad se ha llevado a cabo mediante paleomagnetismo, dataciones 14C y U/Th. En base a una interpolación lineal de las edades medias calibradas se ha datado la base del registro en aproximadamente 355 ka. Se han identificado y cuantificado los n-alcanos, n-metil cetonas, ácidos n- alcanoicos y azufre orgánico del sedimento a lo largo del registro. La interpretación de los diferentes índices establecidos a partir de éstos permite independizar tres Unidades Geoquímicas generales (UG) y nueve Subunidades (S) que definen condiciones paleoambientales distintas (predominio en el aporte de vegetación terrestre/de macrofitas/acuática, lámina de agua más alta vs. más baja, periodos más húmedos vs. más secos).A partir de análisis estadísticos de los índices de n-alcanos (matriz de correlación y análisis de agrupaciones) se han definido tres asociaciones: Grupo 1 (condiciones ambientales más húmedas y fase con lámina de agua elevada), Grupo 2 (con condiciones intermedias) y Grupo 3 (las fases más secas y con lámina de agua más baja). Además, se establece un Indicador Paleoambiental (I.P.) que muestra variaciones notables correlacionables con escenarios paleoambientales distintos (más húmedos vs. más secos) distinguiendo veintiséis Episodios (E): cinco Secos, nueve Húmedos y doce Intermedios.En general, se encuentra una buena correspondencia entre estos Episodios (E) y los eventos paleoclimáticos cortos descritos por Vegas et al. (2010) en este registro, en base a la palinología y geoquímica, así como los Episodios del Oxígeno Marino (MIS) y Eventos Heinrich, que permiten suponer que las oscilaciones paleoclimatológicas registradas en el maar tienen un origen global. Esta correspondencia se confirma por el análisis espectral, que revela que los ciclos interpretados (103, 41, 26 y 23 ka) evidencian influencia orbital. Además, se ha realizado una correlación tentativa entre los episodios paleoambientales de larga duración obtenidos a partir del perfil suavizado del porcentaje relativo de C27 de la Cuenca de Padul (Granada, Sur de la Península Ibérica) y el perfil I.P. suavizado del maar de Fuentillejo, aunque hay diferencias que podrían ser explicadas por la vecindad de Padul a la zona de nieves perpetuas de Sierra Nevada lo que origina marcadas diferencias hidrológicas entre ambos sitios. El análisis por cadenas de Markov ha permitido determinar que los cambios paleoambientales reflejados por los biomarcadores no fueron, en la mayoría de los casos, bruscos pasando, normalmente, por estados transicionales.

Identificación de episodios climáticos fríos mediante el registro de susceptibilidad magnética en la secuencia lacustre del maar de Fuentillejo (Ciudad Real).

Resumen: El maar de Fuentillejo está localizado en la Región Volcánica Central de Campo de Calatrava (Ciudad Real). Desde su inicio se ha comportado como un sistema cerrado y presenta una potencia total de 142 m de sedimentos lacustres, organizados en 23 unidades sedimentarias. Se ha realizado un estudio de la susceptibilidad magnética y densidad aparente de los sedimentos, mediante un equipo de testificación multisensor Geotek. Para obtener la edad del registro se han efectuado dataciones absolutas mediante radiocarbono, U-Th y con el estudio de polaridad magnética, obteniéndose un modelo de edad que permite datar el sondeo FUENT-1 en torno a los 350 ka. Los datos del registro de susceptibilidad magnética, junto con las dataciones efectuadas, permiten identificar una secuencia de eventos erosivos relacionados con los últimos estadios glaciares (LGM: Ultimo Máximo Glaciar y los estadios isotópicos MIS 6 y 8). El registro de susceptibilidad magnética se encuentra atenuado por procesos de disolución de los óxidos de Fe-Ti. Abstract: The Fuentillejo maar is located in the Central Spanish Volcanic Field of Campo de Calatrava (Ciudad Real). Fuentillejo maar-lake was a closed system where up to 142 m depth of lacustrine sediments were deposited. Magnetic susceptibility and bulk density were measured by a GEOTEK multisensor core logger. The chronological framework was constructed based on radiocarbon and U-Th methods, as well as a detailed study of magnetic polarity, yielding an age model that covers last 350 ka. Intervals with terrigenous sediments correspond to high magnetic susceptibility values. These intervals were correlated with erosive events during the Last Glacial Maximum and the MIS 6 and 8 isotopic stages. The record of magnetic susceptibility is attenuated by disolution processes of Fe-Ti oxides.

Incisión fluvial a partir del conjunto multinivel de cuevas de La Galiana (Parque natural del río Lobos, Soria)

El conjunto endokárstico de La Galiana (Cañón del río Lobos, Cordillera Ibérica, provincia de Soria) está formado por tres niveles de galerías horizontales (La Galiana Alta, La Galiana Baja y Cueva del Lago) localizadas a 1099, 966 y 953 m s.n.m. respectivamente. Representan niveles de estabilización de la superficie freática y su nivel de base fluvial. El contexto geomorfológico y los datos paleomagnéticos indican que coladas estalagmítica de La Galiana Alta son anteriores a los 3,596 Ma. Por otro lado, la edad U/Th más antigua obtenida en espeleotemas de La Galiana Baja es de 224 ka. Las diferencias altimétricas entre galerías (133 y 13 m) y edades obtenida permiten calcular tasas máximas de encajamiento fluvial entre 39 y 58 mm/ka.

40ar/39ar Dating of alunite from the Pueblo Viejo Gold-Silver District, Dominican Republic

New 40Ar/39Ar ages for alunite from the Moore and Monte Negro deposits in the Pueblo Viejo district, as well as from a newly discovered alunite-bearing zone on Loma la Cuaba west of the known deposits, are reported here. The ages range from about 80 to 40 Ma, with closely adjacent samples exhibiting very different ages. Interpretation of these results in the context of estimated closure temperatures for alunite and the geologic and tectonic evolution of Hispaniola does not lead to a simple conclusion about the age of mineralization. The simplest interpretation, that mineralization was caused by a buried Late Cretaceous (~80 Ma) intrusion, is complicated by lack of intrusions of this age in the area and absence of alteration in overlying limestone. The alternative interpretation, that mineralization was formed during Early Cretaceous (~110 Ma) magmatism and that the 40Ar/39Ar ages were completely reset by Late Cretaceous thrusting, is complicated by a lack of information on the timing and thermal effects of thrusting in central Hispaniola. Alunite studies have yielded similar unclear results in other pre-Cenozoic ore systems, notably those of the Lachlan fold belt in Australia

Correlating a documentary record of historical floods with the dendrochronological dating of a wooden decking in the old mint of Segovia (Spain)

the aim of this study is to apply an integrated methodological approximation where dendrochronology and documentary analysis allow us to reconstruct the historical flood record of the Segovia Mint. Our hypothesis is that differences between the dendrochronological data of the wooden decking pieces can be related to historical floods and, therefore, they could be used as proxy-source data in future palaeoflood research.

Unconformity-bounded stratigraphic units (UBSUs) in an italian alluvial-plain area: recognizing and dating

We studied the coastal zone of the Tavoliere di Puglia plain, (Puglia region, southern Italy) with the aim to recognize the main unconformities, and therefore, the unconformity-bounded stratigraphic units (UBSUs; Salvador 1987, 1994) forming its Quaternary sedimentary fill. Recognizing unconformities is particularly problematic in an alluvial plain, due to the difficulties in distinguishing the unconformities that bound the UBSUs. So far, the recognition of UBSUs in buried successions has been made mostly by using seismic profiles. Instead, in our case, the unavailability of the latter has prompted us to address the problem by developing a methodological protocol consisting of the following steps: I) geological survey in the field; II) draft of a preliminary geological setting based on the field-survey results; III) dating of 102 samples coming from a large number of boreholes and some outcropping sections by means of the amino acid racemization (AAR) method applied to ostracod shells and 14C dating, filtering of the ages and the selection of valid ages; IV) correction of the preliminary geological setting in the light of the numerical ages; definition of the final geological setting with UBSUs; identification of a ‘‘hypothetical’’ or ‘‘attributed time range’’ (HTR or ATR) for each UBSU, the former very wide and subject to a subsequent modification, the latter definitive; V) cross-checking between the numerical ages and/or other characteristics of the sedimentary bodies and/or the sea-level curves (with their effects on the sedimentary processes) in order to restrict also the hypothetical time ranges in the attributed time ranges. The successful application of AAR geochronology to ostracod shells relies on the fact that the ability of ostracods to colonize almost all environments constitutes a tool for correlation, and also allow the inclusion in the same unit of coeval sediments that differ lithologically and paleoenvironmentally. The treatment of the numerical ages obtained using the AAR method required special attention. The first filtering step was made by the laboratory (rejection criteria a and b). Then, the second filtering step was made by testing in the field the remaining ages. Among these, in fact, we never compared an age with a single preceding and/or following age; instead, we identified homogeneous groups of numerical ages consistent with their reciprocal stratigraphic position. This operation led to the rejection of further numerical ages that deviate erratically from a larger, homogeneous age population which fits well with its stratigraphic position (rejection criterion c). After all of the filtering steps, the valid ages that remained were used for the subdivision of the sedimentary sequences into UBSUs together with the lithological and paleoenvironmental criteria. The numerical ages allowed us, in the first instance, to recognize all of the age gaps between two consecutive samples. Next, we identified the level, in the sedimentary thickness that is between these two samples, that may represent the most suitable UBSU boundary based on its lithology and/or the paleoenvironment. The recognized units are: I) Coppa Nevigata sands (NEA), HTR: MIS 20–14, ATR: MIS 17–16; II) Argille subappennine (ASP), HTR: MIS 15–11, ATR: MIS 15–13; III) Coppa Nevigata synthem (NVI), HTR: MIS 13–8, ATR: MIS 12–11; IV) Sabbie di Torre Quarto (STQ), HTR: MIS 13–9.1, ATR: MIS 11; V) Amendola subsynthem (MLM1), HTR: MIS 12–10, ATR: MIS 11; VI) Undifferentiated continental unit (UCI), HTR: MIS 11–6.2, ATR: MIS 9.3–7.1; VII) Foggia synthem (TGF), ATR: MIS 6; VIII) Masseria Finamondo synthem (TPF), ATR: Upper Pleistocene; IX) Carapelle and Cervaro streams synthem (RPL), subdivided into: IXa) Incoronata subsynthem (RPL1), HTR: MIS 6–3; ATR: MIS 5–3; IXb) Marane La Pidocchiosa–Castello subsynthem (RPL3), ATR: Holocene; X) Masseria Inacquata synthem (NAQ), ATR: Holocene. The possibility of recognizing and dating Quaternary units in an alluvial plain to the scale of a marine isotope stage constitutes a clear step forward compared with similar studies regarding other alluvial-plain areas, where Quaternary units were dated almost exclusively using their stratigraphic position. As a result, they were generically associated with a geological sub-epoch. Instead, our method allowed a higher detail in the timing of the sedimentary processes: for example, MIS 11 and MIS 5.5 deposits have been recognized and characterized for the first time in the study area, highlighting their importance as phases of sedimentation.

Optical absorption analysis of quaternary molybdate- and tungstate-ordered double perovskites

Quaternary-ordered double perovskite A2MM’O6 (M=Mo,W) semiconductors are a group of materials with a variety of photocatalytic and optoelectronic applications. An analysis focused on the optoelectronic properties is carried out using first-principles density-functional theory with several U orbital-dependent one-electron potentials applied to different orbital subspaces. The structural non-equivalence of the atoms resulting from the symmetry has been taken in account. In order to analyze optical absorption in these materials deeply, the absorption coefficients have been split into inter- and intra-non-equivalent species contributions. The results indicate that the effect of the A and M’ atoms on the optical properties are minimal whereas the largest contribution comes from the non-equivalent O atoms to M transitions.

Protein diagenesis in Patella shells: implications for amino acid racemisation dating

Se analiza la racemización de aminoácidos en proteínas inter e intracristalinas en conchas de Patella y su utilización como herramienta geocronológica, fundamentalmente empleadas en yacimientos arqueológicos.The inter- and intra-crystalline fractions of Patella vulgata limpets recovered from archaeological sites in Northern Spain (covering Neolithic, Mesolithic, Magdalenian, Solutrean, and Aurignacian periods) were examined for amino acid composition and racemisation over time. The calcitic apex and rim areas of the shells were found to probably be composed of similar proteins, as the D/L values and amino acids were comparable and varied in the same way with increasing age; however, the mineral structures present in these areas differed. The aragonitic intermediate part of the shell showed a distinctly different amino acid composition and mineral structure. The main protein leaching from the inter-crystalline fraction occurred within the first 6000 yr after the death of the organism. In contrast, the intra-crystalline fraction — comprised of a different protein composition than the inter-crystalline fraction — appeared to behave as a closed system for at least 34 ka, as reflected by the lack of a significant decrease in the amino acid content; however, changes in the amino acid percentages occurred during this period. The concentration of aspartic acid remained almost constant with age both in inter- and intra-crystalline proteins, and its contribution to the total amino acid content increased with age at the expense of other amino acids such as glutamic acid, serine, glycine and alanine. Temperature is thought to play a key role in the amino acid racemisation of P. vulgata and could explain why in the localities belonging to the Gravettian and Solutrean period, which formed during relatively cold conditions, D/L values were similar to those detected in shells from sites formed during the Magdalenian.

Amino acid epimerization dating of coastal neotectonic processes in southeastern Iberian Peninsula: the region between Aguas and Antas river mouths

The coastal area between the mouths of the Aguas and Antas Rivers presents a deformed system of raised marine deposits, some of which have been strongly affected by active tectonics. The use of amino acid epimerization dating of Glycymeris shells from raised coastal deposits allowed determining the age of these marine deposits, all of them linked to highstand sea levels in the Mediterranean realm, with ages between MIS 11 and MIS 1. These results allowed corroborating the age of some previously studied sites, and using new sampling sites, the general aminostratigraphy for the Quaternary raised marine deposits on the Mediterranean coast was confirmed. The main deformation event took place after MIS 11 and continued until MIS 5, and was linked to the activity of the Palomares Faul