Geological controls on regional transmissivity anisotropy

A variety of data indicate that the Carbonate aquifer in southern Manitoba is a heterogeneous and anisotropic aquifer wherein groundwater flow follows preferred flow path networks. Specific capacity tests show that aquifer transmissivity can vary by up to four orders of magnitude within 1 km. Geostatistical analysis reveals a strong anisotropy in the transmissivity field, with better spatial continuity in NE–SW and NW–SE directions, coincident with the dominant orientations of fractures observed in bedrock exposures. However, discrepancies between the orientation of highest fracture density and best transmissivity continuity suggest that either additional geological factors control the preferred flow network or there is a biased representation of the fracture pattern because all direct fracture observations came from the northern part of the study area. In an effort to investigate whether the geographically biased fracture data set represents the fracture pattern for the whole region, Landsat images and digital elevation maps were processed to extract linear features that may indicate subsurface fracture zones in areas where bedrock is covered by glacial sediments. The results suggest a consistent fracture pattern throughout the study area, indicating that the two observed fracture groups might have gone through different processes in terms of permeability development. Alteration by mineral cementation and dissolution along fracture surfaces may have preferentially improved the fracture permeability in one orientation, while reducing it in the other. The in situ stress field is also believed to play a major role in the preferred regional flow network. This paper discusses the evidence for the preferred flow path network and possible geological factors controlling aquifer anisotropy in this region.     

Virtual zooarchaeology: building a web-based reference collection of northern vertebrates for archaeofaunal research and education

Osteological reference collections are a crucial tool in archaeofaunal analysis, but few are comprehensive; most lack a broad range of taxa or multiple individuals per taxon. This problem is especially prominent in arctic zooarchaeology, where difficulty in obtaining, transporting, and processing northern taxa has led to a dearth of appropriate reference collections. The Virtual Zooarchaeology of the Arctic Project, or VZAP, seeks to develop a comprehensive virtual comparative assemblage for the skeletons of northern vertebrates. VZAP (http://vzap.iri.isu.edu) is designed to assist with identifications in the lab or field and provides significant educational value, for both classroom demonstration and personal consultation. The VZAP website presents high-resolution digital photographs and 3D models of skeletal elements via an intuitive graphical user interface, designed to mimic the visual experience of working with a real comparative collection. This custom-built interface, the Dynamic Image Engine, represents a new way to present heritage media in an interactive and engaging format. VZAP also implements unique 3D scanning protocols to increase the realism of 3D models, and delivers them on a platform that allows for point to point measurements, cross-sections, morphological labels, and anatomical orientations.     

Quantification of slag heap volumes and masses through the use of induced polarization: application to the Castel-Minier site

When used for archaeological purposes, geophysical methods are often useful for the exploration, detection and mapping of archaeological remains. In the case of ancient metallurgical activities, slag accumulations form precious mineral records of these activities. Evaluating the volume of slag produced in such locations is an important issue, since it enables an estimate of the amount of metal produced in the smeltery. Unfortunately, slags themselves cannot be easily detected by DC electrical methods. Although they can be easily detected using magnetic techniques, these methods do not allow for an estimate of the quantity of slag, because magnetic fields do not conserve magnetic flux. In the present study we show that the Induced Polarization method (IP) is suited to the quantification of buried slags, provided the slag response has been suitably calibrated prior to the field measurements. The ability to quantify the quantity of slag is based on the quasi-linear relationship between the main IP parameter, i.e., the chargeability, and the slag concentration. This approach provides a new, non-invasive tool for the estimation of the volume of buried slag in palaeometallurgical sites.In this paper, an application of this technique for the site of Castel-Minier, Ariège, France, is presented.     

Ancient DNA in human bones from Neolithic and Bronze Age sites in Greece and Crete

Attempts were made to detect ancient DNA (aDNA) in samples of 88 human skeletons from eight Neolithic and Bronze Age sites in Greece and Crete. Ancient DNA was absent in specimens from Nea Nikomedia, Lerna, Karaviádena (Zakro), Antron Grave Circle A and Mycenae Grave Circle A. For each of three skeletons from Antron Grave Circle B that were sampled, polymerase chain reactions (PCRs) gave products for nuclear but not mitochondrial DNA, but amplicon yield was low and inconsistent with replicate PCRs failing to give reproducible results. With specimens from Mycenae Grave Circle B, evidence for mitochondrial aDNA was obtained for four of the 22 skeletons that were studied, and at Kouphovouno evidence for mitochondrial and/or nuclear aDNA was obtained with eight of the 20 skeletons that were examined. We conclude that, although aDNA might be present in some Eastern Mediterranean skeletons from later centuries of the Bronze Age, it is not commonly found in material from this period and is likely to be absent from older material.     

The potential of chironomid (Insecta: Diptera) larvae in archaeological investigations of floodplain and lake settlements

The head capsules of chironomids (Insecta: Diptera) are well preserved in sediments and can be recognised to a high taxonomic level, usually genus and sometimes species. Work on lake sediments has shown that they can be accurate indicators of water temperature, oxygen regimes, and nutrient status (particularly total phosphorus and chlorophyll-a), as well as heavy metal pollution. No systematic chironomid analyses, however, have previously been undertaken on archaeological deposits. In order to address this we assessed the use of chironomids in three types of archaeological deposit; firstly, a lake core at the edge of a lake settlement (crannog), secondly, a palaeochannel infill adjacent to a multi-period settlement site and lastly, a Roman well deposit from a floodplain environment. The chironomid assemblages are shown to vary significantly both between and within the sites and reflect the immediate environment and the adjacent area. The lake sediment assemblage reflects the construction of the crannog through elevated levels of organic detritus, wood and woody debris. The palaeochannel assemblage reveals changing natural conditions and nutrient enrichment probably associated with settlement during the Saxon period. The well assemblage is taxonomically restricted and indicative of organic debris, dead plant material, animal dung and possibly human effluent deposited after abandonment of the well. Dry storage of the palaeochannel and well sediments for several years did not appear to affect the concentration or state of preservation of the head capsules. The chironomid reconstructions are shown to provide an additional indicator of human activity which has the potential to provide quantitative data on the character of aquatic environments associated with archaeological sites.     

Fluid flow in shear zones: insights from the geometry and evolution of ore bodies at Renco gold mine,Zimbabwe

The geometry of mineral deposits can give insights into fluid flow in shear zones. Lode gold ore bodies at Renco Mine, in the Limpopo Belt, Zimbabwe, occur as siliceous breccias and mylonites within amphibolite facies shear zones that dip either gently or steeply. The two sets of ore bodies formed synchronously from hydrothermal fluids. The ore bodies are oblate, but have well‐defined long axes. Larger ore bodies are more oblate. High‐grade gold ore shoots have long axes that plunge down dip; this direction is perpendicular to the long axes of the low‐grade ore bodies. The centres of the high‐grade ore bodies align within the low‐grade ore bodies along strike in both gently and steeply dipping groups. The range of sizes and shapes of the ore bodies are interpreted as a growth sequence. Geometrical models are proposed for the gently and steeply dipping ore bodies, in which individual ore bodies grow with long axes plunging down dip, and merge to form larger, more oblate ore bodies. The models show that when three or more ore bodies coalesce, the long axis of the merged ore body is perpendicular to the component ore bodies, and that ore bodies in the deposit may have a range of shapes due to both growth of individual ore bodies, and their coalescence. The long axes of the high‐grade ore bodies are parallel to the shear directions of both the gently and steeply dipping dip slip shear zones, which were the directions of greatest permeability and fluid flow. The larger, lower grade bodies, which may have formed by coalescence, are elongate perpendicular to these directions.     

Seasonal migration in South-west France during the late glacial period

It has long been accepted that mobility was a factor in human life in Quaternary SW France, but debate continues as to the purpose, extent, direction, frequency and regularity of the movements. Several different types of evidence are relevant to the problem, and while some scholars have come to rather vague conclusions concerning “occasional forays” or “exchange systems”, others have taken up a firm position after analysis of only one body of data. A reappraisal of all aspects of the problem, in the light of all the evidence available from the region, in fact leads to only one satisfactory hypothesis: that of long-distance seasonal migration by both man and game.Only the reindeer-dominated sites of SW France will be discussed here, as it is from these that the migrations were the most necessary and the most extensive. Movements from other sites, such as those where a horse-dominated economy was practised, would probably have been rather shorter owing to the restricted migration undertaken by the staple resources.