New data on chert catchment analysis in inland Iberia during the Late Pleistocene

In this paper, we present the first results obtained after new fieldwork and laboratory studies of chert catchment sources during the Middle and Upper Palaeolithic in inland Iberia, a region that has been traditionally depicted as marginal and sparsely populated during the last glacial due to its harsh ecological conditions compared to the coastal areas of the Iberian Peninsula. Our main aim is to determine the mobility strategies and social networks of the last Neandertals and first modern humans settled in inland Iberia and neighbouring regions, and eventually test the hypothesis that the last glacial human settlement in the Iberian hinterland was more dense and complex than previously thought. In this study, we focus on the cherts exploited at two archaeological sites: the Peña Cabra and Peña Capón rock shelters. These sites are located in the southeastern foothills of the Central System range, in the province of Guadalajara (Spain), and they have yielded a sequence of human occupations from the Middle and Upper Palaeolithic, respectively. To obtain a detailed picture of the mobility patterns and catchment strategies of the hunter-gatherers settled at these sites, our fieldwork focussed on identifying chert outcrops that could have been frequented and exploited by them. After two field seasons, 22 chert outcrops from eight geological formations were identified and more than 300 samples were collected and analysed. We conducted textural, micropalaeontological, petrographical and geochemical analyses, with the aim of comprehensively characterising the various rock resources available in the study area. Results have shown that different siliceous varieties were available in the area surrounding the sites and both Neandertals and modern humans could have provisioned there. Also, they suggest the potential existence of a network connecting the Tagus and Ebro valleys, but this is a working hypothesis to be tested with future research.European Research Council (ERC)Agencia Estatal de Investigació

Landscape evolution and geodynamic controls in the Gulf of Cadiz (Huelva coast, SW Spain) during the Late Quaternary

The coastal evolution of the El Abalario area (Huelva, southern Spain) during the Late Pleistocene and Holocene is reinterpreted after a refinement of the available geochronology by means of optically stimulated luminescence (OSL) dating. New data come from the analysis of soft sediment deformation, palaeosols, geomorphological mapping, and published seismic surveys on the onshore and offshore Gulf of Cadiz. The present structure of El Abalario dome resulted from the complex interaction of littoral-catchment processes and sea-level changes upon an emergent coastal plain, conditioned by the upwarping of the underlying Pliocene - Pleistocene prograding deltaic sequence. Upwarping is probably related to escape of over-pressurized fluids, accompanied by dewatering, prior to (?) and during OIS (Oxygen Isotopic Stage) 5. Continued upwarping produced the large NW - SE gravitational fault of Torre del Loro (TLF) in the southwestern flank of the dome, roughly parallel to the present coastline during OIS 5 - OIS 4. The resulting escarpment favoured the accumulation of aeolian sand dunes (units U1, U2, and U3) from OIS 5 to early OIS 1. Unit U1 (OIS 5) ends upwards in a supersurface with a thick weathering profile that suggests moist and temperate climatic conditions. Unit U2 accumulated mainly during OIS 4 and OIS 3 with prevailing W/E winds. The supersurface between U2 and U3 records a part of OIS 2, with relative low sea level. Sedimentation of unit U3 took place during the Last Deglaciation (radiocarbon and OSL ages) with prevailing W/SW winds, under a temperate moist climate, that became more arid towards the top (Holocene). A major supersurface with an iron crust-like layer (SsFe) developed during the Holocene Climatic Optimum (OIS 1) under wetter and more temperate conditions than before, fossilizing the TLF. The supersurface is covered by younger aeolian dunes (U4, U5, U6, and U7) transported by W - SW winds since the Late Neolithic - Chalcolithic cultural period (̃5.0 ky cal BP).Financial support from Spanish Projects BTE2002-1065 and BTE2002-1691. This is a contribution to IGCP 495 and to the INQUA “Coastal and Marine Processes Commission”

Tsunami vs. storm surge deposits: a review of the sedimentological and geomorphological records of extreme wave events (EWE) during the Holocene in the Gulf of Cadiz, Spain

The Gulf of Cadiz region of Spain has undergone many studies examining Holocene tsunami and storm deposists. Some of the studies aimed at determining recurrence intervals of events interpreted of tsunamigenic origin. A review of geomorphologic, sedimentary and paleontological features of these deposits suggests that only a few of them can be accurately ascribed to tsunami events; instead, most of them lack conclusive evidence of a tsunamigenci genesis and should be referred to as generated by extreme wave events (EWE

Origen bacteriano de espelotemas tipo moonmilk en ambiente kárstico (Cueva de Altamira, Cantabria, España)

Los espeleotemas subaéreos de tipo moonmilk de la Cueva de Altamira están constituidos fundamentalmente por un entramado de cristales aciculares calcíticos (needlefiber calcite, NFC) y filamentos microbianos activos. El carácter actual de los depósitos estudiados nos ha permitido observar los estadios iniciales de formación, así como las primeras fases de evolución de este tipo de agregados. En trabajos previos se establece el origen de los NFC asociado a rápida precipitación mineral debida a procesos de evaporación y criodesecación. Las estables condiciones microclimáticas de la cueva, con humedad del aire en saturación, nos permiten concluir que su origen no tiene que estar relacionado con dichos procesos. Asimismo se ha comprobado que los NFC de tipo varillas monocristalinas se generan mediante la calcitización de los filamentos microbianos. Los crecimientos epitaxiales y las cadenas policristalinas, en cambio, responden a fenómenos que pueden ser de carácter orgánico y/o inorgánico por precipitación química en un medio acuoso confinado dentro del biofilm.Moonmilk subaerial speleothems of Altamira Cave are constituted by a network of needle-fiber calcite crystals (NFC) and active microbial filaments. These recent deposits allow us the observation of the first evolution stages, as well as defining microclimatic and hydrochemical conditions of mineral precipitation. In previous works, the origin of the NFC has been determined being associated to fast mineral precipitation related with evaporation and criodesiccation processes. From our data, an evolutionary model has been proposed for this type of deposits. The stable microclimatic conditions of the cave, with air humidity close to saturation, lead us to conclude that their origin doesn't have to be related with these processes. Also it has been proven that the NFC of monocrystallyne rods type is generated by means of calcitization of microbial filaments. On the other hand, epitaxial cements and polycristalline chains are related with organic activity and inorganic processes in a confined aqueous environment developed inside the biofilm.El trabajo ha sido financiado por los proyectos MCYT BTE2002-04492 y EC EVK4-2000-00659. Es una aportación al Proyecto IGCP 448 y a INQUA Comission on Carbon

Procesos de precipitación mineral bioinducidos en sistemas kársticos subterráneos: breve revisión y nuevas tendencias

Los microorganismos, en particular las bacterias, habitan en todos los ambientes posibles de la biosfera incluidos los ambientes subterráneos. Desempeñan un papel importante en procesos geológicos tales como la precipitación y disolución mineral, e influyen notablemente sobre los ciclos biogeoquímicos de diferentes elementos. Hasta este momento, son relativamente pocos los estudios orientados a conocer el papel activo de los microorganismos, especialmente las bacterias, en la formación de espeleotemas, de manera que la implicación de la actividad microbiana en la precipitación y disolución mineral en ambientes kársticos es un tema aún sin resolver en geomicrobiología. Actualmente, no está del todo aclarada cuál es la interrelación entre los microorganismos y las fábricas minerales, ni el papel que juegan los microorganismos en la precipitación de carbonatos. Las cuevas son ambientes protegidos donde las fábricas microbianas pueden preservarse sin sufrir modificaciones diagenéticas importantes o destrucción, ofreciendo, por ello, un excelente entorno para estudiar los procesos de biomineralización (desde los propios microorganismos activos a sus depósitos minerales). Las nuevas tendencias en geomicrobiología se basan en la conjunción de diferentes metodologías (microclima, petrología, geoquímica, hidroquímica, microbiología, biología molecular) con un objetivo común: 1) determinar el papel de las diferentes comunidades microbianas que habitan los ambientes subterráneos en los procesos de transformación mineral; 2) identificar las propiedades físicas y químicas de las fases cristalinas bioinducidas, y 3) determinar las condiciones ambientales y las propiedades composicionales y texturales de los soportes rocosos naturales (biorreceptividad) que favorecen o inhiben el desarrollo de las comunidades microbianas.Microorganisms, particularly bacteria, inhabit all possible environments in the biosphere including subterranean ones. They play an important role in geological processes such as mineral precipitation and dissolution, and significantly influence biogeochemical cycles. At present, relatively few studies have focused on the active role of microorganisms, especially bacteria, in the formation of speleothems. Thus, the involvement of microbial activity in the formation of speleothems in caves is a geomicrobiological issue still to be solved. Today, the relationship between microorganisms and mineral fabrics and the role played by microorganisms in carbonate precipitation is unclear. The processes of carbonate deposit formation in caves offers an excellent scenario for research on biomineralization processes (from active microorganisms to their mineral deposits), because caves are protected environments where microbial fabrics can be preserved without extensive diagenetic modification or destruction. The new tendencies on geomicrobiological studies consist on applying different and multidisciplinary methodological approaches (petrology, geochemistry, microbiology, molecular biology) to (1) determine the role of the different microbial communities inhabiting the hypogean environments in the processes of mineral transformation, (2) identifying the physical and chemical properties of bioinduced crystalline phases, and (3) determine the environmental conditions, composition and texture of natural substrates (bioreceptivity) favouring or inhibiting the development of microbial communities.Este trabajo es parte de los proyectos CGL2006-11561/BTE y CGL2006-07424/BOS

Datos geofísicos y evolución sedimentaria de la Depresión de la Janda (Cádiz)

La Janda lake is located ¡rito a tectonic graben filled by Pleistocene and Holocene fluvio-marine sediments. Geophysical survey consisting on Electric-logs and seismic refraction profiles aimed to determining the thickness of Quaternary sediments infilling the graben. Nevertheless, the results are significantly distorted by a saline aquifer that occupies most of the sedimentary filling. In any case it is possible to identify an assymetric subsident area reaching up to 300 m depth, characterised by very low apparent resistivities (1.5-2.4 W/m). This thick geoelectrical unit can be preliminary subdivided into 3 different subunits here called A, 67, B2, characterised by resistivity differences. The shallow 4-6 m thick Unit A consists of a thin lacustrine and alluvial day and silts of Holocene age easily recognized in seismic refraction profiles and drill cores. Unit B can be separated in two subunits; Both are saturated in brackish or saline waters; B1 is a 20-40 m thick unit that thins northward and correspond to the Plio-Pleistocene, B2 is a slightly more resistive unit that extends from this depth to 352 m and corresponds to deeply weathered mio-pliocene sandstones. The upper part of Sub-unit 87 correspond to estuarine sands recorded in a previous core which deposition finishes at ca. 3810 cal BP. A sharp normal fault limits the southern part of La Janda assymetric grabenPeer reviewe

Tsunami vs. Storm surge deposits: A review of the sedimentological and geomorphological records of extreme wave events (EWE) during the holocene in the gulf of Cadiz, Spain

The Gulf of Cadiz region of Spain has undergone many studies examining Holocene tsunami and storm deposits. Some of the studies aimed at determining recurrence intervals of events interpreted of tsunamigenic origin.A review of geomorphologic, sedimentary and paleontological features of these deposits suggests that only a few of them can be accurately ascribed to tsunami events; instead, most of them lack conclusive evidence of a tsunamigenic genesis and should be referred to as generated by extreme wave events (EWE).Peer reviewe

The record of the latter glacial and interglacial periods in the Guadalquivir marshlands (Mari López drilling, S.W. Spain)

El estudio de un sondeo de 65 m en las marismas del Guadalquivir permite reconocer siete intervalos que reflejan cambios climáticos y eustáticos e intensa neotectónica durante tres periodos ¡nterglaciares (IS 71, 5 y i) y dos glaciares (IS 6-Riss-, IS 4, 3 y 2-WQrm). Se discute el valor de las 'vetas' como indicadores paleogeográficosPeer reviewe

El efecto de los ciclos climáticos en las variaciones del nivel del mar

Ejemplar dedicado a: Miscelánea en homenaje a Emiliano Aguirre. GeologíaPeer reviewe