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Igor S. Peretyazhko Victor Ye. Zagorsky Sergey Z. Smirnov Mikhail Y. Mikhailov 《Chemical Geology》2004,210(1-4):91-111
Coexisting melt (MI), fluid-melt (FMI) and fluid (FI) inclusions in quartz from the Oktaybrskaya pegmatite, central Transbaikalia, have been studied and the thermodynamic modeling of PVTX-properties of aqueous orthoboric-acid fluids has been carried out to define the conditions of pocket formation. At room temperature, FMI in early pocket quartz and in quartz from the coarse-grained quartz–oligoclase host pegmatite contain crystalline aggregates and an orthoboric-acid fluid. The portion of FMI in inclusion assemblages decreases and the volume of fluid in inclusions increases from the early to the late growth zones in the pocket quartz. No FMI have been found in the late growth zones. Significant variations of solid/fluid ratios in the neighboring FMI result from heterogeneous entrapment of coexisting melts and fluids by a host mineral. Raman spectroscopy, SEM EDS and EMPA indicate that the crystalline aggregates in FMI are dominated by mica minerals of the boron-rich muscovite–nanpingite CsAl2[AlSi3O10](OH,F)2 series as well as lepidolite. Topaz, quartz, potassium feldspar and several unidentified minerals occur in much lower amounts. Fluid isolations in FMI and FI have similar total salinity (4–8 wt.% NaCl eq.) and H3BO3 contents (12–16 wt.%). The melt inclusions in host-pegmatite quartz homogenize at 570–600 °C. The silicate crystalline aggregates in large inclusions in pocket quartz completely melt at 615 °C. However, even after those inclusions were significantly overheated at 650±10 °C and 2.5 kbar during 24 h they remained non-homogeneous and displayed two types: (i) glass+unmelted crystals and (ii) fluid+glass. The FMI glasses contain 1.94–2.73 wt.% F, 2.51 wt.% B2O3, 3.64–5.20 wt.% Cs2O, 0.54 wt.% Li2O, 0.57 wt.% Ta2O5, 0.10 wt.% Nb2O5, 0.12 wt.% BeO. The H2O content of the glass could exceed 12 wt.%. Such compositions suggest that the residual melts of the latest magmatic stage were strongly enriched in H2O, B, F, Cs and contained elevated concentrations of Li, Be, Ta, and Nb. FMI microthermometry showed that those melts could have crystallized at 615–550 °C.
Crystallization of quartz–feldspar pegmatite matrix leads to the formation of H2O-, B- and F-enriched residual melts and associated fluids (prototypes of pockets). Fluids of different compositions and residual melts of different liquidus–solidus P–T-conditions would form pockets with various internal fluid pressures. During crystallization, those melts release more aqueous fluids resulting in a further increase of the fluid pressure in pockets. A significant overpressure and a possible pressure gradient between the neighboring pockets would induce fracturing of pockets and “fluid explosions”. The fracturing commonly results in the crushing of pocket walls, formation of new fractures connecting adjacent pockets, heterogenization and mixing of pocket fluids. Such newly formed fluids would interact with a primary pegmatite matrix along the fractures and cause autometasomatic alteration, recrystallization, leaching and formation of “primary–secondary” pockets. 相似文献
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The use of headland-breakwater systems along the shore of Chesapeake Bay began in the early 1980s. Properly designed and installed headland breakwaters with beach fill and wetlands plantings provide shore protection and create a “full” coastal profile of beach/backshore/dune which enhances habitat. They create a tertiary buffer for upland runoff and groundwater and provide access and recreation. The wetland grasses also create an erosion resistant turf. The coastal profile accommodates environmental permitting requirements of habitat enhancement for shore protection structures. 相似文献
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基于Pocket PC 的海洋渔业调查数据采集 总被引：1，自引：0，他引：1
针对传统的主要依赖于纸质日志记录海洋渔业资源调查数据所存在的数据质量差、难以保存、作业效率低等弊端,结合Pocket PC移动终端的优越性,提出利用Pocket PC平台记录海洋渔业资源调查数据,并分别就近海调查和远洋调查数据采集提出了相应的基于 Pocket PC 平台的信息化数据采集解决方案。然后以大洋性鱿鱼资源调查为例,设计并开发了一个基于Pocket PC的海洋渔业调查数据采集系统。通过实践检验,该系统可较好地完成大洋性鱿鱼资源调查的数据采集任务,同时也表明了基于 Pocket PC的海洋渔业调查数据采集的可行性和优越性。讨论的数据采集解决方案和相关技术可为海洋渔业和海洋环境相关的调查数据采集提供信息化支持。 相似文献
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The empirical bay shape model proposed by Hsu and Evans in 1989 for predicting the static planform of a pocket beach is expanded to enable the calculation of three-dimensional beach changes on a pocket beach with a seawall. The original formulation was developed on the basis of a second-order regression analysis. Unlike the one-line model of shoreline changes, the model of Hsu and Evans does not require repeated calculations of the wave field and shoreline position, because it was derived on the assumption of null sediment movement within a pocket beach in static equilibrium, hence without the need of applying the continuity condition of total sand volume in the calculation. The expanded model proposed by the present authors satisfies the total sand budget on a pocket beach, by taking into account the concept of depth change due to longshore sand transport. Model tests were carried out and the new model was further applied to the beach changes at Kemigawa on the northeast of Tokyo Bay in Chiba Prefecture, as well as at Oarai in Ibaraki Prefecture, Japan. On both locations, seawall has been installed as countermeasures against beach erosion, where wave sheltering effect of the main breakwater and beach changes in front of the seawall has also been observed. With this expansion, the present model can be applied to predict the three-dimensional beach changes on a coast with seawall on a pocket beach. 相似文献
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Coastal planform studies are a relevant initial stage before launching detailed dynamic field experiments. The aim of this study is to define the planform characteristics of 72 Catalan pocket beaches, natural and man-made, and to determine their sheltering effect, embaymentization and their status of equilibrium. Planform measurements were performed on SIGPAC, 1:5000 orthophoto sets and wave climate was provided by Puertos del Estado (Wana model). Planform parameters were applied and coastal planview indexes were determined.The study shows that the Catalan pocket beaches display a wide range of indentation, suggesting that no single structural, tectonic or morphological control dominates their planform. The man-made pocket beaches typically display indentations which are smaller than those shown by natural pocket beaches. Headland spacing and beach area are positively correlated. The more indented bays are, the shorter their beaches become. Low-indented pocket beaches are the widest and the longest ones.Deep indentation contributes towards beach protection and energy dissipation which counteracts rip efficiency and inhibits the formation of mega-rips. Pocket beaches often show gradual and moderate alongshore changes in texture and beach morphology. One third of the Catalan pocket beaches are “sediment starved”, i.e., 60% and more of their embayed shorelines are deprived of beach sediments. Examination of the status of equilibrium demonstrates that most of the Catalan pocket beaches are in an unstable mode, with indentation ratios that are unrelated to the wave obliquity. 相似文献
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简要介绍了Windows CE及嵌入式开发技术,对基于Pocket PC的多用途测图系统进行设计,并具体分析了其实现过程中地图显示、GPS数据接收、模块通信等各个环节及其实现方法,使用Embedded Visual C 开发出了适用于电力巡检、管线复查、野外草图测绘等多种业务的数字测图系统EmSurvey,实现了电子地图、项目管理、数字测图等基本功能,对系统实际应用中存在的问题进行了分析,并提出相应的解决方案。 相似文献
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