Downward hydrocarbon migration predicted from numerical modeling of fluid overpressure in the Paleozoic Anticosti Basin,eastern Canada

The Anticosti Basin is a large Paleozoic basin in eastern Canada where potential source and reservoir rocks have been identified but no economic hydrocarbon reservoirs have been found. Potential source rocks of the Upper Ordovician Macasty Formation overlie carbonates of the Middle Ordovician Mingan Formation, which are underlain by dolostones of the Lower Ordovician Romaine Formation. These carbonates have been subjected to dissolution and dolomitization and are potential hydrocarbon reservoirs. Numerical simulations of fluid‐overpressure development related to sediment compaction and hydrocarbon generation were carried out to investigate whether hydrocarbons generated in the Macasty Formation could migrate downward into the underlying Mingan and Romaine formations. The modeling results indicate that, in the central part of the basin, maximum fluid overpressures developed above the Macasty Formation due to rapid sedimentation. This overpressured core dissipated gradually with time, but the overpressure pattern (i.e. maximum overpressure above source rock) was maintained during the generation of oil and gas. The downward impelling force associated with fluid‐overpressure gradients in the central part of the basin was stronger than the buoyancy force for oil, whereas the buoyancy force for gas and for oil generated in the later stage of the basin is stronger than the overpressure‐related force. Based on these results, it is proposed that oil generated from the Macasty Formation in the central part of the basin first moved downward into the Mingan and Romaine formations, and then migrated laterally up‐dip toward the basin margin, whereas gas throughout the basin and oil generated in the northern part of the basin generally moved upward. Consequently, gas reservoirs are predicted to occur in the upper part of the basin, whereas oil reservoirs are more likely to be found in the strata below the source rocks. Geofluids (2010) 10 , 334–350     

A NEW METHOD FOR EXTRACTION,ISOLATION AND TRANSESTERIFICATION OF FREE FATTY ACIDS FROM ARCHAEOLOGICAL POTTERY

This paper presents evidence for increased recovery of organic residues from archaeological pottery through use of a microwave‐assisted liquid chromatography protocol. C_16:0 and C_18:0 saturated fatty acids were obtained from archaeological potsherds recovered from nine Neolithic settlements in the Middle East dating between 4700 and 7300 cal bc , including materials that had not produced evidence for the survival of any lipid species through use of ‘conventional’ solvent extraction techniques. Compound‐specific isotopic analyses of C_16:0 and C_18:0 fatty acids in potsherd extracts subsequently revealed δ¹³C/δ¹²C compositions consistent with modern subcutaneous fats of wild boar and goats pastured on lands adjacent to the Jordan Valley, and residues from a modern pottery vessel used in the manufacturing of butter, cheese and yogurt in central Turkey. These results are presented as an illustration of capabilities of the microwave‐assisted recovery protocol. The reclamation of saturated and unsaturated fatty acids from archaeological pottery fragments recovered from a number of the earliest ceramic horizons in the Middle East is herewith reported, and the extraction methods and instrumental analytical techniques are described.     

EFFECTS OF MILLING: A POSSIBLE FACTOR INFLUENCING THE DURABILITY OF HISTORICAL MORTARS

In their literary texts, some classical Roman authors such as Gaius Plinius Secundus and Marcus Vitruvius Pollio stress the importance of milling when preparing mortars. Following these indications, this work describes the effects of milling between lime (calcium hydroxide) and clay brick powder before and after the addition of water. Starting and resulting materials were investigated by XRPD, SEM/EDS, differential scanning calorimetry and thermogravimetry (DSC/TC), colorimetry, densimetry and porosimetry. Prolonged milling changes the mineralogy of the starting materials and increases their reactivity. The final lime pastes, starting from materials milled for varying periods of time, had different mineralogical and physical characteristics. These results may help to clarify the reasons for the marked differences in durability of some historical mortars.     

OXYGEN AND CARBON ISOTOPE ANALYSIS OF HUMAN TOOTH ENAMEL FROM THE NEW KINGDOM SITE OF TOMBOS IN NUBIA

This study examines the feasibility of using oxygen isotope analysis of tooth carbonate to identify immigrants from the New Kingdom site of Tombos in Nubia (n = 30). In comparison with published data, the results (δ¹⁸O_ca,VSMOW = 31.4‰) imply a substantial presence of immigrants. However, further analysis of these data strongly suggests the need to consider hydrological and cultural factors such as the contribution of aquifer waters to the Nile, use of groundwater sources, and differences in handling and storage of water. The carbon isotope analysis, in conjunction with published ⁸⁷Sr/⁸⁶Sr data, provides additional support for the presence of immigrants at Tombos.     

Site maintenance practices and settlement social organization in Iron Age Karnataka, India: Inferring settlement places and landscape from surface distributions of ceramic assemblage attributes

This paper investigates the spatial organization of social relations in settlement contexts through a quantitative and distributional analysis of surface ceramic attributes from Iron Age Period (1200–300 BC) archaeological sites in Southern India. The results discern variation in depositional contexts across each site, from which I infer a variety of basic settlement activity structures (e.g., site maintenance, trash disposal, residence, animal husbandry, metallurgy, ritual). I use these results, together with further analyses of artifact and feature distributions, to infer a basic suite of places, place-making practices and some of the social relations and organizational structures that produced these historically unique Iron Age settlement landscapes.     

Crops and weeds: the role of weed functional ecology in the identification of crop husbandry methods

This paper brings together the results of five present-day studies of arable weed ecology, and applies these to the identification of past crop husbandry regimes on the basis of archaeobotanical weed assemblages. The contrasting husbandry regimes covered by the present-day studies include irrigation and dry farming, fallowing and rotation, intensive and extensive cultivation, and autumn and spring sowing. The weed floras associated with these regimes were analysed in terms of the functional ecology of the species represented. These same functional attributes, that distinguished contrasting regimes, were then measured for the weed species found accompanying crop seeds in two archaeobotanical studies, of the Islamic site of Khirbet Faris, S. Jordan and Neolithic sites in central Europe. Analyses using these functional measurements resulted in the identification of irrigation at the former and in the identification of sowing time and intensive cultivation at the latter.     

A bioarchaeological study of a Western Basin tradition cemetery on the Detroit River

Archaeological monitoring of construction in a Windsor city park on the Detroit River led to the discovery of an isolated cemetery containing the remains of eight individuals assigned to the Late Woodland Western Basin Tradition. At the request and consent of the contemporary First Nation community, tissue samples from five individuals were subjected to radiocarbon dating, mtDNA, and stable isotope analysis to confirm cultural affiliation and further understand the subsistence practices of these people. Radiocarbon dating placed the cemetery at the transition from the Younge phase (AD 900–1200) to the Springwells phase (AD 1200–1400). The stable carbon and nitrogen isotope results provide an unexpected but fuller understanding of Late Woodland Western Basin Tradition subsistence. All individuals were as enriched in carbon as those found on Iroquoian horticulturalist sites to the east, suggesting a very high reliance on maize. Nitrogen isotope values indicate that the protein component of the diet was comprised largely of high trophic level food sources, likely fish. An in situ osteological analysis identified a high number of carious lesions in the visible teeth, also suggesting a diet high in carbohydrates. The mtDNA findings support the antiquity of the Western Basin presence in Northeast North America through genetic links with the Hind Site, an Archaic site in southern Ontario. These results underscore the importance of such studies for providing novel insight into the archaeological histories and lifeways of this distinct Late Woodland tradition. This study also emphazises the need to work with descendant communities to provide them with information on the past that reflects their distinct heritage in the lower Great Lakes region.