THE EFFECT OF SALTS ON THERMAL AND HYDRIC DILATATION OF POROUS BUILDING STONE*

Fifteen desalinated sandstone drill core samples from Umm Ishrin Sandstone Formation in Petra (Cambrian age) were used for this study. The samples were mineralogically analysed using X‐ray diffraction and their physical properties were also determined. Samples with similar physical properties and mineralogical composition were taken for further experimental work. After desalination, thermal and hydric dilatation coefficients were measured, then three types of salts (NaCl, KCl and Na₂SO₄·10H₂O), which have high solubility and consequently are the most dangerous to building stone (and are also detected in the sandstone monuments in Petra), were introduced into the samples and their contents were calculated. The results show that salt crystallization in the pores of building stones can increase their thermal dilatation and decrease their hydric dilatation to varying extents, depending on the nature of the salt. The average increase in the thermal dilatation coefficient per unit mass of salt is the lowest for the Na₂SO₄·10H₂O‐salted samples with a value of 5.3%, while the NaCl‐salted samples have the highest value with 7.8% per salt mass. The average percentage of the decrease of the hydric dilatation coefficient is 1061% for Na₂SO₄·10H₂O‐salted samples per mass of salt content; the NaCl‐salted samples have a value of 1510% per mass of salt content, and the KCl‐salted samples almost the same value. For the salt‐free samples, it was found that in climatic conditions with a high temperature range, the deterioration of sandstone due to temperature fluctuation is more effective than that caused by change in the moisture content, while samples with high salt content suffer more from hydric dilatation.     

Face images in Lower Angara rock art

The Lower Angara rock art database includes relatively complete information on 42 petroglyphic sites with 155 representations of anthropomorphic faces. The classification of these images and their chronology, assessed on various grounds, suggests that they are roughly contemporaneous and are associated with Okunev art of the Late Neolithic and Early Bronze Age (3rd – 2nd millennia BC). Having originated in the Stone Age, the tradition of depicting anthropomorphic faces was practiced by the taiga tribes of the Lower Angara until recent centuries.     

Fracture mineralization and fluid flow evolution: an example from Ordovician–Devonian carbonates,southwestern Ontario,Canada

Petrography, geochemistry (stable and radiogenic isotopes), and fluid inclusion microthermometry of matrix dolomite, fracture‐filling calcite, and saddle dolomite in Ordovician to Devonian carbonates from southwestern Ontario, Canada, provide useful insights into fluid flow evolution during diagenesis. The calculated δ¹⁸O_fluid, ΣREE, and REE_SN patterns of matrix and saddle dolomite suggest diverse fluids were involved in dolomitization and/or recrystallization of dolomite. The ⁸⁷Sr/⁸⁶Sr ratios of dolomite of each succession vary from values in the range of coeval seawater to values more radiogenic than corresponding seawater, which indicate diagenetic fluids were influenced by significant water/rock interaction. High salinities (22.4–26.3 wt. % NaCl + CaCl₂) of Silurian and Ordovician dolomite–hosted fluid inclusions indicate involvement of saline waters from dissolution of Silurian evaporites. High fluid inclusion homogenization temperatures (>100°C) in all samples from Devonian to Ordovician show temperatures higher than maximum burial (60–90°C) of their host strata and suggest involvement of hydrothermal fluids in precipitation and/or recrystallization of dolomite. A thermal anomaly over the mid‐continent rift during Devonian to Mississippian time likely was the source of excess heat in the basin. Thermal buoyancy resulting from this anomaly was the driving force for migration of hydrothermal fluids through regional aquifers from the center of the Michigan Basin toward its margin. The decreasing trend of homogenization temperatures from the basin center toward its margin further supports the interpreted migration of hydrothermal fluids from the basin center toward its margin. Hydrocarbon‐bearing fluid inclusions in late‐stage Devonian to Ordovician calcite cements with high homogenization temperatures (>80°C) and their ¹³C‐depleted values (approaching ?32‰ PDB) indicate the close relationship between hydrothermal fluids and hydrocarbon migration.     

TECHNOLOGY AND PROVENANCE OF A COLLECTION OF ISLAMIC COPPER‐BASED OBJECTS AS FOUND BY CHEMICAL AND LEAD ISOTOPE ANALYSIS*

Chemical and lead isotope analyses were utilized to determine the composition, technology and origin of a collection of Islamic copper‐based objects found in Jordan. The atomic absorption spectrometry results show that the objects were made of different types of copper‐base alloys that contain various amounts of zinc, tin and lead. The use of brass, highly leaded brass and quaternary alloys of Cu‐Zn‐Sn‐Pb in the manufacture of everyday, household objects strongly points to Islamic traditions. The lead isotope compositions of the objects match very well that of the copper ore mined from the Dolomite‐Limestone‐Shale unit of the Arabah copper mines.     

A 'Hut pot'in the National Museum, Bahrain

This note presents a fine softstone vessel which has not previously been fully published. Its findspot supports the recent suggestion that such pots continued to be manufactured until the end of the third millennium.     

CONSTRUCTION OF THE KHOJA ZAYNUDDIN MOSQUE: USE OF ANIMAL GLUE MODIFIED WITH URINE*

As part of an ongoing project at the World Heritage Site of Bukhara, we investigated the glue used in the construction of the Khoja Zaynuddin mosque. Analysis by a range of techniques confirmed that it consisted of a collagen‐based glue. However, the glue contained many non‐protein constituents. The presence of lipid material suggests that the glue was produced by a relatively unsophisticated process. More surprisingly, various marker compounds of urine were found. Study of the viscosity of a mixture of a modern collagen‐based glue and urea showed that the presence of urea at a concentration typical of human urine reduced the viscosity of the glue, thus improving its spreading characteristics and enabling its use at a lower temperature. Whilst the advantages of adding urea to glue were known to craftsmen in Europe and America in the 19th century, it would appear that the builders of Bukhara were aware of the technique, using less pure components, at a significantly earlier date.     

ÉVOLUTION DE L'AGRICULTURE MARAÎCHÈRE AU QUÉBEC DE 1940 À 1990: SUPERFICIES,PRODUCTIONS ET DIVERSITÉ

Depuis plus d'un siècle, l'agriculture québécoise en général, et la production maraîchère en particulier, ont subi d'importantes transformations. Cette étude historique vise à comprendre comment la production maraîchère a évolué par rapport aux changements dans l'environnement décisionnel général de l'agriculture entre 1940 et 1990. L'analyse des données statiques de superficie, de production et de rendement pour 12 légumes ont permis d'identifier trois périodes, intercalées d'années transitoires, dans l'évolution de la production maraîchère référant chacune à une stratégie agricole particulière. La première (1940–1957) correspond à une stratégie agricole de type familial traditionnel; la seconde (1963–1975), à une agriculture marchande spécialisée fondée sur la maximisation des revenus à court terme par intensification; la troisième (1980–1990), à une agriculture marchande diversifiée fondée également sur une maximisation à court terme. Les facteurs externes de l'environnement décisionnel qui ont entraîné ces changements sont identifiés et discutès. For more than a century, Quebec agriculture in general, and market-gardening production in particular, have experienced important changes. This study, using a historical perspective, seeks to understand how market gardening evolved in relation to changes in the broad decision environment for agriculture between 1940 and 1990. Statistical analysis of data on the areas cultivated, production levels, and yields for 12 vegetable crops revealed three distinct periods, separated by periods of transition, in the evolution of market gardening. Each period is characterized by a particular type of agricultural development strategy. The first period (1940–1957) is characterized by a focus on the traditional family form; the second (1963–1975), by a specialized market agriculture driven by short-term income-maximization intensification; the third (1980–1990), by a diversified marketoriented agriculture, also based on short-term income maximization. External environmental factors that stimulated these changes are identified and discussed.     

A seal in the collections of the National Museum, Bahrain

This article describes a Murghab seal amulet recently identified in the collections of the National Museum of Bahrain and discusses some of the other evidence for contact between Central Asia and the Gulf in the early second millennium.     

NON-DESTRUCTIVE ANALYSIS OF OBSIDIAN ARTEFACTS USING NUCLEAR TECHNIQUES: INVESTIGATION OF PROVENANCE OF NEAR EASTERN ARTEFACTS

A non-destructive analytical method using both instrumental neutron activation and proton-induced gamma ray emission techniques was developed to study the provenance of obsidian artefacts from Turkey, Syria and Iraq.     

PLASTER AND MORTAR RADIOCARBON DATING OF NABATEAN AND ISLAMIC STRUCTURES,SOUTH JORDAN*

The study aims to use lime mortars and plasters to radiocarbon date Nabatean and Islamic structures from Petra and Udruh, south Jordan. Fifteen samples from seven structures were characterized by thin‐section, scanning electron and cathodoluminescence microscopy. The lime binders of all the samples and the organic inclusions from nine samples were AMS radiocarbon dated. The dates and the historical data of the samples were compared with each other. The results showed an agreement between the radiocarbon dates of the lime binders and the organic inclusions and the historical data for most of the samples. The radiocarbon dates of the lime binders supported by the radiocarbon dates of the organic inclusions and the archaeological data were helpful in reconstructing a rather precise chronology of the studied structures.