http://www.recercat.cat:80/handle/2072/48806 www.ub.edu Thu, 20 Jun 2013 09:29:02 GMT 2013-06-20T09:29:02Z http://www.recercat.cat:80/bitstream/id/26375/ http://www.recercat.cat:80/handle/2072/48806 http://www.recercat.cat:80/handle/2072/211547 Vegetation changes and human settlement of Easter Island during the last millennia: a multiproxy study of the Lake Raraku sediments Cañellas-Boltà, Núria; Rull, Valentí; Sáez, Alberto; Margalef, Olga; Bao, Roberto; Pla Rabés, Sergi; Blaauw, Maarten; Valero-Garcés, Blas; Giralt, Santiago Earlier palynological studies of lake sediments from Easter Island suggest that the island underwent a recent and abrupt replacement of palm-dominated forests by grasslands, interpreted as a deforestation by indigenous people. However, the available evidence is inconclusive due to the existence of extended hiatuses and ambiguous chronological frameworks in most of the sedimentary sequence studied. This has given rise to an ongoing debate about the timing and causes of the assumed ecological degradation and cultural breakdown. Our multiproxy study of a core recovered from Lake Raraku highlights the vegetation dynamics and environmental shifts in the catchment and its surroundings during the late Holocene. The sequence contains shorter hiatuses than in previously recovered cores and provides a more continuous history of environmental changes. The results show a long, gradual and stepped landscape shift from palm dominated forests to grasslands. This change started c. 450 BC and lasted about two thousand years. The presence of Verbena litoralis , a common weed, which is associated with human activities in the pollen record, the signi ficant correlation between shifts in charcoal influx, and the dominant pollen types suggest human disturbance of the vegetation. Therefore, human settlement on the island occurred c. 450 BC, some 1500 years earlier than is assumed. Climate variability also exerted a major influence on environmental changes. Two sedimentary gaps in the record are interpreted as periods of droughts that could have prevented peat growth and favoured its erosion during the Medieval Climate Anomaly and the Little Ice Age, respectively. At c. AD 1200, the water table rose and the former Raraku mire turned into a shallow lake, suggesting higher precipitation/evaporation rates coeval with a cooler and wetter Pan-Pacific AD 1300 event. Pollen and diatom records show large vegetation changes due to human activities c. AD 1200. Other recent vegetation changes also due to human activities entail the introduction of taxa (e.g. Psidium guajava, Eucalyptus sp.) and the disappearance of indigenous plants such as Sophora toromiro during the two last centuries. Although the evidence is not conclusive, the American origin of V.litoralis re-opens the debate about the possible role of Amerindians in the human colonisation of Easter Island. http://www.recercat.cat:80/handle/2072/211547 http://www.recercat.cat:80/handle/2072/210667 Magnetoestratigrafía de la sección de Vilanova de Prades y su implicación en la datación de las estructuras de las Cadenas Costeras Catalanas (Paleógeno, margen SE de la cuenca del Ebro). López Blanco, Miguel; Garcés Crespo, Miguel; Barberà,X.; Cabrera, Lluís Magnetostratigraphic data have been studied and interpreted along a stratigraphic section on the paleogene deposits on the SE Ebro Basin at Vilanova de Prades locality. http://www.recercat.cat:80/handle/2072/210667 http://www.recercat.cat:80/handle/2072/210668 Resultados preliminares en la caracterización geométrica 3D de un litosoma arenoso de progradación deltaica mediante Georadar (GPR) (Fm. Arenisca de Roda, Eoceno, Cuenca de Graus-Tremp). Coll, M.; López Blanco, Miguel; Marcuello Pascual, Alejandro A set of GPR profiles have been recorded in order to determine the 3D geometry of a prograding delta-front sandbody (Roda sandstone formation, Eocene, Graus-Tremp basin). Common Mid Points (CMP) also have been recorded to obtain the velocity of the electromagnetic wave in ground. In order to build the topsurface of a 3D prism a set of topographic points have been acquired. Most of the GPR profiles are oriented parallel to the progradation direction (NNE-SSW) and show the expected geometries. The 3D prism has been built from the individual profiles, which shows the three dimensional geometry of the sandy lithosome. http://www.recercat.cat:80/handle/2072/210668 http://www.recercat.cat:80/handle/2072/210669 Presencia de la icnoespecie Dactyloidites Ottoi en el complejo de abanico costero de Sant Llorenç del Munt (Eoceno, Cuenca del Ebro, NE de España). Gibert Atienza, Jordi Maria de; López Blanco, Miguel; Ramos Guerrero, Emilio The presence of Dactyloidites ottoi is first recorded in the Eocene Sant Llorenç del Munt fan-delta complex. This constitutes the first citation for the Paleogene. The ichnospecies occurs in the lower part of a prograding fan-delta front sequence, associated to other traces produced by sediment-feeders. This association is substituted in the upper part of the sequence by abundant vertical Ophiomorpha indicating an increase of energetic conditions. The paleoenvironmental setting interpreted for Dactyloidites is consistent with that of previous described occurrences. http://www.recercat.cat:80/handle/2072/210669 http://www.recercat.cat:80/handle/2072/210666 A Mammalian Lost World in Southwest Europe during the Late Pliocene. Arribas, A.; Garrido, G.; Viseras, C.; Soria, J.; Pla, S.; Solano, J.G.; Garcés Crespo, Miguel; Beamud, E.; Carrión, J.S. Over the last decades, there has been an increasing interest on the chronology, distribution and mammal taxonomy (including hominins) related with the faunal turnovers that took place around the Pliocene-Pleistocene transition [ca. 1.8 mega-annum (Ma)] in Europe. However, these turnovers are not fully understood due to: the precarious nature of the period's fossil record; the"non-coexistence" in this record of many of the species involved; and the enormous geographical area encompassed. This palaeontological information gap can now be in part bridged with data from the Fonelas P-1 site (Granada, Spain), whose faunal composition and late Upper Pliocene date shed light on some of the problems concerning the timing and geography of the dispersals. http://www.recercat.cat:80/handle/2072/210666 http://www.recercat.cat:80/handle/2072/210543 The fossil crown wasp Electrostephanus petiolatus Brues in Baltic Amber (Hymenoptera, Stephanidae): designation of a neotype, revised classification,and a key to amber Stephanidae. Engel, M. S.; Ortega Blanco, Jaime The fossil crown wasp Electrostephanus petiolatus Brues comb. rev.(Stephanidae, Electrostephaninae) is re-described from a single male preserved in middle Eocene Baltic Amber. The holotype was lost or destroyed around the time of World War II and subsequent interpretations of its identity have been based solely on the brief descriptive comments provided by Brues in his original account. The new specimen matches the original description and illustration provided by Brues in every detail and we hereby consider them to be conspecific, selecting the specimen as a neotype for the purpose of stabilizing the nomenclature for this fossil species. This neotype exhibits a free first metasomal tergum and sternum, contrary to the assertion of previous workers who indicated these to be fused. Accordingly, this species does indeed belong to the genus Electrostephanus Brues rather than to Denaeostephanus Engel & Grimaldi (Stephaninae). Electrostephanus petiolatus is transferred to a new subgenus, Electrostephanodes n. subgen. , based on its elongate pseudo- petiole and slender gaster, but may eventually warrant generic status as the phylogenetic placement of these fossil lineages continues to be clarifi ed. A revised key to the Baltic amber crown wasps is provided. http://www.recercat.cat:80/handle/2072/210543 http://www.recercat.cat:80/handle/2072/210486 Snakefly diversity in Early Cretaceous amber from Spain (Neuropterida, Raphidioptera) Pérez-de la Fuente, R.; Peñalver, E.; Delclòs Martínez, Xavier; Engel, M.S. The Albian amber from Spain presently harbors the greatest number and diversity of amber adult fossil snakeflies (Raphidioptera). Within Baissopteridae, Baissoptera? cretaceoelectrasp. n., from the Peñacerrada I outcrop (Moraza, Burgos), is the first amber inclusion belonging to the family and described from western Eurasia, thus substantially expanding the paleogeographical range of the family formerly known from the Cretaceous of Brazil and eastern Asia. Within the family Mesoraphidiidae, Necroraphidia arcuatagen. et sp. n. and Amarantoraphidia ventolinagen. et sp. n. are described from the El Soplao outcrop (Rábago, Cantabria), whereas Styporaphidia? hispanicasp. n. and Alavaraphidia imperterritagen. et sp. n. are describedfrom Peñacerrada I. In addition, three morphospecies are recognized from fragmentary remains. The following combinations are restored: Yanoraphidia gaoi Ren, 1995, stat. rest., Mesoraphidia durlstonensis Jepson, Coram and Jarzembowski, 2009, stat. rest., and Mesoraphidia heteroneura Ren, 1997, stat. rest. The singularity of this rich paleodiversity could be due to the paleogeographic isolation of the Iberian territory and also the prevalence of wildfires during the Cretaceous. http://www.recercat.cat:80/handle/2072/210486 http://www.recercat.cat:80/handle/2072/210485 New and revised maimetshid wasps from cretaceous ambers (Hymenoptera, Maimetshidae) Perrichot, V.; Ortega Blanco, Jaime; Mc Kellar, R.C.; Delclòs Martínez, Xavier; Azar, D.; Nel, A.; Tafforeau, P.; Engel, M.S. New material of the wasp family Maimetshidae (Apocrita) is presented from four Cretaceous amber de- posits<br> the Neocomian of Lebanon, the Early Albian of Spain, the latest Albian/earliest Cenomanian of France, and the Campanian of Canada. The new record from Canadian Cretaceous amber extends the temporal and paleogeographical range of the family. New material from France is assignable to Guyote- maimetsha enigmatica Perrichot et al. including the first females for the species, while a series of males and females from Spain are described and figured as Iberomaimetsha Ortega-Blanco, Perrichot & Engel, gen. n., with the two new species Iberomaimetsha rasnitsyni Ortega-Blanco, Perrichot & Engel, sp. n. and I. nihtmara Ortega-Blanco, Delclòs & Engel, sp. n.; a single female from Lebanon is described and figured as Ahiromaimetsha najlae Perrichot, Azar, Nel & Engel, gen. et sp. n., and a single male from Canada is described and figured as Ahstemiam cellula McKellar & Engel, gen. et sp. n. The taxa are compared with other maimetshids, a key to genera and species is given, and brief comments made on the family. http://www.recercat.cat:80/handle/2072/210485 http://www.recercat.cat:80/handle/2072/210206 Magnetoestratigrafía de las sucesiones del Mioceno medio y superior del Vallés occidental (Depresión del Vallés-Penedés, NE España): Implicaciones biocronológicas y cronoestratigráficas. Garcés Crespo, Miguel The magnetostratigraphic analysis of the middle to late Miocene continental deposits from the Valles-Penedes basin, combined with its well-documented fossil mammal record, provides a well-resoluted chronology for the upper basin infill. It is based on the biostratigraphic and magnetostratigraphic cross-correlation of 18 sections throughout the alluvial and transitional/shallow marine sequences in the Western Valles area. The biostratigraphic framework consists of 24 mammal localities of upper Aragonian and Vallesian age. Correlation of the studied sections to the geomagnetic polarity time scale (GPTS) is based on the distinctive pattern of local magnetozones, as well as the radiometric age of the late Vallesian fauna from the Bicorp Basin (9.6 + 0.3 Ma) and the known relationship of the late Vallesian assemblages with marine beds belonging to the planktonic forarninifera N16 zone. It has led to an absolute dating of the fauna1 events and a precise chronostratigraphy of the Vallesian marnrnal stage in its type area. The Hipparion First Appearance Datum (FAD) defines the lower Vallesian boundary and is dated at 11.1 Ma, at the base of chron C5r. ln. It is in good agreement with radiometric ages from the early Hipparion bearing sites in the Vienna Basin (1 1.1 * 0.5 Ma) and the classic Howenegg locality in Germany (10.8 * 0.3 Ma). It also agrees with the age of the turkish localities of Yailacilar (1 1.6 + 0.25 Ma) and Yenieskihisar-2 (1 1.1 * 0.2 Ma) with absence of Hipparion. Al1 these support the isochrony of the dispersa1 of Hipparion throughout the Mediterranean region. A possible isochrony at a larger geographical scale (Old World, Mesogea) must await more reliable ages of the Hipparion FAD in Asia and Africa. The Cricetulodon FAD that defines the MN9a/MN9b boundary occurs at the middle part of C5n. Assuming an on average constant sedimentation rate, this datum has an age of approximately 10.4 Ma. The earlyllate Vallesian boundary is marked by one of the most distinct fauna1 events of the late Neogene: the dispersa1 of the muridae Progonomys into Europe and North Africa, which coincides with an important macromarnmal turnover. The first extensive appearance of Progonomys in Europe (MN9íMN10 boundary) is dated at 9.7 Ma (C4Ar3r), showing a remarkable diachrony with the Himalayan region. F9i d lly, the FAD of Rotundomys bressnnus occurs in the upper part of C4Ar.ln (9.2-9.3 Ma). The Vallesian spans 2.4 Myr, from 11.1 Ma (CSr.ln) to 8.7 Ma (C4An), and correlates to the early Tortonian. http://www.recercat.cat:80/handle/2072/210206 http://www.recercat.cat:80/handle/2072/210207 Los nummulítidos (Nummulites y Assilina) del Paleoceno Superior-Eoceno Inferior de la cuenca pirenaica: Sistemaáica. Tosquella i Angrill, Josep; Serra-Kiel, Josep Se ha realizado el estudio sistemático de los nummulítidos pertenecientes a los géneros Nummulites y Assilina del intervalo Paleoceno Superior - Eoceno Inferior de la Cuenca Pirenaica, a partir de muestras procedentes principalmente del sector meridional de la cuenca. Los taxones descritos se han comparado con especímenes procedentes de otras cuencas de la Mesogea: Alpes suizos (Schlieren- y Gumigelflysch) y austríacos (unidades alóctonas helvéticas), norte de Italia (Verona y Vicenza), plataformas marinas adriáticas (Eslovenia y Croacia), península de Crimea (Ucrania), Cuenca de Haymana (Anatolia central, Turquía), y Salt Range (Pakistán). Se han descrito 98 taxones de nummuiítidos -entre especies y subespecies-, de los cuales: - 66 taxones del género Nummulites, pertenecientes a los grupos de N. perforatus, N. partschi, N. rotularius, N. minewensis, N. globulus, N. laevigatus, N. distans, N. heberti y N. spirectypus. - 32 taxones del género Assilina, pertenecientes a los gmpos de A. spira, A. exponens, A. subgranulosa, A. ammonea, A. canalijera y A. alpina. En este trabajo -y siguiendo las consideraciones de Loeblich y Tappan (1987)- Assilina integra las denominaciones gen6ricas tradicionales de Assilina y Operculina. http://www.recercat.cat:80/handle/2072/210207 http://www.recercat.cat:80/handle/2072/210204 Pisolitos ferruginosos en el Mioceno inferior-medio de Mallorca. Ramos Guerrero, Emilio; Segovia, B. El registro sedimentario Burdigaliense-Langhiense de Mallorca refleja el relleno de pequeños surcos de antepaís que se generaron por subsidencia flexural frente al orógeno bético. Este registro sinorogénico incluye una unidad inferior que caracteriza la sedimentación en una plataforma marina somera (Fm. Sant Elm) y otra superior turbidítica (Fm. Banyalbufar). En el límite entre ambas unidades se ha reconocido, en la zona central de la isla, la existencia de un nivel de pisolitos ferruginosos de menos de 20 cm de potencia. Los pisolitos llegan a superar los 6 mm de diámetro, son esféricos y están constituidos casi exclusivamente por delgadas envueltas concéntricas de goethita, aunque en los pisolitos de mayor tamaño alguna envuelta es de calcita. La posición estratigráfica del nivel de pinolitos coincide, aproximadamente, con el límite entre las dos unidades anteriormente citadas, localizándose inmediatamente antes del inicio de la sedimentación turbidítica, y se correspondería con el máximo transgresivo en la cuenca marina. Tanto el vulcanismo Burdigaliense que ha sido reconocido en la zona como la removilización de suelos lateríticos en relación con la transgresión marina pudieron haber actuado como fuentes suministradoras del hierro. http://www.recercat.cat:80/handle/2072/210204 http://www.recercat.cat:80/handle/2072/210205 Magnetoestratigrafía de los sedimentos lacustres Pliocenos de la sección de Galera (Cuenca de Guadix-Baza, Cordilleras Béticas). Garcés Crespo, Miguel En este trabajo se presenta el análisis magnetoestratigráfico de los sedimentos lacustres del Plioceno superior de la serie de Galera (Cuenca de Guadix-Baza), dondle se cuenta con un rico registro paleontológico del Rusciniense superior y Villaniense. Su correlación con la Escala de Tiempo de Polaridad Geomagnética (ETPG) aporta una datación precisa de la biozonación local de la cuenca de Guadix-Baza y sus correspondientes biocronozonas MN. http://www.recercat.cat:80/handle/2072/210205 http://www.recercat.cat:80/handle/2072/210202 Wasps (Insecta: Vespida=Hymenoptera) from the Early Cretaceous of Spain. Rasnitsyn, A.; Delclòs Martínez, Xavier Wasps and their relatives from the Lower Cretaceous lithographic limestones of Spain have been studied. Thirty specimens representing 30 species (4 of them with undetermined placement), at least 21 genera and 11 families are recorded. We erect 1 new family - Andrenelidae-, 6 new genera and 11 new species: Meiaghilarella cretacica n.gen., n.sp. (Sepulcidae Ghilarellinae), Eosyntexis catalonicus n.sp., Cretosyntexis montsecensis n.gen., n.sp. (Anaxyelidae Syntexinae), Montsecephialtites zherikhini n.gen., n.sp. (Ephialtitidae Ephialtitinae), Karataus hispanicus n.sp. (Ephialtitidae Symphytopterinae), Manlaya ansorge i n.sp. (Gasteruptiidae Baissinae), Andrenelia pennata n.gen., n.sp. (Andrenelidae n. fam.), Cretoserphus gomezi n.gen., n.sp. (Mesoserphidae), Montsecosphex jarzembow skii n.gen., n.sp., Angarosphex penyalveri n.sp., Pompilopterus (?) noguerensis n.sp. (Sphecidae Angarosphecinae), Cretoscolia conquensis n.sp. (Scoliidae Archaeoscoliinae). The Mesozoic family Ephialtitidae is revisited based on the restudy of the type-species. We compare these Spanish Cretaceous assemblages with other ones from various parts of the world: Central and Eastern Asia, England, Australia, and Brazil. The number of genera and families identified in the Spanish fossil-sites is almost the same as in the English Purbeck and Wealden. The absence of some hymenopteran groups as Xyelidae, is consistent with the warm climate know to exist in Spain during the Early Cretaceous. We conclude that both La Cabrúa and La Pedrera assemblages - the two sites that have yielded the greatest number of species- correspond to the Lower Cretaceous"Baissin type" (sensu Rasnitsyn et al., 1998), but including some Jurassic"survivors". La Pedrera assemblage fits equally well in the"angarosphecine subtype", while La Cabrúa roughly corresponds to the"proctotrupid" one, although shows a comparative ly high proportion of angarosphecins. This fact may suggest: a) possibly asynchrony between these two fossilsites, b) environmental differences not reflected in the lithological record, c) different taphonomic processes and/or, d) insufficient sample size - to reflect the reality of the source populations-. La Pedrera assemblage is very similar to those from Weald Clay (England), Bon Tsagan (Mongolia) and Santana (Brazil). La Cabrúa approaches to a some extent, though not quite agrees with the Purbeck (UK), Koonwarra (Australia), and most Lower Cretaceous Asian assemblages. http://www.recercat.cat:80/handle/2072/210202 http://www.recercat.cat:80/handle/2072/210203 Magnetoestratigrafía de las sucesiones cenozoicas de la cuenca de As Pontes(La Coruña, Noroeste de España). Huerta Huerta, Ángel; Parés, J.M.; Cabrera, Lluís; Ferús, B.; Sáez, Alberto La cuenca terciaria de As Pontes (Noroeste de España), asociada a un corredor de fallas transcurrentes de dirección NW-SE, ha sido datada mediante magnetoestratigrafia, para lo cual se han estudiado un total de cuatro sucesiones magnetoestratigráficas. Las litologías estudiadas han sido sobre todo arcillas aluviales y palustres-lacustres, con un contenido variable de materia orgánica. En total se han desmagnetizado unos 900 especímenes, mediante desmagnetización térmica y por campos alternantes. Los minerales responsables de la magnetización en las rocas estudiadas son la magnetita y los sulfuros de hierro. A partir de los datos paleomagnéticos, se puede establecer que la sedimentación en la cuenca comenzó en el cron 10r (parte alta del Starnpiense) y se prolongó, como mínimo, hasta el subcron 6AAr.2n (Aquitaniense superior). Así, la duración de la sedimentación en la cuenca fue de unos 6,2 Ma, abarcando desde la última parte del Oligoceno temprano hasta el Mioceno temprano. La correlación magnetoestratigráfica de las diferentes sucesiones de la cuenca ha permitido establecer una correlación cronológica muy precisa a escala de cuenca, determinando la casi total isocronía de la mayor parte de los diferentes niveles de lignito y de las unidades litoestratigráficas de la cuenca. Por otro lado, las declinaciones medias muestran una rotación de 9'+4' para el relleno sedimentario de la cuenca de As Pontes, en sentido horario con respecto a la declinación del Oligoceno-Mioceno, coherente con el movimiento dextrógiro del corredor de fallas transcurrentes de dirección NW-SE. La datación del registro sedimentario de la cuenca de As Pontes permite establecer que los sistemas de fallas transcurrentes de orientación NW-SE del noroeste de la Península Ibérica fueron fuertemente activos desde la última parte del Oligoceno temprano hasta el Mioceno temprano. La finalización del movimiento principal de estos sistemas de fallas coincidió con el fin de actividad del margen entre la microplaca Ibérica y la placa Europea. Esto implicaría que el final de la actividad tectónica principal coincide en el ofshore y en el onshore del NW peninsular. http://www.recercat.cat:80/handle/2072/210203 http://www.recercat.cat:80/handle/2072/210200 Estratigrafía secuencial de sistemas deltaicos en cuencas de antepaís: ejemplos de Montserrat, Sant Llorenç del Munt, Montserrat y Roda (Paleogeno, cuenca de Antepaís surpirenaica). López Blanco, Miguel After the sedimentological study of the Sant Llorenc del Munt, Montserrat and Roda deltaic systems, a stratigraphic subdivision based on three different scale transgressiveregressive sequences has been developed. This subdivision has been established on the coastal facies belts from the deduced shoreline (and associated facies belts) migration. These transgressive-regressive sequences are formed by a lower transgressive part with a deepening-upwards trend and a retrogradational staclung pattern and an upper regressive part, with shallowing-upwards trend and a progradational stacking pattern. The lowest scale sequences (metrical) have been named 'fundamental sequences'. A series of 'composite sequences', intermediate scale (decametric to hectometric), have been defined afier the study of the staclung pattem of the fundamental sequences. After the study of the stacking pattem of composite sequences there have been defined a series of large-scale (decametric to kilometric) 'composite megasequences'. http://www.recercat.cat:80/handle/2072/210200 http://www.recercat.cat:80/handle/2072/210201 New beetles (Insecta: Coleoptera) from the Lower Cretaceous of Spain. Ponomarenko, A.; Delclòs Martínez, Xavier Three beetles remains from the Lower Cretaceous lithographic limestones of Spain are described. We classified them into two new genus and three new species. One specimen named Tetraphalerus brevicapitisn.sp. was placed in the Cupedidae, and both Megacoptoclava longiurogomphia n.gen., n.sp. and Bolbonectus lithographicus n.gen., n.sp. in Coptoclavidae. http://www.recercat.cat:80/handle/2072/210201 http://www.recercat.cat:80/handle/2072/210198 Influencia de la tectónica en la sedimentación continental de la cuenca del Vallés-Penedés (Prov.Barcelona, España) durante el Mioceno inferior. Cabrera, Lluís A very important alluvial fan clastic sedimentation, took place in the NNESSW trending Valles-Penedes graben (northeastem Spain) during Miocene time. Shallow lacustrine and paludine areas developed in distal zones of these alluvial fan complexes during Burdigalian (Early Miocene). At that time both facies development and their distribution were closely controlled by tectonic activity. Fault scarp retreat and back-faulting processes in the southeastem edge of the basin (observed in westem Valles afea), originated an expansive advance of distal alluvial-fan facies in that direction. The decreasing or cessation of the activity of the southeastern margin fault ca~sedi,n Late Burdigalian time (while faults in the northwestern margin were still active) facies redistribution, and gave way to the assymetry of the basin. Finally lacustrine, marine and transitional deposits of late burdigalian and langhian age, were laid down overlapping the southeastem inactive margins. http://www.recercat.cat:80/handle/2072/210198 http://www.recercat.cat:80/handle/2072/210199 Características estratigráficas y sedimentológicas del 'Garumniense' en el sector de Ager (Pre-Pirineo, Lleida). Colombo, Ferran; Cuevas, J.L. La sucesión estratigráfica de los depósitos continentales de la ' cuenca de Ager corresponde a sedimentos lacustres (Fm Massana), depósitos fluviales y de llanura de inundación (Fm. Figuerola), sedimentos lacustres (Fm. Milla) y una sucesión de materiales palustres, lacustres, fluviales, de lagunas evaponticas y aun mareales (Complejo de Perauba). Todos esos materiales fueron depositados en los diferentes medios sedimentarios citados que se desarrollaron en esa zona entre el Maastrichtiense y el Paleógeno inferior. En concreto, el tránsito entre el Cretácico y el Terciario (m)se produjo en uno de esos medios sedimentarios. Anteriormente se habia correlacionado ese límite con un nivel litoestratigráfico concreto (carbonatos de la Fm. Milla), pero actualmente se conoce que ese evento se produce en el tercio superior de la unidad tem'gena de la Fm. Figuerola. Los datos de paleomagnetismo sugieren que los dinosaunos y las carófitas cretácicas empezaron a desaparacer, en esta zona, unos dos millones de años antes que sucediera el evento asociado al límite K/T. http://www.recercat.cat:80/handle/2072/210199 http://www.recercat.cat:80/handle/2072/210197 Error de inclinación paleomagnética en materiales aluviales del Oligoceno superior del sector Suroriental de la Cuenca del Ebro (Region Surpirenaica, NE de España). Barberà, X.; Cabrera, Lluís; Parés, J.M. En el sector suroriental de la Cuenca del Ebro, la inclinación paleomagnética obtenida en las sucesiones aluviales oligocenas es considerablemente menor que la esperable, si se considera la paleolatitud de referencia calculada para esa región durante el Oligoceno. Este error de inclinación puede deberse a diversos factores, como el control hidrodinámica de las partículas magnéticas en el medio deposicional, la compactación diferencial del sedimento durante el enterramiento, o bien a la deformación tectónica. Este trabajo se ha centrado en su estudio en dos sucesiones dominantemente aluviales, donde previamente se había establecido su magnetoestratigrafia. Las litofacies aluviales y lacustres estudiadas se han agrupado en cinco grupos: areniscas grises, areniscas rojas y versicolores, limos rojos, lutitas rojas y calizas. Se ha demostrado la existencia de una correlación entre la abundancia de filosilicatos y el error de inclinación. De esta manera, las litofacies con un bajo porcentaje de filosilicatos (calizas y areniscas grises) presentan errores de unos 5', estadisticarnente no significativos, con respecto a la inclinación de referencia. Por el contrario, en materiales con un porcentaje más elevado de filosilicatos (limos y arcillas) el error puede llegar a los 25'. Este hecho no tiene repercusión en la interpretación de las polaridades magnéticas, pero si en las reconstmcciones palinspásticas y paleogeográficas basadas en los cálculos de paleolatitudes a partir de las paleoinclinaciones. Los resultados obtenidos demuestran la necesidad de cautela en la propuesta de conclusiones basadas exclusivamente en este tipo de información. http://www.recercat.cat:80/handle/2072/210197 http://www.recercat.cat:80/handle/2072/209955 Characterization of contaminant phases in foraminifera carbonates by electron microprobe mapping. Pena, L.D.; Cacho Lascorz, Isabel; Calvo, E.; Pelejero, C.; Eggins, S.; Sadekov, A. The advent of new microanalytical techniques such as electron microprobe mapping (EMP) and laser ablation microsamplers coupled to mass spectrometers (LA-ICP-MS) provides a new array of possibilities to explore in great detail the trace elements distribution in foraminiferal carbonates. Here we apply these techniques to characterize diagenetic phases present in foraminiferal shells from Ocean Drilling Program Site 1240 in the Panama Basin, a region characterized by the presence of manganese-rich minerals in the sediments. The combined application of these techniques allows us to characterize the elemental and spatial distribution on the surface and across the foraminiferal shells. Results illustrate the presence of at least two different Mn-rich contaminant phases in the foraminiferal carbonates: Mn-rich carbonates and ferromanganese oxides. Elemental maps also highlight the relevance of the foraminifera shell texture and porosity in the distribution and formation of these contaminant phases. In the case of Neogloboquadrina dutertrei, Mn phases form a continuous thin layer in the inner part of the chambers, whereas for Globigerinoides ruber, Mn phases have a rather patchy distribution and are usually found within the pores. Significant high magnesium concentrations are always associated with these Mn-rich phases. These new findings support the need of removing these Mn-rich contaminant phases in order to measure accurately the Mg/Ca ratios in the foraminifera shell and therefore obtain reliable Mg/Ca paleotemperature reconstructions. http://www.recercat.cat:80/handle/2072/209955 http://www.recercat.cat:80/handle/2072/209954 Identification and removal of Mn-Mg-rich contaminant phases in foraminiferal tests: Implications for Mg/Ca past temperature reconstructions Pena, L.; Calvo,E.; Cacho Lascorz, Isabel; Eggins,S.; Pelejero,C. The geochemical composition of foraminifera shells from an Ocean Drilling Program site in the Panama Basin has been analyzed by several analytical techniques (LA-ICP-MS, ICP-MS, XRD, SEM, EDX) in order to identify and evaluate the occurrence of contaminant phases which may bias paleoenvironmental reconstructions. LA-ICP-MS results on uncleaned tests indicate the presence of Mn-Mg-rich contaminant phases at the inner surfaces of the foraminiferal shells (which have Mn/Ca ratios up to 400 mmol mol-1 and Mg/Ca ratios up to 50 mmol mol-1). We have rigorously assessed the ability of different cleaning protocols to remove these contaminant phases and have obtained satisfactory results only when a reductive step is included. The analysis of cleaning residuals collected after each of the different cleaning steps applied reveals that high Mn values are associated with at least two different contaminant phases, of which only one is linked to high Mg values. XRD analysis further reveals that the Mn-Mg-rich phase is the Ca-Mn-Mg carbonate kutnahorite (Ca(Mn, Mg)(CO3)2). Our results demonstrate that the presence of kutnahorite-like minerals can bias Mg/Ca ratios toward higher values (by 7<br>36%) and lead to significant overestimation of past seawater temperatures (by 0.9 up to 6.2°C, in the case of these Panama Basin samples). http://www.recercat.cat:80/handle/2072/209954 http://www.recercat.cat:80/handle/2072/209851 Macrofossils in Raraku Lake (Easter Island) integrated with sedimentary and geochemical records towards a palaeoecological synthesis for the last 34,000 years Cañellas-Boltà, N.; Rull, V.; Sáez, Alberto; Margalef, O.; Giralt, S.; Pueyo Mur, Juan José; Birks, Hilary H.; Birks, H. J. B. (Harry John Betteley); Pla-Rabes, S. Macrofossil analysis of a composite 19 m long sediment core from Rano Raraku Lake (Easter Island)was related to litho-sedimentary and geochemical features of the sediment. Strong stratigraphical patterns are shown by indirect gradient analyses of the data. The good correspondence between the stratigraphical patterns derived from macrofossil (Correspondence Analysis) and sedimentary and geochemical data (Principal Component Analysis) shows that macrofossil associations provide sound palaeolimnological information in conjunction with sedimentary data. The main taphonomic factors in fluencing the macrofossil assemblages are run-off from the catchment, the littoral plant belt, and the depositional environment within the basin. Five main stages during the last 34,000 calibrated years BP (cal yr BP) are characterised from the lithological, geochemical, and macrofossil data. From 34 to 14.6 cal kyr BP (last glacial period) the sediments were largely derived from the catchment, indicating a high energy lake environment with much erosion and run-off bringing abundant plant trichomes, lichens, and mosses into the centre of Raraku Lake. http://www.recercat.cat:80/handle/2072/209851 http://www.recercat.cat:80/handle/2072/209803 The age of the"Grande Coupure" mammal turnover: New constraints from the Eocene<br>Oligocene record of the Eastern Ebro Basin (NE Spain.) Costa, Elisenda; Garcés Crespo, Miguel; Sáez, Alberto; Cabrera, Lluís; López Blanco, Miguel The Grande Coupure represents a major terrestrial faunal turnover recorded in Eurasia associated with the overall climate shift at the Eocene<br>Oligocene transition. During this event, a large number of European Eocene endemic mammals became extinct and new Asian immigrants appeared. The absolute age of the Grande Coupure, however, has remained controversial for decades. The Late Eocene<br>Oligocene continental record of the Eastern Ebro Basin (NE Spain) constitutes a unique opportunity to build a robust magnetostratigraphy- based chronostratigraphy which can contribute with independent age constraints for this important turnover. This study presents new magnetostratigraphic data of a 495-m-thick section (Moià-Santpedor) that ranges from 36.1 Ma to 33.3 Ma. The integration of the new results with previous litho- bio- and magnetostratigraphic records of the Ebro Basin yields accurate ages for the immediately pre- and post-Grand Coupure mammal fossil assemblages found in the study area, bracketing the Grande Coupure to an age embracing the Eocene<br> Oligocene transition, with a maximum allowable lag of 0.5 Myr with respect to this boundary. The shift to drier conditions that accompanied the global cooling at the Eocene<br>Oligocene transition probably determined the sedimentary trends in the Eastern Ebro Basin. The occurrence and expansion of an amalgamated-channel sandstone unit is interpreted as the forced response of the fluvial fan system to the transient retraction of the central-basin lake systems. The new results from the Ebro Basin allow us to revisit correlations for the controversial Eocene<br>Oligocene record of the Hampshire Basin (Isle of Wight, UK), and their implications for the calibration of the Mammal Palaeogene reference levels MP18 to MP21. http://www.recercat.cat:80/handle/2072/209803 http://www.recercat.cat:80/handle/2072/209802 Carbonate and organic matter sedimentation and isotopic signatures in Lake Chungará, Chilean altiplano, during the last 12.3 kyr. Pueyo Mur, Juan José; Sáez, Alberto; Giralt, Santiago; Valero-Garcés, Blas L.; Moreno, Ana; Bao, Roberto; Schwalb, Antje; Herrera, Christian; Klosowska, Bogumila; Taberner, Conxita Sediments in lakes in the Andean volcanic setting are often made up of diatomaceous ooze together with volcaniclastics and small amounts of carbonates. Despite their scarcity, carbonates along with organic matter provide significant paleoenvironmental information about lake systems. This study focuses on the carbonates in Lake Chungará, their morphologies, distribution and origin deduced from the isotopic markers. These markers re flected changes in the water and the biomass between the onset of the Holocene and around 9.6 calkyr BP. These changes are marked by general increases in TOC, TN,and TN-δ15 NAIR, andby fluctuating values of TOC-δ13 CVPDB in its sediments and are probably related to major shifts in the lake surface/volume associated with rises in lake level. An increase in salinity around 10 cal kyr BPis thought to be linked toa short dryperiod, giving rise to the onset of carbonate production. The mid-Holocene arid period between 7.3 and 3.5 cal ka BP, with a maximum of aridity around 6.0 cal kyr BP, was deduced from δ18O VPDB values in the endogenic carbonates. These results match the reconstructions in Lake Titicaca based on benthic diatoms and paleoshore levels. http://www.recercat.cat:80/handle/2072/209802 http://www.recercat.cat:80/handle/2072/209801 Biogeochemical processes controlling oxygen and carbon isotopes of diatom silica in Late Glacial to Holocene lacustrine rhythmites Hernández, Armand; Bao, Roberto; Giralt, Santiago; Barker, Philip A.; Leng, Melanie J.; Sloane, Hilary J.; Sáez, Alberto Biogeochemical cycles and sedimentary records in lakes are related to climate controls on hydrology and catchment processes. Changes in the isotopic imposition of the diatom frustules (δ 18 O diatom and δ 13 C diatom ) in lacustrine sediments can be used to reconstruct palaeoclimatic and palaeoenvironmental changes. The Lago Chungará (Andean Altiplano, 18°15 ′ S, 69°10 ′ W, 4520 masl) diatomaceous laminated sediments are made up of white and green multiannual rhythmites. White laminae were formed during short-term diatom super-blooms, and are composed almost exclusively of large-sized Cyclostephanos andinus.These diatoms bloom during mixing events when recycled nutrients from the bottom waters are brought to the surface and/or when nutrients are introduced from the catchment during periods of strong runoff. Conversely, the green laminae are thought to have been deposited over several years and are composed of a mixture of diatoms (mainly smaller valves of C. andinus and Discostella stelligera ) and organic matter. These green laminae reflect the lake's hydrological recovery from a status favouring the diatom super-blooms (white laminae) towards baseline conditions. δ 18 O diatom and δ 13 C diatom from 11,990 to 11,530 cal years BP allow us to reconstruct shifts in the precipitation/evaporation ratio and changes in the lake water dissolved carbon concentration, respectively. δ 18 O diatom values indicate that white laminae formation occurred mainly during low lake level stages, whereas green laminae formation generally occurred during high lake level stages. The isotope and chronostratigraphical data together suggest that white laminae deposition is caused by extraordinary environmental events. El Niño-Southern Oscillation and changes in solar activity are the most likely climate forcing mechanisms that could trigger such events, favouring hydrological changes at interannual-to-decadal scale. This study demonstrates the potential for laminated lake sediments to document extreme pluriannual events. http://www.recercat.cat:80/handle/2072/209801 http://www.recercat.cat:80/handle/2072/209458 Upper Eocene-Lowermost Miocene charophyte succession in the Ebro Basin (Spain). Contribution to the charophyte biozonation in Western Europe Feist, M.; Anadón Monzón, Pedro; Cabrera, Lluís; Choi, S.J.; Colombo, Ferran; Sáez, Alberto A charophyte succession has been established in nineteen sections and eight isolated outcrops from the Ebro Basin, ranging from the Priabonian ro the Aquitanian. Most assemblages were recovered fmm continuous sections and their abundance and diversity allow to define a new zonal scheme for the Upper Eocene-Lower Miocene of Europe. The new zonation includes nine subdivisions, based on the distribution of thirty-two species and directly correlated with the mammal standard levels. Changes in diversity, occurring mainly in the Middle and Upper Oligocene, have been related to climatíc variations. A new species, Chara sp. A. is also described and figured. http://www.recercat.cat:80/handle/2072/209458 http://www.recercat.cat:80/handle/2072/209457 Sedimentación lacustre en la Cuenca Cenozoica de As Pontes (A Coruña) Sáez, Alberto; Cabrera, Lluís The lacustrine and swampy sequences recorded in the As Pontes basin are rather diverse in terms of facies and sequential arrangement, depending on the considered basin zone. Since these sequences developed synchronously and very close, the paleoclimate conditions had to be similar and the observed differences must be attributed to the tectonic influence. http://www.recercat.cat:80/handle/2072/209457 http://www.recercat.cat:80/handle/2072/209456 Crocodilian and Paleobotanical findinds from tertiary lignites of the As Pontes Basin (Galicia, N.W. Spain) (Crocodylia, Plantae) Cabrera, Lluís; Jung, W.; Kirchner, M.; Sáez, Alberto; Schleich, H.H. From the Tertiary As Pontes basin (Galicia, Spain) the first reptilian remains (Crocodylia, Diplocy nodon s.\.) are described. Together with these findings palaeobotanical data (pollen, fructífications)result from the same sediment sampled. They are used for stratigraphical and palaecological interpretations. Due to these palaeontological informations one might interprete the lower As Pontes lignites as belonging to the Paleogene, most probably Oligocene. Nevertheless complementary data are needed lo confirm this stratigraphic contributíon. http://www.recercat.cat:80/handle/2072/209456 http://www.recercat.cat:80/handle/2072/209455 Coal deposition in carbonate rich shallow Lacustrine systems: The Calaf and Mequinenza sequences (Oligocene, eastern Ebro Basin, NE Spain) Cabrera, Lluís; Sáez, Alberto Two main coal-bearing sequences developed during the Oligocene in the Tertiary Ebro Basin, the Calaf (early Oligocene) and Mequinenza (late Oligocene) coal basins. Coal deposition took place in shallow marsh-swamp-lake complexes which sometimes became closed and evolved under warm climatic conditions with fluctuating humidity. These shallow lacustrine systems are closely interrelated with the terminal parts of the distributive fluvial systems which spread from the tectonically active Ebro basin margins. Laterally extensive lignite-bearing sequences, including rather thin, lenticular autochthonous and/or hypautochthonous coal seams with high ash and sulphur contents, characterized coal deposition in the shallow lacustrine systems. Coal seam geometry, which makes them nearly subeconomic, resulted from the tectonic instability during basin margin evolution and the sometimes closed, arid conditions under which the lacustrine systems evolved. High ash and sulphur contents resulted from the inadequate isolation of peat forming environments from clastic influx and from the very low acidity and sometimes high sulphate contents of the lacustrine waters. Coal exploration in shallow lacustrine sequences similar to those described here must take into account that the spread of coal-forming environments and maxima of coal deposition are usually coincident with lake expansions and retraction or shifting of the terminal fluvial zones interrelated with the lacustrine areas. http://www.recercat.cat:80/handle/2072/209455 http://www.recercat.cat:80/handle/2072/209331 Lake-level and salinity reconstruction from diatom analyses in Quillagua Formation (Late Neogene, Central Andean Forearc, Northern Chile) Bao, Roberto; Sáez, Alberto; Servant-Vildary, Simone; Cabrera, Lluís A sedimentary and micropaleontological study of the Quillagua Formation provides a detailed paleohydrological reconstruction of the lacustrine system which occupied the present-day hyperarid Quillagua<br>Llamara fore-arc Basin (Northern Chile) from lattermost Miocene to Early Pliocene times. http://www.recercat.cat:80/handle/2072/209331