22 research outputs found

    Stratigraphic units of the Apulian Tavoliere plain (Southern Italy): Chronology, correlation with marine isotope stages and implications regarding vertical movements

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    The geologic study of the Apulian Tavoliere plain (Apulia region, southern Italy) is extremely difficult due to the scarcity of outcrops and fauna that could be used for dating. The survey in progress of the 1:50,000 scale geological sheet no. 409 “Zapponeta” (including the coastal zone of the Apulian Tavoliere) has prompted us to tackle this problem by using a large set of borehole data and the AAR dating method applied to ostracod shells, which are capable of colonizing all types of environment as long as there is water. This alternative approach has allowed us to recognise nine stratigraphic units or synthems and, for the first time in this area, to date them, and to find a correlation between them and the cycles of sea level variation. The recognised stratigraphic units are: the Coppa Nevigata sands (NEA; middle Pleistocene: MIS 17–16), argille subappennine unit (ASP; middle Pleistocene: MIS 15–13), the Coppa Nevigata synthem (NVI; middle Pleistocene: MIS 11), the Amendola subsynthem (MLM1; middle Pleistocene: MIS 11), an undifferentiated continental unit (UCI; middle Pleistocene: MIS 8–7), the Foggia synthem (TGF; middle–late Pleistocene: MIS 6), the Carapelle and Cervaro streams synthem (RPL; late Pleistocene: MIS 5–3), and the Inacquata farm synthem (NAQ; Holocene). Within the RPL unit, a buried Cladocora caespitosa bioherm referable to MIS 5.5, lacking in warm fauna, and in which the coral is embedded in clay has been found in some boreholes. This is the first finding of Tyrrhenian deposits with C. caespitosa along the Italian Adriatic coast; the presence of this coral in clayey sediments, a very uncommon occurrence, strengthens the hypothesis that the major fossil reefs grew in coastal waters that were characterised by alluvial inputs of fine sediments, higher turbidity, and higher temperature than today. In addition, on the basis of the current evidence, some consideration about the fauna of the MIS 5.5 layer allows us to hypothesise that the Adriatic Sea underwent a more moderate warming compared to that of the Ionian and Tyrrhenian seas. Instead, the finding in the NVI unit of a tropical lagoonal deposit with stromatolites referred to MIS 11 proves that the warming in this stage was undoubtedly greater than that of MIS 5.5. The MM4 borehole, which goes through the MIS 5 layers of the RPL unit, made it possible to recognise two marine phases during MIS 5: the first is referable to the MIS 5.5–5.3 interval, and the second to MIS 5.1. MIS 5.2 is marked by land emersion, whereas no evidence of land emersion between MIS 5.5 and 5.3 has been found. Also for the first time in this area, uplifting and subsiding areas have been recognised and the vertical movements assessed. In general, the data suggest that the Garganic Apulian foreland and the Amendola highland experienced an uplift, while the central-southern part of the study area, belonging to the Apulian Tavoliere plain, suffered a subsidence with rates increasing from north–northwest to south–southeast. In particular, the finding of the MIS 5.5 buried layer with C. caespitosa has allowed us to fill a gap in the data regarding the recent tectonic movements along the Adriatic coast (Ferranti et al., 2006). This feature proves that there has been a recent subsidence event since MIS 5.5 in the coastal area of the Apulian Tavoliere plain

    Eolianitas costeras del Pleistoceno superior en el "Sitio de Interés Científico de Tufia"(Gran Canarias):sedimentología, petrografía y aminocronología

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    Los niveles de eolianitas costeras de Tufia (Este de Gran Canaria) aparecen de forma dispersa en un área de 54,1 ha y presentan estratificaciones cruzadas de gran escala, bases erosivas, rizolitos y bandas con gasterópodos terrestres. Estos depósitos eólicos están constituidos por arenas de grano fino y, en menor medida, medio, y están entre bien y moderadamente seleccionadas. Los granos terrígenos predominan sobre los bioclastos en las eolianitas de Aguadulce y Botonera, y en los sedimentos de trasplaya, y tienen proporciones similares en las eolianitas de la Cantera. Entre los granos terrígenos destacan los fragmentos de rocas volcánicas básicas y de minerales ferromagnesianos, mientras que entre los bioclastos predominan las mallas de algas coralinas rojas y moluscos. Las edades definidas mediante análisis de racemización/epimerización de conchas de los géneros Theba y Hemicycla oscilan entre 31,2±6,2 y 39±8,8 Ka BP, por lo que son depósitos eólicos del Pleistoceno Superior, relacionados con las Aminozonas 3 y 4 establecidas para las Islas Canarias orientales y coincidentes con los Episodios de Heinrich 4 y 3. Por lo tanto, las eolianitas de Tufia se habrían formado durante una época de regresión marina y las dataciones corresponderían a la etapa isotópica OIS 3. Coastal aeolianite strata from Tufia (Eastern Gran Canaria Island) appear dispersed in an area of 54.1 hectares and they show large scale cross bedding, erosive bases, rhizoliths and terrestrial gastropod shells. These aeolian deposits are formed by fine grain sands and, in lower proportion, medium, and are between well and moderately sorted. The terrigenous grains predominate over bioclasts in the aeolianites of Aguadulce and Botonera, and in the backshore sediments, and these components appear in similar proportions at the Cantera. The volcanic basic rocks and ferromagnesian mineral fragments stand out as terrigenous grains, whereas, among bioclasts the red coralline algae and mollusc fragments predominate. The dates defined through racemization/epimerization analysis of Theba and Helicycla shells range between 31,2±6,2 y 39±8,8 Ka BP, that is why they are aeolian deposits of Upper Pleistocene, related to the 3 and 4 Aminozones established for oriental Canary Islands and coincident with 4 and 3 Heinrich Episodes. Therefore, Tufia aeoleanites would have been formed during a marine regression and the date would correspond with the OIS 3 isotopic stage

    Geomorphological evolution of the Rimac River’s alluvial fan, Lima, Peru

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    The alluvial fan of Lima is a complex landform, resulting from the sediment contributions of the Rimac River and the coalescence of the alluvial fans of the tributaries of the Rimac River. Depositional zones in the fan and changing main channel and distributary channels are influenced by the palaeo-relief inherited from a semi-arid climate and by the climatic changes. The upper sedimentary sequence of the fan, dominant on the Costa Verde, is of Upper Pleistocene–Holocene age. The sediments forming it are non-cohesive and are highly mobile during floods and earthquakes. The dominant features in this sequence, intertwined channel facies and laminar flows, were influenced by the Pleistocene–Holocene postglacial marine transgressions. A deeper understanding of the evolution of the Lima alluvial fan provides insight in to the fan’s future evolution in the framework of active tectonics and climate change. The Lima fan is an area with high human population density and is subjected to floods and debris flows resulting in subsequent loss of human life and properties. Therefore, the improved understanding of the fan’s evolution, resulting from this study, will contribute to a better definition of high risk areas of potential human disaster caused by these natural processes. Cyclic-fandevelopment, presently controlled by glacial sea level lows and palaeo-topography will continue regardless of human intervention in attempts to prevent natural disasters in Lima

    Biometría de Strombus bubonius Lamark 1791 del yacimiento de Cerro Largo (Roquetas de Mar, Almería)

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    This paper deals with a comparative metrical study of the mesogastropods Strombus bubonius and Strombus latus. The former from the raised marine deposits of Cerro Largo (Roquetas de Mar, Almería) of Middle Pleistocene age, and the second still living in the Gulf of Guinea and Cabo Verde Islands. The high correlation between length and maximum width reveals a positive allometrical relationship in fossil and living species. There is a good metrical coincidence between Cerro Largo S. bubonius representatives and S. latus from Cabo Verde, while S. latus representatives from Guinea and Senegal reach larger sizes. It is postulated that a partially developed sexual dimorphism explains the co-occurrence at the same beds of small and big sized S. bubonius shells

    Identificación de las principales fases áridas del Pleistoceno superior en el registro sedimentario lacustre del maar de Fuentillejo (Campo de Calatrava)

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    Se han realizado análisis de facies sedimentarias, geoquímicos (análisis elemental, análisis moleculares de la fracción orgánica), propiedades físicas, palinológicos y mineralógicos para caracterizar el registro sedimentario de la laguna del maar de Fuentillejo, en la región volcánica central de España de Campo de Calatrava, con el objetivo de reconstruir los procesos paleoambientales y paleoclimáticos que controlaron los patrones de la vegetación y la sedimentación. Los primeros 29 m del sondeo FU-1 muestran acusadas variaciones en el aporte de terrígenos, la química de las aguas, la vegetación y en la fracción orgánica a lo largo del Pleistoceno superior y Holoceno. En las facies de dolomicritas (con magnesita y analcima), los datos polínicos muestran un incremento del componente herbáceo, fundamentalmente taxones estépicos –Chenopodiaceae, Artemisia y Ephedra-; junto con un índice Paq bajo, descenso en el porcentaje relativo de alcano n-C27 y un incremento de alcano n-C31. Esta facies, probablemente, es el resultado de un bajo nivel del lago y condiciones salinas-alcalinas, que se han interpretado como el periodo más árido en el techo de la unidad 19.2. Las facies siliciclásticas con valores altos de susceptibilidad magnética, alto contenido en polen de Juniperus, bajo índice Paq, descenso en el porcentaje relativo de alcanos n-C27 e incremento de n-C31 son indicativos de eventos climáticos áridos y fríos. Geochemical (elemental analysis, molecular analysis of organic compounds), physical, palynological, mineralogical and sedimentary facies analysis were performed to characterize the sedimentary record in Fuentillejo maar lake in the Central Spanish Volcanic Field of Calatrava, in order to reconstruct the paleoenvironmental and paleoclimatic processes which controlled vegetation patterns and deposition of different sedimentary facies. The upper 29 m of FU-1 core point out variations in clastic input, water chemistry, vegetation and organic fraction sources in the lake throughout the late Pleistocene and Holocene. In dolomite-mud facies (magnesite and analcime), the pollen data shows an increase of the herbs component, mainly –Chenopodiaceae, Artemisia and Ephedra- steppe taxa; low Paq index, decrease in the relative percentage of the n-C27 alkane and increase in the n-C31 alkane are also observed. This facies was probably the result of lower lake levels and more saline-alkaline conditions which can be interpreted as linked to the most arid periods, especially in the top of unit 19.2. Siliciclastic facies with high magnetic susceptibility values, high Juniperus pollen content, low Paq index, decrease in the relative percentage of the n-C27 alkane and increase in the n-C31 alkane are indicative of arid and colder climatic events

    A new Late Pleistocene non-anthropogenic vertebrate assemblage from the northern Iberian Peninsula: Artazu VII (Arrasate, Basque Country)

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    Late Pleistocene palaeontological sites without human intervention are limited in the Cantabrian region, and even more so those with a good state of preservation and rich biodiversity. A new vertebrate fossiliferous locality discovered at Kobate Quarry (Arrasate, northern Iberian Peninsula) is presented in this article. This site, in which remains of 40 different vertebrate taxa were accumulated, acted as a natural trap. The preliminary vertebrate faunal list includes five amphibian taxa, four reptiles, seven species of birds and 24 mammalian taxa. While small mammals are represented by 13 small mammal taxa (seven in the Order Rodentia, five in the Order Eulipotyphla, and one in the Order Chiroptera), the large mammal fauna comprises eleven species, including ungulates and carnivores. The palaeoecology inferred from this faunal assemblage suggests the existence of large forested areas with some grassland and a watercourse nearby, within a notably warm and humid climate. These palaeoenvironmental conditions, combined with AMS and AAR results carried out in macrofaunal bone samples, suggest that the deposit from Artazu VII would be located in the first half of the Late Pleistocene, in the Marine Isotope Stage (MIS) 5c. Résumé Les gisements paléontologiques de la fin du Pléistocène sont limités dans la région Cantabrique, et encore plus limités sont les sites ayant fourni des restes osseux en bon état de conservation et montrant une grande biodiversité. Nous présentons ici un nouveau site trouvé dans la carrière de Kobate (Arrasate, Nord de la péninsule Ibérique). Ce site a certainement agi comme un piège naturel et contient une accumulation de restes appartenant à 40 espèces différentes de vertébrés. La liste préliminaire de la faune de vertébrés comprend cinq taxons d’amphibiens, quatre de reptiles, sept espèces d’oiseaux et 24 taxons de mammifères. Alors que les mammifères sont représentés par 13 taxons de micromammifères (sept appartiennent à l’ordre Rodentia, cinq à l’ordre Eulipothypla, et un à l’ordre Chiroptera), les grands mammifères sont représentés par onze espèces, y compris des ongulés et des carnivores. Cette association faunique suggère un paléoenvironnement caractérisé par de vastes étendues boisées avec quelques prairies et un cours d’eau à proximité, dans un climat particulièrement chaud et humide. Ces conditions paléoenvironnementales, combinées à des datations AMS et AAR à partir d’échantillons d’os de la macrofaune, permettent de localiser le gisement d’Artazu VII dans la première moitié du Pléistocène supérieur, et plus précisement dans le stade isotopique marin (MEI) 5c

    Los gasterópodos terrestres del Cuaternario Superior de Gran Canaria (Islas Canarias)- Land gastropods of the Upper Quaternary in Gran Canaria (Canary Islands)

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    Hemos estudiado la estratigrafía, cronología y paleontología de ocho depósitos sedimentarios (siete paleodunas y un derrubio de ladera) del Pleistoceno Superior de la isla de Gran Canaria (Islas Canarias). Las paleodunas se caracterizan por una alternancia de dunas y paleosuelos, que varía entre un ciclo en la Playa de Jinámar, y once en el Lazareto (Gando). La cronología de estos depósitos, obtenida por racemización de aminoácidos sobre ejemplares del género Theba y calibrada con 14C, muestra una edad entre 44,4 Ka a 22,2 Ka. La aminoestratigrafía ha permitido asignar estos depósitos a cuatro aminozonas (AM2 a AM5) de las registradas por Ortiz et al. (2006). Las asociaciones fósiles de gasterópodos terrestres están representadas por 20 especies pertenecientes a 8 familias, con un grado de endemismo del 95%. Los cambios faunísticos detectados, con respecto a la actualidad, se refieren a la extinción del 25 % de las especies del Pleistoceno Superior, y a la disminución de la extensión geográfica de algunas especies como Theba arinagae y T. aff. grasseti. - A stratigraphic, chronological and paleontological study of eight sedimentary deposits (seven palaeodunes and a colluvial slide) in the Upper Pleistocene of Gran Canaria (Canary Islands) has been undertaken. The palaeodunes are characterized by dune-palaeosoil alternation, from an only cycle in Playa de Jinámar to eleven in Lazareto (Gando). The chronology of these deposits, obtained by amino acid racemisation and 14C datations in Theba genus samples, displays an age between 44,4 Ka and 22,2 Ka. The aminostratigraphy study appoints to these sediments belong to four amino zones (AM2 to AM5) reported by Ortiz et al. (2006). The land snail fossil assemblages are represented by 20 species belonging to eight families, with an endemic degree around 95%. The detected fossil fauna changes with regard to present fauna reveal an Upper Pleistocene species extinction at about 25% and geographic extension decreasing of some species as Theba arinagae and T. aff. grasset

    The Last Interglacial from a continental area in Western Mediterranean. The Fuentillejo maar lacustrine record, Central Spain

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    The Fuentillejo maar is located in the Central Spanish Volcanic Field of Campo de Calatrava. Fuentillejo maar-lake has been a closed system and contains over 142 m of lacustrine sediments (Martín-Serrano et al., 2009). Geochemical (element analysis, molecular analysis of organic compounds), physical, palynological, stable isotope analysis, mineralogical and sedimentan/ facies analysis were performed to characterize the sedimentan/ record in the 57-59.3 m depth interval of core FUENT-1. These proxies reconstruct the paleoenvironmental and paleoclimatic processes which controlled vegetation patterns, lake water level and deposition of sedimentan/ facies occurred during the Last Interglacial period

    Vegetation evolution during the Last Maximum Glacial Periodin FU-1 sequence (Fuentillejo Lacustrin «Maar», Campo de Calatrava, Ciudad Real)

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    We show data pollen, of core in Fuentillejo-1 (FU-1) located in the maar lake Fuentillejo site (Campo de Calatrava, Ciudad Real), in order to know the palaeoenviromental changes. The sedimentary record upper 10 m (unit 23), show a deposition of different sedimentary facies, during the last 20240 a. cal BP. The decrease of forest and low diversity values are characteristiques to the Last Maximum Glacier. The expansion of thermophilous trees and human activity signal have been identified the Holoceno.Se presentan los datos polínicos, procedentes del sondeo Fuentillejo-1 (FU-1), realizado en el centro de la laguna del maar de Fuentillejo (Campo de Calatrava, Ciudad Real). La descripción del registro sedimentario de los primeros 10 m, correspondiente a la unidad litológica 23 del registro sedimentario del sondeo FU-1, ha permitido interpretar cuáles fueron los condicionantes ambientales y climáticos con anterioridad a 20240 a. cal. BP. El descenso de la masa forestal, la pérdida de diversidad y la existencia de niveles estériles en el contenido de polen definen las características climáticas durante el Último Máximo Glaciar; la recuperación del bosque mediterráneo y la actividad antrópica identifican al Holoceno.</span
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