Search results for " Petr"

Low-temperature Zr mobility: An in-situ synchrotron-radiation XRF study of the effect of radiation damage in zircon on the element release in $H_{2}O…

2006

The release of Zr, U, and Pb from nearly metamict zircon and its recrystallized analog and of Zr from fully crystalline and slightly radiation-damaged zircon in H 2 O + HCl ± SiO 2 fluids was investigated in situ at temperatures between 200 and 500 °C using a hydrothermal diamond-anvil cell and time-resolved synchrotron-radiation XRF analyses. Dissolution of nearly metamict zircon proceeded much faster than that of zircon with little or no radiation damage and resulted in a 1.5 to 2 log units higher Zr molality in 6 to 7 m HCl fluids. Extensive recrystallization of the almost fully amorphous material started at 260 to 300 °C in H 2 O + HCl, and at about 360 °C if quartz was added, and was c…

Solubility and stability of liebigite, Ca2UO2(CO3)3·10H2O(cr), in dilute to concentrated NaCl and NaClO4 solutions at T = 22–80 °C

2019

Abstract The solubility and thermodynamic stability of a synthetic liebigite was investigated in NaCl and NaClO4 solutions within a wide range of ionic strength (0.03 m ≤ Im ≤ 5.61 m), pH (7 ≤ pHm ≤ 9, with pHm = –log [H+]) and temperature (22 °C ≤ T ≤ 80 °C) conditions. A comprehensive characterization of the synthetic solid phase using XRD, quantitative chemical analysis, TG–DTA, SEM–EDS, IR and Raman spectroscopy confirmed the stoichiometry of Ca2UO2(CO3)3·10H2O(cr). At room temperature, liebigite remains stable and controls the solubility of U(VI) in the investigated NaCl and NaClO4 systems with Im ≤ 0.51 m. For the same temperature but high ionic strength (5.61 m NaCl), liebigite trans…

Halloysite nanotubes filled with MgO for paper reinforcement and deacidification

2021

Abstract A novel material for the deacidification and protection of paper has been designed by using MgO filled halloysite nanotubes (Hal). The ability of MgO loaded nanotubes to control the acidic conditions was evaluated by pH measurements in aqueous solvent. Afterwards, paper was impregnated into hydroxypropyl cellulose dispersions containing the consolidating material. A simulation of strong acidic conditions allowed us to evaluate the deacidification effect of the composite material on the samples. In particular, the paper reaches a pH of 7.7 after 1 h exposition to HNO3 vapours when MgO-Hal nanoparticles are added to the impregnation mixture at a concentration of 10 wt% and it remains…

Subduction‐Induced Back‐Arc Extension Versus Far‐Field Stretching: Contrasting Modes for Continental Marginal Break‐Up

2021

Millennial-scale phase relationships between ice-core and Mediterranean marine records: insights from high-precision 40Ar/39Ar dating of the Green Tu…

2013

International audience; With the advent of annually-resolved polar ice records extending back to 70 ka, marine and continental paleoclimate studies have now matured into a discipline where high-quality age control is essential for putting on an equal pace layer-counted timescale models and Late Quaternary sedimentary records. High-resolution U-Th dating of speleothem records and 40Ar/39Ar dating of globally recorded geomagnetic excursions have recently improved the time calibration of Quaternary archives, reflecting the cross-disciplinary effort made to synchronize the geologic record at the millennial scale. Yet, tie-points with such an absolute age control remain scarce for paleoclimatic …

Early Bronze Age painted wares from Tell el-'Abd, Syria: A compositional and technological study

2018

Abstract The ‘Euphrates Monochrome Painted Ware’ (henceforth EMPW) is a ceramic style attested in the Middle Euphrates region in northern Syria at the beginning of the Early Bronze Age, ca. 2900–2700 BCE. This style is not an isolated phenomenon; rather, it must be understood in the context of a general, albeit short-lived, re-introduction of painted ceramics into local assemblages of Greater Mesopotamia. In the present study, we investigate the technology and provenance of the painted pottery from Tell el-'Abd (North Syria) and its relation to contemporary ceramics retrieved at this site. We apply a combination of macroscopic observations, ceramic petrography, and micro X-ray diffraction (…

The production of western Greek amphorae in Agrigento (Southern Sicily): An archaeometric and archaeological characterisation of the late 6th-4th cen…

2022

This paper aims at an interdisciplinary, archaeological and archaeometric characterisation of the western Greek amphorae series produced in late Archaic and Classical-period Agrigento (southern Sicily). The research is based on a macroscopic examination, according to the standardised methods of Fabrics of the Central Mediterranean (FACEM), combined with petrographic analyses of 21 amphorae samples of presumed local fabric found in Agrigento itself. These were found in the artisanal area outside Porta V, in the excavations South of the temple of Zeus, and in several Sicilian consumption sites. Furthermore, a selection of 12 coarse ware samples and three tiles, all of supposed local manufactu…

Ethnoarchaeometric Study of the Traditional Cooking Ware Production Centre of Pabillonis (Sardinia): Investigating Raw Materials and Final Products

2010

Ethnoarchaeometry can be used to test assumptions in ceramic provenance studies. Within the Late Roman Cooking Wares (LRCW’s) commercialised in the Western Mediterranean some fabrics such as Fabrics 1.2, 1.6/1.7 and 1.9 (Fulford and Peacock, 1984) have been proposed to have a Sardinian origin. This motivated a specific project to explore the nature of cooking pottery on the island and the raw clays as well as the production technologies that have been used traditionally for their manufacture. In this paper, the traditional cooking pottery making in Pabillonis (Oristano province) was studied. First, a field survey in the area of Pabillonis was undertaken in order to locate the raw materials …

Mineral control of arsenic content in thermal waters from volcano-hosted hydrothermal systems: Insights from island of Ischia and Phlegrean Fields (C…

2006

This paper documents arsenic concentrations in 157 groundwater samples from the island of Ischia and the Phlegrean Fields, two of the most active volcano-hosted hydrothermal systems from the Campanian Volcanic Province (Southern Italy), in an attempt to identify the environmental conditions and mineral-solution reactions governing arsenic aqueous cycling. On Ischia and in the Phlegrean Fields, groundwaters range in composition from NaCl brines, which we interpret as the surface discharge of deep reservoir fluids, to shallow-depth circulating fluids, the latter ranging from acid-sulphate steam-heated to hypothermal, cold, bicarbonate groundwaters. Arsenic concentrations range from 1.6 to 690…

Sobre la vegetación del Orden Asplenietalia petrarchae en las montañas valencianas

1985

Se han estudiado las comunidades vegetales casmofíticas basífilas, presentes sobre los roquedos cálidos y secos, pertenecientes al orden Asplenietalia petrarchae Br.-Bl. & Mcier 1934, en el territorio de la Comunidad Valenciana y alrededores, detectándose en el mismo los siguientes sintáxones: Alianza Asplenion petrarchae Br.-Bl. & Meier 1934, con la asociación Melieo-Saturejetum fruticosae O. Bolós & Vives 1957. Alianza Teucrion buxifolii Rivas Goday 1955, con las asociaciones: Hippocrepido-Scabiosetum saxatilis (Rivas Goday 1953) O. Bolós 1957, Jasonio-Teucrietum thymifolii G. Mateo 1983, Rhamno borgiae-Teucrietum buxifolii nova y Lapiedro martinezii-Chelanthetum velleae nova. Chasmophyti…