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991.
A relatively closely spaced set of unpegged mortise-and-tenon joints was the significant element revealed in the 7th-century AD shipwreck, Dor D. It provides additional information for the transitional period of shipbuilding in the Mediterranean, and together with additional wrecks it establishes a better database for ship construction in the 4th–11th centuries AD. The preliminary conclusions tend to draw a slightly more complicated picture of the general evolutionary trend, since they present some features that have traditionally been considered as a disappearing technique.  相似文献   
992.
993.
Cathodoluminescence (CL) images of quartz grains in the Appin Quartzite from the aureole of the Ballachulish Igneous Complex (Scotland) reveal a textural complexity that we interpret in the light of published models of the evolution of the contact aureole. Five distinct generations of quartz can be discriminated in CL. The oldest of these is a dark luminescing mottled quartz (Type 1 quartz) that occurs in the centres of pre‐existing grains, in samples collected from 210 m to 0.1 m from the contact. Dark mottled quartz is interpreted to be unrecrystallized material and has a regional metamorphic CL spectral signature. The onset of contact metamorphism resulted in grain growth visible in CL as a series of fine‐scale alternating bands of bright and dark luminescing material (Type 2 quartz), which we attribute to infiltration of repeated pulses of small amounts of H2O along grain boundaries. Close to the intrusion, a subgrain‐scale network of intragranular, bright luminescing features could have resulted from either intragranular microcrack‐controlled infiltration of H2O at high temperatures or intergranular cracking followed by grain growth (Type 3 quartz). Broad bands of bright material on grain boundaries in samples that are inferred to have undergone partial melting are interpreted as quartz crystallized from the melt phase (Type 4 quartz). The final stage in the textural development is marked by a series of aligned fractures, detected in CL by nonluminescing material (Type 5 quartz) and corresponding closely with trails of fluid inclusions. These fractures are interpreted as the pathways for late‐stage, low‐temperature, retrogressive fluids.  相似文献   
994.
The effect of pore size on cementation in porous rocks   总被引:1,自引:0,他引:1  
A. Putnis  G. Mauthe 《Geofluids》2001,1(1):37-41
Halite cementation in porous sandstone from the Lower Triassic Bunter Formation in North‐West Germany has been studied using measurements of porosity and permeability, before and after salt extraction, as well as from petrographic observations. The results show that in cemented sandstones there is a clear tendency for the larger pores to be halite‐filled while the smaller pores, which are responsible for the residual porosity, are left empty. Observations on cemented ‘pin‐stripe’ aeolian sandstones, in which laminations of fine and coarser sand grains alternate on a millimetre scale, indicate that this selective cementation is not due to differences in the brine composition in the pores. The implication, which is also supported by other observations, is that fluids in small pores can maintain a higher supersaturation with respect to crystallization.  相似文献   
995.
A recent advancement in petroleum geochemistry is to model fossil oil composition using microthermometric and volumetric data acquired from individual fluid inclusion analysis. Fourier transform infrared (FT‐IR) microspectroscopy can record compositional information related to gas (CH4 and CO2) and alkane contents of petroleum inclusions. In this study, a quantitative procedure for FT‐IR microspectrometry has been developed to obtain, from individual fluid inclusions, mol percentage concentrations of methane, alkanes and carbon dioxide as constraints to thermodynamic modelling. A petroleum inclusion in a sample from the Québec City Promontory nappe area was used as standard to record a reference spectrum of methane. The analytical procedure is based on the measurement of CH4/alkane and CH4/CO2 band area ratios. CH4/alkane infrared band area ratio is obtained after spectral subtraction of the reference methane spectrum. This area ratio, affected by absolute absorption intensities of methane, methyl and methylene, provides a molar CH4/alkane ratio. Methyl/methylene ratio (CH2/CH3) ratio is obtained following procedures established in previous work. CO2/CH4 concentration ratio is estimated from relative absolute absorption intensities. Application to natural inclusions from different environments shows good correlation between FT‐IR quantification and PIT (petroleum inclusion thermodynamic) modelling.  相似文献   
996.
997.
Examination of the skeleton of an adult male from the Celtic necropolis of Casalecchio di Reno (Bologna, Italy; 4th–3rd century BC) revealed some lesions on the feet, especially bilateral acro‐osteolysis of the metatarsals, and on the tibia, fibula and hand. The morphological and radiographic characteristics of the bones are consistent with a diagnosis of leprosy. Other features of the rhinomaxillary region support this diagnosis. As far as we know, this case could represent the oldest skeletal evidence of leprosy in Europe, indicating the early spread of this disease toward the Western world. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
998.
Analysis of the skeleton from tomb 144 of the early medieval necropolis of Vicenne‐Campochiaro in Central Italy revealed several features indicative of leprosy. The skeleton belongs to a male estimated to be between 20 and 25 years of age at death. The distal halves of the 1st and 2nd left metatarsals present acro‐osteolysis and both legs show severe subperiosteal bone reaction. The facial skeleton shows changes compatible with a chronic inflammatory process, possibly due to an infectious disease. The anatomical distribution of the lesions and their association with other skeletal lesions seems to be compatible with a near‐lepromatous form of leprosy. A differential diagnosis is made, and the skeletal traits pathognomonic of leprosy are discussed. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
999.
The aim of this article is to present a panoramic view of the Basque Country's capacity and competence for self-government. We have analysed the historical process of industrialization, the effects of the industrial crisis and new possibilities for development of the area's own regional policy based on new institutions (Government and Provincial Councils) that emerged from administrative decentralization in Spain after 1980. In the following section, we analyse the scope of authority in EU regions. Some of the cultural and transport infrastructure projects backed by these Basque institutions are studied. These projects have had a considerable impact on the Bilbao Metropolitan Area. The changes observed in the nation state, specifically in Europe, show contradictory effects. However, they have reduced the State's sovereignty but at the same time have prompted the State to retain powers rather than transfer them to lower institutional levels. This clashes with the desire of some regions or historical nations to access greater shares of self-government, such as the case of the Basque Country.  相似文献   
1000.
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