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991.
The North American archaeological phenomenon known as Clovis is famous for the fact that a number of sites that contain diagnostic Clovis artifacts also contain the remains of mammoth and perhaps other extinct genera. In the past, this has led many to assume that Clovis subsistence adaptations were organized around large, now-extinct mammals. It has also seemed to support the argument that the colonization of the Americas by hunters about 11,500 years ago caused the extinction, either directly or indirectly, of some 35 genera of primarily large mammals. Here, we review all sites known to us that have been suggested to provide evidence for the association of Clovis-age archaeological material with the remains of now-extinct Pleistocene mammals. Of the 76 sites reviewed, only 14 provide strong evidence that Clovis-aged people hunted such mammals. Of these sites, 12 contain the remains of mammoth, while two contain the remains of mastodon. Although the prime focus of the analysis we present is on Clovis-age archaeological associations with now-extinct mammals, we conclude that there is no evidence provided by the North American archaeological record to support the argument that people played a significant role in causing Pleistocene extinctions here.  相似文献   
992.
The paper discusses the application of a number of manual trilateration surveying systems, an acoustic surveying system and a photogrammetric system applied to a rigid test frame. Results and relative merits are compared and discussed.  相似文献   
993.
We present a reconstruction of the three‐dimensional (3D) geometry and gold grade distribution of shear zone‐hosted, Au‐mineralized, quartz–tourmaline veins of the Sigma deposit (Abitibi belt). Host shears and veins form a network of anastomosing, steeply dipping structures associated with smaller subhorizontal extensional veins. Our reconstruction has been carried out using the exceptionally large geological database of the mine. From this database, we extracted the geometric position, thickness and gold grades of geometrically best‐defined steep veins contained in a representative subvolume of the deposit. These data allowed the 3D representation of 53 veins, which have been constructed by fitting surfaces through the geometrical data and by contouring thickness and gold grade. The geometry of the network is mainly characterized by: (i) a few large segmented veins, with sinuous and helicoidal shape, and typical vertical dimension of >100 m; (ii) a large number of smaller vertical veins, some of which splay off the steep veins with high dip angles; (iii) subhorizontal extension veins (joints) located at, or close to, the tips of steep veins. The absolute thickness of the vertically short veins is the same as that of the large veins, suggesting that they formed simultaneously, but only a few of them interconnect to form vertically continuous bodies. Patchy, vertically elongated zones of high dilation are present in the large veins, and are poorly correlated with Au‐rich zones. They presumably represent former high‐permeability zones of the network. The highest gold grades occur at the interconnections between the large veins and small splays or subhorizontal joints. This indicates the important role of vein interconnection for fluid flow and gold precipitation within the network. Combining the calculation of the volume of the network with the estimation of tourmaline abundance in the veins, we calculate that 2.1 × 106 m3 of tourmaline and 3.2 × 106 m3 of quartz precipitated during Au deposition.  相似文献   
994.
More than a dozen hydrocarbon seep‐carbonate occurrences in late Jurassic to late Cretaceous forearc and accretionary prism strata, western California, accumulated in turbidite/fault‐hosted or serpentine diapir‐related settings. Three sites, Paskenta, Cold Fork of Cottonwood Creek and Wilbur Springs, were analyzed for their petrographic, geochemical and palaeoecological attributes, and each showed a three‐stage development that recorded the evolution of fluids through reducing–oxidizing–reducing conditions. The first stage constituted diffusive, reduced fluid seepage (CH4, H2S) through seafloor sediments, as indicated by Fe‐rich detrital micrite, corroded surfaces encrusted with framboidal pyrite, anhedral yellow calcite and negative cement stable isotopic signatures (δ13C as low as ?35.5‰ PDB; δ18O as low as ?10.8‰ PDB). Mega‐invertebrates, adapted to reduced conditions and/or bacterial chemosymbiosis, colonized the sites during this earliest period of fluid seepage. A second, early stage of centralized venting at the seafloor followed, which was coincident with hydrocarbon migration, as evidenced by nonluminescent fibrous cements with δ13C values as low as ?43.7‰ PDB, elevated δ18O (up to +2.3‰ PDB), petroleum inclusions, marine borings and lack of pyrite. Throughout these early phases of hydrocarbon seepage, microbial sediments were preserved as layered and clotted, nondetrital micrites. A final late‐stage of development marked a return to reducing conditions during burial diagenesis, as implied by pore‐associated Mn‐rich cement phases with bright cathodoluminescent patterns, and negative δ18O signatures (as low as ?14‰ PDB). These recurring patterns among sites highlight similarities in the hydrogeological evolution of the Mesozoic convergent margin of California, which influenced local geochemical conditions and organism responses. A comparison of stable carbon and oxygen isotopic data for 33 globally distributed seep‐carbonates, ranging in age from Devonian to Recent, delineated three groupings that reflect variable fluid input, different tectono‐sedimentary regimes and time–temperature‐dependent burial diagenesis.  相似文献   
995.
996.
Hallmark events are important redevelopment tools utilised by entrepreneurial governments. The features of these events are analogous to those of entrepreneurial urban governance. This study examined the local impacts of the Sydney 2000 Olympic Games, particularly in relation to its social and political legacies, in three local government areas which hosted Olympic venues. It also investigated the nature of urban governance in Sydney, Australia, as it was manifested in the planning of the Sydney 2000 Olympics. Examples of entrepreneurialism in planning for the Olympics included the centralisation of planning powers, the increasing involvement of the private sector in government activities, and the relaxation of planning processes, resulting in reduced openness, accountability and public participation. Examples of resistance to the anti–democratic tendencies of entrepreneurialism were however evident in some areas, with managerial and democratic concerns remaining important to some local governments. Local community activism was imperative to achieving civic participation and ensuring commitment by local government to these managerial and democratic concerns. Activism also enabled some local communities to secure significant benefits from the Olympic Games.  相似文献   
997.
Samples of red pigment from a group of seven Roman‐period Egyptian mummies, known as red‐shroud mummies, are investigated. Elemental analysis by inductively coupled plasma time‐of‐flight mass spectrometry (ICP–TOFMS) shows that the samples contain mostly Pb (83–92% by weight), along with 0.2–2.0% Sn. All of the samples are found to have similar trace element distributions when normalized to the continental crust, suggesting that they share a common geological origin. Lead isotope ratios are found to match the mixed lead sources typically associated with Rio Tinto, Spain – a site extensively mined for silver during the first century ad . Raman microspectroscopy identifies the major phase of each sample to be red lead (Pb3O4) with a minor phase of lead tin oxide (Pb2SnO4). Lead tin oxide does not occur naturally, and its incidental occurrence within the sample indicates that the material was heated under oxidative conditions at temperatures in excess of 650°C. In archaeological contexts, the high‐temperature oxidative treatment of lead is typically associated with metallurgical refinement processes such as cupellation. Based on this evidence, it is argued that the pigment was produced out of litharge associated with silver cupellation at the Rio Tinto site.  相似文献   
998.
Optical coherence tomography (OCT), a new method for ceramics research, is a nondestructive, three‐dimensional tomography system, which provides subsurface morphology visualization of samples based on the refractive index or dielectric constant differences in the target specimen. In this study, seven shards from different Chinese kilns of Song and Yuan dynasties (10–14th centuries) were scanned to visualize the subsurface morphology of their glazes. The images revealed unique phase assemblage modes in different samples. The results suggest OCT may be used to identify ceramics and provide information about their manufacturing technology.  相似文献   
999.
1000.
The Kosovo war was a decisive catalyst in the development of the EU's international security role. The escalating crisis in Kosovo confirmed that the EU was still unable to prevent, contain or end violent conflict along its own borders. This led the EU to augment both its hard and soft power through the launch of the European Security and Defence Policy and the Stabilisation and Association Process. These initiatives endowed the EU with the potential to make a distinct contribution to international conflict management. Unsurprisingly, this continuing transformation has encountered significant obstacles relating to capabilities, political will and coordination. Concerns have also been raised about how the development of a military dimension has changed the nature of EU power. However, the EU has not abandoned the core principle upon which its international role was founded, namely the need to transcend conflict. Ten years after its failings in Kosovo, the EU is assuming increasing responsibility for conflict management and becoming a more capable international security actor.  相似文献   
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