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图像配准和融合及其在医学影像中的应用 总被引：2，自引：2，他引：2
图像配准和融合是图像分析和处理的基本问题，在医学影像、遥感、计算机视觉等领域有着广泛的应用。本文研究它们在多模态医学影像技术中的应用。本文提出并实现了基于Ｆｏｕｒｉｅｒ变换的图像配准和基于子波变换的图像融合方法，在图像融合中，我们采用特征选择的取大原则，这种准则更适合于来自不同图像中的明显特征 相似文献
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Interplay of tectonics and neogene post-collisional magmatism in the intracarpathian region 总被引：6，自引：0，他引：6
Distribution of the Neogene calc-alkaline magmatism of the Carpathian arc is directly related in space and time to the kinematics of the two major terranes of the Intracarpathian area (Alcapa, Tisia-Getia) along the south-eastern border of the European plate. In the West Carpathians and adjacent areas, the volcanic activity occurred between 20–11 Ma, with large volumes of both acidic and intermediate rocks, generally distributed randomly, sometimes transversally to the orogenic belt and as rare small occurrences along the Flysch belt. In the East Carpathians, the volcanic rocks are distributed along the northern margin of the Zemplin block, the north–easternmost part of the Alcapa and eastward along the front of the Getic block, at the contact with European plate. Between Tokaj-Slanské-Vihorlat up to northern Cãlimani Mountains, the magmatism occurred between 14–9 Ma, and along the Cãlimani-Harghita chain between 9–0.2 Ma. The calc-alkaline magmatic rocks of the Apuseni Mountains are located in the interior of the Tisia block and occurred between 14–9 Ma. The generation of the calc-alkaline magmatism is considered here as the result of complex interplay between plate roll-back and lithospheric detachment tectonic processes and the break-off of the subducted plate, mostly in a post-collisional setting. (1) The magmatites of the Western Carpathians and the Pannonian basin were generated in direct relation to subduction roll-back processes, over the downgoing slab, during the period of lateral extrusion and back-arc extension. In this area, characterized by maximum crustal shortening, we can infer further delamination processes to explain the generation of magmas. (2) The magmatic rocks from the northern sector of the East Carpathians (Tokaj-Slanské-Vihorlat up to the Northern Cãlimani Mountains), resulted after subduction roll-back processes and an almost simultaneous break-off of the descending plate all along the arc segment during main clockwise rotation of the Intracarpathian terranes. (3) In the eastern sector of the East Carpathians (Cãlimani up to Harghita Mountains), the magmatic rocks were generated through partial melting of the subducted slab followed by gradual break-off of the subducted plate along strike (north to south). (4) The Apuseni Mts. magmatic activity resulted in transtensional tectonic regime by decompressional melting of lithospheric mantle, during the translation and rotation of Tisia-Getia block. 相似文献
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Katie?PreeceEmail author Ralf?Gertisser Jenni?Barclay Kim?Berlo Richard?A.?Herd Edinburgh Ion Microprobe Facility 《Contributions to Mineralogy and Petrology》2014,168(4):1061
The 2010 eruption of Merapi (VEI 4) was the volcano’s largest since 1872. In contrast to the prolonged and effusive dome-forming eruptions typical of Merapi’s recent activity, the 2010 eruption began explosively, before a new dome was rapidly emplaced. This new dome was subsequently destroyed by explosions, generating pyroclastic density currents (PDCs), predominantly consisting of dark coloured, dense blocks of basaltic andesite dome lava. A shift towards open-vent conditions in the later stages of the eruption culminated in multiple explosions and the generation of PDCs with conspicuous grey scoria and white pumice clasts resulting from sub-plinian convective column collapse. This paper presents geochemical data for melt inclusions and their clinopyroxene hosts extracted from dense dome lava, grey scoria and white pumice generated during the peak of the 2010 eruption. These are compared with clinopyroxene-hosted melt inclusions from scoriaceous dome fragments from the prolonged dome-forming 2006 eruption, to elucidate any relationship between pre-eruptive degassing and crystallisation processes and eruptive style. Secondary ion mass spectrometry analysis of volatiles (H2O, CO2) and light lithophile elements (Li, B, Be) is augmented by electron microprobe analysis of major elements and volatiles (Cl, S, F) in melt inclusions and groundmass glass. Geobarometric analysis shows that the clinopyroxene phenocrysts crystallised at depths of up to 20 km, with the greatest calculated depths associated with phenocrysts from the white pumice. Based on their volatile contents, melt inclusions have re-equilibrated during shallower storage and/or ascent, at depths of ~0.6–9.7 km, where the Merapi magma system is interpreted to be highly interconnected and not formed of discrete magma reservoirs. Melt inclusions enriched in Li show uniform “buffered” Cl concentrations, indicating the presence of an exsolved brine phase. Boron-enriched inclusions also support the presence of a brine phase, which helped to stabilise B in the melt. Calculations based on S concentrations in melt inclusions and groundmass glass require a degassing melt volume of 0.36 km3 in order to produce the mass of SO2 emitted during the 2010 eruption. This volume is approximately an order of magnitude higher than the erupted magma (DRE) volume. The transition between the contrasting eruptive styles in 2010 and 2006 is linked to changes in magmatic flux and changes in degassing style, with the explosive activity in 2010 driven by an influx of deep magma, which overwhelmed the shallower magma system and ascended rapidly, accompanied by closed-system degassing. 相似文献
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New U-Pb geochronology is used to refine the provenance and evolution of northwest Gondwana Pan-African terranes preserved in the South Carpathians of Romania. The Dr?g?an terrane of Avalonian affinity, from the Danubian domain of the South Carpathians originated in the Panthalassa Ocean and accreted to the Amazonian part of Rodinia not much before 800 Ma, when the F?ge?el orthogneiss was intruded, at around 807–810 Ma. After this event no other Neoproterozoic magmatic pulse is known in the basement of the Dr?g?an terrane. The Ganderian type Lainici-P?iu? terrane from the same domain of the South Carpathians, recorded magmatic pulses at 782 Ma, 739 Ma, 708 Ma, 639 Ma, 600–587 Ma and 574–568 Ma. The East Cadomian Sebe?-Lotru terrane from the Getic domain of the South Carpathians recorded magmatic pulses at 817 Ma, 768 Ma, 685 Ma, 620 Ma, 584 Ma and 550 Ma. Post 630 Ma the northwestern Gondwana margin evolved as an active continental margin at least until 550 Ma, but the pre-630 Ma magmatism could be associated to some island arcs docked with different pre-Gondwanan continental fragments. Independent of the tectonic setting, the post 750 Ma orogens dated in the basement of the peri-Gondwanan terranes are discussed in the frame of the Cadomian orogens, as constituents of the Pan-African orogens in a broader sense. The detrital zircon may also record magmatic pulses from Pan-African orogens other than the Cadomian ones. 相似文献
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The eastern branch of the Romanian Carpathians – the East Carpathians – is essentially an Alpine thrust and fold belt made up in its median part by a Crystalline–Mesozoic zone. This, in turn, is built up by several Alpine nappes (top to bottom): the Wildflysch, Bucovinian, Subbucovinian and Infrabucovinian. In the basement of the Bucovinian and Subbucovinian nappes the following Variscan tectonic units have been identified (top to bottom): Rar?u, Putna, Pietrosu Bistri?ei and Rodna. The Infrabucovinian nappes comprise the Rar?u nappe only. The Alpine nappes have an eastward vergence, opposite to the Variscan ones (present coordinates). In terms of pre-Variscan terranes distribution, the Rar?u nappe involved the Bretila terrane basement and its late Paleozoic cover, Putna the Tulghe? terrane basement, Pietrosu Bistri?ei the Negri?oara terrane basement and Rodna the Rebra terrane basement. These terranes originated along northwestern Gondwana margin during some Ordovician thermotectonic events. They do not represent Cadomian terranes and we call them Carpathian-type terranes. Two igneous protoliths from Bretila terrane basement (i.e. Anie? orthogneiss and H?ghima? granitoid) yield U/Pb LA-ICP-MS zircon ages of 462 ± 3 Ma and 469.2 ± 6.5 Ma, respectively. An orthogneiss from Tulghe? terrane basement yield 462.6 ± 3.1 Ma; the Pietrosu porphyritic orthogneiss from Negri?oara terrane basement yield 461.1 ± 5.2 Ma; and the Nichita? orthogneiss from Rebra terrane basement yield 447.9 ± 2.8 Ma. All these ages suggest the magma crystallization time. Two paragneisses from the Rebra terrane basement show a detrital zircon age distribution characteristic of a NE-African provenance. Regarding the tectonic settings, the lithology of the Bretila terrane suggests a magmatic arc on a continental margin, while of the Tulghe? terrane suggests a back arc environment, and those of the Rebra and Negri?oara terranes suggest a passive continental margin. An Ordovician metamorphism of medium grade (staurolite–kyanite zone) affected the basements of Bretila, Negri?oara and Rebra terranes, whereas a low grade (chlorite to biotite zone) event affects the Tulghe? terrane. With regard to the Variscan orogeny, the existence of a Paleotethys suture is proposed within the metamorphic basement of the East Carpathians. In this interpretation, the Bretila terrane was the upper plate, the Rebra and Negri?oara terrane pair formed the lower plate and the Tulghe? terrane was a component of the suture. The Variscan thermotectonic events reflect isothermal decompression with andalusite + cordierite in the basement of the Rebra terrane and retrogression in the basement of the other terranes. 相似文献
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