Procesos sedimentarios y diagenéticos en el registro arqueológico del yacimiento pleistoceno de la Cueva de El Esquilleu (Picos de Europa, Norte de España)

La cueva de El Esquilleu (Cillórigo de Liébana, Cantabria, N de España) es un gran abrigo rocoso situado en la región de Picos de Europa (Cordillera Cantábrica) que contiene un importante registro sedimentario, arqueológico y paleontológico del Pleistoceno superior, con abundantes evidencias de industrias líticas musterienses y restos óseos de mamíferos y otros vertebrados. La secuencia estratigráfica se compone de 41 niveles agrupados en cuatro unidades litoestratigráficas con diferente significado sedimentario, que han sido estudiadas con metodología geoarqueológica y tafonómica. En la unidad inferior hemos detectado una acumulación de hidroxilapatito de origen diagenético, que hemos estudiado mediante difracción de rayos X (DRX), microscopía electronica de barrido ambiental (MEBA) y termoluminiscencia (TL). Las dataciones radiocarbónicas existentes y su calibración permiten situar este interesante registro durante el OIS 3 en una horquilla temporal comprendida aproximadamente entre 60000 y 37000 BP.El Esquilleu cave (Cillórigo de Liébana, Cantabria, North of Spain) is a rockshelter placed in the Picos de Europa region (Cantabrian Range) that contains an important sedimentary, archaeological and palaeontological record of the Upper Pleistocene (OIS 3) with abundant mousterian lithics industries and bone remains of mammals and others vertebrates. The stratigraphic sequence consists of 41 levels grouped in four litostratigraphic units with different sedimentary meaning studied by geoarchaeological and taphonomical methods. In the low unit we have detected important accumulations of hydroxylapatite of diagenetic origin, studied by X-ray diffraction (XRD), environmetal scanning electron microscopy (ESEM) and thermoluminescence (TL). The radiocarbon dates existing and their calibration allow approximately locate this interesting record during OIS 3 in a temporary bracket between 60000 and 37000 BP

Effects of different UV exposures on the thermoluminescence of high albite

High albite can be used as a new UV dosimeter. Heated natural albite posseses a special property: it has strong thermoluminescence (TL) blue emissions under UV radiation. The TL glow curves of high albite after different times of UV exposure show PhotoTransferred ThermoLuminescence (PTTL) from deeps traps (345oC - 450oC) to shallow traps (150oC) which can be used to store UV damage. The point of inflexion of the process occurs after one hour under UV radiation, the low temperature peaks start gaining in intensity while the high temperature peaks stop dropping and stabilize into a plateau. Samples which have been subjected to UV radiation for 1 hour at different temperatures (RT, 70oC, 105oC and 140oC) give glow curves which display an increase of the maxima peaks according to temperature (up to 300oC). High albite, UV irradiated (for one hour) at 70oC displays a TL signal decrease of 30% after 1000 hours of storage at room temperature with high intensity emissions, for this reason this material could be a good UV dosimeter.Peer Reviewe

Effect of dopants in the luminescent properties of synthetic quartz for dosimetric purposes

Quartz obtained from structural materials (bricks, tiles, etc.) is often employed as a dosimeter using the thermoluminescence (TL) technique in the field of dating and retrospective dosimetry. As known, the TL response depends on the impurities in quartz lattice. For this motive, some members of beta-quartz series were synthesised using the ceramic method from precursor powders -Li2CO3, Al(NO3)3.9H2O, Si(C2H5O)4- with different compositions, to create standard materials. The lattice of aluminosilicates consists of chains of SiO4 and AlO4 tetrahedra forming spirals or rings. The Al3+ ions are replacing Si4+ and a positive charge is needed (trapped holes or Na+, K+, Li+, etc. cations). The Li+ ions are placed in void channels inside the spirals of (Si, Al)O4 tetrahedra. Here some characteristic features of the TL signal in three of beta-quartz with different concentrations of lithium-aluminium were measured in the UV-blue region of the spectrum. Irradiated -quartz samples display high linearity - one of the main features of a dosimeter - after additional radiation doses (from 0.5 to 5 Gy).Peer Reviewe

Strong Calcite-Like Spectra Cathodoluminescence Emission from Allende Meteorite Cai Phases

Calcium–aluminum-rich inclusions (CAIs) of Allende CV3 chondrite were studied by Environmental Scanning Electron Microscopy (ESEM), Energy Dispersive Spectrometry (EDS), Backscattering (BS), and Spectra Cathodoluminescence (CL). CAI minerals show spectra CL curves exceeding the 450,000 a.u. with a large homogeneity along the white inclusions. CL curve features fit perfectly with terrestrial patterns of stressed specimens of weathered marble and limestone in which hydroxyl groups may be involved. Crypto-clusters of CaCO3, undetectable by means of EPMA, EDS, and Micro-Raman techniques, coupled to the CAI phases are inferred from the spectral CL data and from the carbon and calcium contents provided by the EDS probe

Cluster linkages between luminescence emission spectra and continuous trapdistribution in a volcanic sanidine

Volcanic sanidine shows two important characteristics involved in the luminescence emission: (i) a near-infrared emission centred around 700 nm, attributed to Fe3+ substituted for Al3+, and (ii) a Si¿Al highly disordered crystallographic lattice of natural, recently pre-annealed feldspars. Thermoluminescence emission spectra have been obtained from well-characterised transparent crystals of sanidine using a high sensitivity spectrometer. Tests of thermal stability at di9erent temperatures show a continuous trap distribution with progressive changes in the glow curve shape, intensity and temperature position of the peak maximum. The characteristic broad blue emission band displays cluster linkages between blue and red emissions which can be explained by thermal alkali self-di9usion through both bulk and interfaces producing redox changes of the iron ion valence. These complex phenomena could also explain the large fading and tunnelling recombination of sanidine.Peer Reviewe

Composition, Luminescence, and Color of a Natural Blue Calcium Carbonate from Madagascar

Concerning the transparent blue calcite crystals of blue marble from Madagascar, this work suggests that their cavities, accessorial quartz, and marble stress textures do not provide unambiguous characterization of the blue color compared to other white marbles. It is suggested that the presence of stronium (∼850 ppm), barium (∼18 ppm), vanadium (∼10 ppm), and nickel (∼2 ppm) might be considered influential chromophores for the blue color. Blue marble aliquots were characterized to determine their mineralogical, textural, and chemical composition to elucidate luminescence spectra and the causes of the blue color by use of different techniques.The experimental research was supported by the Spanish Ministry of Science and Innovation projects FIS2011-13214-E (sub-programa FIS) EXPLORA and CGL2010-17108/BTE

Thermoluminescence of a lithium aluminium rich beta quartz for dosimetry purposes

A member of the ß-quartz series (Li0.73Al0.73Si1.27O4) was synthesised using the ceramic method from precursor powders - Li2CO3, Al(NO3)3.9H2O, Si(C2H5O)4 - with identical composition. Crystallisation of the gel was obtained by heating the raw material at 800°C for 12 h. The XRD pattern of the synthetic sample indicates a ß-quartz structure with hexagonal symmetry. Thermoluminescence (TL) signals of annealed samples at 1200°C for 12 h, and non-annealed samples, were measured in the UV blue region of the spectrum. The non-annealed irradiated ß-quartz displays two TL peaks at 110°C and 280°C which, after different additional radiation doses (from 0.4 to 5 Gy), display high linearity. The other annealed irradiated aliquots show a similar behaviour and stronger linearity. Thermal treatments at high temperature (1200°C) produce ionic self-diffusion and loss of lithium atoms through the open hexagonal channel of the ß-quartz structure. These [AlO4/Li+](o) defects are responsible for the high radiation sensitivity of the sample.This work has been funded by the DGICYT project PB 95-0108-B and a CSN contract 96/208Peer Reviewe

Blue thermoluminescence emission of the recently fallen meteorite. (Villalbeto de la Peña, Spain)

This paper reports on the thermal stability of the natural blue thermoluminescence (TL) of a well-characterised meteorite fallen in Villalbeto de la Peña (Palencia, Spain) in January 4, 2004. The meteorite specimen exhibits a complex structure of the spectra emission a wide broad maximum peaked at about 320ºC that can be associated with consecutive breaking linking of bonds (e.g. of Al¿O, Cr¿O, Fe¿O) from lattices of several phases, i.e., olivine, low-Ca pyroxene, plagioclase and redox reactions. The natural TL emission seems to be essentially caused by the Na¿Ca plagioclase as the brighter material inside this L6 chondrite. The thermal stability tests, at different temperatures, confirm a continuous trap distribution with progressive changes in the glow curve shape, intensity and temperature position of the main peak. In consequence, the glow curve analysis methods commonly used for synthetic materials based on singlediscrete traps cannot be applied for this material.Peer Reviewe

Luminescence at 400 and 440nm in sanidine feldspar from original and X-ray-induced defects

4 páginas y 3 figurasThe blue luminescence of feldspar crystals with molecular composition Ab38Or60An2 and high-sanidine X-ray diffraction pattern from Miocene rhyolite ash tuffs of the Twin Falls Volcanic Field (Idaho, USA) has been studied by high sensitivity thermoluminescence (TL) up to 400 1C at 2.5 1C/s and radioluminescence (RL) at room temperature. The natural thermally stimulated blue luminescence is composed by a single emission at 400nm at T4200 1C probably linked to defect centres at original chemical impurities. The 50 Gy X-ray-induced TL emission exhibits a very symmetric broad band centred at 440nm and 200 1C, attributed to unstable radiation-induced defects. The RL spectrum displays these two signals which can be explained since irradiation induces charge carriers, and subsequent electron-hole recombinations, in addition to optically active defect centres. The 400nm band seems to be useful for dose reconstruction purposes.The experiment was supported by the CICYT CGL2004-03564/BTE and C.A. de Madrid MATERNAS (CAM) S-0505/MAT/0094 projects. Thanks are also due to Enrique Díaz Martínez (IGME, Madrid, Spain) and W. Rember (Dept. Geol. Sci., Univ. Idaho, Moscow, USA) for the valuable help in the sample collection.Peer Reviewe

Kinetic parameters of lithium and aluminium doped quartz from thermoluminescence glow curves

The thermoluminescence (TL glow-curves of irradiated annealed and non-annealed synthetic beta-quartz (Li0.73 ¿l0.73 Si1.27 O4) synthesized using the ceramic method have been studied Annealed samples (1200°C for 12h) exhibit some changes of shape and intensity in TL glow curves when compared with non-annealed samples in the range of 0.05-5Gy. These changes can be attributed to thermal alkali self-diffusion through the lattice interfaces and tilting of the Al-Si crankshafts involving modifications in the components of the luminescent traps. In non-annealed samples five groups of components at about 110ºC, 180ºC, 210ºC, 325ºC and 425ºC can be found, whereas annealed samples only displays one very intense at ~900º¿ and ¿ lower intensity second peak at ~240 ºC. In this paper, computerized curve-fitting based on general-order kinetics has been used to characterize the glow curve structure resolving trapping parameters for each glow peaks: trap depth (¿), frequency factor (s) and the order of the kinetics (b). The dose dependence of the individual components of the glow curve has been also studied. These data allow us to select the more stable component to be used for dosimetric purposes.Peer Reviewe