高精度磁测在考古勘查中的应用

介绍了考古对象的磁性、磁异常特征及一般工作方法等。例举了在一些地区应用高精度磁测的情况和效果。以具体的实例证明该方法高效率、无损伤等优点的同时,进一步提出该方法在考古应用中应注意研究的问题。     

Early fetal maturity assessed from patterns of ossification in the hand and foot

The assessment of fetal age at death is fraught with many complications and often the determination of the maturity of the fetus is a more realistic solution to the question of fetal viability. This study examines the pattern of appearance of primary centres of ossification in the fetal hand and foot, in an attempt to construct a maturity continuum. The results show that completion of ossification in the hand precedes that in the foot and generally occurs in a more regular pattern. The method proves useful at assessing fetal maturity between the third and tenth months of intra-uterine life. In addition, the relationship to other major centres of ossification is considered.     

Anthropological analysis of the phenomenon of atlas occipitalisation exemplified by a skull from twardogóra (17th c.)—southern Poland

Occipitalisation of the atlas is one of the most frequent osseous anomalies of the atlas. It is characterised by the adhesion of the first cervical vertebra with the basilar part of the occipital bone. The most probable cause of the occipitalisation is a congenital disorder. The atlanto‐occipital fusion may lead to narrowing of the space for medulla oblongata, spinal cord and vertebral artery. This in turn may lead to many physiological symptoms. The skull from Twardogóra, Southern Poland, showed partial atlanto‐occipital fusion and presented an asymmetry in structure and shape of apertures for the vessels and nerves around the foramen magnum. Copyright © 2011 John Wiley & Sons, Ltd.     

Episodic fluid flow within continental rift basins: some insights from field data and mathematical models of the Rhinegraben

Vitrinite reflectance data from a petroleum exploration well in the northern Upper Rhinegraben show an unusual vertical maturity trend. Above and below a 500 m thick marl layer the vitrinite reflectance levels are consistent with modern, conductive, geothermal gradients. Between about 1000 and 1500 m depth, however, vitrinite reflectance levels are significantly elevated (about 0.6%Ro). This anomaly cannot be explained with one‐dimensional conductive or conductive–convective heat transfer models, and thermal effects of sedimentation or igneous intrusion seem implausible for this geological setting. The thermal anomaly that formed this maturation anomaly must have been hydrothermal in origin, two‐dimensional in nature, and persisted long enough to elevate the vitrinite reflectance values within this marl unit, yet it must have dissipated before the thermal perturbation would have altered the organic matter below and above the unit. In this study, we propose that the vitrinite reflectance anomalies were caused by a transient thermal inversion induced by episodic, lateral flow of hot (130–160°C) groundwater along conductive fractures and bedding planes. Heat flow constraints suggest that fluids must have moved rapidly up a vertical feeder fault from a depth of at least 3.6 km before migrating laterally. To test this hypothesis, we present a suite of simple, idealized mathematical models of groundwater flow, heat transfer, thermal degradation of kerogen and vitrinite systematics to explore the episodic flow that could have produced the observed thermal anomaly. In these simulations, a single, horizontal aquifer is sandwiched between two less permeable units: the total dimensions of the vertical section model are 4 km thick by 10 km long. The top of the aquifer coincides with the position of the observed thermal maturity anomaly in the Rhinegraben. Boundary conditions along the left edge of this aquifer were varied through time to allow for the migration of hot fluids out into the basin. Inflow temperature, horizontal velocity, duration and frequency of flow and thickness of the aquifer were varied. We found that a thermal maturity anomaly could only be produced by a rather restrictive set of hydrothermal conditions. It was possible to produce the observed vitrinite reflectance anomaly by a single hydrothermal flow event of 130°C fluid migrating laterally into the aquifer at a rate of 1 m a^?1 for about 10 000 years. The anomaly is spatially confined to near the left edge of the basin, near the feeder fault. If the flow event lasted longer than 100 000 years, then the maturation anomaly disappeared as the lower confining unit approached steady‐state thermal conditions. It is possible that such an event occurred about 5 million years ago in response to increases in fault permeability associated with far field Alpine tectonism.     

Stafne's defects in two mandibles from archaeological sites in Croatia

Salivary gland inclusions in the mandible are relatively uncommon in recent as well as archaeological populations. This condition is well known to oral surgeons, but less so to anthropologists, osteologists and skeletal biologists. At present a limited number of reports pertaining to this condition in ancient populations are available in anthropological and palaeopathological literature, although scattered reports of cases in recent populations are found in dental journals. This paper analyses the prevalence of Stafne's bone defect in a large composite Croatian archaeological series (n = 4250 mandibles), and reports on two cases in which computerised tomography was performed, in order to draw the attention of anthropologists, osteologists and skeletal biologists to this condition when faced with differential diagnosis of odontogenic lesions, cysts and neoplasms in the area of the angle of the mandible. Copyright © 2009 John Wiley & Sons, Ltd.     

Lingual cortical mandibular defects (Stafne's defect): an anthropological approach based on prehistoric skeletons from the Canary Islands

While posterior lingual mandibular depressions (Stafne's defect) are often discussed in clinical reports, they are rarely the subject of anthropological research. This situation is paradoxical since osteologists and skeletal biologists are in a position to enhance understanding of the trait's aetiology by systematically recording the trait in recent and prehistoric skeletal collections. This report reviews anthropological studies of cortical defects of the mandible, recommends a protocol for recording observations in trait variation, and presents new data for the prevalence of Stafne's defect—lingual cortical defects of the mandibular corpus. Among the Guanches of Tenerife in the Canary Islands (Spain), the prevalence of lingual cortical defects is 3.32% (15/452), males are more frequently affected than females, and there is a tendency for individuals with antemortem tooth loss to display larger lesions than individuals without antemortem loss of teeth. Defects of the left side are somewhat more variable in position than defects located on the right. In comparative perspective, prevalence of lingual cortical defects among the Guanches is high, given the overall 1.07% prevalence reported for archaeological series (Finnegan & Marcsik,1980), but is similar to figures reported for the Avar period sample from Hungary 3.73%. Prospects for the use of lingual cortical defects as non‐metric traits of value in population distance studies remain uncertain since variation in trait expression may have a high environmental component. However, if human osteologists routinely include observations of lingual mandibular cortical defects in their analysis of skeletal collections, the data required to elucidate factors responsible for the trait's cultural, ecological, temporal and geographical patterning will more rapidly become established. Copyright © 2002 John Wiley & Sons, Ltd.     

Modeling thermal convection in supradetachment basins: example from western Norway

The juxtaposition of fault‐bounded sedimentary basins, above crustal‐scale detachments, with warmer exhumed footwalls can lead to thermal convection of the fluids in the sediments. The Devonian basins of western Norway are examples of supradetachment basins that formed in the hanging wall of the Nordfjord‐Sogn Detachment Zone. In the central part of the Hornelen and Kvamshesten basins, the basin‐fill is chiefly represented by fluvial sandstones and minor lacustrine siltstones, whereas the fault margins are dominated by fanglomerates along the detachment contact. Prominent alteration and low‐greenschist facies metamorphic conditions are associated with the peak temperature estimates of the sediments close to the detachment shear zone. Fluid circulation may have been active during the burial of the sediments, and we quantify the potential role played by thermal convection in redistributing heat within the basins. Different models are tested with homogeneous and layered basin‐fill and with material transport properties corresponding to sandstones and siltstones. We found that thermally driven fluid flow is expected in supradetachment basins as a transient process during the exhumation of warmer footwalls. We demonstrate that the fluid flow may have significantly affected the temperature distribution in the upper five kilometers of the Devonian basins of western Norway. The temperature anomaly induced by the flow may locally reach about 80°C. The sedimentary layering formed by sand‐ and siltstones strata does not inhibit fluid circulation at the scale of the basin. The presence of fluid pathways along the detachment has an important impact on the flow and allows an efficient drainage of the basin by channelizing fluids upward along the detachment.     

Not just cattle: Cranial perforations revisited

The phenomenon of perforated cattle skulls is well known to archaeozoologists. It is a condition that has not only been reported during routine faunal analyses but, unusually for animal palaeopathological studies, it has also been the subject of dedicated research papers. A revolutionary moment in the understanding of this anomaly came with its detection in the skull of a European bison. As a result of this discovery, a developmental disorder of genetic origin is now accepted as the most probable cause. In this paper, it is suggested that the perforations are caused by a developmental disorder that is expressed during the pneumatisation of the frontal, parietal and occipital bones in animals with a large sinus frontalis. The first published example of this condition in pig supports this hypothesis. It is argued that the anomaly is a hereditary trait caused by a recessive gene, the phenotypic expression of which only appears in homozygous recessive individuals. Higher incidences of this condition in past cattle and pig populations in certain places at times, may therefore testify to the occurrence of population bottlenecks and/or inbreeding practices. Copyright © 2009 John Wiley & Sons, Ltd.